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Full-Text Articles in Agronomy and Crop Sciences

Regulation Of Local Auxin Metabolism During Soybean Nodule Development, Suresh Damodaran Jan 2018

Regulation Of Local Auxin Metabolism During Soybean Nodule Development, Suresh Damodaran

Electronic Theses and Dissertations

Legume-rhizobia symbiosis leads to the development of secondary root organs called nodules. Rhizobia bacteria housed inside nodules assimilate atmospheric nitrogen and convert them into plant usable forms thereby reducing the need for fertilizer application in crop legumes like soybean. Nodule development is a coordinated process orchestrated by multiple plant hormones. In soybean, the auxin responsive gene expression was detected in nodule primordia and in the periphery of mature nodules, primarily in nodule vasculature. Auxin hypersensitivity reduces nodule formation in soybean and also polar auxin transport inhibition at the site of nodule development is not crucial for determinate nodule formation. Therefore, …


Quantifying The Short-Term Impacts Of Cover Crops And Grazing On Soil Health Under An Integrated Crop-Livestock System In South Dakota, Vishal Seth Jan 2018

Quantifying The Short-Term Impacts Of Cover Crops And Grazing On Soil Health Under An Integrated Crop-Livestock System In South Dakota, Vishal Seth

Electronic Theses and Dissertations

Cover crops and grazing under Integrated Crop-Livestock System (ICLS) can impact the rhizosphere nutrient cycling and may have potential to increase the long-term sustainability and economic profitability of agricultural production system. In South Dakota, crop production practices and livestock husbandry are both common which provide the opportunity for ICLS to be successful in this region. However, little is known about the impacts of the cover crops and grazing under ICLS on soil properties in this region. The present study was conducted at South Dakota State University Research Farm (44°20'34.8"N, 96°48'14.8"W), Brookings, SD, to quantify the impacts of cover crops and …


Palmer Amaranth In South Dakota: Growth, Herbicidal Control, And Soybean Yield Loss, Brian Van De Stroet Jan 2018

Palmer Amaranth In South Dakota: Growth, Herbicidal Control, And Soybean Yield Loss, Brian Van De Stroet

Electronic Theses and Dissertations

Palmer amaranth is a growing concern in the United States. Previously thought to only be able to occupy the southern United States, this plant can now be found throughout the northern states as well. Infestations of Palmer amaranth can now be found in South Dakota and is raising many concerns. Palmer amaranth is characterized by large growth and can be highly competitive with many important crops. Soybean is an important crop in South Dakota, as well as the rest of the world, and has not escaped the detrimental aspects of an infestation of Palmer amaranth. The objectives of this study …


Evaluating Mine Soil Prepared By Scraper Pans For Herbaceous Plants And Pine Seedlings At An East Texas Lignite Surface Mine, Hannah Z. Angel Aug 2017

Evaluating Mine Soil Prepared By Scraper Pans For Herbaceous Plants And Pine Seedlings At An East Texas Lignite Surface Mine, Hannah Z. Angel

Electronic Theses and Dissertations

Since 1974, Luminant Mining Company, LLC (Luminant) has planted over 38.7 million trees on its reclaimed lignite surface mine operations in Texas. For decades, the use of improved reclamation techniques on Luminant’s mined lands have resulted in over 31,160 ha reclaimed to forests, wildlife habitat, and pastures with productivity levels similar to those found on unmined lands. The development of new reclamation methodologies offers opportunities to further improve productivity of planted trees at Luminant’s Martin Lake Oak Hill Mine in east Texas. The conventional haulback or ‘truck shovel’ reclamation method uses haul trucks for the selective transport and placement of …


Pinching And Spacing Effects On Cut Sunflower (Helianthus Annuus) Production In East Texas, Rebecca B. Burnett Aug 2017

Pinching And Spacing Effects On Cut Sunflower (Helianthus Annuus) Production In East Texas, Rebecca B. Burnett

Electronic Theses and Dissertations

Three experiments evaluated pinching and spacing on Helianthus annuus in East Texas to determine their effects on growth and development. Experiment 1 was designed to determine the effects of pinching nodes 1, 2, 3, or 4 on ‘Pro Cut Gold’ sunflowers. Results from experiment 1 showed non-pinched plants produced marketable stem lengths and flower sizes, while pinched plants’ stem length, stem diameter, flower diameter, and disk diameter decreased compared to the non-pinched plants. The objective for experiment 2 was to evaluate pinching and spacing treatments on ‘Pro Cut Gold’ sunflowers. All spacings for non-pinched plants in experiment 2 produced marketable …


