Effects of Irrigation and N Fertilization on 15 N Fertilizer Utilization by Vitis vinifera L. Cabernet Sauvignon in China.

This study investigated the interactions between different irrigation and nitrogen (N) fertilization rates and their effects on the ¹⁵N fertilizer absorption and utilization of Cabernet Sauvignon grapevines in a vineyard near Xinjiang, China. The fertilizer treatments consisted of three ¹⁵N-labeled urea nitrate fertilizer applications (191.4, 254.4, and 317.4 kg/ha). The irrigation treatments included two fractions (0.75 and 1.0) of estimated vineyard water use (ET_c). The results showed that: (i) the residual amount of ¹⁵N fertilizer in the soil was mainly in the surface layer (0–20 cm), the residual fertilizer N in the surface layer accounted for 68–87% of the total residual N, the residual ¹⁵N fertilizer at different depths differed significantly, and the residual ¹⁵N was positively correlated with the amount of fertilizer applied (p < 0.05); (ii) The absorption of fertilizer N by grapevines accounted for only 12–17% of the total N absorption, and the proportion absorbed from soil N was as high as 82–87%. There was no significant difference in the amount of N absorbed between different water and fertilizer treatments; (iii) The ¹⁵N uptake under the different water and fertilizer treatments differed and was significantly higher in the roots than in other organs, followed by the fruit, the leaves, and finally, the stems. Our results provide a reference for improving the soil environment and encouraging a sustainable development of the grape industry. According to the experimental results, it was recommended that farmers adopt irrigation levels of 1.0 ETc and fertilizer application of 254.4 kg N/ha. [ABSTRACT FROM AUTHOR]