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

2022 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
The 8-year Nesson Valley irrigated cropping systems study in North Dakota was completed in fiscal year (FY) 2021. Samples and data are being analyzed and prepared by unit and collaborating scientists. Collection of crop and soil samples was completed as scheduled and data quantifying rotation and tillage effects on crop quality, biomass and yield components are being summarized. 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. The impact of treatments on soil biological communities are being determined based on phospholipid-fatty acid and total carbon assays. Greenhouse gas sample was collected to quantify carbon dioxide, nitrous oxide and methane emissions data was for four years. Water movement through the soil profile along with nitrate leaching data was collected for 7 years and data analysis and summarization to determine crop water productivity and nitrogen (N) use efficiency is underway. A secondary objective of the study at Nesson Valley to quantify the effects of rotation and tillage on Rhizoctonia root and crown rot in sugarbeet was terminated following the 2019 growing season. Sub-objective 1.2. In FY 2021 we completed the fourth growing season and data collection year of the 6-year Eastern Agricultural Research Center (EARC) (Sidney, Montana) tillage study where sugarbeet is grown with conventional intensive tillage practices or with various modifications of strip tillage and no tillage. The fifth growing season was initiated in the spring of 2022. The overhead sprinkler irrigation system was rendered inoperable by an early summer windstorm. Replacement parts did not arrive until the end of the summer due to supply chain delays, so we were unable to irrigate plots for the remainder of the growing season. Otherwise, growing conditions were favorable in 2021 and shallow (1 to 1.5 m) ground water allowed the deep-rooted sugarbeet crop to survive until harvest. While the inability to irrigate may have depressed crop yields slightly, crop quality, biomass and yield data were comparable to previous years and to farmers’ yields in nearby fields. Results from the EARC study continue to show that strip-tillage sugarbeet compares well to conventional practices, though yield of sugarbeet grown without preplant tillage (no-till) lags somewhat compared to the other two tillage systems. It is notable that with the inability to apply irrigation water for most of 2021, sugarbeet yield under no-till was the highest of all tillage treatments suggesting greater water-use efficiency with that system. The fourth year of physical soil quality measurements, including soil penetration resistance, moisture content, and bulk density, was completed and the fifth year’s data are currently being collected. Soil properties related to water movement and N leaching were not measured at this location due to lack of personnel. 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 EARC to quantify carbon dioxide, nitrous oxide and methane emissions were terminated after collecting three years of data. 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 (ongoing), and (2) identify the most effective irrigation management practice for dry peas which are typically grown as a dryland crop (completed). The final year of the 8-year Nesson Valley irrigated cropping systems study was completed in FY 2021. Yield data from the Nesson Valley study consistently show that sugarbeet and corn yield about 10% less with no tillage than with full tillage while barley and soybean yields are impacted less by tillage. Subobjective 2.1. The eighth year of a large 8-year dryland cropping systems study near Sidney, Montana, was completed in the fall of 2021. This study was designed to compare no-till dryland 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 not favorable during the 2021 growing season as drought conditions persisted from late summer 2020 throughout the 2021 growing season. Timely rains prevented total crop failure allowing the continued quantification of rotation diversity effects on crop quality, biomass and yield components but we feel results do not satisfactorily represent the cumulative effects of tillage and rotation treatments on these parameters. Moreover, a severe windstorm in June 2021 blew over power lines which came to rest in the study area. Work crews repairing the damage were required to drive equipment on some of the plots in the study, compromising the results further. Consequently, we decided to extend the study for another year (2022). Growing conditions in 2022 have been very good with above normal precipitation and good growing conditions. Planting and fertilizer application were completed according to protocols but were delayed somewhat due to frequent spring rains. Soil samples collected prior to planting and immediately following harvest will allow soil water dynamics to be quantified and applied to the calculation of crop water use efficiency. Soil samples were collected to determine microbial community structure, available soil N, total soil carbon (C) and total soil N. Measurements of greenhouse gas emissions were not completed in order to dedicate limited resources to collecting data in other 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. Subobjective 2.2. A large 6-year dryland cropping systems study was extended at the Froid dryland research farm in Montana for an eighth and final year of data collection. This study was 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, 2019, and 2020 caused four consecutive years of crop failure, drastically limiting soil and plant sample collection. Weather conditions in 2022 have been wetter than average through July 15 resulting in better growing conditions than in previous years, though oilseed and cover crop establishment was still less than ideal. Extended for a third year, the study was planted and maintained throughout the 2022 growing season. Meaningful evaluations of agronomic performance, crop water use efficiency and N use efficiency will be conducted to the degree possible following this final study year. It is not anticipated that another extension will occur. Subobjective 2.3. This study at the Froid dryland research farm will be initiated upon the completion of the current Froid dryland cropping systems study (see Subobjective 2.2).

