Mark C Siemens

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Scholarly Contributions

Chapters

• Fennimore, S. A., & Siemens, M. C. (2023). Mechanized Weed Management in Vegetable Crops. In Encyclopedia of Smart Agricultural Technologies. doi:10.1007/978-3-031-24861-0_244
• Fennimore, S. A., Siemens, M. C., & Zhang, Q. (2023). Mechanized weed management in vegetable crops. In Encyclopedia of Smart Agricultural Technologies. Cham, Switzerland: Springer, Cham. doi:doi.org/10.1007/978-3-030-89123-7_244-2
• Fennimore, S. A., & Siemens, M. C. (2022). Mechanized Weed Management in Vegetable Crops. In In Automation: The Future of Weed Control in Cropping Systems. doi:10.1007/978-3-030-89123-7_244-2
• Fennimore, S. A., Hanson, B. D., Sosnoskie, L. M., Samtani, J. B., Datta, A., Knezevic, S. Z., & Siemens, M. C. (2014). Field Applications of Automated Weed Control: Western Hemisphere. In Automation: The Future of Weed Control in Cropping Systems. Springer, Dordrecht. doi:10.1007/978-94-007-7512-1_9
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  Opportunities for automated weed control vary widely among cropping systems of the Western Hemisphere. High-value conventional and organic horticultural crops may provide the best initial opportunity for automated weed control because of dependency on labor for hand weeding and the lack of effective herbicides. Fresh market vegetable crops are planted year-round in small successive plantings which make them an attractive target for weed control automation equipment. The most likely immediate role for weed control automation in agronomic crops would be in the area of sprayer control so that weed-infested patches could be treated selectively and weed-free patches not treated. If automated weed control solutions are developed and made cost effective and time efficient, then broader adoption of automated weed control technology is possible.
• Fennimore, S. A., Hanson, B. D., Sosnoskie, L. M., Samtani, J. B., Datta, A., Knezevic, S. Z., & Siemens, M. C. (2013). Chapter 9: Field Applications of Automated Weed Control: Western Hemisphere. In Automation: The Future of Weed Control in Cropping Systems(pp 151-169). S.L. Young and F.J. Pierce, eds. Dordrecht: Springer Science+Business Media.

