Michael Wagger1, Robert D. Walters1, and Keith R. Baldwin2. (1) North Carolina State Univ., Dept. of Soil Science, PO Box 7619, Raleigh, NC 27695-7619, (2) North Carolina A & T State Univ., P.O. Box 21928, Greensboro, NC 27420-21928
A residue management tool, the "mechanical roller-crimper", has been used by Brazilian farmers to successfully manage high density cover crop residues in production systems. Our objectives were to evaluate this tool, in conjunction with other weed management strategies, with respect to subsequent weed suppression and cotton lint/soybean grain yield response in a no-till production system. A rye cover crop was established in Fall 2003 at two locations at the Center for Environmental Farming Systems in Goldsboro, NC. Rye growth was terminated chemically and/or mechanically just prior to planting cotton/soybean the following spring. Weed counts were made at planting and 2 and 6 wk post-emergence. Residue decomposition was monitored by placing intact rye residue in 2-mm mesh bags at rates equivalent to field conditions and retrieved at 2, 4 , 8, and 16 wk after planting.Cotton and soybean were successfully established in the rolled rye residue, however, stands were slightly reduced mainly due to lifting of the planter's gauge wheels where residue was unevenly distributed. Decomposition of the rye residue followed an exponential decay function, with approximately 70% of the original rye residue decomposed 16 wk after planting. Weed data revealed a steady increase with time in weed density where herbicide inputs were reduced, despite a mulch cover of 4.5-6.7 t/ha and no soil disturbance. Moreover, reducing herbicide inputs resulted in a yield penalty for both crops. Future work should be directed toward identifying optimum planting dates and seeding rates to maximize cover crop residue production and principal crop performance, modifying existing equipment to plant in high biomass residue systems, and weed management options.
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