3.1.Soil physico-chemical properties
The rhizosphere soils from the eight different treatments differed significantly in terms of physico-chemical characteristics (Table 1). Mulberry rhizosphere soils showed a higher pH value than alfalfa rhizosphere soils; pH was lower in the intercropped system compared to the monocultures (P < 0.01). Nitrogen application resulted in increased pH values in the monoculture system, but lower pH values in the intercropping system. Soil organic matter (OM) contents were significantly decreased in mulberry and alfalfa rhizosphere soil with added nitrogen, while in intercropping systems, this trend was alleviated. In the mulberry treatments, OM contents were significantly higher than in the corresponding treatments of alfalfa, except for the monoculture system without nitrogen addition. Available nitrogen (AN) contents were significantly higher in alfalfa rhizosphere soil than in mulberry soil, and the application of nitrogen increased AN values in both systems (monoculture and intercropping). The soil water content (SWC) was considerably higher in mulberry rhizosphere soil than in alfalfa soil. Nitrogen application and intercropping resulted in increased SWC in mulberry soil, but in decreased values in alfalfa soil.