Project : USDA ARS

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

Location: Agricultural Systems Research

2018 Annual Report

Objectives
1. Develop novel, integrated technologies and management protocols to improve irrigated crop production systems that increase crop yield, diversify crop rotations; reduce economic and environmental risk; improve water and nitrogen use efficiency; and enhance biological resiliency and soil health and fertility. Subobjective 1.1. Develop diverse sprinkler irrigated cropping systems that include bioenergy and legume crops to improve farm economic and environmental sustainability by enhancing system productivity and input efficiency. Subobjective 1.2. Evaluate the effect of crop residue removal in sprinkler irrigated cropping systems on cropping system productivity, C and N sequestration and microbial biomass and activity. Subobjective 1.3. Evaluate the effect of tillage practices on sprinkler irrigated cropping system productivity, C and N sequestration, microbial biomass and activity, crop water productivity, N use efficiency and soil physical properties. 2. Develop sustainable, biologically based cost-effective control strategies for management of specific plant diseases that currently limit productivity in NGP cropping systems. Subobjective 2.1. Develop biocontrol based management using specific Trichoderma species to manage Cercospera leaf spot in sugarbeet and net blotch in barley in NGP cropping systems. Subobjective 2.2. Evaluate the effects of oilseed crops on microbial communities that impact soilborne pathogens in NGP dryland cropping systems. 3. Develop no-till sustainable crop production strategies for long-term dryland crop production systems using diverse crop rotations that include cereals, pulse crops, oilseeds and other bioenergy crops to improve water productivity, N use efficiency and enhance ecosystem services that reduce economic and environmental risks while maintaining high levels of crop production. Subobjective 3.1. Develop no-till diversified dryland crop rotations that include cereal, pulse and oilseed crops and that increase crop water productivity, N-use efficiency, soil quality and whole-farm economic competitiveness while maintaining yield and quality of the individual crops. Subobjective 3.2. Determine the sequence of cereal, pulse and oilseed crops in no-till dryland rotations that optimizes yield, crop water productivity, and N-use efficiency.

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 to double agricultural production by 2050. 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 Montana, western North Dakota), 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 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, nutrients, and agrochemicals through increased efficiency, (2) diversify crop rotations to include cereals, pulse, oilseed, and bioethanol crops, (3) utilize biological control and cultural management for reduced infestation of pests, diseases, and weeds, and (4) increase net farm productivity. 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
Dryland Cropping Systems Research: Crop sequence treatments have been established for two large and complex dryland long-term (2013-2019 and 2013-2021) unit trials with varying levels of cropping intensity and management in 1-, 2-, 3- and 4-yr no-till rotations. Beginning in FY2018, data collected from the Rasmussen Unit Project (2013-2021) will allow determination of the effects of rotation diversity on crop yield and soil quality according to the hypotheses under Objective 3.1. Data are being collected from the Froid Unit Project (2013-2019) that will allow evaluation of the cumulative effects of cropping sequence on crop yield and soil quality parameters so that hypotheses under Objective 3.2 may be addressed. All planting, soil sampling, fertilizer application, and harvest activities were completed in a timely manner. Monitoring soil carbon levels and greenhouse gas emissions from dryland cropping systems studies ended after FY17 completing the data collection phase for Hypothesis 3.1e. Research on the contribution of perennial and annual crop roots to C sequestration in dryland cropping systems is ongoing but is nearing completion. Results to date show that perennial crops have greater root biomass than annual crops which helps in increasing soil carbon and nitrogen sequestration. In annual cropping systems where above ground biomass is harvested for biofuel feedstock or as livestock feed, a mixture of legume and non-legume winter cover crops and a moderate level of nitrogen fertilization can replace part of crop residue removed and increase soil carbon and nitrogen compared when cover crops nitrogen fertilization are not used. This provides valuable information that contributes to Hypothesis 3.1d regarding the benefits of alternative cropping practices that enhance soil quality by improving C and N cycling. Irrigated Cropping Systems Research: The 2017 growing season marked the initiation of a new (Sidney, Montana) irrigated cropping systems study evaluating reduced tillage practices for sugar beet. Tillage treatments were initiated in the fall of 2017 and data regarding the effects of those treatments were collected during the 2018 growing season. Secondary objectives of this 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. The sixth year of the 8-year Nesson Valley (North Dakota) cropping systems study was completed in FY18. Sugar beet grown without preplant tillage (i.e., direct seeded) yielded similar to when conventional preplant tillage practices were used. Yield and crop quality data from both studies will contribute to the accomplishment of Sub-objective 1.3, Hypothesis 1.3a. In FY16, collaborative research with a North Dakota State University researcher was initiated to investigate the effects of rotation and tillage on Rhizoctonia root and crown rot in sugar beet. This collaboration continued in FY18. Research continued to evaluate the effects of tillage systems on soil physical properties in the Nesson Valley irrigated cropping systems study. Soil physical and hydraulic properties in a corn-soybean rotation under no-till and tilled practices were measured to provide data with which to test Hypothesis 1.3d. The fifth year of determining nitrate content in water that had percolated below the root zone was completed along with data analysis and summarization. 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. Water characteristics curves and hydraulic properties for sandy and clay loam soils under soil saturated and unsaturated conditions have also been determined. Wireless real-time soil moisture sensors for measuring soil water contents in the root zone continue to be evaluated for their utility in irrigation management and monitoring crop water use. Soil physical and hydraulic properties from corn-soybean rotation under no-tilled and tilled practices have been measured annually and the fifth year of processing and analyzing water samples for nitrate concentration was completed. Soil-water characteristics curves and hydraulic properties, which can be used for irrigation scheduling, were determined for sandy loam soil at the Nesson site under soil saturated and unsaturated conditions using cutting edge technologies (HYPROB and Equi-pf instruments). These results characterizing soil physical properties as they relate to water and solute movement will help researchers quantify the effects of tillage on soil water and nutrient use efficiency (Hypothesis 1.3c).

