Feasibility of Recovering Soil Nutrients through Flood Water Spreading

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Flood water contains high amount of sediment affecting the fertility of the coarse grain alluvial fans and flood plains through increasing nutrients. In this study, the effects of the flood water spreading on the soil nutrients recovery were investigated during 10 years (2004-2014) at the Poldasht Flood Spreading Station of West Azarbaijan in Iran. Flooded three upper strips were selected at the flood spreading system. Three composite samples resulted from mixing four samples, in each strip were taken from 0-30 cm depth. Soil organic carbon (SOC) and total nitrogen (TN), exchangeable phosphorus (P) and potassium (K) were determined at the laboratory. To statistically analyze the data, t-test, in case of normal distribution, and otherwise non-parametric test of Kruskal Wallis were used. Results showed that the amount of SOC and TN increased from 0.23 to 0.33% and 0.027 to 0.039%, respectively. Noticeably, SOC, TN and P contents in the upper strips were significantly more than in the lower bands (p≤ 0.05). In addition, exchangeable P and K were significantly increased (p≤0.05) from 2.69 to 5.32 and 145.93 to 206.52 ppm, respectively, but there was no significant change in (p≤0.05) K content. These results also showed that flood water spreading increased the soil nutrients which may reduce the fertilizer requirement.