Preplant Weeds in Stale Seedbed and No-Till Cotton

C.D. Elmore


Ground cover from weeds, residue, and cover crops were determined in April 1993 for four cover crop and three tillage treatments in cotton. The four cover crops were none, natural, crimson clover, and wheat. The three tillage treatments in each of the cover crops were no-till, fall rehip, and fall rehip plus subsoil. Spring tillage consisted of smoothing beds in the rehipped plots only. No other tillage or cultivation was performed. Weeds and residue were determined using a relative abundance technique in which percent ground cover by weed specie and residue were estimated from a 0.5 m2 quadrate in 10 percentage increments. Yield of seed cotton was determined by machine picking two rows from each plot. The none cover crop treatment was achieved by two applications of paraquat during the winter.

Ground cover was highest in the no-till tillage treatment and in the natural and crimson clover cover crop treatments. The none cover crop treatment had no vegetation, but residue in the no till none contributed over 25% ground cover. The planted cover crops contributed approximately 40% ground cover with additional ground cover coming from residue and winter weeds. The winter weeds contributing the most were common chickweed (Stellaria media (L.) Vill.), annual bluegrass (Poa annua L.) and the mustards smallflowered bittercress (Cardamine parviflora L.), shepherd's purse (Capsella bursa-pastoris (L.) Medicus CAPBP), and Virginia pepperweed (Lepidium virginicum L.). There were more winter weeds in the crimson clover than in the wheat (25% compared with 3%). Yields were reduced considerably from previous years and were not different among the tillage treatments. The none treatment among the cover crops was better than all others in 1993 (1680 kg/ha) and wheat tended to be lowest (1450 kg/ha).

Reprinted from Proceedings of the 1994 Beltwide Cotton Conferences pg. 1696
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998