Project : USDA ARS

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Research Project: Ecologically-Sound Pest, Water and Soil Management Practices for Northern Great Plains Cropping Systems

Location: Agricultural Systems Research

2020 Annual Report

Objectives
Objective 1: Develop and provide guidance for the use of sustainable crop production strategies for irrigated crop production systems. Subobjective 1.1. Develop diverse sprinkler irrigated cropping systems that include annual legume crops to improve farm economic and environmental sustainability by enhancing system productivity and input use efficiency. Subobjective 1.2. Evaluate the effect of tillage practices on sprinkler irrigated cropping system productivity; input use efficiency; and soil, air, and water quality. Objective 2: Develop no-till sustainable crop production strategies for long-term dryland production systems with diverse crop rotations that include cereals, pulse crops, oilseeds and other bioenergy crops. Subobjective 2.1. Develop no-till diversified dryland crop rotations that include cereal, pulse and oilseed crops, and that increase crop water use efficiency, N-use efficiency, and soil quality while maintaining yield and quality of the individual crops. Subobjective 2.2. Determine the sequence of cereal, pulse, and oilseed crops in no-till dryland rotations that optimizes yield, crop water use efficiency, and N-use efficiency. Subobjective 2.3. Develop dryland crop rotations that reduce periods of fallow in annually cropped systems and increase crop water use efficiency, N-use efficiency, and soil quality.

Approach
Agriculture is facing major challenges in providing food, fiber, and fuel to a growing population with limited land and water resources. With rising incomes, longer life spans, changes in dietary preferences, and demands for improved nutrition, pressures are mounting for producers to improve production efficiencies and ecosystem services. In the northern Great Plains, traditional dryland cropping systems that include conventional tillage with crop-fallow are uneconomical and unsustainable. Also, with the availability of unallocated irrigation water in the Missouri and Yellowstone rivers, areas under irrigated cropping systems are poised to increase in the MonDak region (eastern MT, western ND), resulting in new markets and potential for increased crop diversity. To address these critical issues, best practices for conservation tillage and diversified dryland and irrigated cropping systems must be developed. Our proposed research addresses these needs by utilizing cropping system trials to develop scientifically-sound, diversified dryland and irrigated cropping strategies that: (1) improve management of water, soil, and nutrients, through increased efficiency, (2) diversify crop rotations to include cereals, pulse, oilseed, forage, and bioethanol crops, and (3) increase net farm productivity. Successful completion of this project will provide stakeholders and customers with tools to reduce labor, water, input, and energy requirements while increasing crop yield and quality and improving soil and environmental quality. These tools will be transferred to stakeholders through research paper publications, field tours, focus group meetings, agricultural fairs, bulletins, websites, and other outreach activities.

