Variable irrigation and fertigation effects on response of onion (Allium cepa) in a semi-arid environment

Field experiment was conducted for three years to study the response of onion (Allium cepa L.) to variable irrigation and fertigation in microsprinkler and drip irrigation regimes under semi-arid environment. For this purpose, different soil moisture regimes for the crop were created by variable irrigation, viz 0.60 (I-1), 0.80 (I-2), 1-00(I-3) and 1.20 (I-4) of irrigation water (IW) applied and pan evaporation (CPE) ratio. Three different fertigation (N:P2O5: K2O) @ 50:25:25 (F-1), 75:37.5:37.5 (F) and 100: 50: 50 (F) kg/ha were combined with above treatments for both the irrigation systems. Our study revealed highest onion yield with 1.20 irrigation treatment and fertigation treatment 100:50:50 kg NPK, but reduced significantly with the reduction in irrigation and fertigation under both the microirrigation systems. Irrigation production efficiency (crop yield per unit volume of water applied) was highest with 0.80 irrigation water indicated that water was utilized most efficiently under this irrigation schedule. Results of the study also indicated that fertigation saved 25% nutrient as compared to traditional fertilization. The quadratic production function yielded optimum value of irrigation as 488 mm for maximum onion yield with microsprinkler while drip irrigated crop required 519 mm water to reach the maximum yield potential in a semi -arid environment. Overall results of the study indicated that microsprinkler performed slightly better with I-2 and above irrigation level compared to drip irrigation.