Journals/Publications

• Raja, R., Slaughter, D. C., Fennimore, S. A., & Siemens, M. C. (2023). Real-time control of high-resolution micro-jet sprayer integrated with machine vision for precision weed control. Biosystems Engineering, 228, 31-48. doi:10.1016/j.biosystemseng.2023.02.006
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  The advent of automated technology in agriculture employing robots allows researchers and engineers to automate many of the tasks in a semi-structured, natural farming environment where these tasks need to be performed. Here we propose a fast-intelligent weed control system using a crop signalling concept with machine vision and a precision micro-jet sprayer to target in-row weeds for precision herbicide application. Crop signalling is a novel technology invented to read crop plants by machine to simplify the task of differentiating vegetable crops from weeds for selective weed control in real-time. In-row weed control in vegetable crops like lettuce requires a very precise herbicide spray resolution with a fast response time. A novel, accurate, high-speed, centimetre precision spray targeting actuator system was designed and experimentally validated in synchronization with a machine vision system to spray detected weeds located between lettuce plants. The system processed an image, representing a 120 mm × 180 mm region of row-crop in 80 ms, which allowed the micro-jet sprayer to successfully function at a travel speed of 3.2 km h−1 and selectively deliver herbicide to the weed targets. The analysis of the overall performance of the system to kill weeds in indoor experimental trials is discussed and presented. Findings indicate that 98% weeds were correctly sprayed which indicates the efficacy and robustness of the proposed systems.
• Raja, R., Slaughter, D., Fennimore, S. A., & Siemens, M. C. (2023). Real-time control of high-resolution micro-jet sprayer integrated with machine vision for precision weed control. Biosystems Engineering, 228, 31-48.
• Guerra, N., Fennimore, S. A., Siemens, M. C., & Goodhue, R. E. (2022). Band Steaming for Weed and Disease Control in Leafy Greens and Carrots. Hortscience, 57(11), 1453-1459. doi:10.21273/hortsci16728-22
• Govindaraj, D. K., Zhu, L., Siemens, M. C., Nolte, K. D., Brassill, N. A., Rios, D., Galvez, R., Fonseca, J. M., & Ravishankar, S. (2018). Modified Coring Tool Designs Reduce Iceberg Lettuce Cross-Contamination. J. Food Protection, 82(3), 454-462.
• Kumar, G. D., Zhu, L., Siemens, M. C., Nolte, K. D., Brassill, N., Rios, D. V., Galvez, R., Fonseca, J. M., & Ravishankar, S. (2019). Modified Coring Tool Designs Reduce Iceberg Lettuce Cross-Contamination.. Journal of food protection, 82(3), 454-462. doi:10.4315/0362-028x.jfp-18-317
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  Contaminated coring tools may transfer bacteria to iceberg lettuce. The efficiency of coring tool design modifications in reducing bacterial transfer to lettuce heads was evaluated under simulated field operations. The standard coring tool consists of a stainless steel cylindrical tube welded to a tab that is inserted into a plastic handle. Design modifications included removal of the welded portion, incorporation of a shorter front straight bottom edge, or an angled bottom edge toward the front. In the first study, coring tools of four different designs were inoculated by dipping in a tryptic soy broth (TSB) suspension that contained 8.85 Log CFU/mL of Escherichia coli K-12 and then were used to core 100 lettuce heads, consecutively. Use of the standard tool resulted in 91% ± 9% positive lettuce heads. Removing the welded surface from the standard tool resulted in the highest reduction of E. coli transfer (44% ± 11.9% positive lettuce heads, P < 0.05), whereas incorporation of a short front straight edge with no welding resulted in 65.6% ± 5.6% of the cored lettuce heads being positive for E. coli. Removal of the welded surface resulted in a 40% decrease in E. coli contamination among the last 20 cored lettuce heads (81 to 100), which indicates that coring tool design modifications resulted in reduced cross-contamination. In the second study, the transfer of Salmonella to coring tools after their immersion in rinsing solutions was evaluated using imaging. The tools were dip inoculated for 2 min in water, water with lettuce extract, or TSB containing 7 Log CFU/mL bioluminescent Salmonella Newport; they were then imaged to observe spatial distribution of bacteria. There was greater retention and spatial distribution of Salmonella on the surface of tools immersed in water containing lettuce extract than in TSB and water. The results of the second study indicate that rinsing solutions that contain lettuce particulate and organic load could facilitate cross-contamination of Salmonella Newport to tool surfaces.
• Lefcourt, A. M., Siemens, M. C., & Rivadeneira, P. (2019). Optical parameters for using VIS reflectance or fluorescence imaging to detect bird excrements in produce fields. Applied Sciences.
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  Consumption of produce contaminated with pathogens of fecal origin is the most common source of food borne illnesses. Current practice is to visually survey fields for evidence of fecal contamination, and to exclude problematic areas from harvest. Bird excrement is known to contain human pathogens, and is often not detectable in produce fields using current survey methods. The goal of this project was to identify parameters for optical detection of bird excrements to support development of instruments to be used to supplement existing visual surveys. Under daylight ambient conditions, results suggested that reflectance imaging at around 500–530 nm or 610–640 nm could be used to detect excrements from the three bird species tested. Images were acquired using ad hoc camera parameters; however, normalizing intensities for individual images at 525 nm and using a fixed detection threshold allowed detection of 100% of bird excrements with no false positives against the background that consisted of local soil and fresh romaine and spinach leaves. Similar results were obtained using fluorescence imaging. Fluorescent imaging was accomplished in a darkened room using 405-nm illumination. The largest consistent differences in intensity responses between excrements and the brightest non-excrement object in the background matrix occurred at around 550 nm. Results suggested that using reflectance or fluorescence imaging for detection of bird excrements could be a valuable tool for reducing risks of consuming contaminated produce. One possibility would be to incorporate appropriate reflectance imaging capabilities in drones under the control of the individuals currently conducting field surveys.
• Lefcourt, A. M., Siemens, M. C., & Rivadeneira, P. (2019). Optical parameters for using VIS reflectance or fluorescence imaging to detect bird excrements in produce fields.. Applied Sciences, 9(4), Article 715.
• Raja, R., Slaughter, D. C., Fennimore, S. A., Nguyen, T. T., Vuong, V. L., Sinha, N., Tourte, L., Smith, R. F., & Siemens, M. C. (2019). Crop signaling: A novel crop recognition technique for robotic weed control.. Biosystems Eng., 187, 278-291.
• Everard, C. D., Kim, M. S., Siemens, M. C., Cho, H., Lefcourt, A. F., & O'Donnell, C. (2018). A multispectral imaging system using solar illumination to distinguish fecal matter on leafy greens and soils. Biosystems Eng., 171, 258-264.
• Everard, C. D., Kim, M. S., Siemens, M. C., Cho, H., Lefcourt, A. M., & O'Donnell, C. (2018). A multispectral imaging system using solar illumination to distinguish fecal matter on leafy greens and soils.. Biosystems Eng., 171, 258-264.
• Lefcourt, A. M., & Siemens, M. C. (2017). Interactions of insolation and shading on ability to use fluorescence imaging to detect fecal contaminated spinach. Appl. Sci., 7(1041). doi:10.3390/app7101041
• Fennimore, S. A., Slaughter, D. C., Siemens, M. C., Leon, R. G., & Saber, M. N. (2016). Technology for automation of weed control in specialty crops. Weed Tech., 30(4), 823-837.
• Joshi, K., Ravishankar, S., Nolte, K. D., & Siemens, M. C. (2016). Evaluating survival of Salmonella Newport on iceberg lettuce coring tools and the efficacy of plant antimicrobials and organic sanitizers. J. Food Production, 79, 96 (abstr). Des Moines, IA: IAFP..
• Kumar, G. D., Ravishankar, S., Zhu, L., Nolte, K. D., Siemens, M. C., & Fonseca, J. (2016). Modified coring tool designs reduce iceberg lettuce cross-contamination. J. Food Production, 79, 91 (abstr). Des Moines, IA: IAFP..
• Lati, R. N., Siemens, M. C., Rauchy, J. S., & Fennimore, S. A. (2016). Intra-row weed removal in broccoli and transplanted lettuce with an intelligent cultivators. Weed Tech., 30(3), 655-663.
• Siemens, M. C., & Gayler, R. R. (2016). Improving seed spacing uniformity of precision vegetable planters. Applied Eng. in Agric., 32(5), 579-587. doi:DOI 10.13031/aea.32.11721
• Siemens, M. C., Herbon, R., Gayler, R. R., Nolte, K. D., & Brooks, D. (2012). Automated machine for thinning lettuce - Development and evaluation. American Society of Agricultural and Biological Engineers Annual International Meeting 2012, 4, 3221-3234.
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  Abstract: Despite the tremendous advances made in agricultural mechanization, the precise task of thinning lettuce seedlings is still performed by crews of workers using hand hoes in commercial field production. Finding laborers to perform this physically demanding work is becoming increasingly difficult. The objectives of this project were to 1) develop an automated machine for thinning lettuce to improve labor resource use efficiency and 2) evaluate the performance of the machine as compared to conventional methods. The prototype machine was developed to thin lettuce seedlings nominally planted 2 inches apart to the desired final plant spacing of 10-11 inches. The device is principally comprised of a machine vision system for detecting lettuce seedlings and their location and a system for intermittently delivering an herbicidal spray to kill plants. When tested at a travel speed of 1.5 mph, automated machine thinning performance in terms of plant spacing, plant spacing uniformity, number of live plants per acre and time required for a hand laborer to remove plants missed during thinning was not significantly different from hand thinning when plants were thinned using sulfuric acid (10% v/v), paraquat (1.3 pt a.i./acre) or vinegar (20% v/v) (P = 0.05). Automated machine thinning performance after hand weeding was also not significantly from hand thinning in terms of plant spacing, COV in plant spacing and plant stand when plants were sprayed with any of the five chemicals tested. Based on these results, it was concluded that the automated machine was able to reliably control spray delivery such that plants were selectively thinned to the desired final plant spacing. Yields were not significantly affected when plants were thinned using the automated machine with any of the herbicidal spray solutions tested indicating that the machine was able to deliver herbicidal spray with sufficient accuracy that seedlings are not injured. Further machine development is needed so that a unit more suitable for commercial production can be tested on a large scale to confirm these results and to determine whether such a system is viable for use in commercial production.
