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

Location: Agricultural Systems Research

2019 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 sixth growing season of the 8-year Nesson irrigated cropping systems study was completed in FY19 and the seventh growing season was initiated. Growing conditions were favorable 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. Due to a soil microbiologist critical vacancy, analyses for soil quality were limited to phospholipid-fatty acid determinations to characterize soil microbial community structure and total carbon analyses to quantify soil organic matter dynamics. Soil samples were collected at planting and following harvest according to the established protocols. Greenhouse gas samples were collected for the third consecutive year to quantify carbon dioxide, nitrous oxide and methane emissions. The sixth year of determining nitrate content in water that had percolated below the root zone was completed along with data analysis and summarization so that crop water productivity and N use efficiency can be determined. Real time drainage water volumes are being monitored using automated drainage water samplers. Water draining below the root zone is also being manually collected and nitrate content determined. Soil physical and hydraulic properties were measured and water characteristics curves and hydraulic properties for sandy soils under soil saturated and unsaturated conditions were also determined. Collaborative research with North Dakota State University continued for the fourth year with the objective of quantifying the effects of rotation and tillage on Rhizoctonia root and crown rot in sugarbeet. 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 first growing season and data collection year of the 6-year Eastern Agricultural Research Center (EARC) tillage study where sugarbeet is grown with conventional tillage or various modifications of strip tillage and no tillage. The second growing season was initiated in the spring of 2019. Growing conditions were favorable in 2018 allowing for the collection of representative data quantifying rotation and tillage effects on crop quality, biomass and yield components. Initial results show that reduced tillage sugarbeet compared well to conventional practices, though yield of sugarbeet grown without preplant tillage (no-till) lagged slightly behind that produced by the other two tillage systems. The first year of physical soil quality measurements, including soil penetration resistance, moisture content, and bulk density, were completed and the second year’s data are currently being collected. Effects of cropping system on soil quality were quantified using phospholipid-fatty acid determinations to characterize soil microbial community structure. Total soil carbon was quantified to describe soil organic matter dynamics. Soil samples were collected at planting and following harvest according to the established protocols. Greenhouse gas samples were collected for the third consecutive year to quantify carbon dioxide, nitrous oxide and methane emissions. Secondary objectives of the study at EARC 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 (collaboration with Montana State University). Subobjective 2.1. Develop no-till diversified dryland crop rotations that include cereal, pulse and oilseed crops and 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 2018. The seventh year was initiated in the spring of 2019. 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 generally favorable in 2018 allowing for the collection of representative data quantifying 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, plant-available soil nitrogen, total soil carbon and total soil nitrogen. 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. The sixth year of a large 6-year dryland cropping systems study was completed at the Froid dryland research farm. The seventh year was initiated in the spring of 2019. 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 cause crop failure resulting in very limited soil and plant sampling. Meaningful evaluations of agronomic performance, crop water use efficiency and N use efficiency were not possible due to the extensive hail damage 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. This study at the Froid dryland research farm will be initiated upon the completion of the current Froid farm dryland cropping systems study (see Subobjective 2.2).

Accomplishments
1. Fertilizer nitrogen rates optimize bioenergy feedstock production and environmental quality in semi-arid environments. Renewable bioenergy feedstocks offset the demand for conventional petroleum-based energy resources. Switchgrass is a warm-season perennial grass that has been utilized for ligno-cellulosic ethanol production. Beginning in 2009, ARS researchers at Sidney, Montana, evaluated this bioenergy feedstock crop for its production potential in the semi-arid northern Great Plains, including the impact of nitrogen fertilizer application on biomass production and on environmental quality. Switchgrass biomass production ranged from 1.8 to 12.3 Mg per ha. Application of nitrogen fertilizer at a rate of 28 kg per ha increased biomass in most years. Response to higher nitrogen application rates was inconsistent due to variable rainfall. Biomass from fertilized switchgrass averaged 6.5 Mg per ha compared to 4.4 Mg per ha for the unfertilized control. Soil tests indicated that nitrogen fertilizer application above 28 kg per ha greatly increased the potential of nitrogen being lost to the atmosphere or ground water thus negatively impacting environmental quality in semi-arid environments. This research provides critical agronomic information that will enhance the capacity of the U.S. to produce alternative fuels with minimal environmental impact.

