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<br />
<br />searefi has been conducted extensively for years in North
<br />Dakota, but none has been done on this "new" type of
<br />land.
<br />Disturbing land for coal mining has produced a need
<br />for new methodology. Chemical analyses of soils, fer-
<br />tilizer requirements and soil amendments, methods of
<br />establishing vegetation, and the adaptation of various
<br />species may be different. Therefore, possibly grazing
<br />management on these lands also may have to be differ-
<br />ent. Aquestion of major concern is, will abuse of this
<br />"new" land by overgrazing have more serious conse-
<br />quences than overgrazing nonmined land? Information
<br />to answer this is not presently available.
<br />We initiated a grazing study in 1976 on reclaimed
<br />mined land that should provide some of the information.
<br />Land mined by the Baukol-Noonan Mining Company
<br />near Center, North Dakota was shaped and seeded to a
<br />mixture of smooth bromegrass, crested wheatgrass, in-
<br />termediatewheatgrass, alfalfa, and biannual sweet clover
<br />in 1973. In the spring of 1976, the study area was re-
<br />leased from bond and returned to its original owners.
<br />The Northern Great Plains Research Center, a part of
<br />the Science and Education Administration, United
<br />States Department of Agriculture, then leased the ex-
<br />perimental site. -
<br />Three grazing rates were established for the study.
<br />Pastures of 1.8 acres, (0.7 hectares}, 3.6 acres (1.4 hec-
<br />tares), and 5.4 acres (2.1 hectares) were each grazed with
<br />three yearling steers at stocking rates of 0.6 (0.24 hec-
<br />tare), 12 (0.48 hectaze) and 1.8 (0.72 hectare) acre(
<br />animal, representing heave, moderate, and light grazing
<br />intensities, respectively. Within each pasture, hvo 50-
<br />by 100-foot (15- x 30-meter) exclosures were fenced as
<br />ungrazed controls. Pastures were grazed in spring be-
<br />cause this is the optimum time to graze the cool-season,
<br />introduced species .which predominate at the site. Graz-
<br />ing was continued until vegetation from the moderate
<br />treatment was about half utilized. The effects oC the
<br />three grazing intensities can be compared .with each
<br />other and with the ungrazed controls by measuring
<br />changes in vegetation, soil, and the response and condi-
<br />tion of the animals..411 treatments were duplicated, giv-
<br />ing atotal of six pastures.
<br />Two years' data have been obtained thus far. In 1976,
<br />grazing was started on 41 ay 25 and ended on July 23 for a
<br />55-day grazing season. On May 25, 1976, all pastures had
<br />essentially the same amount of forage available per acre
<br />because they had not been previously han'ested. In
<br />1977, grazing began on May 26 and ended on June 26 for
<br />a 30-day season. Precipitation during this period and for
<br />the previous fall and winter seas only about half of•nor-
<br />mal.
<br />Effects of grazing at different intensities in 1976 car-
<br />ried over into 1977. At the end of grazing in 1976. 625.
<br />1880, 2280, and 3330 pounds/acre (756. 2112. 2560, and
<br />3734 kg/ha) oFvegetation remained for the heavy, mod-
<br />erate, light, and ungrazed intensities, respectively. At
<br />the beginning of grazing in 1977, 650, 1890, 2640, and
<br />2740 pounds/acre (732, 2116, 2958, and 3073 kg/ha) of
<br />vegetation dry matter was available for each of the re-
<br />•
<br />spective intensities. when grazing vas completed in
<br />1977, harvestable forage remained in all pastures except
<br />those heavily grazed.
<br />The heavy removal of forage by the steers in the
<br />heavily grazed pastures in L976 and again in 1977 was
<br />reflected in their average daily gains (ADC) and the beef
<br />gains per acre. No sta[isticalh• significant differences in
<br />ADG were recorded in 1976 or 1977 (or the light or
<br />moderate treatments; each steer gained about 2
<br />pounds/day (0.9 kg). But those grazing in heavih• grazed
<br />pastures gained 1.5 pounds (0.7 kg) in 1976 and only 0.9
<br />pounds (0.4 kg) per day in 1977. Gains per acre were
<br />149,'86, and 72 pounds (167, 96 and 31 kg/ha) in 1976
<br />and 49, 52, and 36 pounds (55, 58, and 41 kg/ha) in 1977
<br />for the heavy, moderate and light pastures, respectively.
<br />The loxver production in 1977 reflects a shorter season
<br />and probable drought effects. However, the significant
<br />observation is the decline in production under the heave
<br />grazing intensity in 1977. The trend towards higher gains
<br />per acre as stocking rates were increased in 1976 resem-
<br />bled those obtained from grazing studies on unmined
<br />land. But the relative reduction in gain produced per
<br />acre under the heave intensity in 1977 indicated animals
<br />lacked adequate forage and were probably losing weight.
<br />So far, only the 1977 data includes grazing intensity ef-
<br />fects. Additional data are required so that climatic differ-
<br />ences, animal differences, and longer-term grazing ef-
<br />fects can be fully analyzed. Therefore, similar data will
<br />be obtained for three additonal years at which time final
<br />effects of grazing intensities on vegetation and animal
<br />production can be concluded.
<br />The composition of the vegetation was determined
<br />with point frames which estimate the compostion of
<br />species and the percentage of plant cover in rangeland. A
<br />frame with 10 sliding pins was placed vertically at pre-
<br />determined locations along six randomly placed perma-
<br />nent line transects within each pasture. Also, each exclo-
<br />sure contained one transect. The first pin in the frame
<br />was slid downward until it hit an object which was re-
<br />corded. The second pin was slid downward, another hit
<br />was recorded, and so on. All hits were added and the
<br />percentage of each object hit was calculated. These per-
<br />centages gave an indication of the species composition
<br />and amount of cover in each pasture.
<br />Living vegetation .vas hit 45 per cent of the time in
<br />ungrazed exclosures at the close of the 1976 grazing sea-
<br />son. Of these live vegetation "hits," 45 per cent were
<br />smooth bromegrass, 20 per cent alfalfa, L9 per cent in-
<br />termediate wheatgrass, 15 per cent crested wheatgrass,
<br />and 1 per cent other species. No harvests or clippings
<br />had been made prior to the grazing study, so another 45
<br />per cent of the "hits" were litter (dead vegetation or
<br />foreign organic matter) and the remaining 10 per cent
<br />were bare soil or rocks. Changes in vegetative cover re-
<br />sulting from grazing will be determined by making simi-
<br />lar measurements in the pastures and the ungrazed con-
<br />trols each year unti{ the study is terminated in 1981.
<br />Other investigations include changes in chemical and
<br />physical properties of the soil caused by grazing treat-
<br />ments. Soil water supply and storage are being measured
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