• Nolte, K. D., Nolte, K. D., Siemens, M. C., Siemens, M. C., & Andrade-sanchez, P. (2011). Integrating Variable Rate Technologies for Soil-applied Herbicides in Arizona Vegetable Production. Arizona Cooperative Extension Publication AZ1538. Tucson, Ariz.: University of Arizona College of Agriculture and Life Sciences..
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  Variable rate technologies and the application of preemergence herbicides Since the mid 1990’s, advances in global positioning systems (GPS), microprocessors, actuators, controllers, plant/soil sensors and geographical information systems (GIS) have spawned the development of new, site-specific, variablerate techniques for chemical applications. At the same time, agricultural production has embraced other new technologies that increase the productivity of mechanized operations such as tractor auto-guidance systems. The combination of automatic tractor steering and variable rate technology is well suited for site-specific application of pre-emergence herbicides. With tractor guidance control and variable rate controllers, growers can increase the efficiency of chemical application by eliminating swath overlap, while increasing the efficacy of herbicide action by applying optimum rates based on soil texture. These technologies have primarily been adopted by growers of major crops such as corn, wheat and soybeans (Koch and Khosla, 2007). Recently however, Arizona vegetable producers have become increasingly interested in using these technologies for variable rate application of soil applied preemergence herbicides. In many fields where vegetables are grown in Arizona, there is large spatial variation of soil properties, including soil texture. In fact, Bauer and Schefcik (1994) found that recommended application rates of preemergence, soil applied herbicides can vary as much as 50% in a given field due to varying soil textures.
• Siemens, M. C., Nolte, K. D., & Gayler, R. R. (2011). Improving lettuce production through utilization of spike wheel liquid injection systems. American Society of Agricultural and Biological Engineers Annual International Meeting 2011, 2, 1447-1457.
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  Abstract: Spike wheel liquid injection systems were developed in the late 1980's as an improved method for applying fertilizer post emergence. Although studies have shown that use of the system provides measurable yield benefits in a variety of crops, limited studies have been conducted in lettuce production systems. This study addresses this shortcoming. The objectives of the project were to determine if spike wheel injection technology can be used in lettuce to 1) improve plant growth, nutrient uptake efficiency and crop yield and 2) determine if the system can be used to deliver soil applied pesticides post emergence. Replicated field trials were conducted in Yuma, Arizona in 2010 to achieve the stated objectives. Use of the spike wheel injector significantly improved mid-season lettuce plant weight and nitrogen uptake levels as compared to conventional knife blade fertilizer application systems. Despite these early advantages, crop yield was not significantly affected by fertilizer applicator method. The data also showed that the soil applied systemic insecticide Coragen can be effectively delivered post emergence using the point injection system. These data were very promising in that it implies that the system could also be used successfully to deliver other soil applied pesticide chemistries post emergence in lettuce crops. This would benefit the industry by greatly increasing the control options growers have for managing pests post emergence. Additional study is needed to confirm/validate the results of this one year study.
• Williams, J. D., Gollany, H. T., Siemens, M. C., Wuest, S. B., & Long, D. S. (2009). Comparison of runoff, soil erosion, and winter wheat yields from no-till and inversion tillage production systems in northeastern Oregon. Journal of Soil and Water Conservation, 64(1), 43-52.
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  Abstract: Conservation tillage systems that reduce soil erosion and maintain or increase soil carbon offer long-term benefits for producers in the inland Pacific Northwestern United States but could result in reduced grain yields due to increased pressure from weeds, disease, and insect pests. Our objective was to compare runoff, soil erosion, and crop yields from a conventional tillage, wheat-fallow two-year rotation and a no-till four-year rotation. The experiment was undertaken within a small watershed to provide results that would be representative of conservation effectiveness at the field scale. Two neighboring drainages, 5.8 and 10.7 ha (14 and 26 ac), in the 340 mm y-1 (13.4 in yr-1) precipitation zone of northeastern Oregon, were instrumented to record rainfall, runoff, and erosion over a four-year period (2001 through 2004). One drainage was cropped to a winter wheat-fallow rotation and received inversion tillage (tillage fallow). The second drainage was cropped in a four-year no-till rotation: winter wheat-chemical fallow-winter wheat-chickpea (no-till fallow). We recorded 13 runoff events from the inversion tillage system and 3 fiom the no-till system. Total runoff and erosion values from inversion tillage drainage were 5.1 mm (0.20 in) and 0.42 Mg ha-1 (0.19 tn ac-1) versus 0.7 mm (0.03 in) and 0.01 Mg ha-1 (
• Long, D. S., Engel, R. E., & Siemens, M. C. (2008). Measuring grain protein concentration with in-line near infrared reflectance spectroscopy. Agronomy Journal, 100(2), 247-252.
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  Abstract: The advent of near infrared (NIR) on-combine sensors gives growers the opportunity to measure the grain protein concentration of wheat (Triticum aestivum L.) during harvest. A study consisting of three sequential experiments (laboratory bench, combine test stand, and field) was conducted to evaluate the performance of an in-line, NIR reflectance spectrometer, referred to as the ProSpectra Grain Analyzer, possessing a factory calibration model. In the laboratory bench experiment, the instrument was mounted to a circulating impeller apparatus designed to simulate a moving stream of grain. The ProSpectra performed well on a validation set of 231 grain samples of soft white winter wheat and explained a high level of protein variability (R2 = 0.91, SEP = 3.1 g kg-1) with a slope near unity. In the second experiment, the sensor was installed on a combine test stand constructed from the cross and exit augers, and clean grain elevator of a combine, to create the grain flow conditions found on a combine. Predicted protein was highly correlated (R 2 = 0.93, SEP = 4.5 g kg-1) with reference protein of nine large (14-kg-1) wheat samples. During the third experiment, the instrument was placed on the exit auger of a Case IH 1470 combine for the harvest of a 17-ha winter wheat field. Prospectra protein predictions correlated well with reference protein measurements (R2 = 0.94, SEP = 3.1 g kg-1). This study demonstrated the feasibility of using in-line NIR reflectance spectroscopy to rapidly (0.5 Hz measurement rate) and accurately (SEP < 5.0 g kg-1) measure wheat protein in a moving grain stream. Copyright © 2008 by the American Society of Agronomy. All rights reserved.
• Siemens, M. C., & Hulick, D. E. (2008). A NEW GRAIN HARVESTING SYSTEM FOR SINGLE-PASS GRAIN HARVEST, BIOMASS COLLECTION, CROP RESIDUE SIZING, AND GRAIN SEGREGATION. Transactions of the ASABE, 51(5), 1519-1527. doi:10.13031/2013.25300
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  A cereal grain harvesting system is introduced that combines existing technologies in a unique way to improve cereal grain harvest performance, increase profitability, and efficiently collect biomass. The harvesting system is comprised of three machines: one to reap grain, harvest biomass, and size crop residue for no-till seeding; a second to thresh and winnow the grain; and a third to separate the grain by quality for added value. This study describes the new harvesting system and the development of one of the system's major components: the reaper/flail harvester. The reaper/flail harvester consists of a mobile power unit, a stripper header to harvest the crop, and a flail to chop the standing residue into small pieces. A prototype harvester was fabricated and tested to determine system design criteria and performance characteristics in terms of machine power requirements, quantity of biomass collected, and bulk density of the material harvested. Trials were conducted in seven wheat (Triticum aestivum L.) fields in Oregon during 2005 and 2006 that ranged in yield from 3.3 to 6.4 t ha-1. Harvester performance was evaluated at various travel speeds, straw chop heights, and with different types of wheat. Flail power requirements were highly linearly correlated with quantity and rate of biomass chopped (R2 = 0.91). The maximum reaping power requirement was 2.7 kW m-1, only slightly higher than the no-load power requirement of 1.9 kW m-1. Power requirements for reaping, conveying, and flailing ranged from a low of 5.0 to a high of 13.5 kW m-1 depending on travel speed, crop yield, biomass concentration, and chop height. Values were linearly correlated with the combined grain, chaff, and biomass feed rate (t h-1) with an R2 of 0.88. Total machine power requirements for a harvester with a 7.3 m header would be about 175 kW, including 75 kW for propulsion, losses, and reserve. Chaff yield in the grain/chaff (graff) mixture harvested exceeded 2 t ha-1 in six of the seven trials. With chaff valued at $23 t-1, collecting 2 t ha-1 of chaff would increase farm revenues by $46 ha-1. Realistic graff densities of awned wheat were less than 1/11 that of clean grain, and new, efficient material handling systems would need to be developed to have harvesting capacities comparable to that of a conventional combine-based system. Awnless wheat had graff densities that averaged about 1/5 that of clean grain. Equipment is commercially available to handle this volume of material and have harvesting field capacities comparable to that of a conventional combine-based system.
• Siemens, M. C., & Hulick, D. E. (2008). A new grain harvesting system for single-pass grain harvest, biomass collection, crop residue sizing, and grain segregation. Transactions of the ASABE, 51(5), 1519-1527.
