North Dakota State University
North Dakota Agricultural Experiment Station
Central Grasslands Research Center

Grazing and Haying CRP Lands

By Paul Nyren, Bob Patton, Brian Kreft, Kevin Sedivec and Jeff Printz

Introduction

The Conservation Reserve Program (CRP) was initiated in 1985 to remove fragile, marginal land from crop production. Producers who enrolled were required to convert marginal acreages to perennial vegetation for a 10-year period. In North Dakota about 2.9 million acres of cropland were retired. Nationwide, over 36 million acres were enrolled. The objectives of the program were to reduce soil erosion, decrease sedimentation, increase herbaceous cover, improve water quality and provide financial incentives for participants. Shortly after the program began, researchers and land management agencies across the nation developed research studies to examine the benefits of the program and to determine how well it fulfilled its objectives. In 1992 the NDSU-CGREC began researching the effects of grazing, and haying CRP acreages in south central North Dakota. The objectives of this study are to determine:

1. The floristic composition and structure of CRP lands and to note changes in species composition due to grazing and haying over a 5-year period.
2. The production and utilization of CRP land vegetation under a seasonlong and twice-over rotation grazing system.
3. The production and quality of hay from CRP lands.
4. The economic returns from grazing and haying CRP lands.

Procedure

Three hundred and seventy acres of privately owned land located approximately 2 miles northwest of Streeter, North Dakota, were used for this study. Annual precipitation for this area averages 17.8 inches. Soils on the study area are a Barnes-Buse on 9% to 15% slopes. The site is classified as highly erodible land (HEL) by the Natural Resources Conservation Service. This land was seeded in 1985 to a mixture of tall wheatgrass, intermediate wheatgrass, sweetclover and alfalfa, and is now subdivided into a 135-acre season-long treatment and a 235-acre twice-over rotation grazing treatment. Ninety acres of CRP land adjacent to the grazing systems are cut for the hay crop each year. These acres were also seeded in 1985 to the same species used in the grazing study. Exclosures are set up on silty sites and are neither grazed nor hayed. These unused areas serve as a control treatment to which the grazed and hayed treatments are compared.

Forage production and utilization are determined using exclosure cages and a paired plot clipping technique on each range site in each grazing treatment pasture. Pastures are sampled before and after each rotation on the twice-over rotation system and at the beginning, middle and end of the grazing season on the seasonlong system.

Each year, floristic composition and changes in the plant community are monitored by sampling percent frequency of occurrence, density per square meter and percent basal cover of all plant species on each range site using 50 frames placed along permanent transects. The amount of basal cover, litter and bare ground are sampled by using a 10-point frame. Fifty 10-point frames are read along each permanent transect. These data will indicate any changes in the amount of actual soil surface occupied by plants or covered by litter from previous years' growth. This is important when predicting the impact that haying or grazing might have on the vegetation's soil holding capacity. The data were checked for errors in plant identification and data entry by comparing the change in the abundance of each species between years for each site with Cochran's Corrected Chi Square Test and Fishers Exact Test using Calcfreq, a computer program which operates on Lotus 1-2-3. Analysis of variance was performed to detect changes in species abundance. An arcsine transformation was used to normalize frequency, and basal cover data.

Models Used

The model Abundance = year + treatment + (year x treatment) was used to test for interactions between years and treatments. The model Abundance = year was used to test for differences in abundance of species between years. A third model (Abundance year 2 - abundance year 1) = treatment was used to test for differences in abundance of species due to treatments. Fisher's least significant difference test was used to compare means. All tests were performed at a significance level of p=0.05.

Since 1992, 32 cow-calf pairs graze the seasonlong pasture and 55 cow-calf pairs graze the twice-over rotational system. The livestock are weighed at the beginning and end of the grazing season and the average daily gain and gain per acre are calculated for each grazing treatment.

Results and Discussion

Table 1 shows the annual forage and hay production, the six-year average production, and the percent utilization. Forage production in 1997 was lower than the 6-year average on both grazing systems, 3,608 lb/acre vs 4,611 for the seasonlong system and 4,093 vs 4,894 for the rotation system. This may be due to the lower than average precipitation in both May and June. During those months precipitation totaled 2.79 inches compared to the long-term average of 5.88 inches. The non-use treatment produced 439 lbs/acre more forage in 1997 than the 6- year average.

Production on the hayed treatment was lower than the 6-year average, 2,364 lb/acre vs 3,649. Table 2 shows the nutrient content of the hay for the 6 years: percent crude protein in 1992 was 8.04%, 8.31% in 1993, 11.26% in 1994, 10.63% in 1995, 6.6% in 1996 and 9.04 in 1997. TDN varied from a low of 43.9 in 1992 to a high of 53.6 in 1996. Table 3 shows the type of grazing system, grazing season length, average daily gains, and the average gains per acre for all years of the study. In 1997, the calves averaged daily gains of 2.94 and 2.86 lbs/head/day and cows averaged 0.77 and 0.82 lb/head/day on the twice-over rotation and season-long systems, respectively. The 6-year average daily gain for calves were 2.87 and 2.91 lb/head/day and 1.40 and 1.51 lb/head for the cows on the twice over and season-long systems, respectively. The average length of the grazing season is 127 days.

A major concern for range managers and livestock producers planning to graze or hay CRP lands is how these stands will respond to grazing and haying pressures.In other words, will the species composition remain desirable? Table 4 shows the species composition changes that have occurred since 1992 as determined by sampling frequency, density and basal cover each year. While the table indicates changes in the seeded species, this may be due to natural succession. Total forage production and species composition changes to date are acceptable and suggest that these CRP tracts can be grazed successfully. Most land managers would prefer to see these highly erodible land (HEL) acreages remain in grass to protect them from soil erosion and to improve the overall quality of the soil. Gebhart et al. (1994) suggests that the perennial grass cover established under the CRP within the Great Plains has resulted in significant increases in soil organic carbon.

March 1998

NDSU is an equal opportunity employer.
This publication will be made available in alternative format for people with disabilities upon request (701) 231-7881

North Dakota State University
North Dakota Agricultural Experiment Station
Central Grasslands Research Center