Location: Agricultural Systems Research2011 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
Laboratory and field data from both 2010 irrigated and dryland research programs are analyzed and statistically summarized. Several manuscripts have been submitted and published. Irrigated cropping systems research included a new project comparing a two-year sugarbeet/malt barley rotation to three-rotations that include legumes and/or bioenergy crops. 2011 was the final year for: (1) a long term Unit study evaluating interactions of high-frequency irrigation and 3-year crop sequences with sugarbeet, malt barley and potato; (2) an evaluation of polymer-coated slow-release urea on sugarbeet grown on sandy soils; (3) a field study on soil nitrogen availability during transitions from perennial grass/alfalfa to annual cropping systems; and (4) evaluations of starter fertilizer benefits for sugarbeet grown with intense, moderate or zero tillage. A new study was started to determine yield effects due to lateral distances between the sugarbeet plant and banded preplant fertilizer under strip tillage. Soil and plant data were collected for the 3rd year of 4-yr tillage depth study. Progress was also made on five different dryland cropping systems research projects, which included the continuation of a multi-site study investigating interactive effects of tillage, diversification, and cultural management practices on crop yield, competitiveness with weeds, water use, and nitrogen cycling and use efficiency. Other investigations included: (1) spring wheat-oilseed (camelina, crambe and B. juncea) rotations replacing summer fallow; and (2) studies on tillage, cultural management and rotation influences on spring wheat, durum, pea, canola, flax, corn, and forage barley. Yield and soil samples were collected and analyzed on the long-term dryland spring wheat cropping systems study initiated in 1984. Initial data were collected on a perennial dryland grass biomass trial with varying levels of N fertility. Aggregate stability and size distribution data and the isolation and storage of dominant bacteria from soil aggregates or from rhizosphere samples from long term dryland rotation comparing continuous malt barley and barley/pea have been completed for 2010. Studies were continued evaluating biological control of P. teres (net blotch disease) on both irrigated and dryland barley by the beneficial fungal pathogen L. arvalis. A parallel trial was continued evaluating control using L. arvalis for both Cercospora leaf spot disease of sugarbeet and net blotch on barley. Rapid PCR detection and ELISA protocols developed at Sidney were applied to evaluate efficacy in soil and plant samples. Modeling agricultural systems at both dryland and irrigated sites using RZWQM2 model is continuing in collaboration with researchers in Ft. Collins, CO. Remote sensing techniques were used for the second year in relation to post-harvest plant residue assessment in the northwest. Fields were located in northeastern Montana, northwest ND, Akron, CO, Pendleton, OR and Pullman, WA.
1. Oilseed crops for biofuel in crop rotations. Sustainable biodiesel and jet fuel production will require widespread planting of oilseed crops. Summer fallow is commonly practiced on several million acres annually in Montana to control weeds and conserve water and nutrients for subsequent wheat production, and these fallowed lands can potentially be planted to oilseed crops. ARS researchers at Sidney, MT, in collaboration with South Dakota State University determined yield, quality, weed and insect pest communities, and water and nitrogen use of three diverse cool-season oilseeds (canola-quality Brassica juncea, camelina and crambe) in two-year rotations with durum wheat. They discovered over a 5 year study that canola-quality Brassica juncea had significantly superior seed and oil yield compared to the other oilseed crops, out-yielding crambe and camelina in seed production by more than 100 and 360 lbs per acre respectively, and similarly out-yielding both in oil per acre by about 175% more than camelina and 145% more than crambe. Under this study, durum wheat yields in rotations with the three oilseed crops were about 25%-35% lower than durum wheat in summer fallow rotations, due to greater soil water use by the oilseed crops. However, when total income from annual crops is compared to rotations in which crops are planted only every other year, producers with annual crops typically earn a higher overall return despite reduced durum wheat yields. Taken as a whole, this research demonstrates that B. juncea’s superior yield and oil producing qualities make it a promising candidate to meet future US biofuel production needs by altering crop rotations in semi-arid areas of the Northern Great Plains.
