Ashok Alva, Soil Scientist
William Boge, Biol. Science Tech.
This research is part of a multidisciplinary research project, entitled “Sustainable Potato Cropping Systems for Irrigated Agriculture in the Pacific Northwest”. The specific objectives are: (i) to determine the effects of reduced tillage and fall-planted cover crops in irrigated potato production systems on weed dynamics, soil biological activity and community structure, and soil micro-flora; (ii) to determine the mechanisms controlling carbon and nitrogen cycling and trace gas fluxes under reduced tillage; (iii) to evaluate potato production, tuber quality, and nitrate leaching below the root zone under different N management practices; and, (iv) to evaluate the soil and plant growth parameters of a potato growth model, and validate the model for different potato production systems. This CRIS contributes to Integrated Agricultural Systems (207, 70%) and Crop Protection and Quarantine (304, 30%) National Programs.
The overall objective of incumbent’s research is to develop basic and applied knowledge through independent and collaborative research on the influence by different N management practices and crop residue management under irrigated potato rotation production systems to optimize the tuber production and quality and to minimize adverse environmental impacts. Specific objectives are: 1) to determine the optimal N management for potatoes under conventional and reduced tillage to minimize N losses and maximize N uptake efficiency; 2) to determine the annual N mineralization from crop residues in a potato rotation system; 3) application of continuous and real time monitoring the soil water content to fine tune irrigation scheduling to minimize water leaching below the root zone; and, 4) to evaluate the soil and plant growth parameters of a potato growth model, and validate the model for different production systems. Different rates of pre-plant and in-season N applications will be evaluated over multiple-year, on-farm experiments, under conventional and reduced tillage to investigate their effects on tuber yield, grade, and specific gravity. Porous cup suction lysimeters will be used for collection of leachate below the root zone for evaluation of water and nitrate leaching. Capacitance probes that work on the principles of dielectric constant will be used to measure the soil moisture content both within and below the root zone. Plant samples will be taken at various times during the growing season to estimate the total dry matter (DM) and partitioning of DM and nutrients into various parts of the plant. The phenology and plant growth components of a potato crop growth model (SIMPOTATO) will be updated using the field data. The model will be validated under field conditions, and evaluated as a decision support aid.
This research will provide new knowledge to develop improved fertilizer management for potato production systems under conventional and reduced tillage to minimize negative effects on the environment, while maintaining high yields and quality. There are limited data describing the impacts of interception, leaching and immobilization/mineralization of the N applied through center pivot/sprinkler irrigation systems or the timing of N-release later in the growing season from decomposing residues. The collaborative research will result in development of integrated recommendations for reduced tillage, cover crops, and improved nutrient and irrigation management for irrigated potato rotation cropping systems. This project will result in database from long-term field studies under commercial production conditions to develop integrated decision support system for irrigated potato production system.
This research is being carried out in collaboration with a large commercial production farm (AgriNorthwest) in a typical Columbia Basin potato production region. This region is known for its high per acre Potato yield in the county. Research collaboration and support also comes from: Washington State Potato Commission (WSPC); Washington State University (Prosser and Pullman, WA); Oregon State University (Hermiston, OR); University of Florida (Homestead, FL); Savannah State University (Savannah, GA); ARS-Crops Systems and Global Climate Change Laboratory (Beltsville, MD); and ARS-Soil Plant Nutrition Research Unit (Fort Collins, CO).