Study of flood water spreading on soil physical and chemical properties in Jajarm project, North Khorasan province

The deposition of transported materials by flood water on soil surfaces in warm and arid region causes some changes in texture, structure, depth and fertility of the soil. According to the study of flood water spreading effect on physical and chemical characteristics of the soil, the study field of flood water spreading of Jajarm in North Khorasan province was chosen. This area has located on alluvial fan with 0.75- 1%slop, 146.3 millimeter mean annual rainfall, arid and extra arid climate. For the period of 4 years (1995-1999), the soil samples were collected from recognizable A and C horizons and the depth of 0-30 centimeter (plow layer) from 7 profiles at three primary strips. The quantity of effective parameters on soil characteristics was determined in laboratory. This process was repeated after three times flood water spreading. Obtained data were analyzed: I) by t-student test to compare different properties of soil before and after flood spreading. II) by split plot procedure with three replicates to compare the whole effects at flood water spreading. The samples variance analysis showed that flood water spreading was effective on sand ratio, clay, organic matter, bicarbonate (p<0.05) and was effective too on Ca, Mg, Cl, Na, SAR and EC (p<0.01). There was a significant difference between the samples before and after spreading of flood water. Comparing the average mean of factors including soil salinity, Ca and Mg on A, C and plow layer before and after flood water spreading showed only different between plowing layers, also results showed that the sand to clay ratio and silt in a horizon were decreased. Flood water spreading had no more effect on the other soil characteristics.