结合多年的田间试验研究，对前人诸多研究结果进行了总结和深入分析。结果表明：农田水肥效应大小与试验方法有关，田间试验与模拟试验得到的结论相反。主要原因在于研究中"水"的概念各不相同，从旱棚试验或盆栽试验的结果推断水肥效应与实际情况相距较大。多数情况下，养分亏缺仍是北方旱区作物增产的主要限制因子。灌水的效果取决于土壤底墒、生育期降水、土壤肥力及灌水时期等各种因素。在现有的水资源条件下，提高养分供应水平是北方旱区大部分农田作物增产的主要途径。加强夏闲期降水的蓄积、提高土壤底墒是冬麦区作物高产的重要条件。

On the basis of field experiments conducted by authors for a few years, the research results published by many others were collected and analyzed. It was showed that the water effect and fertilizer effect on crop production were related to experiment method. The result obtained from field experiments was opposite to that from simulated experiments because the concept of “water” in the experiments was not the same. The result of rainproof-shed experiments or pot experiments didn’t coincide with the field situation. In many cases, nutrient shortage was still the limit factor to increase crop yield in arid zones in Northern China. The effect of irrigation water on crop production depended on the soil water content before sowing, precipitation during crop growing, soil fertility and irrigation time, etc. At the present water resources situation, the main way to increase crop yield in most farmland of arid zone in Northern China was increasing nutrients supply. Enhancing the storage of rainfall during summer fallow period and raising soil water content before sowing were important for winter wheat production.