ABSTRACT
This chapter focuses on the effects of drip fertigation in castor + onion intercropping system on growth/yield attributes and yield, water use and nutrient use efficiency, and cost economics. Drip irrigation at 80% CPE with the application of 100% RDF through WSF recorded significantly higher values of growth and yield attributes castor seed yield, nutrient uptake, an equivalent yield of castor and onion intercrops than the other treatments. Length of the primary spike, number of capsules per spike and the total number of spikes per plant of castor were significantly improved at 80% CPE with 100% RDF as WSF application. Drip fertigation at 80% CPE with 100% RDF as WSF recorded higher castor seed yield (2619 and 2490 kg/ha).
Drip irrigation at 80% CPE with 100% RDF as WSF registered higher uptake of nutrients (N, P, and K) in castor. Drip irrigation at 80% CPE with 100% RDF as WSF recorded increased plant height, more number of leaf sheaths and dry matter production of onion intercrop. The equatorial diameter, polar bulb diameter, number of bulbs plant−1, single bulb weight and bulb yield plant−1 were significantly influenced by drip irrigation at 80% CPE and fertilizer application at100% RDF as WSF than other treatments. Drip fertigation at 80% CPE with 100% RDF as WSF significantly recorded higher marketable onion yield (5316 and 4577 kg/ha) compared to other treatment combinations.
The combined application of irrigation at 80% CPE with fertilizer at 100% RDF as WSF significantly enhanced the nutrient uptake (N, P, and K) of onion intercrop. Under drip irrigation, at 80% CPE with the 156application of 100% RDF through WSF significantly recorded higher castor equivalent yield (6416 and 5759 kg/ha) compared to other treatment combinations. Application of 100% RDF as WSF with 80% CPE showed higher agronomic efficiency (AE) (66.1 kg−1 of nutrient−1). Significantly higher water use efficiency (WUE) was recorded under drip irrigation at 40% CPE with 100% RDF as WSF combination (19.3 kg/ha-mm−1).
Under drip irrigation at 80% CPE maintained higher soil available moisture at 30 cm distance across the lateral at 15–30 cm depth for 24 and 48 hours after irrigation. At the end of fertigation across the lateral, the peak available nitrogen significantly higher at 100% RDF as WSF in the depth of 15–30 cm at 15 and 30 cm from the dripper. The peak availability of phosphorus recorded just below the dripper. Higher available potassium recorded near the emitter point and decreased as the distance increases with a lower level to 30 cm depth on distance and depth. The combination of drip fertigation at 80% CPE with 100% RDF as WSF significantly recorded superior land equivalent ratio (LER) value of 1.59 and 1.52 compared to other treatment combinations.
Drip fertigation at 80% CPE with 100% RDF (75% CF + 25% WSF) recorded maximum net return of Rs. 1, 63, 921 per ha (2732 US$/ha) to surface irrigation with soil application of 100% RDF as conventional fertilizer. Drip irrigation at 80% CPE with 100% RDF as WSF resulted in higher net present value (Rs. 97,019 per ha (1617 US$/ha)) and the discounted benefit-cost ratio (2.30) than other treatment combinations.
