Location: Northwest Irrigation and Soils Research
2024 Annual Report
Objectives
Objective 1: Develop improved practices and strategies for managing inputs in irrigated cropping systems to increase soil health, optimize crop productivity and quality, and minimize negative environmental impacts.
Sub-objective 1A: Identify effects of fertilizer source, timing of application, and nitrification/urease inhibitors on nutrient cycling and field-scale nutrient budgets.
Sub-objective 1B: Identify effects of past manure application rate and frequency on biological indicators of soil health, nutrient cycling, and field-scale nutrient budgets.
Sub-objective 1C: Determine the efficacy of cover crops and minimum tillage to reduce offsite transport of soil nutrients in a dairy forage crop rotation receiving manure.
Sub-objective 1D: Determine the long-term agronomic economic effects of manure applications on crops, soil nutrient (primarily N, C, and P) cycling, and soil health indicators.
Sub-objective 1E: Determine effects of crop rotation, tillage, and residue management on residue breakdown rates and nutrient cycling in irrigated cropping systems.
Sub-objective 1F: Evaluate aboveground biomass yield, forage quality, and nutrient cycling of sorghum-sudangrass hybrids under multiple management practices (row spacing, number of cuttings, and cultivar).
Objective 2: Quantify gaseous emissions from dairy production facilities and manure-amended soils to improve nutrient cycling and reduce environmental impact of these systems.
Sub-objective 2A: Determine the effect of manure application rate and frequency on soil GHG emissions.
Sub-objective 2B: Determine the effect of manure, cover crop, and minimum tillage on soil GHG emissions.
Sub-objective 2C: Determine ammonia transport and dry deposition in the Magic Valley region and improve accuracy of deposition models.
Approach
Resilient irrigated cropping systems in concentrated dairy production regions require proper management of nutrients to maximize agricultural production while minimizing environmental impacts. Dairy farms in the region generally have more cows and produce more milk than in the past. With the increased number of cattle comes an increased production of manure that must be managed. Crop production coexists in the region with a diverse assortment of crops with varying nutrient needs to meet yield and quality goals. The current project will address crop production and environmental issues that results from concentrated dairy and crop production. Broadly, the project objectives are to improve crop nutrient use efficiency, minimize nutrient and greenhouse gas losses to the environment, investigate novel crops, and determine the impact of crop residues in the agroecosystem. These objectives will lead to improved management practices for irrigated cropping systems in semi-arid environments.
Research consists of several continuing long-term studies along with newly developed projects. Objective 1 is focused on how inputs are managed and effect the agroecosystem. The objective is comprised of seven studies. Long-term studies will evaluate the impact of synthetic fertilizers (with and without nitrification inhibitors in one study) and dairy manure on crop response, nutrient cycling, and soil health. New studies will evaluate impacts of novel cropping approaches, including forage cover crops and grasses such as sorghum-sudangrass, on crop production, nutrient cycling, and soil health. Additionally, these studies will address the impact of crop rotation, tillage, and residue management practices on these factors as well. Objective 2 contains three projects focused on determining gaseous emissions from dairy facilities and manure-amended soils. Long term manure application rate effects on greenhouse gas emissions will be studied. A second study will measure the effects of manure, cover crop, and minimum tillage on greenhouse gas emissions. The final project will determine regional ammonia nitrogen transport to improve models that predict ammonia depositions from the atmosphere to the soil surface.
Progress Report
This report documents progress for project 2054-12000-013-000D, titled, “Developing Resilient Irrigated Cropping Systems in Concentrated Dairy Production Areas of the Semi-arid West”, which started in December 2021.
A wide range of studies are ongoing addressing Objective 1, “Develop improved practices and strategies for managing inputs in irrigated cropping systems to increase soil health, optimize crop productivity and quality, and minimize negative environmental impact.” Research on greenhouse gas emissions and soil health as part of the USDA-ARS nationwide greenhouse gas reduction through agricultural carbon enhancement network (GRACEnet) program continued. In this study, dairy manure was applied in the spring and fall, and urea was applied with and without nitrification inhibitors. Silage corn was harvested for yield determinations and nutrient concentrations were measured in the plants. In the spring, soil samples were collected to 60 cm, and are currently being analyzed for nutrients, metals, and organic carbon. The field was planted with barley following the application of spring manure and urea. After harvest of barley this summer, this 12-year field project is scheduled for termination.
Another long-term study is in its 11th year and the fourth year since the last manure application. Silage corn and sorghum sudangrass were harvested and triticale planted on one of the two fields. All soil and plant samples collected to date have been analyzed for nutrient concentrations. Plant samples have been either analyzed for forage quality or shipped for analysis. Data and soils from this long-term study have been used by two University of Idaho graduate students resulting in one publication in FY24 and use for validation of a nutrient model. Data from this study are used to determine the amount of nutrients removed by crops from these soils to help producers determine the length of time necessary to reduce elevated soil phosphorus concentrations back to agronomic ranges below the Idaho state thresholds.
Research has continued on assessing the effects of cover crops and tillage on soil nutrients in a dairy forage crop rotation receiving manure. In FY 24 silage corn was harvested with plant samples analyzed for nutrient content and forage quality.
It is the sixth year of manure priming and manure legacy studies assessing the long-term effects of dairy manure applications on crop production and soil properties. In FY24 sugarbeet was planted and when harvested will complete the second cycle of the three-year cropping rotation. Soil and plant samples from the 2023 cropping year were analyzed for nutrient concentrations to determine nutrient budgets. Manure treatments are being compared to fertilizer treatments to determine the economic value of manure over time. This data will help determine the feasibility of improved manure distribution and fertilizer input reductions. In FY24, two papers assessing the effect of the treatments on the soil microbiome have been prepared for publication (One paper published in Agriculture & Environmental Letters. A second paper was submitted to Agronomy Journal for review).
