Effect of techniques on soil loss, surface runoff and soil moisture storage in hill slopes- Part II

Abstract

A field experiment was conducted at the Instructional Farm, Vellanikkara during June 1981 to February 1982, to study the effect of various Agro-Techniques on soil loss, surface runoff and soil moisture storage in hill slopes. The experiment was conducted with the main objective of studying the effect of cowpea intercropping as well as the different methods of planting of tapioca on reducing soil and water loss in hill slopes. The experiment was laid out in Randomised Block Design with seven treatments and three replications. The treatments consisted of (1) tapioca alone in ridges along the slope, (2) uncultivated bare fellow as a control, (3) tapioca in ridges along the slope with cowpea as intercrop, (4) tapioca in ridges across the slope with cowpea as intercrop, (5) tapioca alone in mounds, (6) tapioca alone in ridges across the slope and (7) tapioca in mounds with cowpea as intercrops. The experiment was conducted in field runoff plots of 24.3 m x 2.7 m size. The runoff from the field were collected directly into water proof polythene lined earthen tanks and measured after each rainfall. From the experiment it is observed that total rainfall was better correlated with runoff and soil loss followed by average intensity. Maximum runoff and soil loss occurred in plots with tapioca alone in ridges along the slope. Cowpea intercropping as well as tapioca planting in ridges across the slope were effective in reducing soil and water losses. Tapioca alone in ridges along the slop recorded the maximum losses of N, P and K being 131.29 kg, 41.44 kg and 124.63 kg/ha respectively. Maximum retention of rainfall was recorded the tapioca in ridges across the slope with cowpea as intercrop. The pH and conductivity of runoff water were not significantly influenced by different treatments. During the dry periods maximum storage and thereby minimum depletion of moisture in 30-45 cm soil layer were recorded by uncultivated bare fallow plot. The treatment with tapioca alone in ridges across the slope recorded greater height of plants, more number of functional leaves per plant, maximum length of tubers and highest yield of tubers. The biometric characters and yield of the intercropped cowpea were not affected by various cultivation methods of tapioca.