Effects Of Biochar On Soil Physical And Chemical Properties And The Growth Of Wheat In Manural Loessial Soil

Biochar is a kind of solid residual produced by thermal decomposition of organicmaterial under limited or absent supply of oxygen, and relatively low temperatures, biocharhas the properties of high internal surface area and microporosity, furthmore,non-biological and biological stability. It has been considerably studied on the applications ofbiochar as soil amendment, soil greenhouse gas emission reduction and soil carbonsequestration in recent years.A field trail was conducted to study the effects of biochar on soil moisture, pH and bulkdensity, soil organic carbon and available nutrient contents, and the responses from wheatgroup leaf area index（LAI）, photosynthetic rate（Pn）, and wheat yield for those in manuralloessial soil of Guanzhong area, Shaanxi Province, PR China. The trail was carried out in therandomly arranged blocks, with5treatments and3replications. The experimental treatmentsincluded5levels of biochar: no biochar （CK）,1000kg hm^-2（T1）,5000kg hm^-2（T2）,10000kg hm^-2（T3） and20000kg hm^-2（T4）, and soil samples were sampled at regularintervals during wheat crop growing season （tillering stage, reviving stage, jointing stage,heading stage, grain filling stage and maturing stage）. The results indicated that the soilmoisture contents of all the treatments showed an increasing trend after a decrease, with therise of biochar application rates, and maximum soil moisture was recorded in T4, whileminimum moisture was recorded in T2. And the soil bulk density in the different treatmentsfollowed a order as CK>T1≧T2>T3>T4, but there was no significant difference of the soilpH between different treatments. The order of soil organic carbon contents of differenttreatments was recorded as T4>T3>T2>T1>CK. The contents of alkaline hydrolysis nitrogenand available phosphorus were highest in T1while the minimum contents were recorded inT4and CK, generally, these two parameters showed an initially increase but decreasingsubsequently trend, with the increasing application rates of biochar. The soil readily availablepotassium contents in the different treatments followed an order as T4>T3>T2>T1>CK. Andin the grain filling stage wheat group LAI of T1, T2were17.51%and18.63%smaller than CK, respectively, T1<T3, and as to the wheat group Pn, T1, T2, T31, T4were16.01%,12.43%,10.75%,7.05%higher than CK, respectively, T4<T1. In the maturing stage the mostwheat spike number was recorded in T1, mediately in T2and CK, and least in T4and T3, butthe differences were not significant. The most grains per spike was recorded in CK, mediatelyin T1and T2, and least in T4and T3, with CK significant exceeded the other four treatments.Besides, T2exhibited a bigger value of thousand kernel weight than T1and T3, which bothexceeded T4and CK, and the differences were significant. The most wheat measured yieldwas recorded in T1, mediately in T2and CK, and least in T3and T4, and the differences weresignificant.It can be concluded that the soil pH differences were not significant in differenttreatments when the soil bulk density decreased gradually with the rise of biocharincorporated rates, and as compared with the low application rates of biochar, higher biocharapplication rates were conducive in enhancing the soil moisture, soil organic carbon andreadily available potassium contents, however, low application rates of biochar markedlyincreased the alkaline hydrolysis nitrogen and available phosphorus contents of soil ascompared with the higher rates of biochar. High application rates of biochar could promotewheat group LAI as soil porosity enlarged and then soil moisture enhanced consequently, buton the other side impede wheat group Pn as soil alkaline hydrolysis nitrogen and availablephosphorus fixed consequently. But the low application rates of biochar could cause aninverse outcome. In aggregate, the low but not high application rates of biochar could benefitwheat production. And the interaction between soil and biochar incorporated undergo a longterm. And long-term stationary experiments would be needed to study the effects of biocharon soil moisture, soil organic carbon and available nutrient contents, and the responses fromthe growth of wheat for those.