Effects of Preceding Rice Cultivation On Salt Accumulation of Surface Soils In the Middle Nile Delta, Egypt.

  Salt accumulation of surface soils due to irrigation agriculture is a common phenomenon in arid region. There were some studies that rice cultivation was fairly effective for salt leaching by the use of irrigation water. In the Nile Delta, however, there are no such conclusive studies on salt accumulation of surface soils. Therefore, present study was conducted to investigate the effect of preceding rice cultivation on salt concentration of the surface soils. Our study sites were conventional farms in the area where samples of surface soils and irrigation water were taken together on 20^th~26^th May, 2010, in addition to the interview for farmers on their irrigation practices. A total of 15 soil samples were collected and divided into 4 types according to the record of preceding rice cultivation: those received no rice cultivation in the past, once in the last year, once in the two years ago, and two years consecutive rice cultivation. These soil samples were from 4 different areas within 5km of the north, south, east, and west of the Agriculture Research Center (ARC), Kafr El-sheikh, Egypt.

  There was no significant difference in pH, Total C and N, and CEC of soil samples. However, exchangeable base showed some difference among 4 areas. Nevertheless this was not attributable to rice cultivation. EC and Water soluble ions showed similar results with exchangeable base. Ion concentration in irrigation water was also different among 4 areas. Probably, the number of days after the last irrigation also affected the amounts of exchangeable base. Based on these results, salt accumulation was variable depending on the quality of irrigation water and the number of days after the last irrigation in each area. However, little or small leaching effect of rice cultivation was suggested on salt accumulation of surface soils.