Terracing, Land Management And Agricultural Soils In The Andagua Valley Of The Southern Peruvian Andes, Blaise Murphy Jan 2017

Terracing, Land Management And Agricultural Soils In The Andagua Valley Of The Southern Peruvian Andes, Blaise Murphy

Electronic Theses and Dissertations

Demographic, socio-political and climatic changes can drastically alter agricultural land management practices, affecting the availability of agriculturally relevant nutrients in the soil. This project investigates the use, reconstruction and abandonment of agricultural terraces and the implications these conditions have on agricultural soil properties of the Andagua Valley in the Western Cordillera of the Southern Peruvian Andes. During the 2016 summer field season, topsoil samples were collected from cultivated and abandoned agricultural terraces between 3229m and 3688m a. s. l. with a range of aspects and ages. Collaboration with a team of archaeologists and anthropologists gave insight into the local and …


Phytophthora Sojae Infecting Soybean: Pathotype Diversity, New Sources Of Resistance And Interaction With The Soybean Cyst Nematode, Rawnaq Nazneen Chowdhury Jan 2017

Phytophthora Sojae Infecting Soybean: Pathotype Diversity, New Sources Of Resistance And Interaction With The Soybean Cyst Nematode, Rawnaq Nazneen Chowdhury

Electronic Theses and Dissertations

Phytophthora root and stem rot, caused by Phytophthora sojae Kaufmann and Gerdemann, is an important disease of soybean (Glycine max L.) in South Dakota. To gain a better understanding of the importance of P. sojae in South Dakota, specifically pathotype diversity, identification of new resistance sources and the interaction with the soybean cyst nematode (Heterodera glycines Ichinohe, SCN), this research was undertaken with the following objectives - 1) to characterize the pathotype diversity of P. sojae causing Phytophthora root and stem rot on soybean in commercial fields in South Dakota; 2) to compare inoculation methods to evaluate for …


Mitigating Risks Of Ochratoxin A Contamination In Oats, Bandana Dhungana Jan 2017

Mitigating Risks Of Ochratoxin A Contamination In Oats, Bandana Dhungana

Electronic Theses and Dissertations

Ochratoxin A (OTA) is a toxic metabolite produced by several species of fungal genera Penicillium and Aspergillus. The major OTA producer in temperate regions (i.e. U.S., Canada, Europe) is Penicillium verrucosum. Oat (Avena sativa), like any other cereal grain, can be contaminated with OTA when storage conditions are favorable for fungal growth. The presence of OTA exceeding the European Union maximum limit of 3 ppb in processed food has been reported in some samples of oat-based breakfast cereals from the US. The use of oat genotypes with limited OTA accumulation would be an effective way to …


Soil Response To Cropping Sequences And Grazing Under Integrated Crop-Livestock System, Hanxiao Feng Jan 2017

Soil Response To Cropping Sequences And Grazing Under Integrated Crop-Livestock System, Hanxiao Feng

Electronic Theses and Dissertations

Integrated crop-livestock system (ICLS) is helpful in diversifying a farm for improving its long-term sustainability and economic benefits. In the United States, the ICLS has been increasing in recent years because of its economic and environmental benefits. However, the impacts of ICLS on soil quality is not well documented in North Dakota. The objective of our study is to assess the impacts of cropping sequences and cattle grazing on the selected soil properties in the crop diversity and livestock integration practice. This study site was established in 2010 at the Dickinson Research Extension Center, Dickinson, North Dakota. The study design …


Molecular Characterization Of Spot Blotch And Bacterial Leaf Streak Resistance In Bread Wheat, Girma Ayana Jan 2017

Molecular Characterization Of Spot Blotch And Bacterial Leaf Streak Resistance In Bread Wheat, Girma Ayana

Electronic Theses and Dissertations

Spot blotch (SB), caused by Bipolaris sorokiniana (Sacc.) Shoem, and bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa (Smith et al.), two important foliar diseases of wheat in the major production regions of the US and the world. Deployment of adequate host resistance against them depends on determining the resistance genes or quantitative trait loci (QTLs) responsible for the trait and identification of genetic markers linked to QTL that facilitate markers assisted breeding. We conducted two independent studies and characterized QTLs for BLS and SB resistance. In the first study, we constructed a genetic linkage map of 1,211 …