Accomplishments
1. Cover crops replace fallow in semi-arid durum cropping systems. The traditional 2-yr rotation of spring wheat followed by summer fallow helps decrease the risk of crop failure in the short term, but long-term consequences include soil carbon depletion, formation of saline-seeps, degraded environment for soil microbiology, loss of habitat for fauna including pollinating insects, reduced soil water holding capacity, and inefficient precipitation storage during fallow with about 60 to 85% of precipitation lost to surface evaporation. Interest among wheat growers in utilizing diverse cover crop mixtures to enhance soil quality is increasing but the lack of immediate financial return on the cost of seeding a traditional cover crop discourages many growers from adopting this practice. However, little is known about replacing the fallow phase in wheat-fallow rotations, for example with a multispecies crop harvested for forage with regrowth left to serve as a standing cover crop. ARS researchers in Sidney, Montana initiated a 6-year study to investigate the production potential of a 10 species crop mix (buckwheat, canola, cowpea, flax, lentil, millet, pea, radish, sorghum, turnip) in place of fallow in 2-year durum rotations. Results from the first 3-year period of the study indicate planting a multispecies crop mix in place of fallow provided on average 1.4 tons per acre (59% of which was radish and pea) of high-quality forage harvested in early summer and an additional 2.4 tons per acre (50% of which was sorghum and millet) unharvested biomass at killing frost left for standing cover to increase ecosystem services compared to fallow. Results from this research show that utilizing a portion of the cover crop growth as forage may offset seeding costs enough to make adoption more economical.

2. Smart soil moisture sensors for irrigation scheduling. Better irrigation scheduling is one of the most critical aspects of irrigated agriculture for improving yield and reducing the adverse impact on quality of surface and ground waters. In team research, ARS scientists in Sidney, Montana conducted a field study at two locations of different soil texture, one in North Dakota and the other in Montana. Their goal was to evaluate HydraProbe, Campbell Time Domain Reflectometry and Watermark real-time soil moisture sensors for their ability to estimate water content in sandy loam and clay loam soils. Results showed that the three sensors provided different estimates of soil moisture contents in both soils. Nevertheless, their work suggests that soil moisture sensors including those used in this study can be suitable for irrigation scheduling without in-situ calibrations by simply setting the upper and lower irrigation trigger limits for each sensor and each soil type. The upper trigger point occurs directly after an irrigation event and the lower trigger point is based on about 50% depletion of available water in the crop root zone and it occurs prior to irrigation refill. This approach can help irrigators to achieve their irrigation scheduling and productivity goals without consuming any time on sensor calibration. The approach requires minimal training and labor, and it can provide useful information to aid producers to determine when and how much to irrigate without causing any damage to their crops, thereby optimizing crop productivity while maintaining environmental quality with minimal water loss.

