Time of grazing effect on subsequent-year standing crop in the Eastern Nebraska Sandhills

Rotational grazing methods provide range managers opportunities to alter the time when grazing occurs on pastures in consecutive years. The effect of time of grazing on subsequent-year standing crop was evaluated within four pastures (42 ± 1 ha) rotated annually within a deferred rotation using a modified Williams design that included mean times of grazing within different pastures from 16 May to 14 June, 13 June to 20 July, 20 July to 29 August, and 27 August to 7 October (i.e., stages of grazing A, B, C, and D, respectively). Subsequent-year standing crop of different plant functional groups was collected from 2001 to 2008 at four topographic positions (i.e., north slopes, south slopes, dune tops, and interdunes) in mid-June and mid-August harvests. During the mid-June harvest, standing crop of subsequent-year warm-season grasses was 51 ± 24 to 117 ± 41 kg·ha^-1 greater (P < 0.1) when grazing occurred during stage A compared with when grazing occurred during stages B and C on north- and south-facing slopes and at the pasture level. During the mid-August harvest on south-facing slopes, subsequent-year warm-season grass standing crop was 265 ± 105 and 341 ± 113 kg·ha^-1 greater (P < 0.03) when grazing occurred during stage A compared with stages B and C, respectively. Overall, grazing on pastures during stage A tended to provide greater amounts of subsequent-year standing crop for warm-season and cool-season graminoids at specific topographic positions. Given that the effect of time of grazing on subsequent-year standing crop varied among topographic positions for different functional groups, a deferred grazing rotation provides a viable management tool to alter the yearly sequence of grazing on pastures to avoid negative effects of grazing Nebraska Sandhills vegetation at critical times in consecutive years.