| Xinjiang saline-alkali land occupies 1/3 of the total arable land in Xinjiang,and the increasingly serious salinization of land seriously limits agricultural production in Xinjiang.Improving saline-alkali soil in Xinjiang to alleviate the pressure of agricultural production.In this study,the saline-alkali soil in Xinjiang was used as the research object to study the structural characterization of modified and unmodified cotton straw biochar by using cotton straw agricultural waste and modified treatment in the experimental base of Tarim University in Xinjiang.The saline-alkali indexes,soil fertility indexes and biomass at harvest were measured by using the methods of indoor soil culture paper cup test and greenhouse pot test under the four biochar gradients of 0%,1%,2%and 4%.Finally,the correlation analysis and comprehensive evaluation of soil indicators were carried out to explore the improvement effect of cotton stalk biochar on saline-alkali soil.The results are as follows:(1)Cotton stalk biochar has obvious fibrous bundle gap structure modified cotton stalk biochar to produce more tiny pore structure with higher degree of surface isomerization.Cotton stalk biochar has a large number of organic functional groups.(2)Cotton stalk biochar had significant effects on saline-alkali soil indicators.Each treatment can reduce soil pH value,4%biochar addition of BS treatment had the best effect than CK by 0.3 units.Compared with CK,2%BC3 treatment had the best effect of reducing salt content by 34.62%.The minimum salt content of modified cotton stalk biochar BA treatment was 4.84g/Kg in pot soil.It was found that 2%biochar treatment had better salt reduction effect than 4%treatment.The addition of biochar from cotton stalk had a good effect on reducing the exchangeable Na~+content in the soil cultivated indoor.The exchangeable Na~+content of each treatment decreased by 40.13%?57.05%compared with that of CK.The exchangeable Na~+content in potted soil decreased by 3.52%?21.68%compared with CK.(3)Cotton stalk biochar increased the content of alkali-hydrolyzable nitrogen,available phosphorus,available potassium and organic matter in saline-alkali soil.Compared with CK,the content of alkali-hydrolyzable nitrogen increased by 6.83%?58.91%,and the content of available phosphorus increased by 1.1?17.5 The available potassium content increased by 4.19%?75.0%,and the organic matter content increased by 1.6?5.0 times.In the pot experiment,the content of available P,available K and organic matter in the soil of most treatment groups gradually decreased with the increase of alkali-hydrolyzable N content in the early stage of the pot experiment,and the content of available P,available K and organic matter in the soil of each treatment increased with the increase of cotton stalk carbon application amount.On the 70th day,modified cotton stalk biochar BC treatment group had the best effect on improving available phosphorus content.Unmodified cotton stalk biochar BD group increased soil available potassium content by 52.14%?78.41%compared with CK.The organic matter content of modified cotton stalk carbon with 4%BA was the highest,which was five times that of CK.(4)The comprehensive evaluation of 4%BC2 treatment was the highest through the comprehensive evaluation of saline-alkali soil indexes in the indoor soil culture cup test.The comprehensive evaluation of pepper biomass in pot experiment showed that the overall effect was the best when the addition of cotton stalk biochar was 4%,and the comprehensive evaluation of biomass in BD treatment was the highest.Correlation analysis of soil physical and chemical properties and nutrient indexes under cotton stalk biochar treatment showed that there were different degrees of correlation between them.In summary,cotton stalk biochar has the effect of desalting and fertilizing the saline-alkali soil and increasing yield. |
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