Effects Of Biochar On The Cd Morphological Transformation Of Different Paddy Soil In Hunan Province And The Biological Effects Of Biochar On The Rice

Currently among the improved utilization measures of mild Cd pollutted farmland, soil conditioner such as inorganic or organic materials are still considered as main measures which suitable for the current situation and pollution situation.In order to provide scientific basis for filtrating biochar amendment resources for the mild Cd pollutted farmland and realizing the validation of local agricultural waste resources, the effects of the pyrolytic temperature on the physical and chemical properties of biochar which pyrolysised under 400??500? from three major economic crops straw (Rice straw, cotton stalk carbon and corn stalk) in Hunan province were studied. And the influences of biochar on morphological transformation of Cd in soil and rice fertility, yield and the Cd content in brown rice were studied through cultivating experiment and pot experiment method based on several main types paddy soil in Hunan province, which total Cd was about 1 mg/kg. The main results were as follows:(1) The influence of pyrolysis temperature on the physical and chemical properties of the biochar indicated that:Under the 400??500? pyrolysis temperature, the carbon rate, organic carbon, total nitrogen decreased with pyrolysis temperature increased, while the pH value, specific surface area, total phosphorus, total potassium increased with pyrolysis temperature increased. The biochar pyrolysised under 500? was selected as soil ameliorant after comparative analysis.(2) Laboratory culture experiments results showed that:After 45d flooding cultivation added biochar, on the whole, three kinds of paddy soil showed that the content of exchangeabale Cd droped while residual Cd rised, and the improving effects of single biochar treatment were superior to combined treatment. The best improving effects in three kinds of paddy soils all were cotton stalk carbon treatment, and the effects of rice straw on alluvial sandy soil improvement was better than other two kinds of soils, while corn stalk showed the best improvement effects on gray clayey.(3) The rice pot experiment results showed that:Three kinds of biochar made different degrees of influence on rice growth and yield and Cd content in brown rice.The treatments of 1% rice straw,1% and 3% cotton stalk carbon,3% corn stalk could all increase rice output and Cd content in brown rice, while the 3% rice straw treatments decreased rice output and Cd content in brown rice, and the 1% corn stalk decreased Cd content in brown rice meanwhile stabilized rice output. The results showed that the best improvement effects was 1% corn stalk treatment.