Data related to physical and chemical properties of paddy soils is necessary for improving rice productivity and designing of sustainable farming techniques and environment protection. In this research, Sefidrood plateaus and upper terraces, river alluvial plain, lowland and Caspian Sea coastal plain landforms in a toposequence were recognized which located in Guilan province of Northern Iran. Five profiles were studied on each landform, which one of them was selected in order to detail study as reference profile. Physical and chemical characteristics were studied by providing disturbed soil samples from the horizons of described soils. Results showed that soil structure was weak granular in all surface horizons and single grain in the subsurface horizons of the Coastal plain. Soil structure was sub-angular blocky and angular blocky in the subsurface horizons of other units. Soil organic matter was high in surface horizons because of accumulation of rice plant residues. Organic matter was the highest level in lowland due to high ground water table and lower decomposition rate. Cation exchange capacity was high in lowland and alluvial plain due to high organic matter and clay content in soils. Clay particles in plateaus lands were lower than other units because of alteration, suitable aeration and occurrence of ferrolysis process. Electrical conductivity was high in subsurface horizons of lowlands and coastal plain because of high ground water table. Exchangeable Na+ was high in subsurface horizons of coastal plain and lowlands due to sea water seepage from depth in these soils. Soil reaction was nearly neutral because of natural and artificial submerged effect. Finally, multivariate analysis of variance (MANOVA) model was performed on soil physical and chemical properties and showed significant difference among landforms. Mean comparison of soil physical and chemical properties using least significant difference test proved significant difference of these properties on soils of studied landforms. Therefore, multivariate statistical analysis i.e. MANOVA model could be applied in exact surveying of paddy soils properties, sustainable land management for agriculture and environment protection.
Modeling Earth Systems and Environment – Springer Journals
Published: Apr 6, 2018