SOIL NITRATE-N VARIABILITY ON CORN FIELDS WITH HIGH MINERALIZATION POTENTIAL
Applied Research
George Silva
Senior Extension Educator
MSU EXTENSION
CHARLOTTE
Abstract
\r\n The soil nitrogen (N) mineralization potential on 20 corn fields, each with a history of manure practices, was studied in 2011 using the pre-sidedress soil nitrate test (PSNT). Ten mid-Michigan corn growers participated in the study. Manure types were dairy, swine, sheep and poultry. Corn was planted in the first week of May and received 20-30 lbs N/acre in a 2x2 starter placement. Representative PSNT soil samples were taken during June 5 – 20 from one foot depth located midway between 30-inch corn rows. This stage coincided with 12-15 inch tall corn and was 4-5 days prior to the sidedress application. The soil nitrate-N concentration ranged from 7 to 35 ppm with an average of 22 ppm. This variability was attributed to the type and amount of manure applied and site-specific factors of soil and climate. Forty percent of fields exceeded the critical PSNT level of 25 ppm and needed no additional N fertilizer at sidedress. Based on the Maximum Return to Nitrogen (MRTN) approach, the growers received an average N credit of 80 lbs /acre, equivalent to about $50/acre in cost savings. In the early wet season of 2011 some fields received in excess of 5 inches of rain between planting and sidedress. Despite conditions favoring high N losses due to leaching and denitrification, the organic manure was capable of retaining and releasing its N gradually. This data provides further credibility to the use of PSNT as a valuable soil diagnostic tool to manage N on Michigan corn.
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Poster has NOT been presented at any previous NACAA AM/PIC
This poster is being submitted for judging. It will be displayed at the AM/PIC if not selected as a State winner. The abstract will be published in the proceedings.
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Authors: G.H. Silva, J. Dahl
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Silva, G. Senior Extension Educator, Michigan State University, Michigan, 48813
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Dahl, J. Manager, Soil and Plant Testing Laboratory, Michigan State University, Michigan, 48824