Profitability and Nitrogen Rate Optimization Associated with Winter Cover Management in No-Tillage Cotton

Abstract

Sustainable cotton (Gossypium hirsutum L.) production will require systems that maintain or augment yields without degrading the soil. Our study was undertaken to determine profitability and fertilizer N rate optimization associated with winter cover management in no-tillage cotton. This study was conducted beginning the fall of 1988 and continued through the 1992 growing season in a producer's field on a Caledonia loam (fine, loamy, siliceous, thermic, Typic Paleudalfs) soil with 0 to 2% slope. Winter cover treatments were fallow, rye (Secale cereale L.), and hairy vetch (Vicia villosa Roth), each combined with 0, 45, 90, and 135 Ib N/acre. Profit maximizing N rates as influenced by varying fertilizer N and lint prices ranged from 81 to 94 Ib/acre for winter fallow, 105 to 117 Ib/acre for rye, and 54 to 68 Ib/acre for hairy vetch. Lint yield at the profit-maximizing N rate varied only slightly in response to changes in fertilizer N and lint prices for each winter cover treatment. Both cover crop systems were found to be more profitable at all fertilizer N and lint prices, with rye averaging $24 to $44/acre and hairy vetch $33 to $51/acre greater returns than for winter fallow. Marginal profitability of rye compared with winter fallow was greatest at a fertilizer N-to-lint price ratio of 0.125, while for vetch it was at 0.375. Inclusion of cover crops in no-tillage cotton production systems can result in greater profitability as a result of increased lint yield and in the case of the legume lower fertilizer N inputs, but yearly variability in yield as well as profit may increase.