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  Abstract: A cereal grain harvesting system is introduced that combines existing technologies in a unique way to improve cereal grain harvest performance, increase profitability, and efficiently collect biomass. The harvesting system is comprised of three machines: one to reap grain, harvest biomass, and size crop residue for no-till seeding; a second to thresh and winnow the grain; and a third to separate the grain by quality for added value. This study describes the new harvesting system and the development of one of the system's major components: the reaper/flail harvester. The reaper/flail harvester consists of a mobile power unit, a stripper header to harvest the crop, and a flail to chop the standing residue into small pieces. A prototype harvester was fabricated and tested to determine system design criteria and performance characteristics in terms of machine power requirements, quantity of biomass collected, and bulk density of the material harvested. Trials were conducted in seven wheat (Triticum aestivum L.) fields in Oregon during 2005 and 2006 that ranged in yield from 3.3 to 6.4 t ha -1. Harvester performance was evaluated at various travel speeds, straw chop heights, and with different types of wheat. Flail power requirements were highly linearly correlated with quantity and rate of biomass chopped (R 2 = 0.91). The maximum reaping power requirement was 2.7 kW m -1, only slightly higher than the no-load power requirement of 1.9 kW m -1. Power requirements for reaping, conveying, and flailing ranged from a low of 5.0 to a high of 13.5 kW m -1 depending on travel speed, crop yield, biomass concentration, and chop height. Values were linearly correlated with the combined grain, chaff, and biomass feed rate (t h -1) with an R 2 of 0.88. Total machine power requirements for a harvester with a 7.3 m header would be about 175 kW, including 75 kW for propulsion, losses, and reserve. Chaff yield in the grain/chaff (graff) mixture harvested exceeded 2 t ha -1 in six of the seven trials. With chaff valued at $23 t -1, collecting 2 t ha -1 of chaff would increase farm revenues by $46 ha -1. Realistic graff densities of awned wheat were less than 1/11 that of clean grain, and new, efficient material handling systems would need to be developed to have harvesting capacities comparable to that of a conventional combine-based system. Awnless wheat had graff densities that averaged about 1/5 that of clean grain. Equipment is commercially available to handle this volume of material and have harvesting field capacities comparable to that of a conventional combine-based system.
• Siemens, M. C., & Jones, D. F. (2008). Segregation of soft white wheat by density for improved quality. Transactions of the ASABE, 51(3), 1035-1047.
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  Abstract: Development of a cost-effective way to segregate soft white wheat (Triticum aestivum L.) by quality would add value to a product that is currently marketed as a low-value commodity. Segregating grain by kernel density for improved quality is a technique that holds promise, but further research is needed. To address this, a study was initiated to determine the relationship of kernel density and soft white wheat quality in terms of test weight, protein content, milling performance, and end-use characteristics. The study was conducted in northeastern Oregon using Stephens soft white winter wheat samples collected from fields representing three different cropping systems over two crop years. Non-separated samples, samples that had been passed over a gravity table once and separated into four density fractions, and samples that had been passed over a gravity table twice and segregated into seven density fractions were analyzed for kernel density and quality characteristics. Correlations between quality characteristics and kernel density ranged from poor to high (r 2 = 0.00 to 0.82) for non-segregated samples, but improved as the sample became more homogenous through segregation by density using a gravity table. For the samples that had been passed over a gravity table twice, wheat quality characteristics of test weight, protein content, milling score, mixograph absorption, and cookie diameter were highly correlated with kernel density (r 2 = 0.94 to 0.95). Break flour yield was also highly correlated with kernel density (r 2 = 0.89). When sets of data for samples that had been passed over the gravity table once and twice were analyzed collectively, correlations between quality characteristics and kernel density were similar, but slightly lower (r 2 = 0.88 to 0.94). Quality scores calculated from these data and used to evaluate overall grain, milling, end-use, and overall wheat quality were also highly correlated with kernel density (r 2 = 0.91 to 0.96). It was concluded that for homogeneous samples of one variety of soft white wheat, kernel density is an excellent indicator of wheat quality. Additional research is needed to determine if this result extends across multiple cultivars of wheat and additional crop years. Analysis of grain segregated into four density fractions showed that there were significant differences in wheat quality between the lowest density fraction, the highest density fraction, and the non-separated sample. These results further indicate that density segregation is effective for separating wheat by quality and were the impetus for the proposal of a new wheat classification system that uses overall wheat quality as the basis for determining grade. Such a system would provide a marketing advantage since wheat grade would better reflect grain value. © 2008 American Society of Agricultural and Biological Engineers.
• Siemens, M. C., & Hulick, D. E. (2007). Development of an alternative, reaper/flail based harvesting system for biomass collection and no-till seeding - 2^nd year. American Society of Agricultural and Biological Engineers - International Conference on Crop Harvesting and Processing 2007, 57-68.
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  Abstract: A harvesting system is introduced that combines existing technologies in a unique way to simplify harvesting equipment, lower production costs and improve grain quality consistency. The harvesting system is comprised of three machines - one to gather the crop and prepare the residue for no-till seeding, a second to thresh and clean the crop, and a third to separate the grain by density/quality. The crop-gathering machine consists of a power unit equipped with a stripper header to harvest the crop and a flail to chop the standing residue into small pieces. A prototype harvester was fabricated to determine system design criteria and performance characteristics in terms of machine power requirements and bulk density of the material harvested. Trials were conducted in seven wheat fields during 2005 and 2006 that ranged in yield from 3.3 to 6.4 t/ha. In this paper, only power requirements for 2005 are reported. Flail power requirements ranged from 3 to 11 kW/m depending on harvesting speed and concentration of biomass. Flail power requirements were linearly correlated with biomass feed rate (t/h) with an R2 of 0.87. Stripper header power requirements ranged from 2.0 kW/m to 2.7 kW/m, only slightly higher than the no-load power requirement of 1.9 kW/m. Total harvester power requirements for harvesting, conveying and flailing ranged from 5.7 kW/m to 13.5 kW/m depending on travel speed, wheat yield and quantity of straw chopped. Total machine power requirements for a harvester with a 7.3 m header would be about 175kW, including 75 kW for propulsion, losses and reserve. The chaff yield in the grain/chaff mixture (graff) harvested ranged from 2.0 to 2.5 t/ha for five of the seven trials. With chaff valued at $23/t, collecting 2 t/h of chaff would increase farm revenues by $46/ha. Realistic graff densities of owned wheat were less than about 1/12 that of clean grain and new, efficient material handling systems would need to be developed to have harvesting capacities comparable to that of a conventional combine based system. Awnless wheat had graff densities that averaged about 1/5 that of clean grain. Equipment is commercially available to handle this volume of material and have harvesting field capacities comparable to that of a conventional combine based system.
• Siemens, M. C., Darnell, T. J., & Hulick, D. E. (2007). Performance of two hoe-type air drills sowing green peas in a conservation tillage system. Applied Engineering in Agriculture, 23(1), 23-29.
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  Abstract: A one year experiment was conducted in eastern Oregon to evaluate the performance of two different types of hoe-type air drills in terms of seeding depth uniformity, emergence, early plant growth, and crop yield when sowing green peas (Pisum sativum L.) in a tilled, leveled field. The seeding systems studied included a banded-row, flex frame air drill with seeding depth controlled by frame elevation and a single-row air drill with individual seeding unit depth control. Experimental design was a randomized complete block design with four replications. At the time of seeding, the field had approximately 5.6 t/ha of winter wheat (Triticum aestivum L.) residue on the soil surface. Depth of seed placement and date of emergence were recorded for 998 plants, while crop yield was determined by hand harvesting a 9.2-m2 area. Despite the significant differences in drill configuration, few differences in performance were found. The banded-row, flex frame air drill without individual depth gauge wheels placed seeds as accurately as the single-row air drill equipped with individual seeding unit depth control. Standard deviation of the mean seeding depth, speed of emergence index, and the percentage of sown seeds that emerged were not significantly different between the two drills. Crop yield and crop yield components including plant population, pods per plant, peas per pod, and pea weight were also not significantly different. The results of this study suggest that in leveled field conditions, there is no benefit to drills equipped with individual seeding unit depth control in terms of seed depth uniformity, seedling emergence, stand establishment, or crop yield. © 2007 American Society of Agricultural and Biological Engineers.
• Siemens, M. C., Jepsen, B., & Hulick, D. E. (2007). Development of a Trigger-On Indicator for a Weed Sensing Spray Unit. Crop Management, 6(1), 1-3. doi:10.1094/cm-2007-0515-01-br