Characterization Of Pyrenophora Tritici-Repentis In Wheat And Rye To Study Tan Spot Susceptibility And Insights Into Its Relationship With Stem Rust Resistance, Sidrat Abdullah Jan 2017

Characterization Of Pyrenophora Tritici-Repentis In Wheat And Rye To Study Tan Spot Susceptibility And Insights Into Its Relationship With Stem Rust Resistance, Sidrat Abdullah

Electronic Theses and Dissertations

Tan spot, caused by the ascomycete fungus, Pyrenophora tritici-repentis (Ptr), is a major foliar fungal disease of wheat worldwide. To date, Ptr isolates have been grouped into eight races based on the production of three host selective effectors (toxins), Ptr ToxA, ToxB, and ToxC, which are associated with necrosis and chlorosis symptoms on wheat differential lines. In order to see the correlation between stem rust resistance and tan spot susceptibility in 1970’s, to know the pathogen virulence profile, and explore the sources of tan spot resistance, we recovered isolates from wheat and rye and evaluated wheat and rye lines with …


Interactive Effects Of Cover Crops, Invertebrate Communities And Soil Health In Corn Production Systems, Claire Lacanne Jan 2017

Interactive Effects Of Cover Crops, Invertebrate Communities And Soil Health In Corn Production Systems, Claire Lacanne

Electronic Theses and Dissertations

The adoption of regenerative farming practices is gaining traction, but the costs and benefits are not often considered on a systems level. Encouraging biodiversity and soil health is the goal of many agricultural practices used in regenerative farming; regenerative systems employ practices which abide by the two main principles of increasing biodiversity and decreasing disturbance, with the goal of encouraging ecosystem functioning to minimize inputs and maximize the productivity of a farm. I examined the management of corn (Zea mays) fields across four states in the Upper Midwest region of the United States. Regenerative systems in this study …


Using Gluten Index To Improve Spring Wheat Loaf Volume Prediction, Yaming Lu Jan 2017

Using Gluten Index To Improve Spring Wheat Loaf Volume Prediction, Yaming Lu

Electronic Theses and Dissertations

Wheat (Triticum aestivum L.) is the most widely cultivated crop in the world and contributes about 20% of the total dietary calories and proteins globally. Unique properties of doughs formed from wheat flour make it feasible to produce a range of food, including bread. Loaf volume is the most perceptible indicator for breadmaking quality. Selection in the early generations for loaf volume is difficult due to the requirement of the large volume of grains and due to the costly, time-consuming, and labor-intensive evaluation process. Identification of simple and reliable predictive tests for loaf volume is highly desirable. This study …


Development Of Best Management Practices For Production Of Ethiopian Mustard (Brassica Carinata) In South Dakota, Phillip Kenneth Alberti Jan 2017

Development Of Best Management Practices For Production Of Ethiopian Mustard (Brassica Carinata) In South Dakota, Phillip Kenneth Alberti

Electronic Theses and Dissertations

Ethiopian mustard (Brassica carinata) is an alternative non-food oilseed crop which has received interest for its potential as a low-input option for production in the Northern Great Plains (NGP). As B. carinata is a new crop to the NGP, the best management practices have yet to be developed. The overall goal of this project was to develop best management practices for B. carinata production in two diverse agroenvironments in South Dakota. Two field experiments were conducted to assess the response of two B. carinata varieties to i) four seeding rates (4.5, 9, 13.5, and 18 kg ha-1 …


Effects Of Corn (Zea Mays L.) Stover Removal And Leaching On Soil Test And Whole Plant K Levels In Corn And K Fertilization/High-Input Treatments On Soybean Using Site-Specific Management To Increase Soybean (Glycine Max) Production In South Dakota, Nick J. Schiltz Jan 2016

Effects Of Corn (Zea Mays L.) Stover Removal And Leaching On Soil Test And Whole Plant K Levels In Corn And K Fertilization/High-Input Treatments On Soybean Using Site-Specific Management To Increase Soybean (Glycine Max) Production In South Dakota, Nick J. Schiltz

