Location: Columbia Plateau Conservation Research Center
2023 Annual Report
Objectives
Objective 1: Quantify impact of intercropped legume cover crops with winter wheat to increase soil carbon and reduce herbicide and synthetic nitrogen (N) fertilizer inputs.
Sub-objective 1.A: Identify the best performing legume cover crops for intercropping with winter wheat that reduces herbicide and synthetic N while improving precipitation use efficiency in intermediate rainfall zones.
Subobjective 1.B: Examine whether legume cover crop intercropped with winter wheat can increase soil organic carbon (SOC), reduce herbicide and synthetic N fertilizer inputs, and reduce CO2 and CH4 emissions.
Objective 2: Measure deep root-zone water dynamics in dryland cropping systems to optimize water storage with tillage, crop residue, cover crop, and weed management.
Objective 3: Examine the use of biostimulants and biochar (such as thermal carbonized manure) as amendments in dryland wheat production systems in order to improve soil and plant health, profitability, and resilience to extreme weather and climate change.
Sub-objective 3.A: Establish whether the addition of biostimulants to soils can enhance plant growth and soil properties to reduce drought stress under semi-arid dryland wheat production conditions.
Sub-objective 3.B: Determine whether the addition of thermal carbonized manure to soils can increase soil pH in the N fertilizer application zone and enhance plant nutrient uptake under semiarid dryland wheat production systems.
Approach
1.A. Establish intercropped wheat with 4-legumes. Determine grain yields and wheat, legume, and weed biomasses. Apply herbicides while control subplots are covered to count weeds per species. Collect soil samples at the start of the experiment and after the 4th growing season. Determine total, organic and inorganic C, and N; and extractable P, NO3-N, and NH4-N. Collect soil samples for in-season N fertilization and determine dissolved and labile C and N at the time of N fertilization and at harvest. Monitor soil temperature and water. Collect CO2, N2O, and CH4 samples for two years. Perform life cycle analysis (LCA) from greenhouse gas (GHG) emissions from (1) diesel combustion at each stage of crop production, delivery of seed, fertilizers, pesticides, and (2) direct field emission of GHG.
1.B. Measurements are made in 1) wheat-fallow under reduced tillage, 2) no-till annual winter wheat, and 3) no-till wheat–wheat–sorghum/sudangrass. Half of the plots are planted and managed using herbicide. The other plots are intercropped with a legume. Monitor solar radiation with Albedometers. Collect soil samples and determine total and labile C and N as in 1.A. Soil temperature, water and GHG will be monitored, and the LCA will be performed as in 1.A.
2. Install soil water sensors below tillage depth in controlled experiments on post-harvest weed control, alternative crops, cover crops, and in farmer’s fields of selected management practices. Install sensors in 5-cm boreholes to monitor the root zone and below the root zone to detect upward and downward water movement. A minimum of 24 profiles under commercial farm practices in different locations are monitored for the soil and yield response to precipitation events, weed growth, and cropping patterns. Soil water storage, water extraction by the crop, and yield are principal measurements. The data is posted online in real-time.
3.A. Plots of no-till continuous wheat-wheat with 3-N fertilizer rates (0, 50, 100 kg N/ha) will be used. Apply biostimulants to 4 subplots within the N main plots at a rate of 3.7 L/ha at the 4th leaf growth stage. Grain, biomass yields, and harvest index are determined. Shoots and roots are sampled at V6 & maturity and stored (- 80°C) until analyzed. The samples are extracted and analyzed for up to 18 endogenous plant hormones, 8-carbohydrate and 11 phenol monomers. Carbohydrate monomers are hydrolyzed by H2SO4, separated by anion chromatography, and detected by pulsed amperometry. Phenol monomers are extracted by CuO oxidation and NaOH hydrolysis and detected by GC. Amino acid monomers are extracted, separated by anion chromatography and detected by pulsed amperometry.
3.B. Poultry litter will be pyrolyzed and compared with conifer wood and wheat straw biochars and replicated plots will be treated with each of the 3 biochars and incorporated by rotary tillage. Soil cores will be collected before and after application of the biochar. Total soil N, S, and C, extractable NO3 and NH4, micro- and macronutrients, soil pH, and EC are determined. Winter wheat will be seeded by hand for 3 yrs. Micro- and macronutrients in the wheat grain and straw will be determined at harvest.
Progress Report
This report documents progress for project 2074-11120-005-000D, “Nutrient Cycling and Precipitation Use Efficiency for Increasing Productivity and Resilience in Dryland Agroecosystems,” which started in October 2021.
In support of Sub-objective 1A, soil samples were analyzed for carbon and nitrogen. Weed infestation was evaluated by counting weed species in ½ x 1 m2 frames in each of the intercropped treatments. First season wheat and residue yields were determined. Daily weather, soil water and temperature data collections will continue until next growing season. This work supports the development of fundamental knowledge of and practices for soil-based management that contribute to greater agricultural productivity, reduced reliance on inputs, resilience to disturbances, and provide ecosystem services.
In support of Sub-objective 1B, 1,200 soil samples were collected from the top 15 cm (approximately 6 inches). Samples were analyzed for dissolved and labile carbon and nitrogen and 164 greenhouse gas(carbon dioxide, nitrous oxide, and methane) samples were collected from wheat and wheat-pea intercropped plots and analyzed weekly during the winter wheat growing season (October-July). Monthly collection from August to September will continue, including surface soil temperature and soil moisture measurements. This work contributes to quantifying driving factors in soil carbon cycling, including organic matter dynamics, carbon sequestration, and carbon dioxide, nitrous oxide, and methane emissions. This work also contributes to development of soil-crop-air strategies, technologies, and practices that ensure producers can adapt to climate change and extremes, remain resilient and profitable, and provide abundant food, feed, fiber, renewable energy, and ecosystems services.