Research on alternative cropping systems and sustainable practices for irrigated semi-arid production continued. The first study is assessing wheat/barley, barley, dry bean rotations, tillage practices, and residue management. Seed and residue yield were determined, and soil samples collected and analyzed. Dry beans were grown for the first year of the study with some yield damage due to insects. Aside from this, these studies have progressed as planned and production for the current growing season is under-way for both dry bean and barley. Research has indicated that soil health changes are slow to occur in the semi-arid environment of the study and that incorporated residues decompose faster than those left on the surface. Additionally, greenhouse gas emissions measurements began in 2024, with early data indicating very low emissions across the study.
The second study investigated sorghum-sudangrass management practices. Crop biomass, crop water use, and forage quality were measured. Sorghum-sudangrass diversifies current semi-arid cropping systems in the region as it provides another warm-season grass that can be grown in addition to corn, especially following a winter forage crop. Samples for this study are completed and full analysis will be undertaken in the near future. This research is providing specific management guidelines to optimize forage production of irrigated sorghum-sudangrass in an intensive dairy production region.
Research continued focused on addressing Objective 2, “Quantify gaseous emissions from dairy production facilities and manure-amended soils to improve nutrient cycling and reduce environmental impact of these systems.” Measurement of greenhouse gas (GHG) emissions, using an automated chamber system, was performed throughout the fall (2023) and winter (2024). Cumulative emissions of nitrous oxide were found to be significantly greater in the manure-treated soils compared to those receiving synthetic fertilizer, despite the fact that the last application of manure occurred in 2019. The cumulative emissions were still found to be positively correlated with the previous manure application rates. This research continues to demonstrate that manure has long-term effects on soil gas emissions and that winter emissions represent a significant fraction of total annual GHG emissions.
In a second study with tillage, manure and cover crop treatments, soil GHG emissions measurement was completed in Fall 2023 at project termination. Nitrous oxide emissions were found to be greater in conventionally tilled versus minimally tilled (i.e., strip tillage) treatments in 2021 only, with no significant differences found in 2022 and 2023. However, all plots were inversion tilled in spring 2022 (moldboard plow), which may have contributed to this result between these main treatments. Analysis of the sub-treatments (manure or no manure with and without cover crop) on nitrous oxide fluxes revealed that emissions were greatest from manured soils with no apparent effect of cover crop. A manuscript of these results is currently being prepared and it will be submitted for peer-review in 2025.
Finally, two ammonia deposition towers were operated in southern Idaho to determine the amount of ammonia deposition at each location as well as determine the environmental factors that control deposition of ammonia in the region. The data from this joint project with the U.S. Environmental Protection Agency (EPA) is being used to improve air quality models that estimate ammonia transport and deposition within the continental U.S. Two papers were published in FY24 utilizing ammonia concentration data obtained as part of this larger project, focusing on evaluating the accuracy of satellite estimates of ground-based ammonia concentrations and estimating dry deposition in the Magic Valley region utilizing current EPA models.
Accomplishments
1. Soil health indicators reveal that past dairy manure applications create a legacy effect. Manure application can impact soil properties for many years after application. ARS researchers in Kimberly, Idaho, measured soil health indicators in soil that last received manure 11 years prior to sampling. Many soil health indicators were different between manure and non-manure soils despite having uniform management practices for the last ten years. These results indicate the long-term and positive impact that manure application can have on irrigated crop production in semiarid regions.
Review Publications
Cady-Pereira, K., Guo, X., Wang, R., Leytem, A.B., Calkins, C., Berry, E., Sun, K., Muller, M., Wisthaler, A., Payne, V., Shephard, M., Zondlo, M., Kantchev, V. 2024. Validation of MUSES NH3 observations from AIRS and CrIS against aircraft measurements from DISCOVER-AQ and a surface network in the Magic Valley. Atmospheric Measurement Techniques. 17(1):15-36. https://doi.org/10.5194/amt-17-15-2024.
Kerner, P., Struhs, E., Mirkouei, A., Aho, K., Lohse, K., Dungan, R.S., You, Y. 2023. Microbial responses to biochar soil amendment and influential factors: A three-level meta-analysis. Environmental Science and Technology. 57(48):19838-19848. https://doi.org/10.1021/acs.est.3c04201.
Leytem, A.B., Walker, J.T., Wu, Z., Nouwakpo, S.K., Baublitz, C., Bash, J., Beachley, G. 2023. Spatial distribution of ammonia concentrations and modeled dry deposition in an intensive dairy production region. Atmosphere. 15(1). Article 15. https://doi.org/10.3390/atmos15010015.
Tarkalson, D.D., Rogers, C.W., Bjorneberg, D.L., Dungan, R.S. 2024. Soil health indicators reveal that past dairy manure applications create a legacy effect. Agricultural & Environmental Letters. 9(1). Article e20128. https://doi.org/10.1002/ael2.20128.
Leytem, A.B., Dungan, R.S., Spiehs, M.J., Miller, D.N. 2024. Safe and sustainable use of bio-based fertilizers in agricultural production systems. In: Amon, B., editor. Developing Circular Agriculture Production Systems. 1st edition. Cambridge, UK: Burleigh Dodds Science Publishing. p. 179-214. https://doi.org/10.19103/AS.2023.0120.16.