تاثير شخم و رژيم هاي متفاوت بارش هاي شبيه سازي شده مصنوعي در ميزان مواد فرسايش يافته در خاك لومي ايستگاه تحقيقات كشاورزي استان آذربايجان شرقي (خسروشهر)

Effect of Tillage and Simulated Rainfall on the Erosion From a Loamy Soil at East Azarbaijan Agricultural Research Station (Khosrowshahr)

Effects of rainfall, simulated by two different methods and at two various rates, on the erosion from a loam soil were studied under both plowed and unplowed conditions. The study was conducted at East Azarbaijan Research Station Center (Khosrowshahr) by employing a factorial experiment based on randomized complete block design with four replications. Rainfall to the experimental plots were simulated by using a rainfall simulator with 100 and 200 mm/hr and a rotating sprinkler with 100 mm/hr. Amount of erosion was determined by conveying the runoff generated during 30 and 120 minutes to the pre-installed containers and then measuring its solid material contents. The results indicated that raising rainfall rate from 100 to 200 mm/hr almost doubled the amount of erosion under plowed soil surface condition; erosion from unplowed soil, where the surface left covered about 50% by the natural vegetation, was not significantly affected. Average amount of erosion during 30 minutes experiment was 18.7 tons/ha from plowed plots as compared to 4.0 tons/ha from the unplowed sites, irrespective to the kind and rates of the rainfall generated. Extending duration of rainfall to 120 min., when steady state infiltration rate was realised, increased erosion to 38.7 and 71.0 tons/ha with 100 and 200 mm/hr rate, respectively, under plowed condition. The corresponding figures were 7.2 and 11.8 tons/ha for undisturbed plots where the soil surface was about 50% covered by the natural vegetation and / or plant residues. Two methods of rainfall generation (simulator and sprinkler) did not produce significant effect on erosion. This implies that even though a small area of soil is depicted and goes under rain with rainfall simulator, however, the results may be applied to large areas or at large scales.