Spring and Fall Cattle Grazing Effects on Components and Total Grain Yield of Winter Wheat

Farmers and ranchers growing winter wheat (Triticum aestivum L.) in the Great Plains have the practical problem of obtaining maximum grazing with minimum loss of grain yield. The objective of this study was to examine the impact of grazing on subsequent grain, straw, and chaff production of a semidwarf winter wheat (‘TAM W-101’). Steers (Bos taurus L.) weighing 250 to 350 kg grazed wheat pasture during 3 yr at the Forage and Livestock Research Laboratory near El Reno, OK. Soils at the study site were fine-silty, mixed, thermic Pachic Haplustolls of the Dale series. Climatic conditions allowed 212 to 338 animal days (AD) ha⁻¹ of fall grazing in 1983 to 1984; 78 to 141 AD ha⁻¹ spring grazing in 1984 to 1985; and 151 to 516 AD ha⁻¹ fall and/or spring grazing in 1985 to 1986. Straw, total grain yield, seed weight, seeds per spike, and spikes m⁻² were determined. Heavy (H) and light (L) fall (F) grazing intensities caused lower (P < 0.05) grain yields compared to controls (C) in 1983 to 1984 (2.94IF-LI and 2.53 [F-H] vs. 3.51 [C] Mg ha⁻¹); lower, but nonsignificantly different grain production after spring (S) grazing in 1984 to 1985 (2.73 [S-L] and 2.44 [S-H] vs. 2.60 [C] Mg ha⁻¹); and mixed results with fall-only, spring-only, and two levels of fall and spring grazing in 1985 and 1986 (2.41 [F-L], 1.37 [S-L], 1.80 [F,S-L], and 1.46 [F,S-H] vs. 1.90 [C] Mg ha⁻²). Grazing generally decreased the number of spikes m⁻¹. Straw yields were lowered by grazing in all 3 yr, therefore, harvest index of grain was nearly always higher for grazed wheat. Weather differences affected grain production from year to year more than grazing stresses within a year. Components of yield were influenced in an inconsistent manner by the treatments. However, grazing did not damage TAM W-101 grain yield, when moderate grazing was used, trampling was avoided, excess autumn forage was removed and/or no severe weather adversities added to grazing stress on the crop. Contribution from USDA-ARS Forage and Livestock Res. Lab., P.O. Box 1199, El Reno, OK 73036.