Update:
“Tracking Cereal Rye Nitrogen Release Through Soil Pools and Cash Crop Uptake” has been successfully established at the existing Armstrong Lab Cover Crop Research Site at the Purdue Agriculture Research and Education Station on April 1, 2017. Cover crop biomass was enriched using a series of pulse labeling application on April 2, April 11, and April 24. During pulse labeling, small amounts of 15N are “spoon-fed” to the cereal rye to maximize uptake. Cereal rye was terminated on 5/10/2017 and biomass was removed on 5/15/2017.
On average cereal rye produced 2,684 kg/ha of aboveground biomass and 50.5 kg N/ha of N uptake. Cereal biomass was refrigerated until it could be applied to correct micro-plots following corn and soybean planting. Corn and soybean were planted in micro-plots on 5/16/2017 at a rate of 32,000 seed/acre and 150,000 seed/acre respectively. Corn micro-plots received 30 lbs N/acre as starter at planting. A side-dress N application of 150 lbs N/acre as urea was applied at the V5 growth stage. Vegetative growth stages were successfully sampled on 7/7/2017 (Corn, V5) and 7/17/2017 (Soybean, V6). Reproductive growth stages tissue samples for both corn (R4) and soybean (R5) were collected on 8/23/2017. Reproductive tissue samples were separated into stover and grain samples. All tissue samples were dried and ground for analysis of total N and 15N stable isotope analysis. At each plant sampling date, 30cm soil samples were also collected for analysis.
Corn and soybean are expected to mature in early October, and a third tissue sample will be collected at maturity to determine 15N content. The 15N analysis will be conducted on all samples during the winter 2017-Winter 2018, and we expect the preliminary analysis to be available by early 2018.