Since the implementation of the Loess Plateau Returning Forestry (Grass) Project in late 1990s, long-term apple planting has led to the universal soil dry layer and a large amount of nitrate nitrogen accumulation, which has seriously restricted the sustainable development of agricultural and regional economy. Therefore, clarifying the effects of apple orchards of different ages converted to food crops on the recovery of deep soil dry layer (soil moisture change), soil nitrate nitrogen accumulation and transport is crucial to the improvement of soil quality and sustainable agricultural development on the Loess Plateau. Weibei dry plateau was used as the study area, and apple orchards of 10, 15, 20 and 30 years old and apple orchards of the same age converted to food crops of 2, 5 and 6 years old were selected for the study. A comparative analysis of the differences in soil water content, soil water storage and nitrate-N content between 0-10 m profiles of each site was used to quantitatively assess the effect of conversion of apple orchards to food crops on deep soil water and N based on a space-for-time approach. The results showed that (1) soil moisture recovered rapidly after conversion to food crops from apple orchards of different stand ages, reaching a depth of around 7.0 m within 2 years. (2) The direct effect of soil water storage after conversion on the accumulation of soil nitrate after conversion was the most important. The conversion of apple orchards of different ages to food crops resulted in varying degrees of nitrate-nitrogen leaching from the soil profile with the recovery of soil moisture. The age of the apple orchard before conversion played a dominant role in the accumulation of nitrate nitrogen in the soil after conversion. The older the stand before conversion, the greater the accumulation of nitrate nitrogen and the shallower the depth of leaching after conversion. (3) Soil leaching of the accumulated nitrate nitrogen lagged behind the downward movement of soil moisture. Above all, soil moisture recovered rapidly after the conversion from different age apple orchards to food crops, which accelerated the leaching of nitrate-N, while the downward movement of soil moisture and nitrate-N did not coincide. A combination of soil moisture restoration and loss of soil quality due to rapid leaching of nitrate nitrogen needs to be considered when carrying out conversions.This study has far-reaching implications for rational optimisation of land use structure and improvement of soil quality.