2. Study identifies best remote sensing technique for evaluating crop residue cover. The use of remote sensing technology in assessing different landscape characteristics for ascertaining agronomic, geophysical, and climatic conditions has increased significantly over the past decade. This information is valuable input in modeling, planning, environmental remediation, and monitoring activities. However, many of the remotely sensed indices available have not been tested under actual field conditions. Consequently, ARS scientists in Sidney, MT, and Akron, CO, and their collaborators in Pendleton, OR, and Pullman, WA, tested the performances of five different remote sensing indices measuring crop residue in their four different locations. They evaluated the indices accuracy under different crops, management/tillage methods and soil types, as well as under various harvesting methods, relative stubble positions and decomposition stages. They determined that the cellulose absorption index (CAI), appears to be the most robust in performance in effectively estimating residue cover and residue amount across the many field variations found in the semi-arid dryland regions of the US. That residue information could be useful in: quantifying biofuel or carbon sequestration potential in croplands, evaluating the sustainability of different cropping systems and assessing “fuel loads” for wildfire potential and abatement in rangelands. The new technique also holds potential for many other field, management, and computer modeling applications as well, such as projecting carbon sequestration and verifying compliance with government farm conservation programs.
3. Proper management means no additional Nitrogen (N) fertilizer needed with strip tilled sugarbeets. The adjusted value of U.S. sugarbeet crop output in 2002 was 2.6 times higher than that in 1948, while the amount of fertilizer and other production inputs required to achieve this output have declined. However, the costs of those inputs, including energy and fertilizers, have been escalating in that same period leading to declining profitability for many farms producing major commodity crops. Past strip tillage research at Sidney, MT showed it was possible to reduce annual production costs by $80-$100/ac/yr on sugarbeet, helping to combat those rising costs. The research also indicated that additional savings could be realized through better N fertilizer management with these reduced tillage systems where fertilizer is banded within the tilled strip. Because this tillage system is relatively new in sugarbeet production, information regarding optimum fertilizer management practices and placement was lacking. Subsequently, in studies evaluating the impact of strip tillage on the efficacy of N fertilizer, Sidney, MT USDA researchers and their collaborators showed that while N availability and uptake by the sugarbeet plant tended to be lower with strip tillage than with conventional practices, sugarbeet yield under strip tillage could be maintained with the same N application rate as conventional tillage provided proper placement and application timing practices were followed. With rising fertilizer costs, maximizing fertilizer use efficiency is critical. This research showed that no additional costly N fertilizer was needed for strip tilled sugar beet production as long as producers follow the new management guidelines developed under the Sidney ARS study.
4. No-tillage with regular management practices increases carbon and nitrogen sequestration and soil quality. For the last several decades wide spread use of conventional tillage practices combined with crop-fallow rotations have resulted in a 30 to 50% decline in dryland soil organic matter and crop yields in the semi-arid northern Great Plains. Soil organic matter is a major source of carbon and nitrogen plant nutrients found in the soil. Therefore, improved management practices are needed to help restore soil organic matter to predevelopment levels in order to sustain long-term crop productivity. Consequently, over the past five years (2004-2008) USDA scientists at Sidney, MT, have conducted studies at the location evaluating the effects of tillage, crop rotation, and cultural practices on soil carbon (C) and nitrogen (N) levels. Results showed that no-tillage in diverse four-year cropping rotations (spring wheat-hay barley-corn-pea) employing conventional management practices (early planting, normal seeding rates, broadcast N fertilization, and short stubble height) increased C and N sequestration in the surface residue and in soil microbial biomass and activity. In contrast, conventional tillage with a continuous spring wheat sequence using the same conventional management practices increased N mineralization and availability to the crop, but reduced available soil organic N for future crops This research shows that no-tillage with a diversified cropping rotation and early planting may be used to increase dryland soil C and soil N sequestration compared to conventional management practices with continuous spring wheat and early planting. A further benefit of this study, the results also showed that soil nitrate-N testing done in the fall may be used to determine N fertilizer applications for the succeeding no-till crops next spring, which saves time for farmers and allows them to plant crops earlier in the season to obtain higher yields.
5. Natural freeze-thaw cycles reduce soil compaction from agricultural practices. Soil compaction due to typical farm field operations is an acknowledged problem in the Northern Great Plains. Intensive farming, inappropriate soil management and heavier machinery have led to increases in soil compaction in recent years prompting greater local and global concerns regarding reductions in crop production and soil quality under mechanized agriculture. That concern has led to increased use of deep tillage and sub-soiling techniques by producers, which involve considerable expenditures of time, money and energy. USDA scientists at Sidney, MT, have found that frequent freeze-thaw cycles over the winter helped alleviate a majority of soil compaction at the 0 to 8 inch depth, which encompasses the underground root zones of many crops. Soil penetration resistance – an indirect measure of how difficult it is for water and nutrients to move through the soil for plant use – was reduced by approximately 70% in compacted soils over the winter at the 0 to 8 inches depths, largely due to the physical effects of freeze-thaw cycles that break up compacted soil structures and particles. In a comparison with unfrozen compacted soils, the penetration resistance was reduced by only about 50 to 60% over the winter, largely due to soil microbial activity and soil shrink-swell cycles resulting from soil moisture changes. These results demonstrate how natural freeze-thaw and winter moisture cycles assist in alleviating soil compaction, thereby contributing to the sustainable growth of agricultural crops and freeing producers from the need to employ additional costly measures to achieve the same results.
