Assessment of the Variability of Soil Properties for OFC Cultivation under Minor Irrigation Systems

Abstract:

Combined paddy and other field crops (OFC) fields are unique from other wetland or upland soils, because of seasonal alternation of wetting and drying conditions resulting anaerobic and aerobic conditions. Therefore, objective of this study was to assess spatio-temporal variation of soil properties in paddy fields under minor tanks with respect to OFC cultivation. Soil samples were collected at two soil depths from 24 locations covering the entire command area of the Bayawa Minor Irrigation Tank (MIT), Sri Lanka. Soil properties were analyzed and mapped using Arc GIS. Hardpan depth (HPD) was also determined by collecting undisturbed core samples at 0, 15, 25, 30, 45 and 60 cm depths from the same locations Statistical analysis was done to identify spatio-temporal variability of each property. Results revealed that, Bayawa command area showed low coefficient of variation (CV) for pH and bulk density, but high CV for saturated hydraulic conductivity (K_s). HPD was found to be varied in each section within the effective root zone. Overall, low K_s, high clay content, high field capacity, poor drainage and the presence of hardpan are major obstacles to introduce OFC. Therefore, introduction of site specific OFC by considering the variability of soil properties is very important for sustainability of the MIT system.