Land Resources & Environmental Sciences
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/11
The Department of Land Resources and Environmental Sciences at Montana State Universityoffers integrative, multi-disciplinary, science-based degree programs at the B.S., M.S., and Ph.D. levels.
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Item Agro-economic returns were reduced for four years after conversion from perennial forage(2019-09) Miller, Perry R.; Bekkerman, Anton; Holmes, Jeffrey A.; Jones, Clain A.; Engel, Richard E.Perennial crops are increasingly converted to annual cropping systems as Conservation Reserve Program (CRP) contracts expire. We compared crop yields and net returns across 2013–2018 for no‐till pulse crop‐wheat (Triticum aestivum L.) (P‐W) systems, preceded either by 10 yr of P‐W or 10 yr of perennial cropping (P‐WPer) at Bozeman, MT. The perennial mixed species planting, dominated by alfalfa (Medicago sativa L.), was split into unharvested and annually harvested treatments 2005–2012. The 2013–2018 experimental design included both systems replicated as main plots, with 50 and 100% recommended available N rates as subplots. Precipitation was below average during three of the first four growing seasons, followed by two wetter than average years. The P‐WPer system had generally lower soil moisture and equal or greater nitrogen supply than the P‐W. ‘Haying off’ (reduced harvest index) occurred in wheat grown 2 and 4 yr after conversion from perennial to annual cropping, which reduced grain yield, and increased grain protein. Crop yield losses in the P‐WPer system averaged 0.84 Mg ha–1 (28%) over 4 yr and two N rates. After adjusting grain prices using historical discounts and premiums for test weight and protein content at Montana grain elevators, P‐WPer net returns were reduced for four consecutive years in three economic scenarios, and for 2 yr in a fourth scenario by a 4‐yr cumulative average of (USD) $731 ha–1 (45%). We conclude annual crop yield and economic returns were compromised for 4 yr following 10 yr of an alfalfa‐dominated perennial cropping system.Item Vulnerability of dryland agricultural regimes to economic and climatic change(2018) Lawrence, Patrick G.; Maxwell, Bruce D.; Rew, Lisa J.; Ellis, Colter; Bekkerman, AntonLarge-scale agricultural systems are central to food production in North America, but their ubiquity could be threatened by vulnerability to economic and climatic stressors during the 21st century. Prior research has focused on understanding the influence of climatic changes on physiological processes in these systems and has increasingly recognized that other factors such as social, economic, and ecological variation and the interaction among these factors may cause unexpected outcomes. We assess the vulnerability of large-scale agricultural systems to variation in multiple stressors and investigate alternative adaptation strategies under novel conditions. We examine dryland farms in Montana’s northern Great Plains (NGP), which represent large-scale semiarid agricultural systems that are likely to be affected by climate change. Farmers in the NGP have experienced three distinct periods of economic- and drought-related stressors since the 1970s, primarily driven by uncertainty in soil moisture, but at times amplified by uncertainty in nitrogen fertilizer and wheat prices. We seek to better understand how farmers evaluate and respond to these conditions. The results indicate that although farmers perceived few alternative agronomic options for adapting to drought, strategies for adapting to high input prices were more plentiful. Furthermore, we find that increasing the overall resilience of dryland agricultural systems to economic and climatic uncertainty requires intrinsic valuation of crop rotations and their field-specific response to inputs.Item Fallow replacement and nitrogen management for reducing nitrate leaching in a semi-arid region(2017-05) John, Andrew A.; Jones, Clain A.; Ewing, Stephanie A.; Sigler, W. Adam; Bekkerman, Anton; Miller, Perry R.Nitrate (NO3 −) leaching into groundwater is a growing global concern for health, environmental, and economic reasons, yet little is known about the effects of agricultural management practices on the magnitude of leaching, especially in dryland semiarid regions. Groundwater nitrate–nitrogen (nitrate–N) concentrations above the drinking water standard of 10 mg L−1 are common in the Judith River Watershed (JRW) of semiarid central Montana. A 2-year study conducted on commercial farms in the JRW compared nitrate leaching rates across three alternative management practices (AMP: pea, controlled release urea, split application of N) and three grower standard practices (GSP: summer fallow, conventional urea, single application of urea). Crop biomass and soil were collected at ten sampling locations on each side of a management interface separating each AMP from its corresponding GSP. A nitrogen (N) mass balance approach was used to estimate the amount of nitrate leached annually. In 2013, less nitrate leached the year after the pea AMP (18 ± 2.5 kg N ha−1) than the year after the fallow GSP (54 ± 3.6 kg N ha−1), whereas the two AMP fertilizer treatments had no effect on nitrate leaching compared to GSPs. In 2014, leaching rates did not differ between each AMP and its corresponding GSP. The results suggest that replacing fallow with pea has the greatest potential to reduce nitrate leaching. Future leaching research should likely focus on practices that decrease deep percolation, such as fallow replacement with annual or perennial crops, more than on N fertilizer practices.Item Pea in Rotation with Wheat Reduced Uncertainty of Economic Returns in Southwest Montana(2015-01) Miller, Perry R.; Bekkerman, Anton; Jones, Clain A.; Burgess, Macdonald H.; Holmes, Jeffrey A.; Engel, Richard E.Pea (Pisum sativum L.) is increasingly being rotated with wheat (Triticum aestivum L.) in Montana. Our objective was to compare economic net returns among wheat-only and pea–wheat systems during an established 4-yr crop rotation. The experimental design included three wheat-only (tilled fallow–wheat, no-till fallow–wheat, no-till continuous wheat) and three no-till pea–wheat (pea–wheat, pea brown manure–wheat, and pea forage–wheat) systems as main plots, and high and low available N rates as subplots. Net returns were calculated as the difference between market revenues and operation and input costs associated with machinery, seed and seed treatment, fertilizer, and pesticides. Gross returns for wheat were adjusted to reflect grain protein at “flat” and “sharp” discount/premium schedules based on historical Montana elevator schedules. Cumulative net returns were calculated for four scenarios including high and low available N rates and flat and sharp protein discount/premium schedules. Pea–wheat consistently had the greatest net returns among the six systems studied. Pea fallow–wheat systems exhibited greater economic stability across scenarios but had greater 4-yr returns (US$287 ha–1) than fallow–wheat systems only under the low N rate and sharp protein discount schedule scenario. We concluded that pea–wheat systems can reduce net return uncertainties relative to wheat-only systems under contrasting N fertility regimes, and variable wheat protein discount schedules in southwestern Montana. This implies that pea–wheat rotations, which protected wheat yield and/or protein levels under varying N fertility management, can reduce farmers’ exposure to annual economic variability.