Soil Health in Dryland Agriculture

Authors: Reardon, Catherine; Acosta Martinez, Veronica

Submitted to: Pendleton Station Field Day
Publication Type: Abstract Only
Publication Acceptance Date: 6/10/2025
Publication Date: 6/10/2025
Citation: Reardon, C.L., Acosta Martinez, V. 2025. Soil Health in Dryland Agriculture. Pendleton Station Field Day. P. 15.

Interpretive Summary: Healthy soils are a crucial component for productive and sustainable agricultural systems. Soil microbial communities are essential to soil functions that drive crop productivity including nutrient cycling, soil structure, and disease suppression. Numerous factors including the environment, soil properties, and management impact the structure and function of the soil microbial communities – understanding these interactions is important to develop and sustain soil health. This talk will discuss research in the Pacific Northwest dryland region under low to intermediate precipitation in which the primary cropping system, winter wheat – fallow, is practiced to store soil moisture and stabilize yields of the winter wheat crop. Crop diversification is one opportunity to enhance soil health. In the wheat-fallow system, we found that a short-term crop rotation with oilseeds (canola and mustard) can improve soil aggregation and reduce first and rate limiting step of nitrification that can leave soil nitrogen in a form (nitrate) susceptible to leaching and gaseous loss through denitrification. This rotation can also maintain carbon, phosphorous and sulfur cycling. Additionally, fungal soil communities are responsive to canola growth both in the short term (root-associated) and with legacy effects. Overall, the effects of various crop management strategies on soil health and soil biology will be discussed.

Technical Abstract: Healthy soils are a crucial component for productive and sustainable agricultural systems. Soil microbial communities are essential to soil functions that drive crop productivity including nutrient cycling, soil structure, and disease suppression. Numerous factors including the environment, soil properties, and management impact the structure (diversity and composition) and function (i.e., nutrient cycling capacity) of the soil microbial communities – understanding these interactions is important to develop and sustain soil health. This talk will discuss research in the Pacific Northwest dryland region under low to intermediate precipitation in which the primary cropping system, winter wheat – fallow, is practiced to store soil moisture and stabilize yields of the winter wheat crop. Crop diversification is one opportunity to enhance soil health. In the wheat-fallow system, we found that a short-term crop rotation with oilseeds (canola and mustard) can improve soil aggregation and reduce the rate of potential ammonia oxidation. Ammonia oxidation is first and rate limiting step of nitrification that can leave soil nitrogen in a form (nitrate) susceptible to leaching and gaseous loss through denitrification. This rotation can also maintain nutrient cycling enzymes related to carbon (glucosidase, glucosaminidase), phosphorous (phosphatase) and sulfur (sulfatase). Additionally, assessment of the fungal intertranscribed region demonstrated that fungi are responsive to canola growth both in the short term (root-associated) and with legacy effects. Overall, the effects of various crop management strategies on soil health and soil biology will be discussed.