Hydraulic performance of existing drip irrigation system and effect of used plastic based mulching system on Rabi onion (Allium cepa)

Abstract

Polythene mulches have been practiced for soil solarisation during winter months in various vegetable crops and have been found superior over other types of mulches, but plastics is create environmental problems. With this in view the present study has be undertaken on clay loam soil at Raipur, Chhattisgarh for Rabi onion. The aim of the experiment was to study the hydraulic performance of existing drip irrigation system under different operating pressure and prepare used plastic based mulching sheet to evaluate their performance in terms of change in micro-climate. In this study eight different types of mulching conditions were considered viz. black plastic mulch (BPM), silver plastic mulch (SPM), used reddish rice bag mulch (RBM), used whitish wheat flour bag mulch (WFBM), used yellowish cement bag mulch (CBM), Paddy straw mulch (PSM), soil mulch (SM) and without mulch (WM) (control) and comparison was done among them in micro-climatic condition. The main micro-climatic parameters like soil temperature, soil moisture content, soil moisture depletion were studied with randomized block designed in three replications. In Hydraulic performances of drip irrigation system were studied for 2.4 l h-1 inline emitters at 1, 1.2 and 1.5 kg cm-2 pressures, discharges from drippers were found to be 1.99 l h-1, 2.22 l h-1 and 2.33 l h-1, coefficient of variation 0.061, 0.044 and 0.029 were found and emission uniformity 95.59%, 96.54% and 96.69% were found, respectively. Also, from this study, it was found that during forenoon soil temperature increases with increasing soil depth but in afternoon the trend was vice-versa. The maximum soil moisture content (27.89%) was found under BPM and minimum soil moisture content (21.52%) was found under used WM. Similarly soil moisture depletion was found minimum in BPM (0.31 mm) and maximum under WM (3.08 mm) under all eight types of mulches. The study concludes that the hydraulic performance of drip irrigation system was found good and needs to be operated at 1.2-1.5 kg cm-2 pressure for 2.4 lh-1 inline emitter. At a particular spacing, the emission uniformity, uniformity coefficient and irrigation efficiencies increases when operating pressure is increased but coefficient of variation and emitter flow variation decreases when operating pressure is increased. Mulching roll can be prepared from used plastic bags which are available with the farmers in plenty and can be reused as mulching material satisfactorily by small and marginal farmers.