Location: Agricultural Systems Research2010 Annual Report
1a. Objectives (from AD-416)
1. Develop strategies for irrigated production systems using increased crop diversity, reduced tillage, and emerging technologies to improve agricultural chemical, water and nutrient use efficiencies. 2. Develop biological based disease control strategies for NGP production systems. 3. Develop dryland production strategies with increased crop diversity and advanced technologies to improve agricultural chemical, water, and nutrient use efficiencies to increase competitiveness and enhance natural resource quality.
1b. Approach (from AD-416)
This project involves eight scientists (8 SYs) and many collaborators that represent a broad range of disciplines focused on the long-term, 10- to 12-year goal of developing sustainable strategies for both irrigated and dryland crop production systems for the MonDak region of eastern Montana and western North Dakota. The ASRU is organized to address basic and applied research issues using an interdisciplinary team approach where multiple hypotheses are tested in four large “Unit Projects.” The “Unit Project” objectives are designed to encompass cropping system development, concurrent development and application of “metrics” or indicators of system performance, and the assessment process by which systems are evaluated and judged. There is considerable overlap, but responsibilities can be generally divided into two broad, overlapping categories with four scientists (Allen, Evans, Lartey and Stevens) primarily examining the systems aspects, and four scientists (Caesar-TonThat, Jabro, Lenssen and Sainju) focusing their research on developing and evaluating various metrics of cropping system performance. These Unit projects focus on biologically diverse cropping systems. Biological control research (Obj. 2) of two plant diseases spans both dryland (Obj. 3) and irrigated (Obj. 1) systems. Three of the Unit projects (one irrigated and two dryland) are currently underway and one new irrigated project will be initiated in 2009. Each Unit project will be replaced by a new Unit project as they are completed.
3. Progress Report
Remote sensing techniques were used for the second year in relation to post-harvest plant residue assessment with collaborators in northeastern Montana; Nesson Valley, ND (Northern Great Plains); Akron, CO (Central Great Plains); Pendleton, OR and Pullman, WA (Pacific Northwest) on malting barley, spring wheat, peas, durum and fallow. A follow-up field data collection was also conducted in spring before planting season in the MonDak region. The cellulose absorption index (CAI) value was shown to readily distinguish fields practicing conservation tillage from those that are not. Soil, plant, and greenhouse gas samples were collected and analyzed and microbial enzymatic activities were completed for the two GRACEnet sites. Work progressed toward determining best management practices for N fertilization for strip till sugarbeet and understanding C cycling in MonDak region cropping systems. A study evaluating the effects of strip tillage systems and high-efficiency irrigation methods on 2-year sugarbeet and malt barley rotations was completed along with an accompanying study to evaluate the effects of strip tillage system on N availability and uptake. Field work was completed for two studies designed to determine optimum fertilizer management for sugarbeet grown on sandy textured soils. A study was continued evaluating polymer-coated slow-release urea as means to improve sugarbeet root yield and reduce N use on sandy soils. Data collection commenced on a new, long term irrigated cropping systems project that includes sugarbeet, legumes, barley and/or bioenergy crops. A four year field study was started to evaluate the effects of freezing and thawing cycles on changing soil physical properties of severely compacted clay soils over time. Collaborative evaluations at dryland and irrigated research sites using the RZWQ2 model were continued. Progress was made in many areas on five different dryland cropping rotation experiments. Selected treatments were replanted during the establishment phase of two perennial biomass trials that includes grasses with varying levels of N fertility compared to binary grass-legume mixtures. The 3rd year was completed of a 2-year spring wheat rotation with oilseeds (camelina, crambe and B. juncea) that replace summer fallow. Determination of the aggregate distributions plus isolation and storage of dominant bacteria from soil aggregates or from rhizosphere samples were completed for several irrigated and dryland studies. Yield and yield components were measured in a camelina investigation varying seeding depths and seeding rates. ASRU scientists developed a primer set for real-time PCR detection of P. teres (Net Blotch disease of barley and wheat). Antibodies for ELISA based detection of both P. teres and Laetisaria arvalis have been developed and tested. Investigations were continued on various L. arvalis treatments as an alternative to fungicide seed treatments for barley. In collaboration with the BLM, a new investigation was started to evaluate the effects of Agaricus spp of basidiomycete fungi (responsible for fairy rings) on communities of native grasses and soil aggregation in rangelands of Eastern Montana.
