Effects of fertigation on yield, water and nitrogen utilization and economic productivity benefit of wolfberry (Lycium barbarum L.)

Objectives This study analyzed the effects of different water and nitrogen conditions on water and nitrogen utilization efficiency, yield and economic benefits of Lycium barbarum, so as to provide a theoretical basis for local Lycium barbarum cultivation to save water and increase yield and efficiency in Qaidam basin.

Methods The experiment was conducted in the Qaidam Basin at Huaiten Tula irrigation area, Qinghai Province from 2018 to 2019. The tested wolfberry cultivar was Ningqi 7, which was two years old. The experiment was a randomized complete block design with two factors, each having three levels. The three irrigation levels were W1 (198 m³/hm²), W2 (158 m³/hm²), and W3 (119 m³/hm²), and the three N levels were N1 (345 kg/hm²), N2 (276 kg/hm²), and N3 (207 kg/hm²). The water storage in 0–100 cm soil profile, the water consumption, water use efficiency (WUE), yield and economic benefit of wolfberry were analyzed.

Results Water and N interaction had a significant effect on soil water storage. The highest soil water storage was recorded in W2N2 treatment in the two trial years. The water use efficiency in water treatments was in order of W2>W3>W1, and that in W1 was79.4% and 59.3% lower than in W2 and W3. The highest WUE was recorded in W2N3 17.26 kg/(hm²·mm). The average N partial productivity (NPP) for the two years was in order W2>W3>W1. Under the same irrigation level, the NPP decreased with the increase of N levels, and the highest NPP (15.71 kg/kg) was recorded in W2N3. The yield and economic benefit of wolfberry were increased with irrigation and N application. The overall yield and economic benefit among irrigation treatments were W2>W3>W1. The wolfberry yield and the net income of W2 and W3 were 49.4% and 29.1% higher; and 3.36 times and 2.88 times respectively higher than thatse of W1. Compared with W2N1, the wolfberry yield of W2N2 and W2N3 treatments increased by 10.6% and 16.7%, respectively, while the net income increased by 29.1% and 41.6%, respectively.

Conclusions Only proper irrigation could significantly increase the water storage in 0–100 cm soil profile and decrease water consumption. Irrigation at 150–160 m³/hm² and N rate of 200–220 kg/hm² (W2N3) is the optimum combination for Lycium barbarum in Qaidam Basin.