Estimation and Comparison of Soil Erosion in Conservation and Conventional Agricultural Systems(Case study: Soybean Agricultural Lands in Gorgan County)

Golestan province has the first rank in Iran in terms of soybean production and area. Most of these areas are located in Gorgan County. Recently, conservation agricultural system is developing in this county. Considering the importance of erosion in soil loss and fertility decline, estimating the amount of soil erosion in agricultural lands is important. The current study carried out in Gorgan University of Agricultural Sciences and Natural Resources, during 2016-2017. Soybean field were selected from four main directions based on five agricultural service centers. In order to 38 conventional fields and 10 conservation fields were evaluated based on Universal Soil Lose Equation (USLE). The maps of USLE parameters were produced by interpolation methods in ArcMap 10.3. According to the results, the average amounts of erosion were estimated as of 55.024 kg ha-1 per year in the conservation fields and 131.31 kg ha-1 per year in the conventional fields. The results showed that there was a significant difference between these two agricultural systems in Gorgan based on T test in the 99% probability level. Also, soil erosion map showed that the eastern part of the county had the most erosion amounts. The reasons of these results were the high rainfall erosivity, soil erodibility and the lack of soil surface coverage from plant residue. Generally, soil erosion was reduced with the implementation of conservation agriculture system, maintaining the plant residue in soil surface and reducing soil tillage. Thus, the effects of erosion can be significantly reduced in fields using conservation of soil as an ecosystem service.