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Water, nutrient and light deficiency during the co-growth period are the major factors limiting the productivity of the apple–maize alley cropping system in Loess Plateau, China. Therefore, it is crucial to optimize the management of water and fertilizer in the region. The effects of different irrigation and fertilizer levels on photosynthetic characteristics, growth, yield, water consumption (ET) and water use efficiency were studied in a young apple-maize intercropping system during 2014–2016. The treatments included three levels of maximum irrigation, namely 50% (W1), 65% (W2), and 85% (W3) of field capacity (Fc), and three different NPK fertilization levels (289.0-118.0-118.0, 412.4-168.8-168.8 and 537.0-219.0-219.0 kg∙ha−1), which were designated F1, F2 and F3, respectively. In addition, the rain-fed (neither irrigation nor fertilizer) crop was included as the control (CK). The F1 significantly increased the net rate of photosynthesis (Pn) and leaf water-use efficiency (LWUE) of both apple and maize. For maize, the effect of irrigation was greater than that of fertilizers on water use, but smaller on growth indicators and yield. The ET of the alley cropping systems increased with the amount of irrigation but decreased as the dose of fertilizers increased. Growth and yield of maize increased when the amount of irrigation increased, but were inversely related to fertilizer dose. The canopy architecture appeared to be regulated through differential absorption of water and nutrients. The Pn and transpiration (Tr) in maize decreased as the distance from the tree line increased, and the extent of decrease grew over time, suggesting greater interspecific competition. It is recommended that dwarf crops should be planted after intercropping for 5 years according to the change in photosynthetic index with intercropping years under different treatments. Multiple regression analysis indicated the following regime to be optimal during the first 3–5 years of the intercropping in terms of the yield of maize and water use in the alley cropping system: maximum watering (85% Fc) and minimum fertilization (289.0-118.0-118.0 kg ha−1 NPK).

A field trial consisting of cotton grown employing a combination of ridge planting, mulching with film, and drip irrigation was laid out on a plot with severely saline soil in a typical inland arid area of Xinjiang. The effect of five levels of soil matric potential set up 0.2 m below the drip emitter, namely −5 kPa, −10 kPa, −15 kPa, −20 kPa, and −25 kPa, were studied in terms of changes in soil salinity (ECe), sodicity (SAR), crop growth and yield components. Drip irrigation increased the leaching of soil salts and decreased the ECe and SAR of each soil layer. Although the levels of soil salt rose again, in spring and winter, after irrigation was discontinued, the root zone (0–40 cm) remained less saline: the ECe and SAR value under the soil matric potential of −5 kPa and −10 kPa were 63% and 49% of its values in 2009 respectively, before the land was brought under cultivation (p ≤ 0.05), showing maximum leaching. The yield of cotton peaked at the soil matric potential of −5 kPa. The germination rate, which was the main factor that influenced the cotton yield, was 67% of that in non-saline soil in the first two years, and increased to 84% in the third year. After three years, the rate of germination in all the treatments exceeded 67%, and the highest rate (78%) was at −5 kPa; in the same treatment, boll yield was 4.40 g per plant. Except for germination rate and the yield of lint and seed, all the yield components increased significantly (p ≤0.05) as ECe and SAR decreased in 2010 and 2011. The correlation between soil salt (salinity and sodicity) and other components such as the number of cotton bolls per plant, the average weight of a boll, and lint percentage varied, probably because water supply was being regulated and, as a result, the physicochemical properties of the soil kept changing constantly. Taking into account the extent of leaching, crop growth, and yield, the lower limit for the soil matric potential should be −5 kPa at 20 cm below the dripper for the first three years during reclamation to promote cotton cultivation on the saline-sodic soil of Xinjiang.