|Baumhardt, Roland - Louis|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2008
Publication Date: 1/1/2009
Citation: Baumhardt, R.L., Schwartz, R.C., Greene, L.W., Macdonald, J. 2009. Cattle gain and crop yield for a dryland wheat-sorghum-fallow rotation. Agronomy Journal. 101:150-158.
Interpretive Summary: High pumping costs and low irrigation well capacities in the Southern Great Plains have led to greater use of less productive and riskier dryland cropping systems. Dryland wheat and grain sorghum are usually grown in a 3-year wheat-sorghum-fallow (WSF) rotation. This rotation can be made more productive by adding cattle grazing. The success of grazing dryland crops needs to be tested. Our objectives were to quantify (1) cattle gain for limited grazing of dryland wheat and sorghum, and (2) grazing effects on the growth and yield of wheat and sorghum. On a Pullman silty clay loam soil at the USDA-ARS, Conservation and Production Research Laboratory, Bushland, TX we started all WSF rotation phases in ungrazed and grazed plots. Cattle gain, fallow soil water storage, and the yield of wheat and sorghum were compared with a randomized complete block ANOVA. Dryland wheat was grazed an average of 31 days for cattle stocked at 3 head/ac of wheat (not counting equal area of sorghum stover). Mean cattle gain was 117 lbs/ac. Ungrazed wheat yielded 25 bu/ac and was not different from the 23 bu/ac grazed wheat yield. Grazing decreased wheat straw yield. But, fallow soil water storage was not affected. Sorghum yielded 2020 lbs/ac in ungrazed plots and was not different from grazed plots averaging 1960 lbs/ac. Grazing of dryland wheat and sorghum stover increased productivity of the WSF rotation by adding cattle gain. Grain yield did not decrease.
Technical Abstract: Increasing pumping costs and declining well capacities in regions like the U.S. Southern High Plains have led to greater reliance on less productive and inherently riskier dryland cropping systems. Dryland wheat (Triticum aestivum L.) and grain sorghum [Sorghum bicolor (L.) Moench] are typically grown in a 3-year wheat-sorghum-fallow (WSF) rotation, which can be intensified by integrating cattle grazing, but suitability of grazing dryland crops in the WSF rotation has not been documented. Our objectives were to quantify (1) cattle gain during limited grazing of dryland wheat and sorghum stover, and (2) grazing effects on the growth and yield of the grazed wheat and subsequent sorghum crop. On a Pullman silty clay loam (fine, mixed, superactive, thermic Torrertic Paleustoll) at the USDA-ARS, Conservation and Production Research Laboratory, Bushland, TX (35' 11’ N, 102' 5’ W) we established, concurrently, all WSF rotation phases in duplicate ungrazed and grazed plots with three replicates. Cattle gain, fallow soil water storage, and the growth and yield of wheat and subsequent grain sorghum were compared from 2000 to 2007 according to a randomized complete block analysis of variance. Dryland wheat was grazed an average of 31 days for cattle stocked at 1.78 Mg/ha and produced a mean gain of 131 kg/ha. Wheat grain yield averaged 1.70 Mg/ha without grazing and was not different from the 1.57 Mg/ha grain yield with grazing. Grazing decreased wheat straw yield, but subsequent soil water storage was unaffected. Sorghum grain yields of 2.26 Mg/ha in ungrazed plots were not different from grazed plots averaging 2.20 Mg/ha. Limited grazing of dryland wheat forage with sorghum stover increased overall productivity of the WSF cropping system by adding cattle gain with no significant reduction in grain yield.