| Chinese chestnut (castnea mollissima) forest is an important economic forests that has been intensively managed in southern China recently. Consequently, soil quality was getting worse and worse with the intensive management (IM). In order to clarity the effects of intensive management of Chinese chestnut on soil biological properties by studing soil biological properties of Chinese chestnut stands with different history. Three site-specific experiments were conducted to study the influences of different ways of cleaning weeds, different types and various rate of fertilizer, different green manures on the biological properties of soil. The results obtained were summarized as follows:1.Soil biological properties of Chinese chestnut stands with different history were tested using chloroform fumigation and Biolog .Three soil samples from natural shrubbery were collected as control. It was shown that compared with shrubbery, microbial biomass carbon(MBC) of soil under Chinese chestnut stand with 5,10 and 20- year's IM decreased by 15.89%,49.16% and 55.13% respectively, and significant difference(P<0.05) among one to another has been observed. The proportion of MBC out of total organic carbon (TOC) of soil under Chinese chestnut stand was measured no significant difference with soil under natural shrubbery during first 5-year of IM, however, it decreased apparently until 10-year's IM and then kept constant afterward. Soil microbial functional diversity measured by average well color density (AWCD) declined greatly by conversion natural shrubbery into IM Chinese chestnut stands. Compared with shrubbery, AWCD value of soil under Chinese chestnut forest decreased by 79.26%, 63.20% and 68.50% respectively after 5, 10 and 20-year's IM, with significant difference(p<0.05). Index of Shannox and McIntosh reflecting soil microorganism diversity were lower in IM Chinese chestnut stands than that under natural shrubbery. Combining AWCD value with diversity indexes, it can be concluded that soil microbial functional diversity of IM Chinese chestnut stands had decreased noticeably during the first-10 year's IM, but no change has been observed afterward, suggesting that a new and special soil microbial communities has been formed after 10-year's IM of Chinese chestnut stands. Soil quality closely related to soil organic and biological properties may decline with intensive management being conducted.2. Intensive management on Chinese chestnut (castnea mollissima) forest with weeds being cleared away is popular, however, it can be predict that soil qualities must have changed as a result. The objective of this study is to test the effects of weeds clearing way on soil properties by conducting a field trial under Chinese chestnut forest. The soil under Chinese chestnut with weeds being plowed into deep soil showed stronger activities of Phosphatase, Sucrase and Hydrogen peroxidase, and so did the soil microbial biomass carbon (MBC) and water-soluble organic carbon (WSOC)comparing with control which having received no any attention. The converse situation has been observed under Chinese chestnut with weeds being cleared away by using herbicide. Considering the fact that soil plowing must result in soil erosion at some extent, the way of weeds being cut but not plowed into deep soil was recommended when farmer managed Chinese chestnut in subtropical zone where precipitation is high.3. Fertilization has become useful way to improve the yield. The objective of this study is to find out the effects of different types and various rate of fertilizer on soil available nutrients and biochemical properties by one year field fertilizer trial. It was found that soil available N,P and K positively response to the increase of fertilizer rate. Organic fertilizer had a positive influence on activities of soil phosphatase and sucrase, and still positive improvement was observed for soil water-soluble organic carbon(WSOC) and microbial biomass carbon (MBC). It was concluded from this trial that the practice of fertilization enriched the soil available nutrients and organic fertilizer has better effect on soil biochemical and biological properties than mineral fertilizer.4.The objective of this study is to test the effects of green manure on soil nutrient and bio-properties under chestnut plantation. A manure trial with planting rye grass, white clover, green gram, the mixture of three of them, and control with no any vegetation (CK). It was found that soil total organic carbon (TOC) and total nitrogen (TN) were much higher (P<0.05)in Chinese chestnut plantation planted with green manure compared with control and the similar tendency was true for soil microbial biomass carbon (MBC) and water-soluble organic carbon (WSOC). Comparing the treatments with different types of green manure, green gram was among the best to improve soil TOC, TN and enzymatic activities, however, there was no improvement to observed respect to soil available N, P, and K after one year manure trial. |
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