Navigating water and nitrogen practices for sustainable wheat production by model-based optimization management systems: A case study of China and Pakistan

Water and fertilizer losses have often affected wheat yield per unit area in China and Pakistan. The 2-year field experiments were conducted at six research stations. The experimental sites in China were Tongzhou, Qiliying and Yuanyang. In Pakistan were Faialsaabad, TandoJam and Dokri. Fertilizer treatments were: N275, N207 and N135 kg ha−1 in Tongzhou and N125, N105 and N90 kg ha−1 in Faisalabad. While the irrigation treatments were: W210–230, W160–190 and W110–140 mm ha−1 in Qiyliying, W350, W305 and W250 mm ha−1 in Yuanyang, W435, W400 and W365 mm ha−1 in TandoJam and W380, W340 and W300 mm ha−1 in Dokri. The grain yields, water and N losses were simulated using the WHCNS model. The model showed a good ability to capture the effects of management practices and read the environmental diversity. The study revealed that major contributors to water and N losses were N leaching (r=0.98), evaporation and drainage (r=0.77–0.96) rates. In Tongzhou, the N207 treatment maintained yield, NUE and decreased N loss. In Faisalabad, the N125 increased yield but led to higher N loss and reduced NUE. Furthermore, the decline in surface soil water content was a common issue in Pakistani sites and wheat yields were 27.48–41.60 % lower than in China. In Qiliying, the W160–190 and W110–140 and in Yuanyang, the W300 and W250 treatments decreased the annual average water loss by 33.49–12.38 mm and 66.06–55.01 mm, respectively. In TandoJam, the W400 and W365 and in Dokri, the W380 and W340 treatments decreased water loss by 72.34–45.87 mm and 56.84–37.82 mm compared to the full irrigation amount. Overall, results showed that 17.39–23.81 % of water use could be decreased without yield penalty in Qiliying and 14.29 % in Yuanyang. In Pakistani sites of TandoJam and Dokri, a decreased irrigation amount of 10.5 % is recommended.