TILLAGE AND COVER CROP EFFECT ON COTTON YIELD AND WEED CONTROL

C.D. ELMORE AND J.R. WILLIFORD

ABSTRACT

Cotton (Stoneville 825) yield and weed control were compared from three tillage treatments and four cover crops for five years on a mixed soil with Sharkey Clay subsoil near Stoneville, MS. The tillage treatments were no-till, fall rehip, and fall suboil plus rehip. Beds were knocked off in the spring for planting, with no other spring or summer tillage. The cover crops were none, natural, crimson clover, and wheat. None was achieved with winter applications of paraquat to maintain a ba:re soil condition. Natural was the natural winter vegetation. Cover crops were planted each fall with a cyclone seeder or no-till drill after fall tillage. The experiment was a randomized complete block with a split plot arrangement of treatments with cover crops as the whole plots. Plots were four rows wide by 120 feet long. Yield of seed cotton and weed species at harvest were recorded. Weed control was with preplant foliar application (PFA) of glyphosate or paraquat (for crimson clover) in mid March to 1 April. A PRE application of metolachlor plus fluometuron was applied to all plots. POST herbicides included directed applications of MSMA plus cyanazine and fluazifop as needed. No-till seed cotton yield was equal to tilled treatments until the fifth year when the no-till yield was reduced 15% (2640 vs. 2300 kg/ha). Cover crops were not a factor for seed cotton yield until the fourth and fifth years, when continued use of wheat as a cover crop seemed to depress cotton yields (2400 and 2340 compared with 2620 and 2590 for 1991 and 1992, respectively). Weed control was adequate, although purple nutsedge (Cyperus rotundus L.) and pigweeds (Amaranthus spp.) were somewhat more of a problem in the no-till cotton.





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Document last modified July 8, 2004