Joseph R. Lawrence1, Quirine M. Ketterings2, Greg Godwin1, and Karl J. Czymmek3. (1) Cornell University, 813 Bradfield Hall, Ithaca, NY 14853, United States of America, (2) Cornell Univeristy, 817 Bradfield Hall, Ithaca, NY 14853, (3) Cornell University, ProDairy, 818 Bradfield Hall, Ithaca, NY 14853
For the production of corn (Zea mays L.) in rotation with grass/legume sods, decomposition of sods will supply nitrogen (N) to the corn crop. Beyond starter N, additional manure and/or fertilizer applications can result in N losses with potentially significant environmental and economic implications. Our objectives were to determine (1) the effects of sidedress N applications on the dry matter (DM) yield and quality of first year corn; and (2) effectiveness of current NY critical levels for the Illinois Soil N Test (ISNT) x organic matter (OM) combinations in identifying sites that were non-responsive to N. Thirteen field trials (10 on-farm trials and 3 research station trials) were conducted throughout NY. Each on-farm trial consisted of four sidedress N rates (0, 45, 89 and 134 kg N ha-1) replicated four times with no more than 34 kg N ha-1 in the starter band. The 3 research sites also contained a no starter control. Averaged across all sites, sidedress N did not impact DM yields. The overall mean was 17.3 Mg ha-1 (sd = 0.21). Not adding any N (no-starter treatments) resulted in significantly lower yields (15.5 Mg ha-1). Crude protein (CP) increased from 68.0 g kg-1 in the no-starter to 72.0, 75.0, 78.0 and 79.0 g kg-1 when 0, 45, 89 and 134 kg N ha-1 were applied, respectively. No other quality parameters were affected by additional N. The critical ISNTxOM levels derived in earlier studies in NY successfully identified 11 of the 13 non-responsive sites. We conclude that (1) for DM yield no additional N is needed for first year corn; and that (2) the ISNTxOM combination shows promise as a tool for N management in NY. The increase in CP requires further investigation to determine its importance for milk production, farm economics and farm N balances.
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