Agronomy and Horticulture, Department of


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A Thesis Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Agronomy, Under the Supervision of Professor Walter H. Schacht and Professor Jerry D. Volesky. Lincoln, Nebraska: May, 2012

Copyright 2012 Jordan R. Johnson


Ultrahigh stocking density (113,000 kg·ha-1 to as high as 1 million kg·ha-1 of beef) or mob grazing has been suggested to build soil, increase forage production and plant diversity, and improve grazing distribution compared to less intensive grazing systems. Experimental evidence does not completely support such conclusions. The overall focus of this research is based on the approach of building soil by optimizing above ground plant growth coming in contact with soil surface by trampling 60% of above ground plant growth. The objective of the study was to compare the effect of mob grazing and simple rotational grazing systems on forage utilization, harvest efficiency, percentage of plant mass trampled, and animal performance of grazing cattle on a subirrigated meadow in the Nebraska Sandhills. The three different grazing methods compared in this study were: ultrahigh stocking density with a single grazing period (mob grazing); 4-pasture rotation with a single grazing period (4-PR-1); and 4-pasture rotation with two grazing period (4-PR-2). Cattle were rotated through 120 mob-grazed pastures and 4 pastures in each of the 4-pasture rotation treatments in 2010 and 2011. In 2010, the stocking density for mob grazing, 4-PR-1, and 4-PR-2 treatments was 224,170 kg·ha-1, 7,472 kg·ha-1 and 4, 982 kg·ha-1, respectively, and 201,753 kg·ha-1, 6,725 kg·ha-1 and 4, 982 kg·ha-1, respectively, in 2011. The stocking rates were uniform for the grazing treatments at 8.15 AUM·ha-1 in 2010 and 7.41 AUM·ha-1 in 2011. Grazing period per pasture for the mob grazing, 4-PR-1, 4-PR-2 grazing treatments was 0.5, 15, and 20 days, respectively. In 2010, steers trampled 58%, 39%, and 17% of the available standing crop in the mob, 4-PR-1, and 4-PR-2, respectively. Percentage trampled was 62%, 29%, and 19% for mob, 4-PR-1, and 4-PR-2, respectively in 2011. High percentage of trampling in the mob grazed pasture reduced forage intake resulting in low weight gains (0.13 kg·d-1). This long-term study will determine the effect trampling on soil organic matter, physical properties, and vegetation dynamics.

Advisors: Walter H. Schacht and Jerry D. Volesky