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  Intermittent spray systems that automatically spray only when weeds are present have been commercially available since 1992 and can significantly reduce herbicide usage by 50 to 90% as compared to broadcast applications (2). The Weedseeker (NTech Industries, Ukiah, Calif.) is one such system that utilizes optics to detect the presence of weeds. The system works by exploiting the fact that chlorophyll selectively absorbs red wavebands of light and reflects near-infrared light (1). Each sensor unit has its own built-in light source and a sensor that detects the light reflected back to the unit over a 12-inch-wide field of view. When the sensor detects an increase in the ratio of near-infrared to red light above the base threshold level, a solenoid valve is activated to spray the weed. Although the sensor unit reliably detects the presence of green plants (2), a major drawback with the current design is that it doesn't provide any feedback to the user when one of the spray units is actively spraying. This is problematic, particularly on wide-boom, multi-sensor-unit sprayers since each sensing unit is calibrated independently in the field prior to spraying from the reflectance of the ground surface beneath it whenever the calibration button is pushed. If one of the sensing units is calibrated when the sensor is over a weed, the unit will not detect weeds of similar size or smaller when spraying. Also, because the sensing unit is sensitive to background reflectance, if one of the sensors is calibrated when it is positioned over a spot of ground that is not characteristic of the rest of the field, the unit will "ghost fire" and spray when weeds are not present. Either scenario is undesirable, but likely to occur since recalibration is necessary several times during the day due to changes in ambient light and field conditions. To overcome this problem, a trigger-on indicating device was developed to help the operator determine that the sensor units are operating correctly. The Weedseeker unit has a small LED on the back of the unit that illuminates whenever the unit is spraying. The device developed utilizes a phototransistor to detect when the LED is illuminated and activate a super-bright LED that is visible from the tractor cab (Fig. 1). The circuit designed includes a resistor and a NPN transistor that function to prevent low levels of light from activating the super-bright LED (Fig. 2). All electronic components are encased in a waterproof BUD box and attached to a Weedseeker sensor via Velcro and zip ties (Figs. 1 and 3). An opaque, nontranslucent flexible rubber washer is used to seal the phototransistor from ambient light and dust (Fig. 1). Power is supplied by two 1.5-V, AA batteries. Fig. 1. Trigger-on indicator assembly for Weedseeker sensor unit.
• Siemens, M. C. (2006). EFFECT OF GUARD SPACING, GUARD ATTACHMENTS AND REEL TYPE ON CHICKPEA HARVESTING LOSSES. Applied Engineering in Agriculture, 22(5), 651-657. doi:10.13031/2013.21997
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  The economic viability of chickpea (Cicer arietinum L.) is limited in part due to excessive gathering losses during mechanical harvest. Eight different combine header configurations were investigated to determine if header technologies developed for other pulse crops were also effective at reducing harvesting losses in chickpea. Equipment evaluated were two types of knife guards, two guard attachments, and two types of reels. The experiment was laid out and analyzed as a randomized complete block design and then further analyzed as two, two-way factorial designs. Depending on header configuration, header losses accounted for 58% to 99% of total harvesting losses which ranged from 3% to 20% of total yield. Double density guards reduced header losses by 54% as compared to single density guards when used with an air reel. Reductions in header losses did not occur when double density guards were used with the batted pick-up reel. Averaged across both reel types, long finger guard attachments were found to reduce losses by 44% as compared to guards without the attachment. As compared to the batted pick-up reel, the air reel reduced header and total harvesting losses by more than 54% when used with double density knife guards and guard attachments. When the header was configured with double density guards, long finger guard attachments and the air reel, header losses were 3% of total yield, while total losses were 4% of total yield and significantly lower than for any other header configuration. As compared to the conventionally equipped header with a batted pick-up reel and single density guards, this header configuration reduced header and total losses by 86% and increased combine yield by 126 kg/ha. The results of this study indicated that chickpea header losses can be excessive and that combinations of header technologies can be used to significantly reduce chickpea harvesting losses to levels comparable with other pulse crops.
• Siemens, M. C. (2006). Effect of guard spacing, guard attachments and reel type on chickpea harvesting losses. Applied Engineering in Agriculture, 22(5), 651-657.
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  Abstract: The economic viability of chickpea (Cicer arietinum L.) is limited in part due to excessive gathering losses during mechanical harvest. Eight different combine header configurations were investigated to determine if header technologies developed for other pulse crops were also effective at reducing harvesting losses in chickpea. Equipment evaluated were two types of knife guards, two guard attachments, and two types of reels. The experiment was laid out and analyzed as a randomized complete block design and then further analyzed as two, two-way factorial designs. Depending on header configuration, header losses accounted for 58% to 99% of total harvesting losses which ranged from 3% to 20% of total yield. Double density guards reduced header losses by 54% as compared to single density guards when used with an air reel. Reductions in header losses did not occur when double density guards were used with the batted pick-up reel. Averaged across both reel types, long finger guard attachments were found to reduce losses by 44% as compared to guards without the attachment. As compared to the batted pick-up reel, the air reel reduced header and total harvesting losses by more than 54% when used with double density knife guards and guard attachments. When the header was configured with double density guards, long finger guard attachments and the air reel, header losses were 3% of total yield, while total losses were 4% of total yield and significantly lower than for any other header configuration. As compared to the conventionally equipped header with a batted pick-up reel and single density guards, this header configuration reduced header and total losses by 86% and increased combine yield by 126 kg/ha. The results of this study indicated that chickpea header losses can be excessive and that combinations of header technologies can be used to significantly reduce chickpea harvesting losses to levels comparable with other pulse crops.
• Siemens, M. C., & Wilkins, D. E. (2006). Effect of residue management methods on no-till drill performance. Applied Engineering in Agriculture, 22(1), 51-60.
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  Abstract: Excessive crop residue on the soil surface impedes drill performance and subsequent crop production in conservation tillage systems. To address this issue, 10 different residue management strategies were evaluated to determine their effect on no-till drill performance in terms of seedling establishment, early plant vigor, and crop yield. Field conditions were characterized by size, concentration, and distribution of residue. Residue management strategies included leaving tall standing stubble, using various chopping and spreading devices, and removing the residue by baling. Experiments were conducted in northeastern Oregon fields that had been previously seeded to winter wheat and produced 9.8 and 10.5 t/ha of residue in 2000 and 2001, respectively. Winter and spring wheat plots were seeded with a hoe-type no-till drill. For the residue management methods used in this study, stand establishment and seedling dry weight were reduced by 20% to 58% and 22% to 46%, respectively, when the full quantity of residue was left on the soil surface as compared to those where the residue concentration was reduced by baling. Seeding into high concentrations of residue left by non-uniform residue distribution systems also caused reductions in stand establishment and early plant growth. Long standing stubble and high concentrations of loose straw greater than 18 cm in length caused unacceptable drill plugging. Successful drill operation was achieved in crop residues exceeding 9.8 t/ha when stubble height was less than or equal to row spacing and the majority of cut straw was cut into pieces less than 18 cm long. Although consistent yield differences were not found, the results of this study showed that residue concentration and size have an important influence on no-till crop yield potential and drill operation.
• Wilkins, D. E., & Siemens, M. C. (2006). EFFECT OF RESIDUE MANAGEMENT METHODS ON NO-TILL DRILL PERFORMANCE. Applied Engineering in Agriculture, 22(1), 51-60. doi:10.13031/2013.20181
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  Excessive crop residue on the soil surface impedes drill performance and subsequent crop production in conservation tillage systems. To address this issue, 10 different residue management strategies were evaluated to determine their effect on no-till drill performance in terms of seedling establishment, early plant vigor, and crop yield. Field conditions were characterized by size, concentration, and distribution of residue. Residue management strategies included leaving tall standing stubble, using various chopping and spreading devices, and removing the residue by baling. Experiments were conducted in northeastern Oregon fields that had been previously seeded to winter wheat and produced 9.8 and 10.5 t/ha of residue in 2000 and 2001, respectively. Winter and spring wheat plots were seeded with a hoe-type no-till drill. For the residue management methods used in this study, stand establishment and seedling dry weight were reduced by 20% to 58% and 22% to 46%, respectively, when the full quantity of residue was left on the soil surface as compared to those where the residue concentration was reduced by baling. Seeding into high concentrations of residue left by non-uniform residue distribution systems also caused reductions in stand establishment and early plant growth. Long standing stubble and high concentrations of loose straw greater than 18 cm in length caused unacceptable drill plugging. Successful drill operation was achieved in crop residues exceeding 9.8 t/ha when stubble height was less than or equal to row spacing and the majority of cut straw was cut into pieces less than 18 cm long. Although consistent yield differences were not found, the results of this study showed that residue concentration and size have an important influence on no-till crop yield potential and drill operation.
• Siemens, M. C., & Long, D. A. (2005). Improving wheat quality consistency by density segregation. 2005 ASAE Annual International Meeting.