1. Affordable, reliable remote sensing technique verified for use in ag computer models. Increasingly sophisticated computer models allow for assessments of the impacts of soil, water and energy conservation and new production methods on the sustainability of various cropping systems. But these assessments are only as good as the tools used to measure the many variables involved. Crop residue cover, a key indicator of soil carbon storage and soil conservation benefits, is one such variable that has previously been highly labor intensive and expensive to accurately calculate. To address that issue, ARS scientists at Sidney, MT in collaboration with researchers at the ARS Hydrology and Remote Sensing Laboratory, Beltsville, MD, examined use of the remotely-sensed cellulose absorption index (CAI) to evaluate crop residue cover and the subsequent sustainability of various cropping systems in semi-arid regions. Measurements were made in 2009 and 2010 in the Northern Great Plains (Sidney, MT and Akron, CO) and Pacific Northwest (Pendleton, OR and Pullman, WA) regions using a ground-based multispectral camera, digital photography and transect lines on research plots and grower fields to assess post harvest residue measurements of different dryland cropping systems. Scientists have determined that CAI can be used to provide reliable estimates of crop residue cover in these semi-arid dryland regions, which can, in turn, be utilized in computer models to help determine the sustainability of different cropping systems in these regions. In addition, in collaboration with scientists at the Livestock and Range Research Laboratory in Miles City, MT. the technique has also been shown to successfully assess residue cover and subsequent “fuel loads” for computer models looking at wildfire potential of rangelands. The technique also holds potential for many other computer model applications looking at carbon sequestration and to aid compliance with government farm conservation programs.
2. Legumes and annual forage crop rotations enhance desirable soil properties for sustainable dryland yields in the semi-arid Northern Great Plains. Maintaining adequate levels of soil water and soil nitrogen (N) are critical for sustainable dryland crop yields in semi-arid regions. Also, nitrogen fertilization is a significant expense for producers. The introduction of alternative crop rotations incorporating nitrogen-rich legumes holds promise for improved sustainability and profitability in the region. However, the time, expense and expertise needed to evaluate new cropping rotations and their impacts prevent interested producers from exploring or adopting these options on their own. Consequently, Sidney, MT ARS scientists initiated a four-year study of two dryland rotations comparing continuous alfalfa and no-till durum-annual forage sequences and assessing their impacts on soil nitrogen and water levels. They found that inclusion of perennial and annual legume forages in rotation with cereal crops can help sustain soil nitrogen and water levels by supplying nitrogen and reducing soil water uptake. The study showed that alfalfa increased soil carbon and nitrogen storage and nitrogen mineralization at the surface layer due to increased root biomass, and reduced water and nitrate-N content in surface and subsurface layers. Nitrogen mineralization and availability were greater in durum-Austrian winter pea/barley hay than in the other durum-annual forage sequences studied. Overall, the research showed that growers can reduce production costs (i.e. N fertilization amounts) while maintaining crop yields through incorporation of legume forages such as Austrian winter pea hay in rotation with cereal crops. The research also shows that production of dryland alfalfa can reduce N leaching and increase soil carbon and available soil N. Soil carbon sequestration also provides climate change benefits and may also benefit producers economically under carbon trading programs.
