| Poplar is one of the most suitable plant species of short rotation industrial timber. In recent years, the planting areas have continuously extended in the northern Jiangsu area. In order to strengthen the comprehensive development of Poplar timberland resource and enhance the utilization ratio of undergrowth space, agroforestry system of Poplar plantations and development of undergrowth economy have gradually risen. This research aims to figure out which Chinese herb is the most suitable for intercropping under Poplar by discussing influence on growth conditions and soil properties of Poplar when intercrop two kinds of Chinese herbs(Taraxacum mongolicum and Prunella vulgaris) under Poplar and analyzing the differences between different intercropping modes of Chinese herbs. In the meanwhile, carry out different formula fertilization tests and study different fertilizer ratio’s influence on Chinese herbs production and soil fertility, in order to provide important data for enhancing Chinese herbs production and improving soil fertility. The results show that:1. Intercropping Chinese herbs under Poplar woodland has some impact on the growth of poplar. Compared with pure Poplar woodland, diameter and height of Poplar intercropping with Taraxacum mongolicum has respectively increased by 10.66% and 7.65%, while diameter and height of Poplar intercropping with Prunella vulgaris has respectively increased by 6.75% and 4.40%.2. Intercropping Chinese herbs under Poplar woodland has obvious impact on physical, chemical and biological properties of soil, but their effect degree has differences. Compared with pure Poplar woodland, physical properties of soil of Poplar woodland intercropping with Taraxacum mongolicum and Prunella vulgaris have all improved, such as soil density, maximum moisture capacity, capillary water capacity, field capacity, total porosity, etc. For example, soil density has respectively decreased by 12.9% and 4.2%. Field capacity has respectively increased by 38.4% and 7.2%. Compared with pure Poplar woodland, the amount of soil organic matter, soil total nitrogen and soil hydrolysable nitrogen of Poplar woodland intercropping with Taraxacum mongolicum has respectively increased by 47.3%, 25.3% and 7.4%, while the amount of soil total phosphorus and soil available phosphorus has decreased slightly. The amount of soil organic matter, soil total nitrogen, soil hydrolysable nitrogen and soil total phosphorus of Poplar woodland intercropping with Prunella vulgaris has all decreased. The decreased range is about 0.9%~32.8%. While the amount of soil available phosphorus has increased slightly. Compared with pure Poplar woodland, the activity of soil invertase, soil urease, soil alkaline phosphatase, soil catalase and microbial biomass carbon and nitrogen of Poplar woodland intercropping with Taraxacum mongolicum has all increased slightly. The activity of soil invertase and soil urease of Poplar woodland intercropping with Prunella vulgaris has increased, while the activity of soil alkaline phosphatase, soil catalase and microbial biomass carbon and nitrogen has all decreased slightly. It shows that soil fertility of Poplar woodland intercropping with Taraxacum mongolicum s has improved, while soil fertility of Poplar woodland intercropping with Prunella vulgaris has reduced slightly.3. Fertilization has impact on growth and Chinese herbs production of Poplar intercropping with Chinese herbs. In Poplar woodland intercropping with Taraxacum mongolicum, fertilization has promoting effect on diameter and height of Poplar. In the treatment of N3P0、N2P1、N3P3, the amplification is big. In the treatment of N1P2, aerial part dry weight of Taraxacum mongolicum achieves its maximum, obviously higher than non-fertilization treatment. Under different N levels, aerial part production of Taraxacum mongolicum shows N1, N2 significantly higher than N3. While under different P levels, P1, P2 shows slightly higher than P3. In Poplar woodland intercropping with Prunella vulgaris, fertilization has promoting effect on both diameter and height of Poplar. In the treatment of N3P3 and N0P2, the growth rate is the highest. In the treatment of N2P2, fruit cluster dry weight of Prunella vulgaris achieves its maximum, obviously higher than non- fertilization treatment. In the treatment of high N and P, fruit cluster production of Prunella vulgaris significantly reduces.4. Fertilization has no obvious impact on physical properties of soil of Poplar intercropping with Chinese herbs. In Poplar woodland intercropping with Taraxacum mongolicum, compared with non-fertilization treatment, fertilization treatment has no significant difference. In the treatment of N2P3, soil