| [Object] Xinjiang is the largest production base of cotton in China and is rich in resources ofcotton stalk. Biochar was produced from dried cotton stalks via pyrolysis in oxygen-limitedconditions. The influence of biochar on inorganic phosphorus forms of grey desert soil wereinvestigated and effects of different pyrolysis temperature biochars and application rates ongrowth and nutrient uptake of cotton under different P application rates were also evaluated inthis study. The objective of this study is to improve biochar reasonable application and toenhance P use efficiency.[Method] Effects of biochar on inorganic P forms in soil were studied with an indoorsimulation experiment. Cotton stalks (CS) and biochar (BC) were used as soil amendment inthis experiment, and the blank soil was set as the control (CK). Each soil treatment wasapplied three levels of P fertilizer (P2O5) as0,0.25and0.5g/kg of soil weight (referred as P0,P1and P2). The influence of biochar with different pyrolysis temperatures and applicationrates on growth and nutrient uptake of cotton were investigated with a pot experiment undergreenhouse conditions in years of2011and2012. Three qualities of biochar produced at450℃,600℃and750℃(referred as BC450, BC600and BC750) were used as the soil organicamendment, and an untreated soil was set as control (CK) in this experiment. Moreover, theapplication rates of BC750were set as0(CK),1%(BC1%) and2%(BC2%), respectively.Each soil treatment was applied three levels of P fertilizer (P2O5) as0,0.25and0.5g/kg ofsoil weight (referred as P0, P1and P2).[Result](1) Ca10-P was in a dominate position in soil inorganic P, accounting for more than60%oftotal inorganic P; followed by Ca8-P, accounting for more than20%of total inorganic P. Thecontents of inorganic P, Ca2-P and Al-P in soil were significantly increased by phosphatefertilizer application, but the content of O-P and Ca10-P were not affected. Ca2-P in soil wasimproved by application of cotton straw and biochar. The contents of Ca2-P and Al-P in soilunder biochar treatments were significantly higher than those under cotton straw and CKtreatments, but the content of Ca8-P and Fe-P in biochar treatments were decreased. Thoseresults suggest that application of biochar can improve the inorganic P availability in greydesert soil.(2) The P content and availability in soil were promoted with biochar added. With thepyrolysis temperature of biochar increasing, the content of water-soluble P and total P of soilwere increased significantly. The order of influence of biochar on soil P content waswater-soluble P> total P> available P.(3) Under different P application rates, the dry matter weight of cotton was significantlyhigher under biochar treatments than that under control (CK) in both2011and2012, but therewere differences among three biochar treatments between2011and2012. Cotton plantbiomass was increased with biochar pyrolysis temperature and application rate increased and the highest dry matter weight of cotton was found under the treatment of BC750withapplication rate at2%in this study.(4) The result of greenhouse pot experiment showed that biochar not only promoted thegrowth of cotton, but also influenced the cotton nutrients uptake. The application of biocharhad a significant impact on nutrient uptake of cotton. The uptake amounts of N, P and K incotton plant were significantly higher under biochar treatments than those under CK. Theorder of nutrient uptake amount under different pyrolysis temperature biochars were750°C>600°C>450℃> CK, and the application rates of BC750were followed with BC2%> BC1%>CK.[Conclusion] The application of biochar can change inorganic P forms in gray desert soil,increase soil water-soluble P and total P content, and promote cotton growth and nutrientabsorption, improve phosphorus utilization. |
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