6. Irrigation and no tillage enhance beneficial bacteria in dryland soil. Few reports have focused on the impacts of irrigation, tillage, and cropping systems on soil microbial communities contributing to soil aggregation ( a measure of soil quality) in semi-arid areas. Soil aggregation is the natural clumping of soil particles that subsequently create open pathways for water and nutrient movement and plant root growth underground. In earlier studies, Sidney, MT, ARS researchers have identified a number of soil bacterial communities contributing to soil aggregation and are now looking at the impacts of various farming practices on those communities. USDA researchers at Sidney, MT, compared irrigation, tillage and cropping system effects on the distribution of soil aggregates and key soil-aggregating bacterial communities at a site in western North Dakota from 2005 to 2008. Two irrigation treatments (irrigated vs. non-irrigated) under six management practices that contained malting barley with no-till and conventional tillage and an established no-till Conservation Reserve Program grass-mixture planting were studied. The results demonstrated that irrigation and no tillage substantially increased development of soil aggregates and improved soil stability. Moreover, irrigation and management practices that develop high organic matter at the soil surface favored the growth and survival of specific, beneficial groups of bacteria which have been shown to aid soil aggregation in both non-irrigated (dryland) and irrigated conditions. This information provides valuable management guidelines, particularly to producers using irrigation with no-till practices, on ways to improve their soil quality and the sustainability of their farming operations.
7. Novel DNA technique adapted for rapid identification of small grain disease. USDA researchers in Sidney, MT, have developed a unique set of genetic diagnostic tools that allow scientists to rapidly identify key genetic fragments unique to fungal plant diseases plaguing agricultural producers, including Cercospora leaf spot, a major disease in sugarbeets. Recently, Sidney, MT, researchers have adapted the technique to detect the presence of another common fungal crop disease, net blotch in small grains. In that study, researchers were able to rapidly detect and confirm net blotch infection in several leaves in test barley fields. With this successful detection, scientists will now be able to move quickly forward in evaluating the efficacy of a new fungal biological control agent being studied for use against net blotch. That agent shows real promise in providing growers with a new, environmentally friendly, disease management tool for sustainable crop protection.
8. Seeding rate impacts dryland corn production more than row configuration. Growers and researchers in the northern Great Plains are seeking suitable cropping alternatives to the common wheat-summer fallow cropping system that uses stored soil water inefficiently and contributes to soil degradation. Dryland corn acreage has increased in semi-arid NE Montana and NW North Dakota from about 7,000 acres in 2001 to 69,000 acres in 2010. However, dryland corn yields are highly variable and growers lack information on appropriate best management practices. USDA scientists at Sidney, MT, have evaluated various dryland corn seeding rates and the effect of conventional planting vs 3 different “skip-row” configurations in which some rows are not planted or “skipped” to provide a potential yield advantage because soil water “stored” in the skipped rows could be available for the planted rows later in the season. Reduced seeding rates may also offer a potential yield benefit, with fewer plants competing for limited soil water, and also reduces the cost of seed compared to more traditional approaches. Research conducted over three years at four sites showed greater corn yields at the lowest seeding rate (10,000 seeds/ac) during relatively dry years with about 10 inches of growing season precipitation. However, with above normal growing season precipitation (13 to 18 inches), corn yields were greatest at the highest seeding rate (16,000 seeds/ac). There was no yield advantage to any of the skip-row planting configurations in wet or dry years, and in many cases skip-row corn yielded significantly less than corn planted in every row. This research shows that dryland producers using reduced seeding rates in forecasted dry years can improve their bottom line through both lower seed costs and better yields than they have experienced in the past using regular row spacing.
