Effects of different intercropping modes on the physicochemical properties and enzyme activity of soil in young Camellia oleifera forests

【Objective】To study the effects of different intercropping modes on the physicochemical properties and enzyme activity of soil in young Camellia oleifera forests, and to provide theoretical basis for selecting suitable management modes and rational fertilization for young C. oleifera forests. 【Method】The young C. oleifera forest planted in 2017was used as the experimental site. From 2021 to 2023, it was planted consecutively with soybean, peanut, corn, common vetch and pepper respectively. With the pure C. oleifera plantation as the control(CK), the soil physical and chemical properties and enzymes activity were measured, and the single and comprehensive fertility indexes were calculated. 【Result】The organic matter content in the rhizosphere soil of C. oleifera under intercropping with peanuts was the highest among all the intercropping modes, which increased by 119.80% compared to CK, while intercropping with peppers had the lowest organic matter content, which increased by 74.54% compared to CK. The highest total nitrogen content was in the common vetch intercropping mode, which was 3.92 times as that of CK, and the lowest was in corn intercropping mode, which was 2.88 times as that of CK. The content of alkali hydrolyzable nitrogen was in the order of common vetch>peanut>soybean>corn>pepper>CK, and the content ranged from 54.68 to 153.56 g/kg. Intercropping peppers had the lowest total phosphorus and available phosphorus contents, which were 2.33 and 1.06 times as those of CK, respectively. The content of available copper, available manganese, and available zinc in intercropping peanut mode was the higher compared to other modes, and the difference was significant compared to CK(P<0.05, the same below). The effective iron content of intercropping corn mode was significantly higher than other modes. The effective boron content of intercropping common vetch mode was significantly higher than other modes. The acid phosphatase activity(ACP) in the rhizosphere soil of C. oleifera was the highest in intercropping common vetch mode, which was as 2.88 times as that of CK.Intercropping peanut mode had the highest soil catalase(CAT) activity, which was as 2.32 as that of CK. The differences in soil sucrase(SC) and urease(UE) activities among different intercropping modes were not significant(P>0.05), but both showed significant differences compared to CK. The soil comprehensive fertility index of different intercropping modes was ranked as follows: peanut>common vetch>soybean=corn>pepper>CK. The soil comprehensive fertility level of peanut was evaluated as level II, while other intercropping modes were evaluated as level III. 【Conclusion】The intercropping of C. oleifera with peanuts has the best effect on improving soil physical and chemical properties and enzymes activity, with the highest comprehensive fertility index, making it a suitable intercropping model for promotion in karst areas.