Posted on Dec 01, 2010
Nitrogen fertilizer costs have fluctuated wildly in the past few years. Sorghum silage is an attractive crop because it requires less fertilizer than corn silage. However, fertilizer guidelines are not available for forage sorghum production in the desert southwest. In order to develop these guidelines, we propose to conduct a nitrogen fertilizer rate study in Maricopa, AZ. Nitrogen fertilizer will be applied to forage sorghum at 8 rates varying from 0 to 350 lbs N/acre in split applications during the season. The lower portion of the stem will be sampled six times during the growing season and analyzed for nitrate. In addition and new to the proposal this year, the whole plant and most recently developed leaf will be analyzed for total N. Preliminary post-plant nitrogen fertilizer guidelines will be developed based on lower stem nitrate, plant N, and leaf N.
Publishable guidelines can only be established with 2 or more years of data. The proposed research was funded in 2009 and this proposal represents the second year of work. The plant and leaf N analyses were not included in the 2009 proposal, but these analyses will be performed on the 2009 samples based on suggestions of the reviewers.