9. Irrigation and management impact on greenhouse gas emissions in agriculture. Little is known about the effects of irrigation and various management practices on greenhouse gas emissions from agriculture in the semi-arid northern Great Plains. Agriculture accounts for about 25% of the carbon dioxide emissions resulting from human activity, and an even higher percentage of the nitrous oxide emissions, primarily due to the use of nitrogen fertilizers. Both gases contribute to global warming. USDA scientists at Sidney, MT, evaluated the effect of irrigation, tillage, crop rotation, and N fertilization on greenhouse gas emissions from 2008 to 2010 in western North Dakota. The goal was to help producers identify practical alternatives, using existing crop and management options, for reducing emissions of carbon dioxide and nitrous oxide in their irrigated operations. Under the study, researchers found that irrigation increased carbon dioxide emissions compared with no irrigation especially when air and soil temperatures increased. In contrast, irrigation had a variable effect on nitrous oxide emissions. Tillage did not influence carbon dioxide emissions, but nitrous oxide emissions were greater with conventional tillage than with no-tillage. Nitrogen fertilization increased both carbon dioxide and nitrous oxide emissions compared with no fertilization on irrigated lands. Both carbon dioxide and nitrous oxide emissions were lower with a malt barley-pea rotation than in continuous malt barley production, in part because less nitrogen fertilizer was needed with the introduction of field peas into the cropping rotation. Peas are legumes that fix nitrogen in the soil, making it available for succeeding crops. The study provides a new alternative crop rotation (malt-barley and pea) to producers for reducing greenhouse gas emissions while improving the sustainability of their operations.
10. Management practices effect on dryland crop yields and greenhouse gas emissions. Improved management practices are needed to sustain dryland crop yields and reduce greenhouse gas emissions. The greenhouse gases studied included carbon dioxide and nitrous oxide. Agriculture accounts for about 25% of the carbon dioxide emissions resulting from human activity, and an even higher percentage of the nitrous oxide emissions, primarily due to the use of nitrogen fertilizers. Both gases contribute to global warming. USDA scientists at Sidney, MT, have evaluated the effect of tillage, cropping sequence, and nitrogen (N) fertilization on malt barley yields from 2006 to 2010 and greenhouse gas emissions from 2008 to 2010. Under the yield study, malt barley grain yields increased with nitrogen fertilization and were greater following fallow than following either malt barley or field pea especially during drier years. No-tilled continuous cropping and N fertilization increased carbon dioxide emissions compared with conventional-tilled crop-fallow and no N fertilization. In contrast, conventional-tilled crop-fallow and N fertilization increased nitrous oxide emissions. Methane emissions, another greenhouse gas under study, were negligible. This research is part of a nationwide USDA research program (GRACEnet) to assess soil carbon sequestration and greenhouse gas mitigation in various agricultural management practices. This research is providing agricultural producers with practical, regionally adapted management options to mitigate greenhouse gas emissions and increase soil carbon sequestration for sustainable cropping systems.
11. Portable chamber effectiveness in measuring soil carbon dioxide emissions. Carbon dioxide (CO2) is one of the greenhouse gases responsible for global warming. Agricultural practices contribute about 25% of the total CO2 emissions attributable to human activity. Consequently research efforts are underway to identify alternative practices to reduce those emissions, but existing methods for measuring those gases in the field are complex and costly. A portable chamber using an infrared analyzer is a simple, rapid, and inexpensive alternative method for measuring CO2 but its effectiveness and precision compared to the standard method which employs static chambers using gas chromatographs is not well known. Consequently, USDA scientists at Sidney, MT, instituted a study comparing the two processes under both dryland and irrigated cropping systems in eastern Montana and western North Dakota and under various management practices in loam and sandy loam soils. They found that the CO2 measurements varied with treatments more in the portable than in the static chamber, averaging 9% lower in loam soil under dryland cropping systems, and 84% greater in sandy loam soil under irrigated and non-irrigated cropping systems. However, the CO2 variations from the portable and static chambers were found to be consistent across treatments. Those results indicate that while the portable chamber may provide a more reliable measurement of CO2 emissions under dryland conditions in loam soil, they also indicate that rapid and reliable measurement of variations in CO2 emissions can be made with a portable chamber under many conditions, reducing the need for a more tedious, complex, and expensive static chamber.
Sainju, U.M., Lenssen, A.W., Caesar, T., Jabro, J.D., Lartey, R.T., Evans, R.G., Allen, B.L. 2011. Dryland residue and soil orgranic matter as influenced by tillage, crop rotation, and cultural practice. Plant and Soil Journal. 338:27-41.