Electronic Theses and Dissertations

Potassium is important for crop production. Corn stover removal has the potential to reduce exchangeable and soluble soil potassium (K+) needed for optimal plant growth in addition to grain yield. An experiment was conducted in Aurora, SD, USA, to observe the effects of corn stover removal on water soluble and exchangeable soil test K+ (STK) levels and corn grain yields across a five-year period. Abundant K+ reserves were recorded between the initial and final sampling periods. While corn grain yields were affected by removing corn biomass, exchangeable and solution K+ levels were relatively unaffected by stover removal. Potassium fertilizer has …


Restoration Of Eroded Lands With Biochar As Soil Amendment In South Dakota, Saroop S. Sandhu Jan 2016

Restoration Of Eroded Lands With Biochar As Soil Amendment In South Dakota, Saroop S. Sandhu

Electronic Theses and Dissertations

Biochar is produced from incomplete pyrolysis of plant biomass. Due to the unique properties of biochar such as a higher number of micropores, surface area and carbon content, and recalcitrant nature of carbon, biochar is hypothesized to improve physical and hydrological properties of soil. This study assesses the impact of biochar on soil organic carbon, physical and hydrological properties of two landscape positions under a corn (Zea mays L.)-soybean (Glycine max L.) rotation. Three types of biochar including corn stover, ponderosa pine (Pinus ponderosa Lawson and C. Lawson) wood residue, and switchgrass (Panicum virgatum L.) were applied in the field …


Evaluation Of Tillage, Crop Rotation, And Cover Crop Impacts On Corn Nitrogen Requirements In Southeastern South Dakota, Sara Louise Berg Jan 2016

Evaluation Of Tillage, Crop Rotation, And Cover Crop Impacts On Corn Nitrogen Requirements In Southeastern South Dakota, Sara Louise Berg

Electronic Theses and Dissertations

Nitrogen (N) is a vital factor of corn (Zea mays) production. Previous work in South Dakota has shown that there is uncertainty as to whether nitrogen requirements are the same for corn raised under no-till (NT) versus conventional till (CT) production systems. The objective of this study was to evaluate whether N requirements continue to be greater under long-term NT versus CT production systems in southeastern South Dakota, while also considering effects from cover crops and crop rotation. This was a two year study conducted at the SDSU Southeast Research Farm near Beresford, SD; it was superimposed on a long-term …


Distribution And Characterization Of The Soybean Cyst Nematode, Heterodera Glycines (Hg) Types In South Dakota, Krishna Acharya Jan 2016

Distribution And Characterization Of The Soybean Cyst Nematode, Heterodera Glycines (Hg) Types In South Dakota, Krishna Acharya

Electronic Theses and Dissertations

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is an endoparasitic nematode and one of the major pests of soybean (Glycine max L.) in the United State and all over the world where soybean is grown. SCN is ranked first among the biological factors that cause yield loss in soybean. The estimated yield loss by this nematode is $1b annually in the United States alone. SCN is thought to have been first found in China. It was first identified in the United States in 1954 in North Carolina and in South Dakota in 1995. To date, SCN continues to spread …


Soil Salinity Study In Northern Great Plains Sodium Affected Soil, Tulsi P. Kharel Jan 2016

Soil Salinity Study In Northern Great Plains Sodium Affected Soil, Tulsi P. Kharel

Electronic Theses and Dissertations

Climate and land-use changes when combined with the marine sediments that underlay portions of the Northern Great Plains have increased the salinization and sodification risks. The objectives of this dissertation were to compare three chemical amendments (calcium chloride, sulfuric acid and gypsum) remediation strategies on water permeability and sodium (Na) transport in undisturbed soil columns and to develop a remote sensing technique to characterize salinization in South Dakota soils. Fortyeight undisturbed soil columns (30 cm x 15 cm) collected from White Lake, Redfield, and Pierpont were used to assess the chemical remediation strategies. In this study the experimental design was …


Volunteer Glyphosate-Resistant Corn And Soybean Competition And Control, Jill Alms Jan 2015

Volunteer Glyphosate-Resistant Corn And Soybean Competition And Control, Jill Alms

Electronic Theses and Dissertations

The continuous use of glyphosate-resistant crops has resulted in volunteer crops with the same herbicide resistance as the cash crop and an increasing weed problem. Volunteer corn reduces soybean yields however; little research has examined corn yield loss due to volunteer corn or volunteer soybean competition. These studies investigated yield loss and control of volunteer soybean in corn, and volunteer corn in soybean and corn. Using several densities of competitive plants, the yield loss was fit to a hyperbolic equation that indicated incremental yield loss (I value) to be 29.9 for volunteer corn in soybeans, 5.6 for volunteer corn in …


