Cotton Response to Winter Annual Cover Crops and N Fertilization

P.J. Bauer and S.H. Roach


 
ABSTRACT

A field experiment was conducted in 1989 to investigate the N requirements of cotton (Gossypium hirsutum L.) when grown following winter annual cover crops. Treatments in the experiment were cover crops of crimson clover (Trifolium incarnatum L.), Austrian winter pea [Pisum sativum spp. avense (L.) Poir], rye (Secale cereale L.), or winter fallow (winter covers were disk-incorporated 21 days before planting cotton) and four N levels of 0, 56, 112, and 168 kg ha-1. One-half of each N treatment was sidedress applied (as ammonium nitrate) shortly after planting and the other half was sidedress applied when plants had pinhead size squares. The experiment had four replicates and the design was a randomized complete block in split-plot arrangement with winter cover treatment as the main plots. Leaf area, dry weight, and fruit counts were made from plants collected from one m of row at 55 and 86 days after planting (DAP). Petiole nitrate levels were measured in the youngest fully mature leaves collected weekly beginning at 61 DAP. Winter cover treatment did not substantially modify cotton stands or early season growth. A significant cover X N interaction occurred for leaf area at 86 DAP with the clover winter cover treatment having greater leaf area at the 0 N level than winter fallow, but no difference occurred at the other N levels. No yield response to added N was found in the clover plots. Seedcotton yield under both winter fallow and rye winter cover plateaued at 56 kg N ha-1. In the winter pea plots, 112 kg N ha-1 increased seedcotton yield above the 0 N level but there was no increase (above the 0 N level) with the 56 or 168 kg N ha-1 levels, Petiole nitrate levels in the cotton grown without added N following clover and winter peas were similar to levels of the winter fallow treatment with 56 kg ha-1 added N.



Reprinted from 1990 Proceedings: Beltwide Cotton Production Research Conferences pg. 484
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998