|Renier, Robert -|
|Yost, Matt -|
|Coulter, Jeff -|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 30, 2012
Publication Date: September 17, 2012
Citation: Renier, R., Yost, M., Russelle, M.P., Coulter, J. 2012. Using the presidedress soil nitrogen test to predict nitrogen requirement of no-tillage corn following alfalfa [abstract]. Proceedings of the 30th Brazilian Meeting of Soil Fertility and Plant Nutrition Conference, September 17-21, 2012, Maceio, Alagoas, Brazil. Technical Abstract: Due to its perenniality and capacity for symbiotic nitrogen (N) fixation, alfalfa increases the amount of soil N for the succeeding crop. A common crop rotation in Minnesota and other Midwestern states is to follow a multiple-year stand of alfalfa with at least 1 year of corn. Many farmers are replacing aggressive surface tillage with no-tillage to reduce both costs for seedbed preparation and the risk of soil erosion. Tillage intensity has been related to soil N mineralization rate, which raises the question of N supply to corn planted notill after alfalfa. The Pre-Sidedress N Test (PSNT) provides a potential index of N availability to corn because it takes account of early-season N mineralization. The objective of this study was to evaluate the accuracy of the PSNT in notill corn after alfalfa. The experiment was designed as a randomized complete block with four replications at seven Minnesota farms. At the 4- to 6-leaf growth stage, PSNT samples were taken to the 30-cm depth and N was applied at 45 kg/ha to one-half of the plots. Corn was hand-harvested to measure grain yield. PSNT interpretation systems from Wisconsin and Iowa were evaluated against the measured response of corn grain and silage yield to N. Using current guidelines, additional N would have been recommended by both state systems for all farms, but only one farm had a significant silage yield response and two farms had significant grain yield responses. No alternative levels of nitrate in the PSNT produced improved interpretations. Therefore, the PSNT may not be reliable for notill corn after alfalfa.