Location: Columbia Plateau Conservation Research Center
Project Number: 2074-12210-002-001-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Aug 1, 2019
End Date: Jul 31, 2024
Objective:
Develop intensified production systems for dryland wheat cropping that enhance resilience by reducing input costs through N fixation and weed competition, and increasing revenue through yield gain, enhanced water infiltration and storage, and disease suppression.
Approach:
Two cropping trials, one for alternative crops (AC) and one for cover crops (CC), will be conducted. The winter wheat (WW)-chemical fallow (CF) system will be intensified with AC at a low precipitation (<250 mm) site as a WW-AC-CF rotation and at a high precipitation (<420-mm) site as a WW-AC rotation. Alternative crops include winter peas, winter lentil, mustard, barley, teff and safflower. The trial will be initiated by planting AC in a new place in the field for crop year (CY) 2020 and 2021 (low), or 2021 and 2022 (high) for two concurrent and offset evaluations per site. CC trial with fall-seeded CC will be assessed at the low precipitation site in WW-cover crop fallow (WW-ccF) where CC are terminated in early spring before depleting soil moisture for subsequent WW. Spring- and winter-planted cover crops include winter pea, phacelia, clover, mustard, radish or turnip, common vetch, barley, two mixtures, and fallow. The CC trial initiates with CC planting for CY 2020, 2021, 2022 for 3 concurrent and offset evaluations. All sites are managed under no till. The experimental design will be a randomized complete block with four treatment replications. AC will be seeded into WW stubble with a no-till disk drill (6.5’ wide, 9 openers, 7.5” row spacing) with plot sizes of 13×40’. Starter fertilizer will be placed below the seed. Additional fertilizer will be applied to WW and AC in the spring based on university recommendations. Weeds will be controlled with recommended post-emergence herbicides. Biomass, plant density, tillers, and weed density and weed cover per species will be evaluated within two 1 m2 frames placed within each plot. Weeds will be counted in AC prior spraying and pre-harvest, and at three times in the CC. Plots will be harvested with a small-plot combine. Harvest data for AC and WW will include grain yield, grain protein (or oil) concentration, test weight, and nutritional value of wheat grain. Soil water balance for AC will be determined by soil cores taken before spring seeding and after harvest for all plots. In addition to soil cores, all plot replicates in the CC trial will be instrumented with PR2 Profile Probes equipped with data loggers for continuous measurement of soil water. Soil chemistry (e.g. nitrite, ammonia, phosphate, pH) will be analyzed before planting and after harvest at two to three increments within the 30 cm of soil. Total N, total C, and soil organic matter will be analyzed post-harvest. Nutrient cycling enzyme activity related to C, N-, S-, and P- will be quantified from soil under AC and CC. Plant pathogens will estimated visually in the field through disease notes and the causal agents in soil will be quantified based on DNA abundance. Pathogen challenge experiments will be conducted in the lab to evaluate soils for disease suppressive properties in CY2021 and/or 2022. Results will be used to identify benefits or detriment of intensified cropping to the primary wheat crop in terms of herbicide use, disease incidence, nutrient availability, soil quality, and water availability.
