Study the effect of different green manure plants on soil organic matter and nitrogen in salinity condition

In order to study the effect of different green manure plants on soil organic matter and nitrogen in salinity condition, an experiment was conducted in Randomized Complete Block Design with 4 replications. The treatments included plants white clover (Trifolium repens), vetch (Vicia peregrine), vetch (Vicia sativa), sorghum (Sorghum bicolor) and turnip (Eruca sativa) which were watered with natural saline water from Urmia lake (soil salinity: 2.7 dS m-1). Changes in soil nutrient elements and nitrogen mineralization were measured during different time periods after plant residues incorporation in soil. The results indicated that sorghum green residues resulted in the highest amount of fresh and dry weight of shoot and root, yield (38800 kg/ha) and organic carbon (0.93 %). No significant differences were obtained among the remaining plants for organic carbon. The highest soil nitrogen content was observed in white clover (0.11 %). The plants white clover (0.11%) and vetch (0.10%) resulted in higher total nitrogen in corresponded soil samples following five months residues incorporation. The C/N ratio decreased significantly after 3 and 5 months incorporation of white clover, vicia and vetch in soil. Ammonium N (NH4-N) and nitrate N (NO3-N) content were achieved to the highest amount in vetch, white clover and sorghum, respectively. It was concluded that sorghum and white clover could be introduced as proper green manure for salinity condition because of higher yield and biomass, increasing the amount of soil organic carbon, lower amount of C/N and increasing soil total and mineral nitrogen.