3. Annual forages identified as profitable alternatives to summer fallow in semi-arid dryland farming operations. Economic forces are driving the replacement of wheat-summer fallow cropping systems by diversified, continuous (every year) cropping systems in dryland crop production areas of the semi-arid Northern Great Plains, but results are quite variable and growers lack direction. ARS scientists at Sidney, MT have determined that annual spring-seeded forage crops use less water than cereal grains, including durum, and may be a suitable replacement option to summer fallow. A five year experiment was completed that compared yield, quality, and water and nitrogen use of durum-fallow rotations with two-year rotations of continuous durum and three annual forages: forage barley, forage barley interseeded with field pea, and foxtail millet. Averaged over years, preplant soil water and residual nitrogen content were greater for durum following fallow than for durum following annual forages, resulting in reduced total fertilizer N requirement and greater yield, water use, grain N accumulation and nitrogen recovery index (NRI) following fallow. In addition, replacing summer fallow with annual forages reduced durum grain yield by 10.8 bushel acre-1. But while those factors appear to favor the wheat-fallow system, forage yields of nearly 2.5 ton acre-1 produced a higher annualized return over the five-year study period for all three wheat-forage rotations, greatly reduced herbicide use and substantially lowered total fertilization costs, despite reduced wheat yields. Under the study, the annualized net returns in the three annual forage-durum systems were $51 acre-1, $31 and $14 acre-1 greater than for fallow-durum, respectively.
4. Minimal tillage practices shown to substantially reduce sugarbeet production costs. Sugarbeet growers in the Northern Great Plains are looking for ways to reduce the cost of energy, labor and time invested in farming while increasing profits. Tillage practices are a major expense, but different approaches may influence physical, chemical, and biological properties of the soil environment in different ways and, thereby, crop yield and quality. A 4-yr field study was conducted by ARS scientists at Sidney, MT comparing three tillage practices: no tillage; strip tillage (10-cm deep) and deep tillage with chisel plow of (30-cm deep) on a sandy loam soil planted to sugarbeet at the North Dakota State University irrigated research farm near Williston, ND. Deep tillage represents the conventional method used in the region, and it typically requires larger equipment, more time and more fuel to complete as opposed to no tillage or strip tillage methods. The data showed that strip tillage had no significant effect on root yield, sucrose content, or sucrose yield, and, unlike no tillage, sugarbeet population emergence was not significantly impacted. In the latter instance, the data showed that sugarbeet emergence was significantly lower in no tillage than in either strip tillage or deep tillage for all dates throughout the growing season. This research demonstrated that farmers could substantially reduce tillage costs using minimal tillage practices (i.e. strip tillage) with little significant effects on sugarbeet yield or quality. As a result of this study and related studies at the Montana USDA lab, sugar beet producers in the Northern Great Plains and in other regions have begun incorporating strip tillage in their operations in ever increasing numbers because of the economic benefits demonstrated.
5. Identification of production practices that improve spring wheat and field pea yield and nitrogen use in semi-arid environments. Primary constraints to dryland crop production in the Northern Great Plains are available soil water and nitrogen (N) fertility; however, these factors may be either positively or adversely influenced by crop rotation, tillage, and management practices. In an effort to better understand and predict these influences, ARS researchers at Sidney, MT initiated a unique long-term, multi-disciplinary study examining several diverse, multi-year crop rotations using varied tillage and conventional and ecological management practices. In their preliminary results, ARS researchers found that diversification beyond a two-year rotation did not improve spring wheat yield, although field pea appears to yield consistently higher when planted every third or fourth year compared to every other year. Researchers also found that conventional tillage systems by themselves did not impact crop yield compared to no till, and that ecological management practices increased yields of pea, but decreased yields of spring wheat, although the latter is largely attributable to the later planting date used under the ecological system, as opposed to other ecological practices. To date, results from this long-term study suggest that an increased level of rotation diversification with wheat and pea (annual legume) rotations and ecological management can improve total yield, in part through increased N use efficiency. This further indicates that reduced costs associated with no tillage and decreased economic and environmental risk associated with no-till practices can improve N use efficiency and increase economic returns to producers. Ultimately, researchers hope to provide the region’s producers with several different cropping strategies for increasing net returns while maximizes environmental benefits as a result of this study.
