Using Automated Lysimeter to Measure Nitrate Leaching From Winter Rye Cover Crop Planed in Different Dates.

Fall and winter losses of N leaching in corn fields are avoidable and can be reduced or prevented if cover crops are planted early enough to be effective. Planting date of cover crops has a critical effect on  its nutrient recovery efficiency. Determining the amount of after-harvest nitrate leaching requires an accurate leachate sampling method. Automated lysimeters have recently been used for collecting soil water sample. Winter rye cover crop was planted from early September to October at biweekly intervals in Deerfield, Massachusetts in 2008 and 2009. A randomized complete block design with four replications was used. Hourly soil-water tension data and daily soil-water samples (volume and concentration) were collected using automated lysimeters installed in each plot (16 automated lysimeters in total). Tissue and soil samples were taken during fall, winter and next spring. Automated lysimeters showed a reliable performance in the field condition. Treatments did not have significantly different soil-water tension and leachate volume. By the end of fall, plots planted in September 1^st had significantly lower amounts of soil nitrate-N and soil-water nitrate concentration.  Also cover crops in these plots contained highest amount of tissue nitrogen  compared to other planting dates. First date of planting also had significantly higher amount of soil nitrate and tissue nitrogen than other treatments early in the next spring. The last date of planting (September 29^th) showed no significant difference in soil N with no-cover-crop treatment. These results confirmed the effectiveness of cover crop in N recovery and the importance of planting date of winter rye for maximum nutrient recovery.