Progress Report
Sub-objective 1.1 Develop diverse sprinkler irrigated cropping systems that include legume crops to improve farm economic and environmental sustainability by enhancing system productivity and input use efficiency. The seventh growing season of the 8-year Nesson Valley irrigated cropping systems study was completed in fiscal year 2020 and the eighth and final growing season was initiated. Growing conditions were favorable in 2019 allowing for the collection of representative data quantifying rotation and tillage effects on crop quality, biomass and yield components. Results to date show a benefit to rotation diversity for soybean, sugarbeet, and corn while barley performed better in a 2-year rotation with sugarbeet than in a 4-year rotation following soybean. The soil microbiologist critical vacancy has now been filled and data analysis and summarization for microbial community structure based on phospholipid-fatty acid determinations and total carbon to quantify soil organic matter dynamics has begun. Soil samples were collected at planting and following harvest according to the established protocol. Greenhouse gas sample collection to quantify carbon dioxide, nitrous oxide and methane emissions was discontinued due to the impacts of the COVID-19 pandemic and maximized telework but four years of quality data were collected from 2016 to 2019. The seventh year of determining nitrate content in water that had percolated below the root zone was compromised due to unusually high fall precipitation but data analysis and summarization to determine crop water productivity and nitrogen use efficiency is being conducted for prior years. A secondary objective of the study at Nesson Valley to quantify the effects of rotation and tillage on Rhizoctonia root and crown rot in sugar beet was terminated following the 2019 growing season. Data analyses and summarization are underway. Sub-objective 1.2. Evaluate the effect of tillage practices on sprinkler irrigated cropping system productivity, input use efficiency and soil, air and water quality. We completed the second growing season and data collection year of the 6-year Eastern Agricultural Research Center (EARC) tillage study where sugarbeet is grown with conventional tillage various modifications of strip tillage and no tillage. The third growing season was initiated in the spring of 2020. The seventh growing season of the 8-year Nesson Valley irrigated cropping systems study was completed in fiscal year 2020 and the eighth and final growing season was initiated with tillage treatments continuing according to protocol. Growing conditions were favorable at both locations allowing for the collection of representative data quantifying tillage effects on crop quality, biomass and yield components. Yield data from seven years consistently show that sugarbeet and corn yield about 10% less with no tillage than with full tillage while barley and soybean yields are less impacted by tillage. Initial results from the EARC study show that strip-tillage sugarbeet compared well to conventional practices, though yield of sugarbeet grown without preplant tillage (no-till) lagged somewhat compared to the other two tillage systems. The second year of physical soil quality measurements, including soil penetration resistance, moisture content, and bulk density, was completed and the third year’s data are currently being collected. Soil properties related to water movement and nitrogen leaching were not measured at this location due to deficiency in personnel. The soil microbiologist critical vacancy has now been filled and data analysis and summarization for microbial community structure based on phospholipid-fatty acid determinations and total carbon analyses to quantify soil organic matter dynamics have begun. Soil samples were collected from both sites at planting and following harvest according to the established protocols. Greenhouse gas samples were collected for the third consecutive year from the EARC project to quantify carbon dioxide, nitrous oxide and methane emissions. Secondary objectives of the EARC study are to (1) evaluate wheat planted in 12-inch rows instead of the more conventional 7.5-inch rows and (2) identify the most effective irrigation management practice for dry peas which are a typically grown as a dryland crop. Sub-objective 2.1. Develop no-till diversified dryland crop rotations that include cereal, pulse and oilseed crops that increase crop water use efficiency, nitrogen-use efficiency, and soil quality while maintaining yield and quality of the individual crops. The sixth year of a large 8-year dryland cropping systems study near Sidney, Montana was completed in the fall of 2019. The seventh year was initiated in the spring of 2020. This study is designed to compare no-till cropping systems consisting of various cereal grains, pulses and oil seeds with varying levels of diversity (i.e., continuous cropping, 2- and 4-year rotations). Growing conditions were moderately favorable in 2019 allowing for the collection of representative data quantifying rotation diversity effects on crop quality, biomass and yield component. All planting, soil sampling, fertilizer application, and harvest activities were completed in a timely manner. Soil samples were collected prior to planting and immediately following harvest so that soil water dynamics can be quantified and applied to the calculation of crop water use efficiency. Soil samples were also collected to determine microbial community structure, available soil nitrogen, total soil carbon and total soil nitrogen. Measurements of greenhouse gas emissions were not completed in order to dedicate limited resources to irrigated cropping systems studies. Greenhouse gas sampling in a subordinate study at the same site showed that rotation did not significantly affect emissions of carbon dioxide, nitrous oxide or methane gases. Sub-objective 2.2. Determine the sequence of cereal, pulse and oilseed crops in no-till dryland rotations that optimizes yield, crop water use efficiency, and nitrogen-use efficiency. The sixth year of a large 6-year dryland cropping systems study was completed at the Froid dryland research farm. An additional (seventh) year was initiated in the spring of 2020. This study is designed to compare various cropping sequences in cropping systems of durum, dry pea and oil seed crops. Severe hail during the 2018 growing season and severe drought in 2017 and 2019 caused three consecutive years of crop failure, drastically limiting soil and plant sampling. Weather conditions in the spring of 2020 were also unusually dry causing the failure of oilseed and cover crops. Meaningful evaluations of agronomic performance, crop water use efficiency and nitrogen use efficiency were not possible due to the unfavorable weather conditions, leading to the decision to extend the study beyond the original 6-year period. Sub-objective 2.3. Develop dryland crop rotations that reduce periods of fallow in annually cropped systems and increase crop water use efficiency, nitrogen-use efficiency, and soil quality. This study at the Froid dryland research farm will be initiated upon the completion of the current Froid dryland cropping systems study (see Sub-objective 2.2).

