بررسي شدت چراي دام در برخي از خصوصيات فيزيكي خاك مراتع لسي مراوه تپه

Effects of animal grazing on some physical characteristics of loose soil in Maravetapeh rangelands, Golestan, Iran

Rangelands in Maravetapeh with the loose soil not only are the major area for grazing animals in Golestan province but also they are as the winter rangelands for the animals that migrate to this area. thus the area is under over grazing. In order to recognize any changes in infiltration, runoff coefficient and bulk density of soil, which are very important in erodibility of soil erosion, an investigation was carried out in the form of completed randomized blocks in 3 replications. The experimental treatments were selected as : 1-Not grazing plots, 2 -- Grazing equal to the half of productivity capacity, 3 -Grazing equal to of productivity capacity, 4 -Over grazing to the double of productivity capacity and 5- Over grazing to the triple of productivity capacity. Bulk density of soil surface form treatment number 3 is highest and it is equal to 1. 27 grlcm . The lowest value of bulk density in soil surface is 1.09 and it is belong to the treatment number I and 2. Amount of runoff after each rainfall event has been measured. Infiltration rate and bulk density of soil surface were determined in the end of each year. Analysis of variation has been done and the results showed that the infiltration rate of 11. 67 cm/hr in the soil under over grazing to the triple of productivity capacity is the lowest value, while, this rate in the no grazed area as well as in the soil under grazing equal to the half of productivity capacity is highest value which is around 25. 24 cm/hr. the amount of runoff in treatment number l and 2, is equal to 45. 6 m/hec/year and this figure is equaled to 130. 28m` Thee/year for treatment number 5 ( triple grazing ). Tus The over grazing in this kind of rangelands therefore causes compaction and increasing runoff coefficient.