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Weed Management Systems for Semiarid Areas of the Central Great Plains

G.A. Wicks, P.W. Stahlman, and R.L. Anderson
1995 NCWSS Proceedings, Vol. 50.
Abstract. Weed management during the fallow periods in the winter wheat-fallow areas has changed from tillage to tillage plus herbicides or no-tillage and herbicides during the past 30 years. The two most common rotations, winter wheat-fallow and winter wheat-corn or grain sorghum-fallow have benefited from the use of herbicides. Herbicides have allowed farmers to use less tillage, which have resulted in more crop residue retention, increased water infiltration, reduced evaporation, and reduced erosion and sediment loss. More water saved means more technology can be used, thus, increasing crop yields, lowering unit costs, and stabilizing crop production. However, herbicides alone do not ensure successful crop production practices. Crop production practices should employ several facets of weed management that improve economics and reduce risks. Atrazine allows farmers to practice no-till crop production successfully in semiarid areas and has been used in the winter wheat-corn or grain sorghum-fallow rotation for 30 years in the central Great Plains. Farmers growing corn or grain sorghum consider atrazine essential for successful ecofarming. Atrazine is cost effective and can be applied after wheat harvest, early preplant, preemergence, or postemergence to corn or grain sorghum and it will control several germinating weed species for an extended period. Glyphosate or paraquat usually is combined with atrazine to improve control of emerged weeds before planting. Summer annual grasses are more difficult to control than broadleaf weeds in the three-year rotation. Alachlor, cyanazine, and metoachlor are commonly applied preplant or preemergence to improve summer annual weed control. By using no-till and herbicides, grain yields have been increased through better weed control and soil and water conservation, compared with conventional tillage practices. Soil erosion from wind and water has decreased because of more crop residue, and land has become more productive. Non-irrigated crop production has been stabilized in much of the central Great Plains by using ecofallow. This crop production system enables the farmer to maintain the crop residues required for conservation compliance.