SOIL CONSERVATION SYSTEMS FOR SUSTAINABILITY OF PACIFIC NORTHWEST AGRICULTURE
Location: Land Management and Water Conservation Research
Project Number: 5348-11120-004-00
Start Date: Oct 01, 2006
End Date: Sep 30, 2011
1. Determine crop and tillage management impacts on carbon (C) and nitrogen
(N) cycling and related soil biophysical properties. Determine impacts of cropping and tillage systems on water quality and maintenance of the soil resource base. Hypothesis. No-till practices will control storm and snow-melt runoff and soil loss from drainages and watersheds under PNW conditions. 2. Develop conservation cropping and tillage systems that improve agroecosystem performance (production, stability and sustainability) and minimize adverse environmental impacts to air, water, and soil resources. 3. Determine the amount of crop residues that must remain on the land to maintain soil organic carbon and sustain production. 4. Estimate the trade-off between the short-term benefits to growers who harvest crop residues as biofuel or biomass to produce feedstocks versus the long-term benefits to soil, water, and air resources associated with retaining crop residues to build soil organic matter and sequester carbon. 5. Develop an N budget framework for N management decision-aid tools for conservation cropping systems.
Objective 1 consists of five subobjectives. Our first subobjective is to determine the effects of C quality and quantity on soil biophysical properties and function in the seed-zone including aggregation, soil biology community dynamics and plant-microbe interactions. The research will document tillage and undercutting disturbance effects on the soil microbial populations, community structure and activity. Analyses include soil pH and electrical conductivity, aggregate distribution, bulk density and soil moisture content. Total C and N will be determined. We will investigate soil organic matter (SOM) components by fractionation, isolation and characterization. The second subobjective will be to determine tillage and cropping system effects on soil organic and inorganic N and C dynamics, and greenhouse gas emission. We will study microbially mediated transformations and the factors controlling these transformations at the landscape level. We will set up permanent areas on the USDA Conservation farm and the Cunningham Research Farm in Pullman, Washington. We will use in situ gross mineralization rates of native soil organic matter to predict the crop’s extra fertilizer needs to meet yield goals. In addition, we will monitor the microclimate of each area for parameters such as temperature, moisture and solar radiation and normalizing the N transformation data for each area and thus predict N availability over time across landscape areas. These analyses will be conducted on different cropping systems and tillage management to determine the N efficiency of each system and for predicting fertilizer needs of each system. Subobjectives 4 and 5 will evaluate the economic and natural resource trade-offs in harvesting crop residues for bio-energy. Field-scale crop residue and soil C data from the WSU Cook Agronomy Farm will be analyzed including crop residue quantities, value as a bio-fuel, nutrient content and contribution to soil C sequestration using standard laboratory, geospatial techniques and the CropSyst model. The third objective in the overall project plan in collaboration with Pendleton, is to develop and evaluate tillage and crop residue management practices for successful conservation systems. Field experiments will consist of two N management treatments (uniform application of N fertilizer and site-specific N management) with extensive measurements that capture the full variability of the field. Our approach will be to collect field-scale data that will allow spatial and temporal analyses. Site-specific yield and protein maps will be combined to establish realistic yield and protein goals for geo-referenced locations within a field. The combination of yield and grain protein data also provides information on the amount of N removed in the grain at harvest and will be used with GIS methods to compute variable-rate N recommendations for wheat. Replaces 5348-11120-003-00D (9/06). Associated with Pendleton, OR, project 5356-11120-002-00D.