Project Number: 5354-21660-001-00
Project Type: Appropriated

Start Date: Dec 14, 2003
End Date: Sep 11, 2008

Objective:
1)Determine the effects of reduced tillage and fall-planted cover crops in irrigated potato production systems on weed dynamics and develop weed management strategies that minimize the negative impacts of weeds. 2)Understand the processes controlling soil biological activity and community structure of the:(i)soil micro-flora, (ii)plant pathogens, (iii)nematodes, and (iv)insects under reduced tillage and cover crops in irrigated potato production systems. 3)Determine and understand the mechanisms controlling carbon and nitrogen cycling and trace gas fluxes under reduced tillage in irrigated potato production systems. 4)Evaluate potato crop performance, potato tuber quality, soil fertility and nitrate leaching below the rootzone under variable rates of preplant and inseason N applications under conventional and reduced tillage. 5)Evaluate the soil and plant growth parameters of a potato growth model, and validate the model for major potato cultivars and different management practices.

Approach:
1)A standard and reduced tillage practice will be evaluated in a 3-year crop rotation of field corn/field corn/potato. The experimental design is a randomized strip split plot design with 4 replications, and includes 4 N treatments in each tillage treatment. The treatments consist of preplant N application rates of 56, 112, and 168 kg N ha-1 with remaining N (total N at 336 kg ha-1) applied as inseason fertigation beginning 3 weeks after emergence. 2)A 4-year crop rotation of winter wheat/sweet corn/sweet corn/potato and cover crop treatments will be investigated. Cover crops include white mustard, winter wheat, and oat-hairy vetch. 3)In a parallel experiment, the effects of different rates of preplant N and rates and frequencies of inseason N application on the tuber yield and quality of Ranger Russet and Umatilla Russet cultivars will be investigated. In all the above trials, effects of various treatments on:(i)microbial diversity and activity; (ii)nitrogen transformation, uptake, and losses; (iii)weed management; (iv)pathogens and nematodes populations; (v)gas fluxes; (vi)nutrient cycling and soil quality will be evaluated. 4)The data will be used to develop decision support systems for sustainable management of irrigated potato rotation system. Formerly 5354-13610-002-00D (11/03).