Impacts Of Spring-Interseeded Cover Crops On Late-Emerging Weed Suppression And Ground Cover In Corn (Zea Mays L.) Production Systems, Alex D. Bich Jan 2013

Impacts Of Spring-Interseeded Cover Crops On Late-Emerging Weed Suppression And Ground Cover In Corn (Zea Mays L.) Production Systems, Alex D. Bich

Electronic Theses and Dissertations

Any alternative crop management strategy will only be adopted by growers if yield is not negatively impacted, fits within a current management practice, is easily implementable with minimal cost, or provides other beneficial features such as weed control or suppression. Corn production that incorporates a cover crop as an alternative weed control strategy and ground cover may support a sustainable system that is less dependent on herbicidal weed control. In addition, the cover crop may be used as a fall forage, act as a slow release fertilizer source the following year, and provide ground cover to reduce soil erosion. In …


Tillage Erosion Coefficients For Selected Tillage Tools, Javier Mollinendo Jan 2008

Tillage Erosion Coefficients For Selected Tillage Tools, Javier Mollinendo

Electronic Theses and Dissertations

Soil loss as a result of differential translocation of soil by tillage is widespread in regions with irregular topography. Tillage erosion models are based on field derived transport coefficients that are specific to the tillage tool being used. Variables like speed and depth of tillage can modify tillage erosion transport coefficients. Four treatments were established for this research: moldboard plow, chisel plow, tandem disk, and no-till drill. The primary research site was located in Rock County MN, 43° 39 '40.24 "N, and 96° 24' 17.25" W, with a fine-loamy, mixed, superactive, mesic Cumulic Endoaquolls (USDA, 2006). The objectives of this …


Breaking Seed Dormancy In Three Poaceae Species, Heidi Jo Larson Jan 2002

Breaking Seed Dormancy In Three Poaceae Species, Heidi Jo Larson

Electronic Theses and Dissertations

Seed dormancy is a major impediment to germination testing in seed testing laboratories. Dormant seeds are alive but do not germinate under conditions favorable for germination of non-dormant seeds of the same species. Dormancy in many p􀊆ant species can be broken using a single ·treatment or a combination of treatments. Treatments commonly used are light or dark, various temperature regimes, prolonged exposure to cold treatments (pre-chilling), and the use of growth hormones or other chemicals. Three Poaceae species, winter wheat (Triticum aestiivum), prairie drop seed V (Sporobolus heterolepis), and prairie cordgrass (Spartina pectinata), were the subject …


The Relationship Between Reciprocal Spring By Winter Wheat Crosses And The Contribution Of Their Parents To Hybrid Performance, George Warren Partelow Jan 1986

The Relationship Between Reciprocal Spring By Winter Wheat Crosses And The Contribution Of Their Parents To Hybrid Performance, George Warren Partelow

Electronic Theses and Dissertations

Five diverse spring and five diverse winter wheat cultivars were crossed in all possible spring by winter combinations including their reciprocals to determine whether agronomic differences in reciprocal spring by winter crosses occur, and to determine the relative contribution of spring and winter parents to general and specific combining ability. Traits examined in the F1 generation in this greenhouse study included: 1) grain yield (g/plant) 2) number of spikelets per spike 3) total kernel weight (g) per spike 4) number of kernels per spike 5) number of tillers per plant 6) weight (g) of 100 kernels 7) length (mm) of …


Technology And Economics Of Commercial Scale Ethanol Production From Fodder Beets, William Ray Gibbons Jan 1986

Technology And Economics Of Commercial Scale Ethanol Production From Fodder Beets, William Ray Gibbons

Electronic Theses and Dissertations

Fodder beets yield two to three times more fuel ethanol per hectare than corn. This increased productivity should reduce feedstock costs and, consequently, ethanol production costs. The major factor that has limited use of this crop is the lack of a proven technology to process fodder beets -- economically and energy efficiently -- to fuel ethanol on a commercial scale. Research reported herein rectifies this situation by examining the technical and economic feasibility of community scale fuel ethanol production from fodder beets using two novel, continuous fermentation systems solid-phase fermentation and diffusion fermentation. Laboratory scale, batch fermentation trials were first …


