Impact of drip fertigation on nutrient use efficiency, dynamics, water productivity and bulb yield in Aggregatum onion

A field experiment was conducted on aggregatum onion (Allium cepa L. var. aggregatum Don.) under a drip irrigation system to evaluate the water productivity, nutrient use efficiency, nutrient dynamics and yield of onion in order to optimize the best fertigation level. The experiment was designed in a Randomized Block Design (RBD), with treatments replicated 3 times. The treatment details are as follows: T1-100 % nitrogen (N) through fertigation with100 % phosphorus (P) and potassium (K) applied as basal; T2 - 100 % N and K through venturi as fertigation and basal application of 100 % P; T3 - 100 % N, P and K through fertigation; T4 – 75 % N, P and K through fertigation with basal application of 25 % N, P and K; T5 – 75 % N through fertigation with 75 % P and K applied as basal; T6 - 75 % N and K through venturi as fertigation with basal application of 75 % P; T7 - 75 % N, P and K through fertigation; T8 – 75 % of N, P and K through fertigation and 25 % of 75 % N, P and K applied as basal; T9 - 50 % N 100 % P and K applied as basal and 50 % N applied on 30 DAT; T10 - absolute control (no fertilizer). The results indicated that the bulb yield of aggregatum onion was significantly higher in 100 % N, P and K through fertigation (23.24 to 23.47 t ha-1). Among the different fertigation treatments, the 100 % N, P and K through fertigation recorded higher water use efficiency (75.08 to 78.44 kg/ha mm), water productivity (7.841 to 7.508 kg m-3) and nutrient use efficiency, which was comparable to the 75 % N, P and K through fertigation.