Effects On Physic-chemical Properties Of Soil After Planting Rubber Or Not In Hainan Province

The status of soil physical and chemical properties in rubber plantation have important significance to rubber soil fertility, diagnosis fertilization and rubber industry sustainable development. This study made a complete investigation to the rubber plantation(YangJiang、HongTian、DaFeng、ZhongJian、DongTia、DanZhou and FuRongTian) of Hainan, which has the representative. Through comparison and analysis with reference soil, Research the change trend of chemical and physical properties of rubber plantation soil in the 0-20cm and 20-40cm two layers, understand chemical properties and physical properties and their inherent relationship between each other, grasp the present situation of soil physical and chemical for provides some theoretical basis to fertility improvement, balanced fertilization and sustainable utilization. The main research results are as follows:1、After years of planting rubber the soil chemical properties and Nutrient contents(Organic matter, quick-acting potassium, available nitrogen, available phosphorus, exchangeable calcium、magnesium, CEC) in rubber plantation has show a downward trend. Only organic matter has significant difference compared to the reference soil, but various nutrient content have downtrend obvious and most of them have less than or in the critical value of the soil nutrient standards. Various nutrient contents in each rubber plantation have the different downward trend. DaFeng、HongTian and YangJiang area are lack of organic matter; DaFeng and HongTian area are lack of available nitrogen; The area lack of exchangeable calcium are DaFeng、DongTai and ZhongJian. In addition to HongTian, the rest area are lack of magnesium. Most common the rubber plantation soil is lack of phosphorus, followed by magnesium.2、The nutrient content in 0-20cm soil layer of rubber soil and reference soil are respectively larger than its in 20-40cm soil layer. In 0-20cm soil layer, the nutrient content of rubber soil all less than reference soil, but each nutrient in different areas has the different downward trend. In DongTai area, compared with reference soil the organic matter content has the most obvious reduce, reduced by 48.8%, but in DaFeng area only reduced by 13.4%; The available phosphorus were not significantly changes in two layers of the rubber soil and reference soil. In 0-20cm soil layer the organic matter of rubber soil has significant difference compared to the reference soil, the others are not. In 21-40cm soil layer the chemical properties of rubber soil have not significant difference compared to the reference soil3、Through the correlation analysis to the nutrient content of rubber soil, the results showed that, soil organic matter, available nitrogen and CEC content are related to each other; The soil pH was value positively correlative with the content of CEC.4、After many years of growing rubber, most of the soil physical properties(Natural water content, field capacity, maximum water holding capacity, total porosity, capillary porosity, bulk density, water stable aggregates) of rubber plantation in Hainan have show a downtrend. Overall, in surface soil the field capacity, maximum water holding capacity, total porosity and capillary porosity are higher than the lower layer. On the contrary, the bulk density and<0.01 clay content, are less than the lower layer; The natural water content has no significant change.5、Through the comparative analysis to physical properties in 0-20cm and 20-40cm soil layer of the rubber soil and reference soil. The results show that:After planting rubber,the structure of rubber soil has been destroyed, the rubber soil physical properties(field capacity, maximum water holding capacity, total porosity, capillary porosity) are less than reference soil in the 0-20cm soil layer. The soil bulk density is exactly the opposite. In the 20-40cm soil layer, rubber plantation soil physical properties compared with the reference soil has little difference and no significant changes. Through analysis of differences, in the 0-20cm soil layer, rubber plantation soil bulk density、field capacity、total porosity and water stable aggregate content separately with the reference soil was significantly lower, there were significant differences, while in 20～40cm soil layer did not reach differences significant.6、The correlation analysis to rubber plantation soil physical properties indicated that the content of Field capacity, maximum water holding capacity, total porosity and capillary porosity were significantly positively correlative to each other. Soil bulk density Soil bulk density respectively with the field capacity、the maximum water holding capacity, total porosity, capillary porosity and<0.01mm clay content were significant negative correlation. The content of<0.01mm clay and water holding capacity and total porosity were significantly positively correlative. This indicates that the interaction between different physical properties are obvious.7、The correlation analysis to rubber plantation soil physical properties and chemical properties, the results show that, the content of soil organic matter respectively with the field capacity、maximum water holding capacity and total porosity were significantly positively correlative, was significantly negative correlative with the content of soil bulk density.