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  Abstract: The end-use quality of grain crops can vary significantly within a given field. Research was conducted in northeastern Oregon to determine the amount of wheat quality variability due to landscape position and if improvements in the consistency of wheat quality delivered at the farm gate could be made by segregating wheat by landscape position and/or kernel density. The study was conducted on soft white winter wheat collected from fields representing three different cropping systems including annual cropped no-till, chemical fallow no-till and conventionally tilled summer fallow. Samples were taken from four areas in each field representative of the hilltops, north facing slope, bottom and south facing slopes and replicated three times. A portion from each sample was combined to form an additional sample representative of the grain collected from the entire field. The combined sample was separated into four density fractions using a gravity table. Grain from each sample location, representing the entire field and the four density fractions were analyzed for wheat quality factors including federal grade and a grain quality score based on test weight and kernel protein content. Federal grade and grain quality score were found to vary significantly across the field in all cropping systems. Grain from various landscape positions differed significantly in federal grade and grain quality score as compared to the control sample. Kernel density was also effective at segregating grain by quality with high and low density fractions having significantly better and lower quality respectively than the control sample. Sorting grain by density was superior to sorting grain by landscape position not only in the magnitude of separation obtained, but also in reducing the amount of quality variation within a sample.
• Siemens, M. C., Wilkins, D. E., & Correa, R. F. (2004). Development and evaluation of a residue management wheel for hoe-type no-till drills. Transactions of the American Society of Agricultural Engineers, 47(2), 397-404.
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  Abstract: Adoption of conservation tillage in the Pacific Northwest lags that of the U.S. in part due to the lack of reliable seeding equipment for planting into the high residue densities encountered in this region. To overcome this problem, a drill attachment was developed to manage heavy residue next to the furrow opening tines of hoe-type no-till drills. The U.S. patented device consists of a fingered rubber wheel, a rubber inner ring, and a spring-loaded arm that pivots about vertical and horizontal axes. The performance of the device was evaluated in terms of stand establishment and yield in Oregon and Washington. Test site locations varied significantly in the amount and condition of crop residue and were planted to a variety of different crops. As compared to the standard no-till drill without the attachment, use of the residue management wheel was found to increase the stand establishment of small seeded crops such as canola and mustard by over 40% and large seeded crops such as wheat and barley by approximately 17%. Increases in stand establishment were attributed to fewer piles of residue covering the seed row. Use of the device also significantly increased crop yield by up to 12% in 8 of the 20 trials conducted (P ≤ 0.10). Although the residue management wheel costs $300 per unit to fabricate, using the device may be economically feasible if it results in significant improvements in both stand establishment and yield.
• Wilkins, D. E., Siemens, M. C., & Correa, R. F. (2004). DEVELOPMENT AND EVALUATION OF A RESIDUE MANAGEMENT WHEEL FOR HOE-TYPE NO-TILL DRILLS. Transactions of the ASABE, 47(2), 397-404. doi:10.13031/2013.16033
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  Adoption of conservation tillage in the Pacific Northwest lags that of the U.S. in part due to the lack of reliable seeding equipment for planting into the high residue densities encountered in this region. To overcome this problem, a drill attachment was developed to manage heavy residue next to the furrow opening tines of hoe-type no-till drills. The U.S. patented device consists of a fingered rubber wheel, a rubber inner ring, and a spring-loaded arm that pivots about vertical and horizontal axes. The performance of the device was evaluated in terms of stand establishment and yield in Oregon and Washington. Test site locations varied significantly in the amount and condition of crop residue and were planted to a variety of different crops. As compared to the standard no-till drill without the attachment, use of the residue management wheel was found to increase the stand establishment of small seeded crops such as canola and mustard by over 40% and large seeded crops such as wheat and barley by approximately 17%. Increases in stand establishment were attributed to fewer piles of residue covering the seed row. Use of the device also significantly increased crop yield by up to 12% in 8 of the 20 trials conducted (P < 0.10). Although the residue management wheel costs $300 per unit to fabricate, using the device may be economically feasible if it results in significant improvements in both stand establishment and yield.
• Wilkins, D. E., Siemens, M. C., & Albrecht, S. L. (2002). CHANGES IN SOIL PHYSICAL CHARACTERISTICS DURING TRANSITION FROM INTENSIVE TILLAGE TO DIRECT SEEDING. Transactions of the ASABE, 45(4), 877-880. doi:10.13031/2013.9933
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  Converting from intensive tillage to no–till systems often increases soil strength, but the long–term impact of no–till on soil strength is not fully understood. Soil strength (evaluated with a hand–held cone penetrometer) and soil water content were evaluated in the top 30 cm of a replicated wheat/fallow rotation in a Pacific Northwest silt loam (coarse–silty, mixed, mesic, typic Haploxeroll). Soil water content was significantly lower in the no–till plots than in intensive tillage plots, which required a correction to remove the impact of soil water on penetrometer resistance. A regression equation was developed to adjust cone index values for soil water content. Comparisons of cone penetration resistance, adjusted for soil water, were made among intensive tillage, first–year no–till, and 17–year no–till. First–year no–till soil was resistant to penetration, but after 17 years of no–till the soil strength was lower and approached tilled conditions. Cone index values just below the plow layer (18 cm) increased from 2 to 3 fold the first year of no–till, but after 17 years of no–till the cone index values were not statistically different between no–till and intensive tillage below the tillage layer. This research demonstrated that silt loam soil structure improved with time during transition from intensive tillage to no–till.
• Wilkins, D. E., Siemens, M. C., & Albrecht, S. L. (2002). Changes in soil physical charactersistics during transition from intensive tillage to direct seeding. Transactions of the American Society of Agricultural Engineers, 45(4), 877-880.
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  Abstract: Converting from intensive tillage to no-till systems often increases soil strength, but the long-term impact of no-till on soil strength is not fully understood. Soil strength (evaluated with a hand-held cone penetrometer) and soil water content were evaluated in the top 30 cm of a replicated wheat/fallow rotation in a Pacific Northwest silt loam (coarse-silty, mixed, mesic, typic Haploxeroll). Soil water content was significantly lower in the no-till plots than in intensive tillage plots, which required a correction to remove the impact of soil water on penetrometer resistance. A regression equation was developed to adjust cone index values for soil water content. Comparisons of cone penetration resistance, adjusted for soil water, were made among intensive tillage, first-year no-till, and 17-year no-till. First-year no-till soil was resistant to penetration, but after 17 years of no-till the soil strength was lower and approached tilled conditions. Cone index values just below the plow layer (18 cm) increased from 2 to 3 fold the first year of no-till, but after 17 years of no-till the cone index values were not statistically different between no-till and intensive tillage below the tillage layer. This research demonstrated that silt loam soil structure improved with time during transition from intensive tillage to no-till.
• Siemens, M. C., & Coates, W. E. (2000). Control system for the mobile truss of a cable-drawn farming system. Applied Engineering in Agriculture, 16(3), 211-216.
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  Abstract: A control system was developed for indexing and positioning the mobile truss of a cable-drawn farming system. The system was tested over a length of 170 m using a five tower, 175 m long, truss assembly. A statistical analysis of the test results showed that the probability of position error being controlled to within ±12 cm and ±24 cm were verified at the 99.7% and 99.99% confidence levels, respectively. Based on these results, it was concluded that the objective of developing an indexing and positioning system capable of providing ±24 cm accuracy was achieved.
• Siemens, M. C., Wilkins, D. E., & Wuest, S. B. (2000). Managing and distributing residue for conservation tillage in the Pacific Northwest. 2000 ASAE Annual Intenational Meeting, Technical Papers: Engineering Solutions for a New Century, 1, 1559-1572.
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  Abstract: In the agricultural regions of the Pacific Northwest, adoption of reduced tillage systems lags that of the United States as a whole. The limited adoption of this practice in the Pacific Northwest is due not only to economic and agronomic concerns, but also to the lack of trouble free, reliable seeding equipment for planting into the heavy residue encountered in this region. A project was initiated to develop a residue management strategy that would improve hoe-type no-till drill performance. Three types of combines, various seedbed preparation methods and different seeder attachments were investigated on a plot that yielded 85 bu/ac of winter wheat and had approximately 9,000 lbs/ac of residue. Acceptable no-till drill performance in terms of stand count, plant growth and yield potential was obtained when standing stubble was less than 8 in. tall and the residue was uniformly distributed. Uniformly distributing residue was the most important factor for maximizing direct seed drill performance in heavy residue. Drill attachments such as a coulter and a patent pending residue management wheel yielded mixed and improved results respectively. As expected, when nearly all residue was removed drill performance was excellent. Chopping the residue into fine, 1.25 in. long pieces provided stand counts and seedling yield potential parameters equivalent to those of removing the residue completely. It is not known whether cost of the energy required for this operation is economically viable, but does provide some hope for an improved residue management strategy over what is currently available.
• Siemens, M. C., & Coates, W. E. (1997). System analysis of four types of cable drawn farming systems. Paper - American Society of Agricultural Engineers, 1.
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  Abstract: Four cable drawn farming systems, including a single engine system, a double engine system, a perimeter system, and a double implement system were analyzed to determine which was best suited for Arizona in terms of performance, cost and reliability. The single implement system was found to be the simplest, least expensive system to construct and have a field capacity only 8% lower than the best performing double implement system. The parameters that affect single implement system performance were then optimized, yielding a system having a field capacity 5% lower than a tractor based system.

