Abstract:

Revealing the effects of water and nitrogen coupling at different growth stages on yield and water productivity of potato in agro-pastoral ecotone has great significance for the efficient utilization of water and fertilizer of potato. In this study, soil data, meteorological data and management data from Zhangbei and Wuchuan in the northern of agro-pastoral ecotone were used to drive the calibrated APSIM−Potato model. Different gradients were set for irrigation and nitrogen fertilizer, respectively, irrigation gradients were 0, 60, 120, 180, 240mm, and nitrogen application amounts were 0, 50, 100, 150, 200, 250, 300kg·ha⁻¹, respectively. Two growth stages of seedling stage, tuber formation stage and tuber expansion stage were selected as the combination of irrigation and nitrogen fertilizer application, with the same amount of irrigation and N fertilizer applied for the both two stages. The effects of water and nitrogen coupling on potato yield, water consumption and water productivity at different growth stages were analyzed the optimal water-nitrogen coupling scheme was recommended based on the highest yield and the highest water productivity respectively. The results showed that the potato yield of Wuchuan and Zhangbei stations were 12700−25600kg·ha⁻¹ and 14200−24900kg·ha⁻¹ under different water-nitrogen coupling scenarios at different growth stages. Under the scenario of maximum yield, the combination of potato tuber formation stage and expansion stage was selected; the irrigation amount and N fertilizer amount were 90mm and fertilized 75kg·ha⁻¹ for the formation stage and expansion stage at Wuchuan, and the amounts were 60mm and 75kg·ha⁻¹ for the formation stage and expansion stage at Zhangbei, and the highest yields were 25600kg·ha⁻¹ and 24900kg·ha⁻¹ for the two stations. The potato water productivity of Wuchun and Zhangbei was 5.3−9.0kg·m⁻³ and 5.9−8.5kg·m⁻³. Under the scenario of maximum water productivity, two growth stages of potato tuber formation stage and expansion stage were selected; Wuchuan irrigated 90mm and fertilized 50kg·ha⁻¹, Zhangbei irrigated 60mm and fertilized 50kg·ha⁻¹ for the formation stage and expansion stage, and the highest water productivities were 9.0kg·m⁻³ and 8.5kg·m⁻³. 

Key words: Potato, Irrigation, Fertilizer, Yield, Water productivity