Photosynthetic characteristics, soil nutrients, and their interspecific competitions in an apple–soybean alley cropping system subjected to different drip fertilizer regimes on the Loess Plateau, China

Imprecise irrigation hinders the sustainable development of fruit tree–crop intercropping system in Loess Gully Area China. Drip fertigation was applied for two years as part an apple–soybean to optimize local water and nutrient management patterns. The effects different drip fertilizer levels on photosynthetic characteristics, soil nutrients, their interspecific competitions were studied. treatments four levels, namely 60% (W1), 70% (W2), 80% (W3), 90% (W4) field capacity (Fc), three nitrogen fertilization 59 (F1), 92 (F2), 124 kg∙ha–1 (F3). control (CK) a rain-fed (neither nor fertilizer) crop. net rate (Pn), transpiration (Tr), soybean yield (GY) increased at first, but then decreased application rose. partial factor productivity (PFP) increased, available content showed opposite trend. Pn Tr positively correlated with distance from apple tree row. competition intensity light 2018 2019, while root nitrate (NN) increased. correlation between aboveground belowground parts weak varied years. A principal component analysis that treatment W3F2 had highest comprehensive score. Thus, combination Fc is optimal system. multiple regression indicated input range 4624.49–4795.75 m3·ha−1·a−1 combined 84.10–107.27 kg·ha−1·a−1 suitable based integrated benefits length density, GY, Pn, PFP during first 4–5