Abstract:

The study investigates the effects of legume intercropping on soil nutrients and fruit quality in Ziziphus mauritiana orchards, a field experiment was conducted in a ‘Persimmon Jujube’ orchard. The dwarf early-maturing soybean cultivar ‘Cuilyubao’ was selected as the intercropping species. Two treatments were established: clean tillage and intercropping with ‘Cuilyubao’ dwarf early-maturing soybean, and arranged in a randomized block design. Soil pH and nutrient content were measured before soybean planting, during soybean harvest, and during Z. mauritiana harvest. Differences in fruit quality indicators were analyzed after fruit maturity. The results showed that the depletion of soil nutrients in the soybean intercropping area was significantly lower than in the clean tillage area. Upon completion of the entire growth cycle of Z. mauritiana, a comparative analysis of soil nutrients from the clean tillage treatment and soybean intercropping treatment against pre-experimental baseline levels (before soybean planting) revealed the following: soil organic matter content increased by 4.00 g/kg in the soybean intercropping area, while it decreased by 12.60 g/kg in the clean tillage area; hydrolytic nitrogen content declined by 4.62% in the intercropping area, compared to a 52.14% reduction in the clean tillage area; available phosphorus content decreased by 33.23% in the intercropping area, whereas it dropped by 90.60% in the clean tillage area; available potassium content fell by 14.81% in the intercropping area, contrasting with a 54.98% decrease in the clean tillage area; exchangeable calcium content rose by 4.60 cmol/kg in the intercropping area, but declined by 6.75 cmol/kg in the clean tillage area; exchangeable magnesium content increased by 1.80 cmol/kg in the intercropping area, while it decreased by 0.79 cmol/kg in the clean tillage area. The slower depletion rate of soil nutrients in the orchard following soybean intercropping demonstrates that intercropping with soybeans contributes to enhanced soil nutrient retention. Fruit quality analysis of Z. mauritiana from both treatments revealed that the soybean intercropping area demonstrated higher levels of soluble solids and soluble sugar compared to the clean tillage area, specifically, the soluble solids content increased by 13.43%, while soluble sugar content rose by 13.41%. These findings indicate that soybean intercropping not only enhances soil nutrient availability but also improves the fruit quality of Z. mauritiana. The intercropping pattern of Z. mauritiana and soybean can improve soil nutrient status through soybean nitrogen fixation and straw return, reduce nutrient loss, enhance the intrinsic quality of fruits, and provide a scientific basis for reducing chemical fertilizer use and promoting ecological cultivation in Z. mauritiana orchards.

Key words: Ziziphus mauritiana, soybean, intercropping, physicochemical properties of soil, soil nutrients, fruit quality, quality regulation