The Spatial Distribution Of Soil Moisture, Soil Nutrients, Light In Different Ages’ Apple And Soybean Intercropping Systems On Loess Plateau Of West Shanxi Province

In order to study the interactions in the fruit-crop intercropping system and how it changes along with the tree age, we conducted an experiment with 4-year-old,6-year-old and 8-year-old apple-soybean intercropping system on Loess Plateau of West Shanxi Province. We adopted the method of positioning monitoring and analysis of soil moisture, soil nutrient and photosynthetic active radiation characteristics, combined with the feature of soybean growth and yields and provided theoretical basis for sustainable management of the apple-soybean intercropping system. Results showed that:(1) Study on soil moisture showed that:Soil moisture content increased with increasing soil depth in vertical direction and increased with increasing distance from the tree row. In terms of total soil moisture, the 8-year-old intercropping system> the 4-year-old intercropping system> the 6-year-old intercropping system, the specific performance was that the 8-year-old intercropping system was 3.13% higher than the 4-year-old intercropping system and 10.38% higher than the 6-year-old intercropping system, but on spatial variation, it showed the 4-year-old intercropping system> the 6-year-old intercropping system> the 8-year-old intercropping system.(2) Study on soil nutrients showed that:In vertical direction, with the increasing soil depth, available K, available P and organic matters decreased, while total N increased at first and then decreased. In horizontal direction, with the increase in the distance from tree row, soil nutrient contents in 4-year-old intercropping system and 6-year-old intercropping system showed a "W" type distribution, while the 8-year-old intercropping system had a "M" type distribution(except total N).Coincidently, all the extreme values (maximum or minimum) appeared in the distances of 1.5, 2.5 and 3.5 m from tree row, and soil nutrient contents at the maximum points were significantly different from those at the minimum points(P<0.05). Nutrients competition relations between apple trees and crops changed gradually with the growth of the trees, and the competition of soil nutrients in the 8-year-old intercropping system was fiercest.(3) Study on PAR showed that:as the tree grew, the value of PAR in the intercropping systems deceased. Compared with 4-year-old intercropping system, value of PAR in 6-year-old intercropping system decreased by 27.29% while that in the 8-year-old intercropping system decreased by 37.86%. And value of PAR in different systems had significant difference (P<0.05). Diurnal changes of PAR showed a "Λ" type, and almost all the maximum value were at the 1 pm.(4) Study on growth characteristics and yield showed that:As plant age growing, average plant height, biomass and yield intercropping soybean were gradually reduced, and the value of soybean height, biomass and yield in different tree ages had a significant difference(.P<0.05). Compared with the monoculture soybean, in 4 years,6 years and soybean intercropping system, plant height dropped by 0.54%,7.90% and 26.38% respectively, and the biomass reduced by 1.13%,6.74% and 82.35% respectively, and production decreased by 0.60%,8.33% and 0.60% respectively. In 4 years intercropping system, PAR was the most important factor which influence the production of soybean (P< 0.01), followed by total nitrogen content (P< 0.05). In 6 years intercropping system, soybean production was mainly effected by the available P content (P< 0.01), the soil moisture content (P< 0.05) and organic matter content (P< 0.05). In intercropping system of 8 years, soybean growth was mainly limited by photosynthetic effective radiation intensity and available P (P< 0.05).