| Soil nutrient maintenance is an important ecological and environmental problem facing China.In China,the area of planted forests ranks first in the world.P.massoniana and Eucalyptus are widely planted with fast-growing and high-yield characteristics.However,due to the long-term single pure forest management model,the soil fertility decline.of P.massoniana and Eucalyptus plantations,forest biodiversity reduction,productivity decline and other issues.Biochar has been widely used as a soil amendment in agro-ecosystems,and there are relatively few studies on the improvement of soil ecosystems in plantations.In this study,the biomass charcoal with straw as raw material was selected,and the typical subtropical plantation tree species in South Asia--39-year-old P.massoniana(coniferous tree species)and 13-year-old Eucalyptus(broad-leaved tree species)pure forest soil were selected as test soil samples,by adding different proportions.Two groups of indoor culture experiments were carried out on organisms and litter:?:?soil CK(S),?soil+ 2%biomass carbon(2B),?soil + 5%biomass carbon(5B),? soil+ 10%raw Material charcoal(10B),? soil + 20%biomass charcoal(20B);?:?soil + 5%litter CK(SL),? soil + 2%biomass charcoal + 5%litter(2BL),?Soil + 5%.biomass charcoal + 5%litter(5BL),? soil+10%biomass charcoal + 5%litter(10BL),? soil + 20%biomass charcoal + 5%litter(20BL),5 replicates per treatment.The effects of soil pH,nitrogen(N),phosphorus(P)content and soil enzyme activity on P.massoniana and Eucalyptus plantations were studied.Soil nutrients and microorganisms of two typical degraded plantations were studied.The relationship between functions reveals the effects of different proportions of biomass charcoal and litter input on the nutrient cycling of typical degraded plantation red soil and its mechanism,and provides a scientific basis for the development of management measures for plantation with higher soil nutrient retention.The main findings are as follows:(1)Different proportions of biomass charcoal can significantly increase the soil pH value of P.massoniana and Eucalyptus plantations(p<0.05),and the pH value increases with the increase of biomass carbon addition ratio.Among all the treatments,the most significant effect was achieved at a biochar content of 20%.(2)Under the condition of adding only biomass charcoal,20%of the biomass carbon addition can significantly increase the content of nitrate nitrogen(NO3--N)in P.massoniana and Eucalyptus forests at different culture time,and can significantly increase the two The net nitrification rate of the forest stands significantly decreased the net ammoniation rate(p<0.05),but had no effect on the ammonium nitrogen(NH4+-N)content of the two stands;in the case of litter leaves,The 10%and 20%biochar could significantly increase the NO3'-N content of P.massoniana and Eucalyptus forests at different culture time(p<0.05),and 20%of the biomass charcoal significantly increased the net nitrification rate of Masson pine forest.The 10%and 20%biochar input significantly increased the net nitrification rate of Eucalyptus forests(p<0.05).(3)In the case of adding only biomass charcoal,adding different proportions of biomass charcoal had no effect on the available P content of P.massoniana,and different proportions of biomass charcoal could significantly increase the available P content of Eucalyptus forest in different culture time(p<0.05),20%biochar charcoal significantly increased the phosphate mineralization rate of P.massoniana forest,while different proportions of biomass charcoal had no effect on the P mineralization rate of Eucalyptus forest in different culture time.In the presence of litter leaves,different proportions of biomass charcoal could significantly increase the fast-acting P content of P.massoniana forest at 90d and 180d(p<0.05),while 10%and 20%of biochar were added in culture.Both 90d and 180d significantly increased the fast-acting P content of eucalyptus forest(p<0.05).The P mineralization rate of the two forests increased with the increase of the proportion of biomass carbon,but the difference was not significant.(4)Under the condition of only adding biomass carbon,the activity of a-glucosidase(AG)in P.massoniana and Eucalyptus forest was significantly increased by adding 20%of biomass charcoal at different culture time for C-invertase.The ?-glucosidase(BG)activity of P.massoniana and Eucalyptus forests was significantly increased by adding 5%biomass charcoal at the early stage of culture(30 days),but the ?-1 and 4 xylosidase(BX)activities of P.massoniana and Eucalyptus forests were decreased by different proportion of biomass carbon addition at different culture time.The effect on the activity of N-invertase was irregular.For P invertase,the addition of 10%and 20.%biomass charcoal could significantly inhibit the ponytail at 30 days and 90 days after culture.The(AP)activity of phosphatase in P.massoniana forest(p<0.05)was inhibited by adding different proportion of biomass charcoal at 30 d,but the inhibition decreased with the increase of culture time.Under the condition of litter leaf addition,the AG activity of P.massoniana was significantly increased by adding 10%and 20%biomass charcoal at different culture time for C-invertase(p<0.05).The addition of 20%biomass charcoal in Eucalyptus forest could significantly increase its AG activity at different culture time(p<0.05).The BG activity of P.massoniana and Eucalyptus forests was significantly increased by adding 10%and 20%biomass charcoal at 30 d and 90 d(p<0.05),but the BX activity of Eucalyptus forest was significantly decreased at the middle stage of culture(90 d).For N turn the effect of enzyme activity was not obvious.For P-invertase,the addition of 10%and 20%biomass charcoal significantly increased the AP activity of P.massoniana forest at the late stage of culture,but at the early stage,the addition of 10%and 20%biomass carbon could significantly increase the AP activity of Eucalyptus forest(p<0.05). |
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