6. Malt barley-field pea rotation lower greenhouse gas emissions and reduced nitrogen fertilization. Maintaining sustainable crop yields and lower carbon dioxide emissions with respect to nitrogen (N) fertilizer rates are major concerns in irrigated and dryland cropping systems in the Northern Great Plains. Increased N fertilization can boost yields, but also plays a major role in various greenhouse gas emissions, which makes finding the proper balance important for producers and the environment. Two large studies by ARS scientists at Sidney, MT have demonstrated that a no-tilled malt barley-field pea rotation may be an economically viable alternative for producers hoping to strike that balance. Results from a three year dryland and a five year irrigated-dryland study comparing the effects of tillage, cropping sequence, and N fertilization in northeastern Montana and northwestern North Dakota have shown that no-till malt barley-pea rotations reduced N fertilization rates by 20 kg N ha-1 and increased annualized malt barley yield compared with conventionally tilled malt barley-fallow cropping systems. Other findings show tillage increased carbon dioxide (CO2) flux compared with no-tillage in irrigated cropping systems, but had no effect on crop yield and CO2 flux in the corresponding dryland cropping systems. Continuous, every year cropping also increased total crop returns and CO2 fluxes compared with fallow in dryland cropping systems. Similarly, N fertilization increased crop yield, but reduced CO2 flux compared with no N fertilization in both irrigated and dryland systems. These studies show that better selection of cropping systems and tillage can reduce both CO2 emissions and the need for purchased N fertilizers for both dryland and irrigated cropping systems. This study is part of a nationwide ARS effort designed to provide producers with strategies for reducing agriculture’s greenhouse gas emissions and provide a scientific base for carbon trading programs.
7. Best nitrogen fertilizer management practices identified for strip till sugarbeet production. The profitability of many farms producing major commodity crops is declining because of escalating costs of energy, fertilizers, and other purchased inputs. Strip tillage of sugarbeet is receiving wide spread attention because of the potential to substantially reduce energy and equipment costs for producers. ARS researchers at Sidney, MT have shown that while N availability and uptake tend to be somewhat lower with strip tillage than with conventional tillage practices, sugarbeet yield can be maintained at comparable levels with the same N application rates used for conventional tillage systems as long as proper placement and application timing practices are followed. This research has demonstrated that guidelines for N fertilization of conventional tillage sugarbeet can successfully be applied to strip till sugarbeet production. This finding provides important information regarding N management for sugarbeet grown with strip tillage systems where fertilizer is banded within the tilled strip. It also saves agronomists the time and expense that would otherwise be required to develop new fertilizer recommendations specifically for strip tillage.
8. Sheep grazing can control weeds and increase nutrient cycling in soils to sustain crop yields. Wheat and livestock producers are looking for ways to reduce herbicide and feed costs, respectively. The largest use of glyphosate herbicides in Montana is for control of volunteer wheat during noncrop, fallow periods. In collaboration with Montana State University, ARS scientists at Sidney, MT conducted a five-year study to evaluate and compare the effects of sheep grazing with chemical fallow and tilled fallow management systems on soil properties, weed community, and spring wheat yields. Results document that grazing slightly reduced soil carbon, and available nitrogen, phosphorus, and potassium contents, along with pH, cation exchange capacity, and electrical conductivity by reducing the amount of crop residue returned to the soil compared with tilled and no-tilled treatments. Grazing, however, increased soil calcium, magnesium, and sodium contents. Grazing had no effect on wheat grain and biomass yields, but reduced the need for herbicides by reducing populations of some problem weed species. The study demonstrated that properly timed sheep grazing can be an effective way to economically control volunteer wheat and other weeds and sustain crop yields by reducing selection pressure for weed resistance to glyphosate, decreasing potential leaching of nitrates, and increasing nutrient cycling in soils.
9. Increased host range of Turnip vein clearing virus determined. Since discovery of Arabidopsis thaliana as a host of Turnip vein clearing virus (TVCV), scientists have used the plant as a model for studying virus transmissions in plants. Recently, new hosts of TVCV have been identified by an ARS scientist at Sidney, MT in collaboration with colleagues at the University South Carolina at Columbia and Sumter. This work confirmed the long held hypothesis that TVCV had a broad host range, and the identification of new hosts enables additional studies on how a single virus interacts with different hosts in the process of causing infection. The discovery is a major step forward in the crucial understanding of several mechanisms in host-pathogen interactions including intercellular movement of viruses, long distance movement of viruses within a host, and virus transmission across hosts. This increased understanding is ultimately expected to aid in developing management practices limiting virus transmission in plants such as methods that could curb seed transmission of plant pathogenic viruses either through breeding or emerging molecular techniques. This increased understanding also has implications well beyond plant systems. Understanding the mechanisms of virus transmissions in plants, not only provides opportunities to (combat/limit) those transmissions in crops, but may also provide additional insights regarding virus transmissions in animals and humans.