Accomplishments
1. High-quality forage can be produced from cover crops in place of summer fallow. Summer fallow degrades soil quality and is a non-sustainable cropping practice. Planting cover crops in place of fallow helps improve soil quality, but can also provide a source of high quality forage. ARS researchers in Sidney, Montana, planted a 10-species crop mix (buckwheat, cowpea, flax, lentil, millet, mustard, pea, radish, sorghum, turnip) in place of fallow in 2-year durum rotations from 2014 to 2019. Forage harvest in early summer averaged 3.4 Mg ha-1 with a relative feed value of 154 and an overall forage quality rating of prime. Averages for crude protein, acid detergent fiber, neutral detergent fiber, and digestible dry matter were 19, 30, 44, and 66%, respectively. Nitrate averaged 1664 Mg kg-1 resulting in a toxicity risk rating of moderate. Subsequent to forage harvest, regrowth of cover crops terminated by killing frost averaged 6.4 Mg ha-1 of unharvested standing cover. Given the growing interest among producers in incorporating a diverse cover crop mix into their dryland cropping system to improve soil biological function, these research results provide information about how a cover crop might also provide an immediate economic return when utilized as a forage.

2. An effective method for irrigation scheduling. Accurate irrigation scheduling methods are needed to improve crop production, increase water use efficiency, and reduce adverse impacts of crop production on water quality through movement of nutrients by surface runoff or deep percolation to water resources. ARS researchers in Sidney, Montana, evaluated an irrigation scheduling method based on output from wireless soil moisture sensors coupled with information obtained from site-specific soil water retention curves. Soil moisture sensors were installed within rows of sugarbeet in two soils of substantially different texture to continually monitor moisture content in the 2-foot soil profile. Information from soil moisture sensors was then correlated to soil water storage capacity for each soil type. This site-specific context was found by determining specific soil moisture levels corresponding to field capacity (the soil maximum water storage potential) and permanent wilting point (soil water content below which plants are unable to survive). These parameters were determined based on soil water retention curves for sandy loam and clay loam soils generated using automated laboratory equipment. Findings demonstrated that the field capacity level of soil moisture content, available water capacity and soil water retention curve data are useful information for irrigation scheduling and water management when correlated to soil moisture sensor output. This research provides growers with an effective strategy and new information to determine the amount and timing of irrigation applications in order to maintain profitable crop production while reducing the risk of negative environmental impact.

3. Chemical soil health can be improved by carefully managing nitrogen fertilizer inputs. Reduction of soil organic matter content and soil pH is an increasing problem in long-term cereal-fallow and continuous-cereal grain systems of the northern Great Plains. The combination of no-tillage practices and continuous nitrogen fertilization depletes the soil of chemical constituents that contribute to soil health. ARS researchers in Sidney, Montana, in collaboration with the University of Ilorin, Nigeria, reported that 13 years of continuous no-till cereal (barley or spring wheat) cropping increased soil organic matter and Olsen-phosphorus, but reduced soil pH and cation exchange capacity compared to a tilled cereal-fallow rotation. Over-use of nitrogen fertilizer decreased soil pH, potassium, calcium, magnesium, and cation exchange capacity. Remediating these effects on chemical soil properties requires a costly application of a liming material such as calcium carbonate. Annualized grain yield was greater with no-till continuous cereal production and the cereal-pea rotation than with tilled cereal-fallow. Cereal grain growers can enhance chemical soil health and crop yield by using no-till practices, rotating with an annual legume and following recommended nitrogen fertilization practices. Results emphasize the importance of careful nitrogen fertilizer management not only to reduce fertilizer input costs but also to slow soil acidification and reduce the amount of corrective lime needed to maintain soil pH within an acceptable range.

U.S. DEPARTMENT OF AGRICULTURE

Agricultural Systems Research: Sidney, MT