| Purple soil and yellow soil are the typical soils in agricultural regions of Southwest China. Due to plentiful rainfall, high population density, extensive utilization of hillside fields etc., the soil erosion and acidification were getting more severe. These characteristics lead to the significant clayification, acidulating, yellowing and impoverishment of the soils. Improving soil fertility and quality are key issues for the development of agriculture. In recent years, the application of biochar technology provides a new way to solve these problems in agriculture. But the effects of biochar fertilization in different solis are still controversial. This is correlated to the physical and chemical properties, application amount of biochar and soil types. In this paper, we chosed the pot experiment, and studied the influences of different proportion of rice husk biochar on the nutrient gradient, pH value, microbial community composition, enzyme activity, growth status and its dynamic change of the crops in purple soil and yellow soil. This experiment could provide a theoretical basis and practical guidance for the future improvement of the southwest region of purple soil and yellow soil. The results are as follows:1. The soil pH value of purple soil and yellow soil were effectively increased with the biochar fertilization. The pH of the purple soil and yellow soil increased by 1.0~1.6 and 0.5~1.0 units, respectively. And the amont of the organic material, total phosphorus, available phosphate, available potassium also increased with the increasing amount of biochar content.There was no significant difference in total K and total nitrogen content of soil between applying biochar treatment and without biochar treatment at different stages of cultivation, to some extend, decreased amount of soil available nitrogen content.2. The amount of actinomycetes in purple soil, the bacteria and actinomycetes in yellow soil was increased significantly by biochar treatments during all different sampling times. And these increases are correlated to the increased of the amount biochar positively, 4% biochar treatment reached maximum, which was 1.4~2.9, 3.1~8.8 and 1.0~5.9 times higher than contrast, respectively. The number of bacteria in purple soil increased heavily with the increasing of biochar at 30 d, in 4% biochar treatment increased by 53.1% than control; while the amount of bacteria grew slowly at 60 d, 180 d and 180d(P), and the effectiveness of the the biochar was not change significant. The amount of fungi in yellow soil increased significantly after some amount of biochar fertilization at 30 d, 60 d and 180 d, which increased by 31.0%, 53.8% and 30.6% than control, respectively. But the amount of fungi in yellow soil decreeased significantly with the increase of biochar fertilization at 180d(P), which decreeased by 89.1% than control. The amount of fungi in purple soil had no significant difference in different treatment at 30 d, but it decreased in 60 d and 180 d, 4% biochar treatment down to a minimum, which increased by 43.2% and 44.2% compared with the control group; And it increased significantly with increasing amount of biochar fertilization at 180d(P), 4% biochar treatment reached maximum, which was 3.04 times than control.3. We explored the influence of the different proportion of biochar on the microbial community composition and diversity by high-throughput sequencing technology in purple soil and yellow soil. Through the yellow soil bacterial diversity index calculations showed that Chao1 index of each adding biochar treatment were higher than the control treatment and Shannon index displayed a fluctuating trend. Compared to control, the biochar fertilization in yellow soil increased relative abundances of some bacteria such as Proteobacteria, Bacteroidetes, Verrucomicrobia and decreased relative abundances of the bacterias Actinobacteria, Chloroflexi, Firmicutes. Meanwhile, biochar fertilization changed the bacterial genera community structure in the yellow soil, such as Nocardioides and Arthrobacter, which are good for the growth and protection of plants. And the relative abundance of certain plant pathogenic bacteria, such as Pseudomonas Pseudomonas, decreased.Purple soil bacterial diversity index calculations showed that Chao1 index of 0.8% and 4% biochar treatments were lower than the control. Adding biochar treatments increased the Shannon index and the relative abundance of Gemmatimonadetes. However, it decreased the relative abundance of Actinomycetes and Verrucomicrobia. The community structure of bacterial genera was changed makebalely with biochar treatments in purple soil. And the Sphingomonas which has the function of the degradation of aromatic compounds only increased in 0.8% biochar fertilization and decreased with 2% and 4% biochar fertilization. The relative abundance of Nocardioides and Arthrobacter decreased.Yellow soil fungal diversity index calculations showed that Chao1 index were lower than the control treatment only with 2% biochar treatment, and Shannon index of all biochar treatments were lower than the control with all biochar treatment. Adding biochar increased the relative abundance of fungi Zygomycota, decreased relative abundance of the Ascomycota, Basidiomycota; And the relative abundance of Chytridiomycota only increased with 2% biochar fertilization.Purple soil fungal diversity index calculations showed that Chao1 index of each biochar treatment was lower than the control, and Shannon index was higher than the control. Adding different ratio of biochar, the relative abundance of fungi Ascomycota, Chytridiomycota increased and the relative abundance of Zygomycota decreased; The relative abundance of Basidiomycota increased only with 2% biochar treatment.4. With the different proportion of biochar fertilization in the yellow soil, the soil sucrose activity decreased significantly(except the 180 d sampling). In all different sampling times,2% biochar treatment invertase activity decreased to a minimum, which decreased by 63.5%, 64.9%, 49.4% and 58.6 % compared with the control.The highest soil sucrose activity wes achieved when the concentration of biochar was 4% amonst all the sampling phases, which was 2.1~4.8 times higher than control. And the time evolving differences among all the treatments were different significantly, 4% biochar treatment increased by 18.0%~67.1% than control. The urease activity in different treatments in purple soil had no significant difference, except the 180 d sampling. The biochar fertilization at the early phase(30d-60d) in yellow soil and purple soil also have no significant influences on the catalase activity. With the increase of incubation time, catalase activity increased significantly, and catalase activity increased to the highest with 4% biochar fertilization.5. The oilseed rape plant height and plant biomass in yellow soil were significantly increased in all treatments. The plant height with 0.8%, 2% and 4% biochar fertilization increased by 4.00~4.60 times, which were significantly higher than the group without biochar fertilization. And the biomass accumulations of oilseed rape with 0.8%, 2% and 4% biochar fertilization increased 8.49 ~ 11.44 times, which were significantly higher than the control. The oilseed rape plant height increased significantly only with the 0.8% biochar in purple soil, which increased by 16.52% compared to the control. And the plant biomass with the 0.8% biochar fertilization increased by 8.19% compared to the control. And the oilseed rape plant height and plant biomass decreased significantly with 4% biochar fertilization. |
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