In support of Objective 2, soil water sensor profiles transmitted data for part of the year from three farmers’ fields until rodent damage interrupted the network. A report was sent to participating farmers with graphs of the water use by the crops and recharge by rainfall. Rodent-proof cable has been purchased and has been installed in a new long-term experiment and sensors will be installed. Additional farmers have received agreements which will allow more sites to be instrumented after harvesting this year. The cover crop plots we intended to instrument have not been established yet, but an agreement has been reached for us to instrument another long-term tillage experiment after harvest. This research contributes to developing cropping systems that promote resilience to climate change.
Progress was made on projects which contribute to advancing our understanding of innovative, nontraditional soil amendment research, including biostimulants and biochars, to develop cropping systems that enhance agroecosystems and promote resilience to climate change. In support of Sub-objective 3A, crop yields were collected from the 12 plots. Biostimulants were applied late in the season because of high winter precipitations and low spring precipitation.
In support of Sub-objective 3B, 60 soil samples from four replications were analyzed for pH, nutrient, carbon and nitrogen. This contributes to advancing our understanding of nontraditional soil amendments that improve soil pH and plant nutrient availability which enhance agroecosystems productivity that promote resilience to climate change.
Accomplishments
1. Optimum tillage timing for soil water storage after a long fallow. Creation of a dry soil mulch to maintain near-surface moisture is used in many regions of the world for the timely establishment of crops after long fallow. Before the availability of herbicides, the first tillage during fallow was timed to kill weeds, but now the optimum timing for tillage depends on the interplay of evaporation and infiltration of rain. An ARS researcher in Pendleton, Oregon, along with a collaborator at Washington State University, measured the effect of delaying soil mulch creation progressively later in the spring and summer on weed-free fallow for winter wheat in the Mediterranean inland Pacific Northwest drylands of the United States. Seed-zone water and total stored water produced by different tillage timings were surprisingly constant. On average, only 2 percent of water was lost in the top 1.0 m (3.28 ft) of soil over an 80-day period. Tillage near the end of June often produced maximum soil water content. Presentations and on-line materials explain to farmers how to use this information to reduce tillage operations and improve weed control.
2. Soil organic carbon differences between no-till and minimum tillage. Interest in soil organic carbon (SOC) levels is focused on both soil quality and sequestering carbon from the atmosphere. An ARS researcher in Pendleton, Oregon, along with collaborators at Washington State University and Oregon State University, carefully measured SOC at three sites where long-term, randomized, replicated studies compared minimum tillage and no-till wheat--fallow in the low-precipitation inland Pacific Northwest, United States. To overcome seasonal, annual, and rotational effects, a soil sample was taken from each plot monthly for three years. The top 0- to 20-cm soil depth was analyzed for SOC. The tilled treatment had 7.21 g/kg of SOC compared to 7.04 for the no-till treatment (p < 0.004). There was a large variation in SOC month-to-month, but differences were 46 to 31 in favor of tillage and those 46 had larger SOC differences. The researchers conclude that no-till did not result in more soil carbon in these systems and therefore farmers can use judicious tillage when needed as an aid to sustainable production.
3. Impact of land use/cover change and slope gradient on soil organic carbon. An in-depth understanding of soil organic carbon (SOC) change with changes in land use and land cover (LULC) and slope gradient is crucial for climate change adaptation and mitigation measures. An ARS researcher in Pendleton, Oregon, along with collaborators at Haramaya University and University of Nebraska, quantified the impact of LULC change and slope gradient on SOC stock in the Anjeni Watershed in Ethiopia. Four land use types were quantified using Landsat imagery analysis. As expected, plantation forest had a significantly higher SOC than cultivated land, and gentle slopes had the highest SOC than steeper slopes. However, higher SOC stock and SOC sequestration rate was recorded when cultivated land was converted to grassland, while lower SOC stock and sequestration rate was recorded when land use changed from cultivation to a plantation forest. The results indicated that LULC changes and slope gradient had a major impact on SOC stock and carbon (C) sequestration rate over 30 years.
Review Publications
Wuest, S.B., Schillinger, W.F. 2022. Tillage timing to improve soil water storage in Mediterranean long fallow. Agricultural Water Management. 272. Article 107835. https://doi.org/10.1016/j.agwat.2022.107835.
Gollany, H.T. 2022. Assessing the effects of crop residue retention on soil health. In: Horwath, W., editor. Improving Soil Health. 1st edition. London, UK: Burleigh Dodds Science Publishing. p. 189-218. https://doi.org/10.19103/AS.2021.0094.12.
Milori, D., Martin-Neto, L., Gollany, H.T., de Babos, D.V., Leva Borduchi, L.C., Villas-Boas, P. 2023. Soil analysis using laser-induced breakdown spectroscopy. In: Goss, M.J., Oliver, M.A., editors. Encyclopedia of Soils in the Environment: Earth Systems and Environmental Sciences. 2nd edition. Amsterdam, NL: Elsevier. https://doi.org/10.1016/B978-0-12-822974-3.00211-1.
Wuest, S.B., Schillinger, W.F., Machado, S. 2023. Variation in soil organic carbon over time in no-till versus minimum tillage dryland wheat-fallow. Soil & Tillage Research. 229. Article 105677. https://doi.org/10.1016/j.still.2023.105677.