10. Long-term soil aggregation in semi-arid dryland systems is aided by a no-till wheat-lentil rotations. Soil aggregate formation and stability are key indicators of soil health, which, in turn, is a key factor in sustaining crop yields and quality, increasing soil water storage and reducing erosion, particularly in semi-arid regions like the Northern Great Plains. Soil aggregation is significantly impacted by common farming practices, including tillage and the types and sequences of crops grown, but until recently those effects have been not been quantified. ARS researchers at Sidney, MT developed a set of biological markers specifically to study the long-term tillage and cropping effects on soil aggregation and aggregate stability in dryland areas of the semi-arid eastern Montana area. In this study, researchers used those markers to compare soil aggregation levels in long-term spring-wheat systems using varied tillage and alternating crops, along with continuous wheat and wheat-fallow. Results have conclusively shown that: 1) aggregate stability improved over 12 years of no-till continuous spring wheat systems compared to wheat-fallow rotation with the values approaching those of samples from nearby perennial grass fields, and 2) long-term, continuous wheat-lentil rotations did not differ in aggregate stability compared to a wheat-fallow rotation. However, leaving lentil residues on the soil surface to control erosion was shown to minimize N mineralization making more N available to the subsequent crop, thereby reducing economic and environmental risks to the region’s producers. Consequently, leaving moderate amounts of lentil residue on the soil surface in no-till wheat-lentil rotations was found to be a better alternative for farmers in eastern Montana interested in long term sustainability of their operations than fallow or tilled lentil-wheat systems.
11. Collaborations expand crop diversity in the northwestern U.S. and boost rural economic development. A major agronomic concern in the Northern Great Plains region is the limited diversity of crops grown by producers, especially in dryland areas. That limited diversity increases risk to producers, contributes to disease and pest problems and impedes rural economic growth by limiting options to producers and small businesses. Consequently, ARS scientists at Sidney, MT are participating in two large, regional collaborative research initiatives with the intention of increasing dryland cropping diversity for the region’s producers and promoting rural economic development in these areas. Partners include the National Pulse Crop Association, several major universities, producers, seed companies, biofuel refiners, and various major end users of biofuels including airports and transportation providers. The first initiative is evaluating sustainable cropping systems, incorporating various dryland pulse crops produced in the Pacific Northwest and the Northern Great Plains regions. Researchers are also looking at the human health benefits associated with these same pulse crops. The second initiative enhances collaborative efforts with a consortium of universities, industry and ARS researchers evaluating sustainable cropping systems incorporating various oilseed crops produced across the region to ensure continuity of jet fuel supplies for commercial and defense aviation and other uses. In addition to their widespread regional focus, these initiatives also address cropping diversity and economic development issues raised by stakeholders in several local focus group meetings in eastern Montana and western North Dakota, where the vast majority (80%) of the nation’s annual pulse and oilseed crops are grown.
5. Significant Activities that Support Special Target Populations
A Native American Intern from South Dakota who is attending the United Tribes Technical College in Bismarck, ND had an 8 week internship with the Agricultural Systems Research Unit in Sidney, MT in 2010. The intern assisted with research on remote sensing of agricultural plant residues as part of a national ARS multi-location project. He initiated a small, personal research project on determination of plant residues (specifically, cheat grass and yellow clover) in rangelands. Overall, the internship was quite positive for both the student and ARS.
Jabro, J.D., Stevens, W.B., Iversen, W.M., Evans, R.G. 2010. Tillage depth effects on soil physical properties, sugarbeet yield and quality. Communications in Soil Science and Plant Analysis. 41: 7:908 -916.