Effects of Different Cropping Systems on Fertility of Paddy Soil

To study the effects of multiple cropping systems on some characteristics of paddy field soil, this experiment was conducted by using a randomized complete block design (RCBD) with four replications at the Agricultural Research Center of Mazandaran for two years during 2009 - 2011 cropping seasons. The treatments consisted of four multiple cropping systems as: maize – clover - rice, maize – canola - rice, maize – broad been - rice and fallow - rice which were assigned to the plots. Results showed that pH and EC, were not significantly affected by multiple cropping systems, but the effect of multiple cropping systems on available organic matter, nitrogen, phosphorous and potassium were significant. The highest OM, total N and available P of paddy soil were obtained after maize – clover – rice.Highest available K was also obtained after fallow – rice cropping systems. The minimum OM, N, P and K content of paddy soil belonged to maize – canola – rice cropping system. Based on the climate and soil conditions of paddy fields in Mazandaran maize - clover – rice cropping system increased production and soil fertility more than other cropping systems.