| A large number of studies have indicated that biochar has significant effects on crop yield improvement and mitigation of the greenhouse gas emissions due to its unique physical and chemical properties.It is of important significance to quantify the effects of management practices and biochar quality on crop yield and greenhouse gas emissions.By collecting global relevant published literatures,we selected relative independent studies and a meta-analysis method was undertaken to quantify the effect of biochar characteristics?e.g.,raw material,pyrolysis temperature,C/N,pH etc.?and artificial application management practices?e.g.,application amount and duration?,soil properties?soil texture and pH?on the crop yield improvement,soil CH4,CO2,N2O fluxes and also some research about the responses of fruit and vegetables yield,soil properties and soil N2O fluxes to biochar application under the closed environment conditions in the greenhouse facilities which has no climate influence.The main progress and results of the study are as follows:?1?Biochar could improve crop yield significant by 15.0%of average compared with the control.As for crop types,the effect of biochar on crop yield was significantly different:The yield increase of cash crop?25.3%?was significantly higher than that of grain crop?10.0%?.?2?The characteristics of biochar had significant impact on crop yield.Biochar produced with pyrolysis temperature lower than 600?,pH over 7,and C/N value between 20—300,obtained significant increase in crop yield ranging from 9.2%to26.6%.Moreover,the improved percentage of crop yield decreased with increase in pyrolysis temperature and biochar C/N.?3?As for different soil texture and acidity,the order of improving effect was clay soil>sandy soil>loamy soil.The improving effect of biochar application to acid soil?29.2%?was 7.9 and 2.5 times of that to neutral and alkaline soil.?4?The application rate of biochar was controlled at 10.0—40.0 t·hm-2 with crop yield increase 15.5%—18.0%,while the yield increased by 17.3%—17.5%during the period of six months to one year.?5?In general,biochar application significantly decreased soil N2O emissions,particularly in the 20—50 C/N value of biochar;soil CH4 showed a significant negative response to biochar amendment with wood or straw waste only in coarse soils.?6?For all GHG emissions,negative effects of biochar made by agricultural wastes such as wood,straw and shell residue application occurred in soils with coarse texture,and meanwhile,decreased global warming potential?GWP?and greenhouse gas emission intensity?GHGI?by a mean response ratio of-21.6%and-36.8%,respectively.?7?The biochar of livestock and poultry manure can improve the soil fertility significantly by the rich nutrient content,and it is more favorable for the yield of greenhouse crops,and the average yield by 66.4%,in addition,the responses of soil N2O emissions to biochar application which made from the plant feedstock such as shell residue,straw and wood revealed-44.0%fluxes.A comprehensive analysis concluded,the greenhouse crop yield increased by31.2%while the emission of N2O from greenhouse soil mitigated by 51.4%through the low-dose application of straw biochar which pyrolysised at a range from 401?to500?and C/N value range from 20 to 100.This is conducive to the sustainable development of greenhouse cultivation industry. |
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