density, maximum moisture capacity, capillary water capacity, field capacity, total porosity, capillary porosity and non-capillary porosity respectively increase 0.93 times, 1.04 times, 1.09 times, 1.02 times, 1.04 times, 1.08 times and 0.83 times, slightly higher than other fertilization treatments. In Poplar woodland intercropping with Prunella vulgaris, compared with non-fertilization treatment, fertilization treatment has no big difference. In the treatment of N0P3 and N3P3, there are some improvements.5. Fertilization has different impacts on chemical properties of soil of Poplar intercropping with Chinese herbs. In Poplar woodland intercropping with Taraxacum mongolicum, fertilization has obvious influence on soil ph value, organic matter, hydrolysable nitrogen and available phosphorus. However, it has no influence on total nitrogen and total phosphorus. In the 16 kinds of fertilizer treatments, organic matter and total nitrogen achieve their maximum, respectively increasing 2.12 times and 1.26 times than non-fertilization treatment, in the treatment of N1P2. In the treatment of N3P3, hydrolysable nitrogen and total phosphorus achieve their maximum, respectively increasing 1.85 times and 1.29 times than non-fertilization treatment. While in the treatment of N2P3, available phosphorus achieves its maximum, increasing 1.94 times than non-fertilization treatment. In Poplar woodland intercropping with Prunella vulgaris, fertilization has obvious influence on organic matter, hydrolysable nitrogen, available phosphorus and total nitrogen. However, it has no influence on total phosphorus. In the 16 kinds of fertilizer treatments, organic matter, hydrolysable nitrogen, total phosphorus and available phosphorus all achieve their maximum, respectively increasing 1.35 times, 1.81 times, 1.11 times and 1.64 times than non-fertilization treatment, in the treatment of N2P2. Total nitrogen achieves its maximum in the treatment of N2P3 and the second is in the treatment of N2P2.6. Fertilization has impact on soil enzyme activity of Poplar intercropping with Chinese herbs. In Poplar woodland intercropping with Taraxacum mongolicum, in spring, enzyme activity of invertase, alkaline phosphatase, urease and catalase achieves their maximum respectively in the treatment of N1P1, N0P3, N2P2 and N2P1, obviously higher than non-fertilization treatment. In summer, enzyme activity achieves their maximum respectively in the treatment of N1P2, N2P3, N2P2 and N2P0, showing significant difference with non-fertilization treatment. In autumn, enzyme activity achieves their maximum respectively in the treatment of N2P3, N3P1, N2P2 and N2P1, showing significant difference with non-fertilization treatment. In general, enzyme activity of invertase is highest in summer, secondly in spring, thirdly in autumn. Enzyme activity of alkaline phosphatase and urease is highest in summer, secondly in autumn, thirdly in spring. Enzyme activity of catalase is highest in summer, secondly in spring, thirdly in autumn. In Poplar woodland intercropping with Prunella vulgaris, enzyme activity of invertase achieves its maximum in the treatment of N2P2 both in spring and summer, showing significant difference with non-fertilization treatment. Enzyme activity of alkaline phosphatase achieves its maximum in the treatment of N3P2 in spring, showing no big difference with non-fertilization treatment. It still achieves its maximum in the treatment of N3P2 in summer. However, it shows significant difference with non-fertilization treatment. Enzyme activity of urease and catalase achieves their maximum in the treatment of N2P2 in spring. In summer, it achieves maximum respectively in the treatment of N2P2 and N3P1. In general, enzyme activity of invertase and alkaline phosphatase is higher in summer than in spring. On the contrary, enzyme activity of urease and catalase is higher in spring than in summer.7. Fertilization has impact on microbial biomass carbon and nitrogen of Poplar intercropping with Chinese herbs. In Poplar woodland intercropping with Taraxacum mongolicum, in the 16 kinds of fertilizer treatments, microbial biomass carbon and nitrogen show highest content both in the treatment of N2P2, respectively 360.31mg/kg and 36.01mg/kg. There are significant differences with non-fertilization treatment, increasing respectively 87.3% and 101.5%. In poplar woodland intercropping with Prunella vulgaris, in the 16 kinds of fertilizer treatments, microbial biomass carbon and nitrogen show highest content both in the treatment of N2P2, respectively 218.52mg/kg and 33.52mg/kg. There are significant differences with non-fertilization treatment. |
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