Proceedings Publications

• Kocher, M., Smith, J., Arnett, G., Werning, J., Siemens, M., & Hanna, H. (2024). Advances in Determining Singulating Seeder Performance: ASABE Standard S658. In 2024 ASABE AIM.
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  The advancements in precision planting technologies have been numerous over the last 30 years and the performance efficiencies gained in the accuracy of seed placement by this technology have been tremendous. These advancements have far exceeded the capability of some of the industry accepted test procedures developed over thirty years ago for describing performance of singulated planting equipment. A working group composed of individuals from industry and universities was formed over three years ago to create more modern laboratory test procedures to quantify, for comparison purposes, performance of singulated planting equipment. This working group has completed a successful ballot and the new standard (ASABE S658) for evaluating planter seed spacing performance has been published. This voluntary test standard is composed of three parts: S658-1, Singulating Seeding Equipment Test Methods Part 1: General Information S658-2, Singulating Seeding Equipment Test Methods Part 2: Monitoring System Performance S658-3, Singulating Seeding Equipment Test Methods Part 3: Seed Spacing Performance The X658 working group as part of the ASABE MS-49 Crop Production Systems, Machinery, and Logistics Committee believes there is a need to communicate and introduce the details of these test procedures to the ASABE community so that going forward these procedures can be used when comparing the performance of these systems and thus minimizing any ambiguity when communicating performance. This paper focuses on the testing of planter row unit performance (Parts 1 and 3) rather than testing of planter monitor systems (Part 2). In addition to the nuts and bolts of testing procedure and analysis in the Standard document, ASABE hosts Excel workbooks that can do all the calculations, plot graphs, and enter the results in the report formats.
• Siemens, M. C., Godinez, Jr., V., Bahr, N., & Fennimore, S. A. (2021). Development and evaluation of a novel band-steam applicator for controlling soilborne pathogens and weeds in lettuce. In 2021 ASABE Annual International Meeting.
• Siemens, M. C. (2020, March). Machine Vision Systems for Automated Weeding – Current Technologies and Future Directions. In 2020 Weed Science Society of America Annual Meeting.
• Raja, R., Slaughter, D. C., Fennimore, S. A., & Siemens, M. C. (2019, July). Precision weed control robot for vegetable fields with high crop and weed densities.. In 2019 ASABE Annual International Meeting.
• Joshi, K., Ravishankar, S., Nolte, K. D., & Siemens, M. C. (2016, August). Evaluating survival of Salmonella Newport on iceberg lettuce coring tools and the efficacy of plant antimicrobials and organic sanitizers. In Annual Meeting of the International Association for Food Protection, No. P1-42, J. of Food Production Supplement A, 79, 96 (abstr)..
• Siemens, M. C., & Gayler, R. R. (2016, July). Alternative systems for cultivating and side dressing specialty crops for improved nitrogen use efficiency.. In 2016 ASABE Annual International Meeting.
• Lati, R. N., Siemens, M. C., & Fennimore, S. A. (2015, February). Intelligent cultivators – New tool for improved integrated weed management in vegetable crops. In 55th Annual Meeting of the Weed Science Society of America, In Proc. 2015 Weed Sci. Soc. of America Ann. Meeting., Abstract no. 194..
• Siemens, M. C. (2015, July). Improving seed spacing uniformity of precision vegetable planters. In 2015 ASABE Annual International Meeting, ASABE paper No. 152190060, pp. 11. St. Joseph, Mich: ASABE..
• Siemens, M. C. (2014, Spring). Robotic weed control. In 66th Annual California Weed Science Society 66: 76-80.
• Siemens, M. C., Siemens, M. C., Nolte, K. D., & Nolte, K. D. (2014, Spring). Improving pest control options through split application of insecticides using spike wheel liquid injection technology.. In 2013 American Society for Horticultural Science Conference.
• Siemens, M. C., Herbon, R., Gayler, R. R., Nolte, K. D., & Brooks, D. (2012, Fall). Automated machine for thinning lettuce - Evaluation and development. In ASABE paper No. 12-1338169, pp. 14. St. Joseph, Mich: ASABE.
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  ASABE paper No. 12-1338169
• Siemens, M. C., Nolte, K. D., & Gayler, R. R. (2011, Fall). Improving lettuce production through utilization of spike wheel liquid injection systems. In ASABE paper No. 1111245, pp. 11. St. Joseph, Mich: ASABE..
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  ASABE paper No. 1111245
• Siemens, M. C., & Hulick, D. E. (2007). Development of an Alternative, Reaper/Flail Based Harvesting System for Biomass Collection and No-Till Seeding - 2nd Year. In International Conference on Crop Harvesting and Processing, 2007 (electronic only).
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  A harvesting system is introduced that combines existing technologies in a unique way to simplify harvesting equipment, lower production costs and improve grain quality consistency. The harvesting system is comprised of three machines - one to gather the crop and prepare the residue for no-till seeding, a second to thresh and clean the crop, and a third to separate the grain by density/quality. The crop-gathering machine consists of a power unit equipped with a stripper header to harvest the crop and a flail to chop the standing residue into small pieces. A prototype harvester was fabricated to determine system design criteria and performance characteristics in terms of machine power requirements and bulk density of the material harvested. Trials were conducted in seven wheat fields during 2005 and 2006 that ranged in yield from 3.3 to 6.4 t/ha. In this paper, only power requirements for 2005 are reported. Flail power requirements ranged from 3 to 11 kW/m depending on harvesting speed and concentration of biomass. Flail power requirements were linearly correlated with biomass feed rate (t/h) with an R2 of 0.87. Stripper header power requirements ranged from 2.0 kW/m to 2.7 kW/m, only slightly higher than the no-load power requirement of 1.9 kW/m. Total harvester power requirements for harvesting, conveying and flailing ranged from 5.7 kW/m to 13.5 kW/m depending on travel speed, wheat yield and quantity of straw chopped. Total machine power requirements for a harvester with a 7.3 m header would be about 175kW, including 75 kW for propulsion, losses and reserve. The chaff yield in the grain/chaff mixture (graff) harvested ranged from 2.0 to 2.5 t/ha for five of the seven trials. With chaff valued at $23/t, collecting 2 t/h of chaff would increase farm revenues by $46/ha. Realistic graff densities of awned wheat were less than about 1/12 that of clean grain and new, efficient material handling systems would need to be developed to have harvesting capacities comparable to that of a conventional combine based system. Awnless wheat had graff densities that averaged about 1/5 that of clean grain. Equipment is commercially available to handle this volume of material and have harvesting field capacities comparable to that of a conventional combine based system.
• Siemens, M. C., & Hulick, D. E. (2006). Development of an Alternative, Reaper/Flail Based Harvesting System for No-Till Farming. In 2006 Portland, Oregon, July 9-12, 2006.
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  A harvesting system is introduced that combines existing technologies in a unique way to simplify harvesting equipment, lower production costs and improve grain quality consistency. The harvesting system is comprised of three machines – one to gather the crop and prepare the residue for no-till seeding, a second to thresh and clean the crop and a third to separate the grain by density/quality. The crop-gathering machine consists of a power unit equipped with a stripper header to harvest the crop and a flail to chop the standing residue into small pieces. A prototype harvester was fabricated to determine the system design criteria and performance characteristics in terms of machine power requirements and bulk density of the material harvested. Trials were conducted in three wheat fields that ranged in yield from 3.3 to 5.4 t/ha. Flail power requirements ranged from 3 to 11 kW/m depending on harvesting speed and concentration of biomass. Flail power requirements were linearly correlated with biomass feed rate (t/h) with an R2 of 0.87. Stripper header power requirements ranged from 2.0 kW/m to 2.7 kW/m, only slightly higher than the no-load power requirement of 1.9 kW/m. Total harvester power requirements for harvesting, conveying and flailing ranged from 5.7 kW/m to 13.5 kW/m depending on travel spend, wheat yield and quantity of straw chopped. Total machine power requirements for a harvester with a 7.3 m header would be about 175kW, including 75 kW for propulsion, losses and reserve. The chaff yield in the grain/chaff mixture (graff) harvested ranged from 1.6 to 2.5 t/ha. With chaff valued at $23/t, collecting 2 t/h of chaff would increase farm revenues by $46/ha. Realistic graff densities of awned wheat were less 1/13 that of clean grain and efficient material handling systems would need to be developed. Awnless wheat had graff densities that were 1/4 that of clean grain and therefore could be handled with commercially available equipment.
• Siemens, M. C., & Long, D. A. (2005). Improving Wheat Quality Consistency by Density Segregation. In 2005 Tampa, FL July 17-20, 2005.
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  The end-use quality of grain crops can vary significantly within a given field. Research was conducted in Northeastern Oregon to determine the amount of wheat quality variability due to landscape position and if improvements in the consistency of wheat quality delivered at the farm gate could be made by wheat segregation. The study was conducted on soft white winter wheat collected from fields representing three different cropping systems including annual cropped no-till, chemical fallow no-till and conventionally tilled summer fallow. Samples were taken from four areas in each field representative of the hilltops, north facing slope, bottom and south facing slopes and replicated three times. A portion from each sample collected was then combined proportionally to form an additional sample representative of the grain collected from the entire field. This combined sample was then separated into four density fractions using a gravity table. Grain from each sample location, representing the entire field and the four density fractions were analyzed for wheat quality factors including test weight, kernel weight, kernel size, kernel hardness and protein content. A combine yield monitor and protein sensor were used to record yield and protein across the entire field. The results will be analyzed to determine the amount of field variability in wheat yield and quality and if segregating the grain by density is a feasible method of improving grain quality consistency.
• Wilkins, D. E., Siemens, M. C., & Correa, R. F. (2003). Development and Evaluation of a Residue Management Wheel for Hoe-Type No-Till Drills. In 2003, Las Vegas, NV July 27-30, 2003.
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  Adoption of conservation tillage in the Pacific Northwest lags that of the United States in part due to the lack of reliable seeding equipment for planting into the heavy residue encountered in this region. To overcome this problem, an attachment was developed to allow a hoe-type no-till drill to handle large amounts of residue and improve drill performance. The patented device (U.S. 6,345,671) consists of a fingered rubber wheel, a rubber inner ring, and a spring loaded arm which pivots about vertical and horizontal axis. The unit is designed to attach to the tool bar of hoe-type no-till drills and positioned so that the inner ring is next to the furrow opening shank. When seeding, the ground driven rubber fingered wheel and inner ring hold down and “walk” through crop residue, preventing it from building up on the shank and seed tube. The device was evaluated in 2000 and 2001in Oregon and Washington. Test site locations varied significantly in the amount and condition of crop residue and were planted to a variety of different crops. The results showed that as compared to the standard drill, the residue management wheel was found to increase seedling stand count of small seeded crops such as Canola and mustard by over 40 percent and large seeded crops such as wheat and barley by 16 percent. These differences were found to be statistically significant. Increases in stand generally resulted in increases in crop yield of 6-8 percent, but these differences were not always statistically significant.

