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Fertilizer N and Legume Cover Crop Management Effects on No-Till Cotton Production

J.M.Thompson, J.J. Varco


A field study was conducted from 1992 through 1995 to determine the effects of fertilizer and legume N in no-tillage cotton production on lint yield, total cotton N uptake, and apparent fertilizer N recovery. Fertilizer N rates of 0, 40, 80, 120, and 160 lb/acre were applied in combination with winter fallow cover management using either broadcast ammonium nitrate (AN) or subsurface banded urea-ammonium nitrate (UAN) solution. Additionally, there was a winter cover system using a hairy vetch cover crop in combination with all N rates used with winter fallow except the highest. The four year predicted maximum lint yields with corresponding N rates were as follows: broadcast AN - 962 lb lint/acre at 108 lb N/acre; banded UAN solution - 918 lb lint/acre at 98 lb N/acre; and vetch-UAN - 907 lb lint/acre at 45 lb/N acre. Vetch plots with no added fertilizer N had high cotton total N uptake values and proved to be more efficient at N uptake when compared to fertilized winter fallow plots at the same N uptake value, but less efficient in terms of lint produced per unit of N applied. Apparent fertilizer N recovery in the vetch UAN system was much less than that of the winter fallow UAN system demonstrating that a fertilizer N addition in an already large vetch and soil N pool did little to increase apparent fertilizer N recovery.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 1395 - 1397
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998