2. Continuous cropping ameliorates soil compaction. Compacted soils reduce air, water and nutrient movement which, in turn, restrict root growth and can reduce crop yields by 40 to 50%. Tillage has been the practice of choice to remedy soil compaction but tillage-induced soil disturbance greatly accelerates decomposition of crop residues on the soil surface and organic matter within the surface soil layer compared to no-till conditions. Break down of these carbon reservoirs greatly increases the risk of soil erosion and carbon dioxide emission resulting in negative impacts on both soil and environmental quality. Alternatively, given sufficient time, crop roots may break up soil compaction by penetrating the compacted layer. Roots eventually decay, creating channels that allow water, nutrients and air to move more freely through the soil profile. The traditional 2-yr rotation of wheat-fallow in dryland areas constrains root growth during the fallow phase. ARS scientists in Sidney, Montana, evaluated the effect of crops with varying rooting characteristics on soil compaction. No-till cropping systems with durum wheat rotated with camelina, carinata, a cover crop mix, or fallow were evaluated on a field with a history of tillage- and traffic-induced soil compaction. There was no amelioration of compaction after one 2-year cropping cycle but compaction was reduced by 28% (2.244 MPa to 1.628 MPa) after two cycles, regardless of the rooting characteristics of the rotation crops. Results suggest that avoiding fallow (i.e. continuous cropping) crop roots will improve compacted soils and eliminate the need for expensive tillage operations, which tend to provide only a short-term improvement while reversing many of the benefits of no-till production on soil quality.

3. Annual legumes help optimize nitrogen balance in northern Great Plains dryland cropping systems. Nitrogen can be added to crops through nitrogen fertilization, compost and manure applications, biological nitrogen fixation, rainfall, and irrigation and lost through crop uptake, volatilization, leaching, denitrification, and surface runoff. Measuring nitrogen inputs, outputs and retention in the soil provides a picture of nitrogen flows in the agroecosystem and a measure of cropping system performance and environmental sustainability. This metric, referred to as nitrogen balance, was used to evaluate northern Great Plains dryland grain cropping systems. Scientists at ARS in Sidney, Montana, found that a no-till barley-pea cropping system, where only modest amounts of nitrogen fertilizer were applied, increased crop nitrogen removal, enhanced soil nitrogen storage, and decreased nitrogen loss to the environment, compared to a tilled fallow-barley system. This low nitrogen-input system resulted in a nitrogen balance close to zero, which is a notable improvement compared to the negative nitrogen balance observed with the tilled-fallow system. Producers can enhance dryland crop yield and quality and reduce nitrogen fertilizer input and nitrogen loss to the environment by using no-till barley-pea rotation with a modest nitrogen rate.

4. Cover crops and residue management reduce greenhouse gas emissions. Adding cover crops to a crop production system can provide many crop, soil, and environmental benefits, but the effect of cover crops on greenhouse gas emissions has been poorly characterized. A researcher at ARS in Sidney, Montana, in collaboration with Northwest University in Xian, China, and Chinese Academy of Sciences, the University of Agriculture in Peshawar, Pakistan, and New Mexico State University found in a meta-analysis that cover crops increased carbon dioxide emissions compared to no cover crop. Legume cover crops increased nitrous oxide emissions while nonlegume cover crops reduced these emissions. Carbon dioxide and nitrous oxide emissions were less when cover crop residue was allowed to remain on the soil surface compared to when the residue was incorporated into the soil. Although cover crops can increase greenhouse gas emissions compared to conventional practices that do not include a cover crop, ecosystem services and soil health benefits provided by cover crops might outweigh increased carbon dioxide emissions. Moreover, allowing cover crop residues to remain on the soil surface will help mitigate carbon dioxide and nitrous oxide emissions resulting from both legume and nonlegume cover crop production. Results from this research provide critical information for the growing number of farmers who are incorporating cover crops into their production systems throughout the U.S.

5. Less nitrogen fertilizer needed for sugarbeet following soybean. Synthetic nitrogen fertilizer is one of the largest inputs in sugarbeet-based irrigated cropping systems of the northern Great Plains. Sugarbeet is usually grown following a small grain. If an annual legume precedes sugarbeet, it provides biologically-fixed nitrogen which may alter seasonal nitrogen availability patterns. If there is too much or too little nitrogen available at critical growth stages, yield and quality are negatively affected. ARS researchers at Sidney, Montana, evaluated the performance of sugarbeet grown following soybean compared to sugarbeet following barley. Where soybean preceded sugarbeet, the target nitrogen fertilizer rate was reduced by 25 to 30 kilograms per hectare due to nitrogen provided by soybean residue. Mid-season plant-available nitrogen in the soil was 3 to 4 milligrams per kilogram lower following soybean than following barley. Nitrogen status of the sugarbeet plant, as indicated by nitrate-nitrogen content of the leaf petiole, showed a similar trend. Despite this, sucrose yield was greater following soybean than following barley two of seven years and was similar in the other five years. Results suggest that soil and plant organic nitrogen are released more evenly throughout the growing season following soybean than following barley. It was concluded that growing sugarbeet following soybean reduces the amount of nitrogen fertilizer required for sugarbeet without negatively affecting yield. Moreover, soybean requires no synthetic nitrogen fertilizer because it is able to meet its own nitrogen needs through biological nitrogen-fixation. When both soybean and sugarbeet production years are considered, nitrogen fertilizer costs are about $275 per hectare lower compared to the rotation with barley in place of soybean. Reducing the use of nitrogen fertilizer benefits growers’ bottom line and reduces environmental impact resulting from the production and use of nitrogen fertilizers.