Presentations

• Siemens, M. C. (2019, July 9). High speed centimeter scale resolutions sprayer for precision weed control.. ASABE Annual International Meeting. Boston, MA: ASABE.
• Siemens, M. C., & Kirchhoff, C. (2016, January). Robovator - Robotic Intra-Row Weeding. Automated Technologies Field Day. Yuma, AZ: Arizona Cooperative Extension.

Poster Presentations

• Siemens, M. C., Godinez, Jr., V., Bahr, N., & Fennimore, S. A. (2020, Fall). Design and Evaluation of a Band-Steam Applicator for Controlling Soilborne Pathogens and Weeds in Lettuce. 2020 Arizona Cooperative Extension Conference.
• Siemens, M. C., Godinez, Jr., V., Bahr, N., & Fennimore, S. A. (2020, July). Design and evaluation of a band-steam applicator for controlling soilborne pathogens and weeds in lettuce. ASABE Annual International MeetingASABE Paper No. 2001375. St. Joseph, Mich: ASABE..
• Kumar, G. D., Zhu, L., Nolte, K. D., Siemens, M. C., Fonseca, J., & Ravishankar, S. (2016, August). Modified coring tool designs reduce iceberg lettuce cross-contamination. Annual Meeting of the International Association for Food Protection. St. Louis, MI.
• Kamini, J., Kamini, J., Siemens, M. C., Siemens, M. C., Nolte, K. D., Nolte, K. D., Ravishankar, S., & Ravishankar, S. (2015, September). Understanding the attachment of Salmonella Newport on lettuce coring tools and efficacy of organic sanitizers against the pathogen. 2015 Food Safety Conference.
• Kamini, J., Siemens, M. C., Nolte, K. D., & Ravishankar, S. (2015, October). Evaluating survival of Salmonella Newport on iceberg lettuce coring tools and efficacy of plant antimicrobials and organic sanitizers. 2015 CALS Poster Forum.
• Kamini, J., Siemens, M. C., Nolte, K. D., & Ravishankar, S. (2015, October). Evaluating survival of Salmonella Newport on iceberg lettuce coring tools and efficacy of plant antimicrobials and organic sanitizers. Cactus- Institute of Food Technologists Regional Meeting.
• Siemens, M. C., Gayler, R. R., Nolte, K. D., & Wang, G. (2015, February). Innovative Cultural Practices for Improving Nutrient Use Efficiency. 2015 Southwest Ag Summit.

Creative Productions

• Tourte, L., & Siemens, M. C. (2018. Assessing Use of Automated (Mechanized) Technologies in Vegetable Crops.. Salinas Valley Agriculture - ANR Blogs. https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=28921

Others

• Siemens, M. C. (2020, April 15). High Speed Centimeter Scale Resolution Sprayers for Precision Weed Control in Vegetable Crops. AZ Veg IPM Update. 15 April. Vol. 11, Issue 8. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, April 29). Precision Cultivating Technologies for Improved Weed Control. AZ Veg IPM Update. 29 April. Vol. 11, Issue 9. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, August 5). Automated Lettuce Thinner Effects on Weed Control. AZ Veg IPM Update. 5 August. Vol. 11, Issue 16. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, December 9). Zapping Weeds with High Voltage Electricity. AZ Veg IPM Update. 9 December. Vol. 11, Issue 25. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, July 20). Automated Lettuce Thinner Effects on Weed Control. AZ Veg IPM Update. 20 July. Vol. 11, Issue 15. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, July 6). Robotic and Automated Technologies for In-Row Weeding in Vegetable Crops. AZ Veg IPM Update. 6 July. Vol. 11, Issue 14. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, Jun 10). Video: Band-Steam Applicator for Controlling Soilborne Pathogens and Weeds in Lettuce. AZ Veg IPM Update. 10 June Vol. 11, Issue 12. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, June 24). Band-Steam Applicator for Controlling Soilborne Pathogens and Weeds in Lettuce. AZ Veg IPM Update. 24 June Vol. 11, Issue 13. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, May 13). Videos on Precision Cultivation Technology and High Speed Centimeter Scale Resolution Sprayers. AZ Veg IPM Update. 13 May. Vol. 11, Issue 10. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, May 27). Point Injection – A Low Disturbance System for Delivering Soil Applied Pesticides. AZ Veg IPM Update. 27 May. Vol. 11, Issue 11. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, November 11). 2020 Advances in Automated Thinning and Weeding Technologies Update #3. AZ Veg IPM Update. 11 November. Vol. 11, Issue 23. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, November 25). 2020 Band-Steam for Weed and Disease Control in Lettuce – UC Davis Trial Results.. AZ Veg IPM Update. 25 November. Vol. 11, Issue 24. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, October 14). 2020 Advances in Automated Thinning and Weeding Technologies Update #1. AZ Veg IPM Update. 14 October. Vol. 11, Issue 21. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, October 28). 2020 Advances in Automated Thinning and Weeding Technologies Update #2. AZ Veg IPM Update. 28 October. Vol. 11, Issue 22. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, September 16). Point Injection – A System for Delivering Highly Immobile Pesticides Post Emergence. AZ Veg IPM Update. 16 September. Vol. 11, Issue 19. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C. (2020, September 30). Controlling Fusarium Wilt of Lettuce Using Steam Heat – Trial Initiated. AZ Veg IPM Update. 30 September. Vol. 11, Issue 20. Tucson, Ariz.: University of Arizona, Yuma Agricultural Center..
• Siemens, M. C., Soni, A., & Marjari, N. (2016, January). Web-Based Tool for Analyzing Planter and Automated Lettuce Thinning Machine Performance - v. 2. Web. http://testsite.seedandplantspacinganalyzer.webhost.uits.arizona.edu/sps-analyzer
• Siemens, M. C., & Soni, A. (2015, August). Web-Based Tool for Analyzing Planter and Automated Lettuce Thinning Machine Performance. Web. http://seedandplantspacinganalyzer.webhost.uits.arizona.edu/sps-analyzer
• Siemens, M. C., & Gayler, R. R. (2014, Spring). Seed metering system and apparatus for precision metering of seed. Invention Disclosure. University of Arizona Tech Launch Arizona. Docket Number UA 15-098. 7 pp..