Long-Term Ecological Grazing Intensity Research in the Missouri Coteau of North Dakota

Introduction

A grazing intensity research project was initiated at the CGREC in 1989. The objectives are to determine the effect of grazing intensity on livestock performance and profitability and its effect on the sustainability of forage production. Five treatments are included: no grazing, light, moderate, heavy and extreme grazing. Each treatment is replicated three times in pastures of about 30 acres each except that the no grazing treatment consists of six 0.3-acre exclosures, placed on both overflow and silty range sites. Livestock are not rotated between pastures and each pasture receives the same treatment each year. We try to stock the pastures each year so that when the cattle are removed in the fall, 65%, 50%, 35% and 20% of the forage produced in an average year is remaining on the light, moderate, heavy and extreme treatments respectively. For these pastures that means 2046, 1641, 942, and 493 lbs/ac. of forage remaining on the light, moderate, heavy and extreme pastures, respectively. Table 1 presents the stocking history of the study and Figure 1 shows how much forage was remaining at the end of the grazing season each year. Adjustments in stocking pressure are made each year based on information from previous years to attain the desired grazing intensities. Changes in the vegetation are determined by monitoring permanent plots located on silty and overflow range sites in each pasture and the six exclosures. Table 2 gives the average production on these range sites during each year of the study and the total precipitation for the year.

Above ground biomass remaining (lbs/acre) on each treatment at the end of the grazing season from 1989 to 2004.
	Treatment
Year	Light	Moderate	Heavy	Extreme
1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004	2,078 2,634 2,385 1,915 2,924 2,017 2,772 2,552 2,550 2,674 2,269 2,387 1,933 1,225 2,434 1,801	2,074 2,383 1,494 1,353 2,256 1,728 1,906 1,975 1,711 1,848 2,108 2,246 1,883 1,132 2,128 1,775	2,035 2,023 833 574 1,290 1,393 1,583 1,064 689 686 806 1,130 1,197 701 1,205 1,284	1,701 1,985 641 406 608 901 504 513 560 522 609 718 617 329 678 518
Ideal Remaining	2,046	1,641	942	493

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