Review Publications
Fu, X., Sainju, U.M., Zhao, F., Wang, J. 2019. Soil microbial community and carbon and nitrogen fractions responses to mulching under winter wheat. Applied Soil Ecology. 139:64-68. https://doi.org/10.1016/j.apsoil.2019.03.018.
Jabro, J.D., Iversen, W.M., Stevens, W.B., Sainju, U.M., Allen, B.L. 2019. Tillage effects on drainage fluxes and nitrate leaching through unsaturated zone under irrigated corn-soybean rotation. Applied Engineering in Agriculture. 35(3):293-300. https://doi.org/10.13031/aea.13127.
Ma, Q., Zhang, K., Jabro, J.D., Ren, L., Liu, H. 2019. Freeze-thaw cycles effects on soil physical properties under different degraded conditions in Northeast China. Environmental Earth Sciences. https://doi.org/10.1007/s12665-019-8323-z.
Sainju, U.M., Singh, H.P., Singh, B.P., Chiluwal, A., Paudel, R. 2018. Soil carbon and nitrogen under bioenergy forage sorghum influenced by cover crop and nitrogen fertilization. Agrosystems, Geosciences & Environment. 1:180004. https://doi.org/10.2134/age2018.03.0004.
Sainju, U.M., Ghimire, R., Pradhan, G.P. 2019. Improving dryland cropping system nitrogen balance with no-tillage and nitrogen fertilization. Journal of Plant Nutrition and Soil Science. 182:374-384. https://doi.org/10.1002/jpln.201800630.
Muhammad, I., Sainju, U.M., Zhao, F., Khan, A., Fu, X., Wang, J. 2019. Regulation of soil CO2 and N2O emissions by cover crops: a meta-analysis. Soil & Tillage Research. 192:103-112. https://doi.org/10.1016/j.still.2019.04.020.
Fu, X., Wang, J., Sainju, U.M., Liu, W. 2018. Soil nitrogen fractions under long-term crop rotations in the Loess Plateau of China. Soil and Tillage Research. 186:42-51. https://doi.org/10.1016/j.still.2018.10.004.
Nash, P.R., Gollany, H.T., Sainju, U.M. 2018. CQESTR simulated response of soil organic carbon to management, yield, and climate change in northern Great Plains region. Journal of Environmental Quality. 47:674-683. https://doi.org/10.2134/jeq2017.07.0273.
Wang, J., Ghimire, R., Fu, X., Sainju, U.M., Wenzhau, L. 2018. Straw mulching increases precipitation storage rather than water use efficiency and dryland winter wheat yield. Agricultural Water Management. 206:95-101. https://doi.org/10.1016/j.agwat.2018.05.004.
Ghimire, R., Ghimire, B., Mesbah, A.O., Sainju, U.M., Idowu, O.J. 2019. Soil health responses to cover crops in winter wheat-fallow system. Agronomy Journal. 3(4):2108-2115. https://doi.org/10.2134/agronj2018.08.0492.
Sainju, U.M., Lenssen, A.W., Allen, B.L., Jabro, J.D., Stevens, W.B. 2019. Pea growth, yield, and quality in different crop rotations and cultural practices. Agrosystems, Geosciences & Environment. 2:180041. https://doi.org/10.2134/age2018.10.0041.
Lenssen, A.W., Sainju, U.M., Allen, B.L., Jabro, J.D., Stevens, W.B. 2018. Dryland corn production and water use affected by tillage and crop management intensity. Agronomy Journal. 110:2439-2446. https://doi.org/10.2134/agronj2018.04.0267.
Gesch, R.W., Long, D.S., Palmquist, D.E., Allen, B.L., Archer, D.W., Brown, J., Davis, J.B., Hatfield, J.L., Jabro, J.D., Kiniry, J.R., Vigil, M.F., Oblath, E.A., Isbell, T. 2019. Agronomic performance of Brassicaceae oilseeds in multiple environments across the Western USA. BioEnergy Research. 12(3):509-523. https://doi.org/10.1007/s12155-019-09998-1.