Project Number: 6618-22000-036-13
Project Type: Trust

Start Date: Jul 01, 2010
End Date: Sep 30, 2012

Objective:
1. Characterize the movement, persistence, and degradation products of soil fumigants under seep and drip irrigation systems. 2. Measure the effects of fumigant applications under seep and drip irrigation on crop yield and the control of soilborne pests. 3. Define the levels of association between persistence and degradation of fumigants in soil and their subsequent effects crop yield and pest control.

Approach:
Experiments will be conducted at the USDA, ARS C-24 Research Farm in St. Lucie County, FL. The farm is designed to accommodate seep irrigation with perimeter and lateral irrigation canals used to vary water table depths. The farm also contains the infrastructure for drip irrigation. Field experiments will consist of two 0.5 acre (75 x 475 ft) production blocks. A drip irrigation only block will be created by modifying the lateral ditch to exclude water, thus preventing the water table from being raised or lowered. The other block will be operated under seep irrigation only. Each block will receive 350-50-350 lbs of N-P2O5-K2O with 50-50-50 lbs N-P2O5-K2O applied preplant as a starter mix. The seep irrigated block will receive the additional 300-0-300 of N-P2O5-K2O as a preplant hot band applied in the center of the bed. The drip irrigated block will receive the additional 300-0-300 of N-P2O5-K2O as supplemental applications of liquid fertilizer applied through the drip irrigation system. Treatments will consist of 3 fumigant applications and an untreated control. Fumigants will be applied using back-swept shanks spaced 12 in apart at 8 in depths. Behind the application shanks, a bed (30 in wide x 8 in high) will be formed and pressed using a pan attached to the same implement. Beds will be immediately covered with a 30-µm thick, silver metalized film using a second implement. Six-week-old pepper seedlings will be transplanted into the plastic mulched beds on 2 rows with 10 in spacing between plants. Plots will be scouted weekly and treated when necessary for foliar pests. A randomized complete block design will be used with 6 replications. Each replicate plot will be a single bed 100 ft long. Beds will be arranged on 5 ft centers. Within each row, a 25 untreated section will be used to physically separate replicate plots. The experiment will be conducted in fall production seasons of 2010 the spring production seasons of 2011.