Optimizing drip fertigation management to simultaneously improve the yield, water productivity and fertilizer agronomic utilization efficiency of grapes in different precipitation year patterns

The aim of this study was to address the problems of water scarcity and low water and fertilizer use efficiency in vineyards in the Guanzhong Plain of Shaanxi, China. In the experiment, drip fertigation technology was used, including three irrigation levels (W3 (100% M, and M as the irrigation quota), W2 (75% M) and W1 (50% M)) and four fertilization levels (F3 (648 kg/hm2), F2 (486 kg/hm2), F1 (324 kg/hm2) and F0 (0 kg/hm2)). Traditional fertilization (CG) and a rainfed (CK) treatments were used as control treatments. Field experiments were conducted in Yangling, Shaanxi, China from 2019 to 2021 (wet years in 2019 and 2020, and dry years in 2021) to determine irrigation and fertilization intervals corresponding to higher crop yields and water and fertilizer utilization efficiency in different precipitation patterns. The results showed that, compared with the CK and CG treatments, the drip irrigation and fertilization treatment increased grape yield and significantly improved water productivity and fertilizer agronomic use efficiency. The highest grape yields were obtained in the F2 treatment under drip fertigation, and the highest grape yields were 16044 kg/hm2 and 12728 kg/hm2 in wet years and dry years obtained at W1F2 and W2F2, respectively. With the same fertilization level (F2), the grape yields of the W1, W2 and W3 treatments in wet years increased by 37.95%, 23.73% and 23.50% compared with those in dry years, respectively. The optimal irrigation and fertilization intervals determined by the response surface method were: the irrigation amount ranged from 8 to 11 mm and 32-38 mm, nitrogen application ranged from 182 to 190 kg/hm2 and 162-164 kg/hm2, phosphorus application ranged from 116 to 131 kg/hm2 and 98-100 kg/hm2, and potassium application ranged from 216 to 225 kg/hm2 and 194-201 kg/hm2 in wet years and dry years, respectively. This provides a guideline for the precision management of irrigation and fertilization of grape under different precipitation year types in Guanzhong Plain of Shaanxi Province.