Location: Livestock, Forage and Pasture Management Research Unit
Project Number: 3070-21500-001-011-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Jun 30, 2023
End Date: Jun 30, 2026
Objective:
To evaluate mowing and burning treatments as methods for increasing utilization of little bluestem by grazing cattle. Specifically, the cooperator will determine the preference and utilization of little bluestem among areas receiving dormant season burns, areas receiving dormant season mowing at one of 2 heights (short or mid-canopy), and a control that is neither burned or mowed.
Approach:
The cooperator and ARS will conduct an experiment to evaluate the effects of burning and mowing treatments on the utilization of little bluestem in comparison to an untreated control. We will identify 3 areas at the Southern Plains Experimental Range (SPER) where the plant community is dominated by little bluestem, uniform, and sufficiently large to provide voluntary DMI for 3 beef steers (familiar the SPER vegetation) during 3 short duration (4 days) grazing periods each year without using more than 40% of the annual forage produced inside experimental patches. Each pasture will be divided into 12 patches so that each of the 4 treatments is represented in 3 patches.
Treatments will be randomly assigned to patches within each pasture and completed during the dormant season (February or March) before grazing the first growing season. These pastures will be grazed again a second growing season without repeating any treatments. Ally’s between patches and areas between the exterior patches and boundary fence will be rotary tilled as need to apply treatments and before each grazing period so as to remove any vegetation that is not within a treatment patch and to provide areas for example, near water, that steers can use without being within a patch.
Before any grazing begins, 2 production cages (2.62 m2) will be randomly placed within each patch. At the end of each growing season, a 0.5 m2 quadrat will be clipped to ground level from each production cage (avoiding previously clipped areas) and 2 to 6 quadrats, depending on the pattern of use, from the grazeable areas within each patch. The clipped vegetation will be sorted into current and, if present, previous year’s growth for the component species. Little bluestem culms will be further separated into grazed reproductive, ungrazed reproductive, grazed vegetative, and ungrazed vegetative culms.
Utilization will be evaluated using post processed kinematic GPS and activity collar data. Use will be characterized at the patch (grazing time spent where the head was within a treatment patch area), feeding station (grazing time spent where the head was within the semi circular area that a steer can reach without moving its feet), and if possible with these collars, the bit (grazing time spent where the head was within a 1 to 2 dm3 volume) scales. Each patch will be gridded into hexagons that represent potential feeding stations and grazing use within each hexagon be classified into potentially 3 levels of preference, depending on how even the use is among all interior hexagons (those not overlapping an ally), based on the collar data recorded within each treatment area.
Prior to the first and soon after each subsequent grazing period, high resolution photographs will be collected from each patch. The imagery will be used to map vegetation characteristics across the patches.