Accomplishments
1. Potential carbon mineralization is an effective soil health indicator for dryland cropping systems. Much of the agricultural soil throughout the world has been degraded by intensive tillage and topsoil erosion. As efforts increase to regenerate healthy, productive soil in many crop production areas, assays are needed to allow managers to monitor changes in chemical, physical and biological soil quality. Labile carbon fractions that change rapidly within a growing season are promising soil health indicators, but they must be correlated with soil properties and crop yields to be suitable metrics. ARS researchers in Sidney, Montana, in collaboration with researchers at the Soil Health Institute, evaluated the relationships among soil carbon fractions and 62 soil properties and mean crop yields in two long term (14 and 36 years old) experiments in dryland farming systems in eastern Montana. They reported that potential carbon mineralization, which indicates soil microbial activity, was better related to soil properties and crop yields than other soil carbon fractions. Producers can use potential carbon mineralization as a promising indicator to measure soil health in dryland cropping systems in the semiarid climatic conditions.

2. Impact of drought on dryland crop productivity. Diversified cropping systems have improved overall grain yield productivity in semi-arid cropping systems compared to the traditional practice of wheat-summer fallow. Pulse and cool-season oilseed crops are commonly included in diversified rotations in the northern Great Plains (NGP) but periods of limited rainfall that are common in the NGP impact rotational crops differently. From 2013 to 2022, ARS researchers in Sidney, Montana, evaluated durum wheat rotations that included three cool-season oilseed crops (camelina, canola, safflower) and a pulse crop (pea). During cropping seasons marked with low rainfall, i.e. drought conditions, oilseeds were particularly prone to crop failure compared to durum and pea. Contributing factors to low oilseed yield included soil crusting that limited seedling emergence, small seed size with limited reserves for initial growth, and poor seed set from heat-induced flower abortion during reproductive stages of growth. Durum and pea were much less prone to crop failure in times of drought than camelina, canola, and safflower.

3. Better plant available water capacity under no-tillage practices. Maintaining adequate soil moisture levels is essential in irrigated crop production systems and tillage typically causes soil water to be lost more readily to evaporation. ARS researchers in Sidney, Montana, conducted a long-term field study to evaluate the effect of tillage on plant available water in the top 30 cm of soil during the corn phase of an irrigated 2-yr corn-soybean rotation. No-tillage increased plant available water capacity amounts in the sandy loam soil by approximately 26% compared to intensively tilled soils because there is no soil disturbance when no-tillage practices are used. This work increases our understanding of how conversion to no-tillage management practices in irrigated crop production systems can enhance water storage, water use, and crop productivity while maintaining environmental quality and soil health. No-tillage contributes to improved soil health and quality, more sustainable crop yields and greater water-use efficiency. Findings show farmers some of the benefits of converting their irrigated cropping systems to no-tillage as a way to increase their bottom line rather than using costly intensive tillage practices.

4. Effects of tillage intensity and diverse crop rotation on soil biological health. Soil microbial communities play a central role in the ecological function and biological stability and are therefore closely related to soil quality. A field study was carried out by ARS researchers in Sidney, Montana, to analyze the 8-year effect of tillage intensity and crop rotation on microbial community biomass and community composition using phospholipid fatty acid (PLFA) profiles to assess soil microbial community structure. No-tillage (NT) with increased crop residue returned to the soil resulted in significantly higher total PLFAs compared to conventional (i.e., intensive) tillage (CT) due primarily to an increase in both fungal and bacterial PLFAs. Crop rotation had little effect on soil bacterial communities, but it led to higher fungal biomass in a diverse sugarbeet-corn-soybean-barley rotation than in a sugarbeet-barley rotation, regardless of tillage intensity. Soil microbial communities mediate many soil functions and understanding which crop rotation or tillage practices impact different microbial communities is critical to the development of cropping strategies that optimize soil microbial functions.

U.S. DEPARTMENT OF AGRICULTURE

Agricultural Systems Research: Sidney, MT