3. Diversified crop rotation and improved management enhance pea yield and water use. Continuous cropping allows dryland farmers to better utilize the limited amount of precipitation in the semi-arid northern Great Plains. However, the crop chosen to replace the fallow phase must leave enough moisture in the soil for the wheat crop grown during the following year. Cool-season pulse crops such as pea and lentil are planted in early spring and mature in early summer allowing the soil to accrue moisture from late summer rains that would be removed by longer-season crops. Pea has been grown to replace fallow in the wheat-fallow system and has been a particularly good fit in arid and semiarid regions, but growers need more information about best management practices that enhance dryland pea yield and water-use efficiency. ARS researchers at Sidney, Montana found that a longer crop rotation with non-legumes and increased seeding rate and wheat stubble height enhanced pea yield and water use efficiency compared to a shorter crop rotation and conventional seeding rate and stubble height. Research from this research will help producers increase dryland pea yield by efficiently utilizing soil water using extended crop rotations with non-legumes and by increasing seeding rate and stubble height.

4. Carbon sequestration and nitrogen balance vary with crop rotations. Soil carbon content is an important indicator of soil health and represents a reservoir of sequestered carbon that can lessen the impact of increase C-based greenhouse gas emissions to the atmosphere. Nitrogen can also can be lost to the environment through various pathways and cam be a source of greenhouse gases. It is vital to agricultural producers and non-producers alike that we understand how agricultural practices affect soil carbon sequestration and nitrogen balance, especially in the in the northern Great Plains where little carbon sequestration research has been conducted. ARS scientists in Sidney, Montana reported that soil carbon sequestration increased with continuous non-legume or a two-year rotation of a legume and non-legume crop compared to more diversified, extended crop rotations. In contrast, diversified legume-based rotations reduced nitrogen fertilization rate, increased crop nitrogen uptake, reduced nitrogen loss to the environment, and enhanced nitrogen surplus compared to continuous non-legume monocropping. A two-year rotation of legume-non-legume crops can enhance soil carbon and nitrogen sequestration, increase crop nitrogen uptake, optimize nitrogen balance, and reduce external nitrogen inputs compared to non-legume monocropping. Previous research has shown that rotating a non-legume such as wheat with an annual legume such as pea improves system productivity and water-use efficiency. This new research shows that this cropping system also improves carbon sequestration and nitrogen balance resulting in enhanced soil quality and reduced environmental impacts.

5. Direct-seeded sugar offers lower input costs and protection from soil erosion. Increased labor and tillage costs during the past decade have led to greater interest in reduced tillage among sugar beet growers. Direct-seeding, where seed is planted without any preplant tillage, offers potential cost and soil conservation benefits but greater challenges as well. ARS scientists in Sidney, Montana found that direct seeding led to more uniform seedling emergence, which was likely the result of better soil moisture during germination. However, sucrose yield was 10-15% lower with direct seeding than with intensive tillage in three of five years. In the other two study years, yield was unaffected by tillage or rotation diversity. The lower yield in some years may be attributable to slower early season growth which in turn leads to slower development of a full crop canopy and less interception of solar radiation. Soil temperature was from 3 to 12 °C cooler with direct seeding than with intensive tillage during the critical emergence and seedling growth periods. These cooler soil temperatures may have reduced mineralization of soil organic nitrogen and caused early season nutrient deficiency. If this negative effect on early season growth can be overcome, direct seeding could provide comparable yields compared to conventional practices with much lower fuel and labor costs and better protection against soil degradation.

U.S. DEPARTMENT OF AGRICULTURE

Agricultural Systems Research: Sidney, MT