Western Kansas has received much needed rains within the past few weeks. However, many locations suffering from drought conditions either missed these showers o r did not receive enough precipitation to end their drought situation. Grasses in our native rangelands primarily respond to drought by reducing leaf growth and production, which in turn reduces forage yield. Secondary responses, such as reduced carbohyd rate production and storage, reduced root growth, and reduced new tiller recruitment, also result from low moisture and having less leaf growth present. Studies in northeast Colorado and at the KState Ag Research Center in Hays have shownthat several years of near normal precipitation followed by one year of severe drought reduced forage production from 25 to 60% of normal, depending on management of the rangelands in previous years. At Hays, yields of new rangeland growth during the drought year were 220 and 800 lbs/acre greater for the moderate and lightly utilized pastures compared to the heavily utilized pasture (Fig. 1). The year following the drought year, above average precipitation was received, and light or moderate grass utilization prior to and during the drought year resulted in 600 to 1490 lbs/acre more forage than the heavily utilized pastures during the recovery.
In these studies, the moderate utilization would be similar to the concept of ‘take half leave half’. If grass was not heav ily utilized during the drought year, moderate stocking may resume the year following drought since the main determinant of annual forage yield is current year precipitation. However, producers should be ready to reduce stocking rates early in the season if precipitation does not return to avoid heavy grass utilization. Heavy grass utilization reduces leaf area and mulch accumulation, which lowers rainfall infiltration rates. In addition, less root volume to absorb soil moisture compounds the effect of lower water infiltration in heavily utilized pastures, so an artificial drought situation can be created by pasture management rather than the climate. To maintain vigorous rangelands with the greatest opportunity to remain environmentally sustainable and economically productive, a moderate stocking rate should be established. Under moderate rates, individual animal gain is near maximum and production per acre is near optimum for economic returns. Furthermore, forage not utilized during one growing season is carried over into the next year and is available in case drought conditions limit new growth.
Moderate stocking rates vary by precipitation zone, range site, and vegetative composition, so producers should investigate recommended rates for their area. To prepare for future drought, producers should consider diversifying their cow/calf herd with stocker animals. The cow herd size could remain consistent, and adjustments to reduce overall stocking rate to prevent overutilization during drought could be made by selling stocker animals early and reallocating those acres to their cow/calf herd. This would avoid low cow prices during drought dispersion and high cow replacement prices during drought recovery.
Improving animal distribution with fencing, water developments, burning, or supplement and mineral tubs can also help to limit overutilized and low vigor areas in pastures. Vegetative composition of Kansas’ western rangelands will shift towards high buffalograss proportions under repeated heavy utilization. Other grasses, such as big and little bluestem, sideoats and blue grama, and western wheatgrass are more productive than buffalograss. Management that reduces buffalograss composition and increases other desirable grasses is an indication that grazing practices are improving pasture composition, vigor, and production. Shortgrass rangelands of western Kansas are resilient and have survived numerous droughts, but preventing heavy utilization prior to and during drought can help to limit the loss of production during years of low rainfall and can improve the rate and extent of recovery once more abundant precipitation resumes.
Source: Keith Harmony, range scientist, AgricultureResearchCenter – Hays – Beef Tips