Genetics Of Flower Abortion And Pod Type In Soybean, Krishna P. Sharma Jan 1986

Genetics Of Flower Abortion And Pod Type In Soybean, Krishna P. Sharma

Electronic Theses and Dissertations

Field studies were conducted in 1982, 1983 and 1984 in ten soybean (Glycine max (L.) Merrill) genotypes of maturity group 00 to III, to evaluate the effects of genotype and year on flower abortion (FA), flowers/raceme (FPR), raceme length (RL), pod types (PT), seeds/raceme (SPR), seed weight (SW), and yield/raceme (YPR). Reproductive efficiency index (REI) was calculated for parental genotypes and their segregating populations. The effects of main stem node position and raceme flower position on FA and PT were also studied. Genetic studies were on F2's of 13 crosses plus F3 and F4 generations of …


The Effect Of Soil Storage Methods And Soil Microbes On Carbofuran And Terbufos Degradation, Muriel Monteleone Runholt Jan 1986

The Effect Of Soil Storage Methods And Soil Microbes On Carbofuran And Terbufos Degradation, Muriel Monteleone Runholt

Electronic Theses and Dissertations

The purpose of this research was to determine optimal soil storage methods for soils used in carbofuran and terbufos degradation studies. The effect of soil microbes on degradation was also observed. An LD50 study, using 22 day old crickets (Acheta domestica), was undertaken to establish the appropriate LC dose for carbofuran in the soil storage studies. A carbofuran use history failure soil and a noninsecticide use history soil of the same type were collected from the SDSU experimental farm in Centerville, South Dakota. After initial degradation and microbial analysis, the soils were stored air-dried and with a moisture level …


Growth And Development Of Oat (Avena Sativa L.) Cultivars In Response To Water Stress, Abdel-Fattah H. Belal Jan 1986

Growth And Development Of Oat (Avena Sativa L.) Cultivars In Response To Water Stress, Abdel-Fattah H. Belal

Electronic Theses and Dissertations

Water stress occurs frequently in the North Central Plains and causes significant reductions in plant growth, development and grain yield. These effects of water stress apparently are dependent on the ability of plants to adapt to less than optimal environments. Plant water potential is dynamic, changing not only with the soil water content and atmospheric conditions, but also with the stage of growth. When plant water potentials become limiting, various physiological processes associated with plant growth, development and final yield are affected. The reduction in productivity in semi- arid environments is directly related to the inability of crop plants to …


Predicted Response To S1 Selection For Agronomic And Disease Resistance Traits In Two Sunflower Populations, Syed Sadaqat Mehdi Jan 1986

Predicted Response To S1 Selection For Agronomic And Disease Resistance Traits In Two Sunflower Populations, Syed Sadaqat Mehdi

Electronic Theses and Dissertations

Variances, heritabilities, genetic and phenotypic correlations, and predicted gains were computed for quantitative disease resistance and agronomic traits from pooled S1 family data of Gene Pool II and ND 761 Helianthus annuus L. populations. Broad-sense heritability estimates for all traits were significant in both populations. Observed genotypic correlation coefficients were larger than their corresponding estimates of phenotypic correlation coefficients. Significant positive genetic correlations between resistance to Alternaria blight and Septoria leaf spot; and non-significant genetic correlations between Sclerotinia wilt disease reaction and agronomic traits were observed in both populations. Resistance to Phoma black stem was not significantly correlated with resistance …


Atrazine And Cyanazine Interception And Retention On Crop Residue, Mark A. Wrucke Jan 1986

Atrazine And Cyanazine Interception And Retention On Crop Residue, Mark A. Wrucke

Electronic Theses and Dissertations

The effect of several variables on herbicide interception and retention by crop residue was investigated. Variables considered include residue type and amount, amount of rain, time of rainfall occurrence, and herbicide formulation. Experiments were conducted in the greenhouse using corn (Zea mays), soybean (glycine max), and wheat (Triticum aestivum) residue. Simulated rainfall was applied using a modified potsprayer. Herbicide concentration in washoff water was determined using the pyridine-alkali colorimeteric technique for chloro-s-triazine herbicides. As the percent ground cover increased, the amount of herbicide reaching the soil surface at application decreased. With normal residue levels attained in South Dakota, 60% or …