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

2021 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
Subobjective 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 final growing season of the 8-year Nesson irrigated cropping systems study (Nesson Unit Project) was completed in Fiscal Year (FY) 2021. Growing conditions were favorable in 2020 allowing for the collection of representative data quantifying rotation and tillage effects on crop quality, biomass and yield components. Results 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. Analysis of soil microbial community structure based on phospholipid-fatty acid determinations and total carbon to quantify soil organic matter dynamics is ongoing. Greenhouse gas sample collection to quantify carbon dioxide, nitrous oxide and methane emissions is complete after four years of quality data were collected from 2016 to 2019. Analysis and summarization of crop water productivity and nitrogen (N) use efficiency data is in progress. Subobjective 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 third growing season and data collection year of the 6-year Sidney tillage study (Sidney Unit Project) where sugarbeet tillage treatments are conventional tillage, various modifications of strip tillage, and no tillage. The fourth growing season was initiated in the spring of 2021. The final year of the 8-year Nesson Unit Project was completed in FY 2021. Growing conditions were favorable in 2020 at both locations allowing for the collection of representative data quantifying tillage effects on crop quality, biomass and yield components. Yield data from the Nesson Unit Project 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. Results from the Sidney Unit Project show that strip-tillage sugarbeet compares well to conventional tillage practices. Yield of sugarbeet grown without preplant tillage (no-till) lags somewhat compared to the other two tillage systems. The third year of physical soil quality measurements, including soil penetration resistance, moisture content, and bulk density, was completed and the fourth year’s data are currently being collected. Soil microbial community structure based on phospholipid-fatty acid determinations and total carbon analyses to quantify soil organic matter dynamics are in progress. Soil samples were collected from both sites at planting and following harvest according to the established protocols. Greenhouse gas sampling at Sidney to quantify carbon dioxide, nitrous oxide and methane emissions were terminated after collection three years of quality data. Secondary objectives of the Sidney Unit Project 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. 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. The seventh year of a large 8-year dryland cropping systems study near Sidney, Montana was completed in the fall of 2020. The eighth year was initiated in the spring of 2021. 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 early in 2020 but drought conditions have continued from late summer 2020 through the 2021 growing season. Timely rains in both years prevented total crop failure allowing the continued quantification of rotation diversity effects on crop quality, biomass and yield components. 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 N, total soil carbon (C) and total soil N. 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. A large 6-year dryland cropping systems study was extended at the Froid dryland research farm and a seventh year of data collection was completed. 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 2020 were also unusually dry causing the failure of oilseed and cover crops. Extended for a second year, the study was planted and maintained throughout the 2021 growing season. Drought conditions persisted in 2021 but timely rains prevented crop failure. Meaningful evaluations of agronomic performance, crop water use efficiency and N use efficiency will be conducted to the degree possible.

Accomplishments
1. Effect of soil compaction on corn grain yield. Soil compaction due to field operations is an acknowledged problem by growers worldwide. It affects soil quality, reduces crop productivity, and degrades environmental quality. Previous research has shown that compacted soils can reduce crop yield by 40-50% in some areas depending on the depth and level of compaction. There are approximately 169 million acres of compacted soils affected by farm machinery traffic alone worldwide. In team research, ARS scientists in Sidney, Montana, conducted a long-term field study to evaluate the effect of soil compaction on corn grain yield in an irrigated corn-soybean rotation in sandy loam soil. They found that corn grain yield decreased by 7.8% as soil compaction increased from 228 psi to 300 psi and about 33% as soil compaction increased from 228 psi to 400 psi. The adoption of better farming management practices and reducing traffic passes from field operations are essential for minimizing soil compaction and sustaining crop productivity while maintaining environmental quality and soil health.

2. Diversified crop rotation enhances crop water and nitrogen productivity. Producers in dryland cropping systems in the northern Great Plains use crop-fallow or continuous monocropping that can inefficiently use soil water and reduce annualized crop yield. Improved management techniques are needed to enhance crop yield and water and nitrogen productivity. ARS researchers at, Sidney, Montana, reported that more diversified, longer crop rotations increased crop yield, soil water storage, and water productivity compared to continuous monocropping. Alternate-year rotation of cereal and pulse crops increased nitrogen productivity, but lack of grain production with forage reduced annualized grain yield with the cereal-pulse-forage rotation compared to continuous monocropping. Growers in the northern Great Plains can enhance crop yield, as well as water and nitrogen productivity, by using diversified crop rotations instead of continuous monocropping in dryland cropping systems.

3. No-till enhances soil and environmental quality and sustains crop yields. No-till practices are very effective at reducing soil erosion but their effect on soil and environment quality and crop yields compared to conventional tillage can vary from one region to another, depending on soil and climatic conditions and the crops grown. In a review on the impact of tillage on crop yields, soil health, and environmental quality, an ARS researcher in Sidney, Montana, found that the advantage of no-till on crop yield varied in irrigated cropping systems but yield was usually similar to or greater in no-till than conventional tillage in dryland cropping systems due to enhanced soil water conservation. Similarly, the effect of no-till on soil organic matter, a key indicator of soil health, varied in humid areas, but was typically greater in no-till than conventional tillage in arid and semiarid regions. While nitrogen leaching was greater in no-till than conventional tillage, no-till reduced net greenhouse gas emissions, regardless of the cropping system. Producers can benefit from enhanced soil health and environmental quality while sustaining crop yields by using the no-till system.

4. Cover crop mix reduces durum yield in 2-year dryland crop rotations. The traditional practice of summer fallow in dryland rotations with wheat is unsustainable and leads to numerous environmental problems. From 2015 to 2019, ARS researchers in Sidney, Montana, evaluated a cover crop mix as a replacement for the chemical fallow phase in a no-till 2-year durum rotation. The 10-species cover crop mix harvested for forage at radish bloom averaged 3.1 Mg ha-1 and an additional 5.4 Mg ha-1 of unharvested biomass at killing frost in the fall. Durum yield following fallow averaged 1.9 Mg ha-1 compared to 1.4 Mg ha-1 following the cover crop mix. This 26% reduction in durum grain yield could be justified by the additional high-quality forage production, increased biomass accumulation, and increased ecosystem services afforded by the cover crop mix as a fallow replacement.

5. Effect of preceding crops on soil microbial communities in a dryland no-tillage system. Soil microorganisms play an essential role in healthy soil ecosystem and crop rotation has been documented as a driving factor influencing soil microbial community composition. Soil fungi are particularly important in a healthy soil because they are very effective at breaking down certain plant residues and releasing the nutrients they contain. ARS researchers in Sidney, Montana, investigated how introducing oilseed crops and cover crops affects soil microbial community biomass and structure in semi-arid dryland durum cropping systems. An oilseed crop (either Ethiopian mustard or camelina) or a cover crop consisting of 10 different plant species was planted instead of fallowing the soil every other year between durum crops. The researchers determined the differences and similarities in the microbial communities in the soil right next to the roots (rhizosphere) of these alternative crops that preceded durum. In two of four years, the proportion of soil fungi was higher when Ethiopian mustard or cover crop was grown than when camelina was grown. A particularly beneficial soil fungus called arbuscular mycorrhizae was also higher following the cover crop compared to the other rotation options. Changes in the abundance of specific rhizosphere microbial groups due to the preceding crop may play a key role in improving the yield of subsequent crops as well as overall soil health and quality. This research provides new information to the scientific community and will help dryland farmers make management decisions that impact soil quality and long-term productivity in durum-based crop rotations.

U.S. DEPARTMENT OF AGRICULTURE

Agricultural Systems Research: Sidney, MT