Pedo-transfer Functions for Determining Soil Water Retention and Assessing their Utility in Simulation Model for Predicting Rice Growth and Yield

Abstract

As a case study to determine soil water retention using pedo-transfer functions and assessing their utility in simulation model for predicting rice growth and yield, soil samples were collected at various depths (0- 0.15, 0.15-0.30, 0.30-0.45, 0.45-0.60, 0.60-0.90, 0.90-1.20 m) from 3 locations viz., Satyabadi, Kanas and Dhenkanal of Odisha, representing land ecologies of moderate surface waterlogging (0.5-0.75 m), severe surface waterlogging (>1.0 m) and non-waterlogged upland soils, respectively. The soil texture was clay at all depths at Kanas and Satyabadi whereas, texture of the Dhenkanal soils ranged from sandy clay loam to clay loam. The bulk density was higher in soils of Kanas and Satyabadi while it was low in Dhenkanal. The profile organic carbon stock was higher in waterlogged soils of Kanas and Satyabadi (66.6 and 78.8 Mg ha-1, respectively) than that of Dhenkanal site (59.2 Mg ha-1). Soil moisture retention at field capacity (0.033 MPa) ranged between 0.381 to 0.603 m3 m-3 at Kanas, 0.335 to 0.503 m3 m-3 in Satyabadi and 0.319 to 0.446 m3 m-3 in Dhenkanal at different depths. At permanent wilting point (1.5 MPa), the moisture content varied from 0.185 to 0.262, 0.172 to 0.246 and 0.108 to 0.139 m3 m-3 at Kanas, Satyabadi and Dhenkanal, respectively. Pedo-transfer functions in the form of linear equations were developed for estimating soil water retention at field capacity and wilting point using basic soil properties. These pedotransfer functions derived soil water constants were used in soil module of DSSAT 4.5 model for predicting rice crop growth and yield. With pedo-transfer derived soil moisture data, the error (%) for maximum LAI was 2.39%, while the error (%) for maximum dry biomass and grain yield were 4.46 and 6.73, respectively. The lower errors indicate that the model predicted crop growth and yield close to the actual values with pedo-transfer derived soil moisture data.