Understanding the effects of land‐use change in drylands on nutrient use efficiencies and losses within the food production‐consumption system provides insights on nutrient management strategies and the effectiveness of land‐use policies. Weibei Dryland is considered an example to use to evaluate changes in nitrogen (N) flows through the food chain following conversion of croplands to apple orchards, using the Nutrient flows in Food Chains, Environment and Resources Use (NUFER) model, and we also modelled the effects of 20% reduction in N fertilizers on apple yields to obtain a balanced fertilization strategy. The apple orchards area increased from 9.6 × 10⁴ ha in 1978 to 72 × 10⁴ ha in 2013, while the area under cereals decreased from 186 × 10⁴ ha in 1978 to 152 × 10⁴ ha in 2013. The increased income due to apple orchards led on‐one‐hand to more N fertilization to get a higher apple yield, and on‐the‐other‐hand promoted the consumption of animal foods. Consequently, nitrogen use efficiency of crop production (NUEc) and the combination of crop and animal production (NUEc+a) decreased, but nitrogen use efficiency of animal production (NUEa) and N losses increased between 1978 and 2013. The modelled scenario of 20% reduction in N fertilization amounts will still keep optimum apple yield but will significantly decrease N losses from the apple orchards. We therefore, suggest that the key measures for improving nitrogen use efficiency and decreasing N losses after conversion to cash crops are: (a) reducing N fertilization as well as balancing various inorganic fertilizers; and (b) implying organic fertilizers.

中文翻译：

---

干旱地区将农田转变为经济作物：氮素流失的后果以及食物链系统中氮素利用效率的下降

了解干旱地区土地利用变化对粮食生产-消费系统中养分利用效率和损失的影响，为养分管理策略和土地利用政策的有效性提供了见识。渭北旱地被认为是一个示例，可利用食物链，环境和资源利用中的营养流模型评估农田转化为苹果园后通过食物链的氮流变化，并且我们也进行了建模氮肥减少20％对苹果产量的影响，以获得平衡的施肥策略。苹果园面积从 1978年的9.6×10 ⁴公顷增加到 2013年的72×10 ⁴公顷，而谷物下的面积则从186×10 ⁴减少 公顷1978年为152×10 ⁴ 苹果园的收入增加，一方面导致更多的氮肥施肥，以提高苹果的产量，另一方面也促进了动物性食品的消费。因此，1978年至2013年间，农作物生产的氮利用效率（NUEc）以及作物和动物生产的组合（NUEc + a）下降，但动物生产的氮利用效率（NUEa）和氮损失增加。模拟情景20施氮量减少的百分比仍将保持最佳的苹果产量，但将显着减少苹果园的氮损失。因此，我们建议，提高氮素利用效率和减少转为经济作物后减少氮素损失的关键措施是：（a）减少氮肥的使用并平衡各种无机肥料；（b）暗示有机肥料。