Can Manure Replace the Need for Starter Nitrogen Fertilizer?

Current New York land grant university fertility guidelines for corn ( Zea mays L.) recommend the use of 22 to 34 kg N ha –1 of band‐applied starter fertilizer. On‐farm research was conducted in 2006 and 2007 on a western New York dairy farm with an alfalfa ( Medicago sativa L.)–corn rotation to evaluate the need for starter N for corn in regularly manured fields. In 2009, the study was expanded to include 21 fields varying in soil type, manure history, and soil N supply potential as expressed by the Illinois soil N test (ISNT). At the western New York farm, there was no increase in corn silage yield or quality with starter N use in first‐, second‐, or fourth‐year corn fields. The results of the statewide assessment also showed that for fields with optimal ISNT‐N, manure could replace starter N without a decline in corn silage yield or quality. Starter N fertilizer application was needed for optimal yield in fields deficient or marginal in ISNT‐N and without a manure history. For such fields, manure could replace the need for starter N as long as sufficient N was applied with the manure, indicated by corn stalk NO 3 test (CSNT) results between 750 and 2000 mg NO 3 –N kg –1 . A response of silage yield to starter N was common when CSNT‐N was <750 mg NO 3 –N kg –1 . We conclude that manure can replace the need for starter N, but rates should be adjusted to obtain CSNT values between 750 and 2000 mg kg –1 .