生物碳对灰漠土有机碳及其组分的影响

土壤有机碳是影响土壤肥力和作物产量高低的决定性因子。以棉花秸秆为原料,在高温厌氧条件下热解制备生物碳,通过盆栽试验探讨了生物碳对新疆灰漠土有机碳及其组分的影响。试验设置3种生物碳:棉花秸秆分别在450℃、600℃和750℃下热解制备(以BC450、BC600和BC750表示);每种生物碳的施用量分别为5 g·kg-1、10 g·kg-1和20 g·kg-1(占土壤重量的比例);同时,以空白土壤为对照(CK)。结果表明:施用生物碳可促进小麦生长,两茬小麦的地上部干物质重均显著高于对照。施用生物碳可显著提高土壤总有机碳,且生物碳热解温度越高,施用量越大,提高作用越明显。各生物碳处理土壤易氧化碳含量均显著高于对照;生物碳低、中施用量处理(5 g·kg-1、10 g·kg-1)土壤水溶性有机碳含量显著高于对照,但高施用量处理(20 g·kg-1)与对照无显著差异;除BC750低施用量处理(5 g·kg1)外,其余各生物碳处理土壤微生物量碳含量也均显著高于对照。生物碳不同热解温度对土壤易氧化碳和微生物量碳含量的影响表现为BC450>BC600>BC750;但对土壤水溶性有机碳含量无显著影响。生物碳不同施用量对土壤易氧化碳的影响表现为10 g·kg-1≈20 g·kg-1>5 g·kg-1,水溶性有机碳含量为5 g·kg1≈10 g·kg-1>20 g·kg-1。生物碳对土壤微生物商的影响总体表现为:生物碳的热解温度越高,施用量越大,土壤微生物商越低。因此,合理的施用棉花秸秆生物碳可显著增加灰漠土有机碳储量,改变土壤有机碳组分,提高土壤生产力。

Effects of biochar on organic carbon content and fractions of gray desert soil

Soilorganic carbon is critical for soil fertility and crop yield.Biochar(BC) is a carbon-rich organic material derived from incomplete pyrolysis of biomass and can constitute a significant fraction of soil carbon due to its prolonged lifespan in soils.The study investigated the influence of biochar on wheat growth and soil organic carbon in grey desert soils under greenhouse experiment.The objective was to learn how this soil amendment improved crop growth and increased soil carbon storage.Biochar was produced from dried cotton stalks via pyrolysis in oxygen-limited conditions.Three qualities of biochar produced at 450 ℃,600 ℃ and 750 ℃(referred as BC450,BC600 and BC750) were used as the soil organic amendment in the study.The experiment was that of 3×3 factorial design with three qualities of biochar(BC450,BC600 and BC750) and three application rates(5 g·kg-1,10 g·kg-1 and 20 g·kg-1 of soil weight) plus an un-amended soil set as the control(CK).Wheat was planted for two consecutive growth seasons in 2009.The first-season of wheat was May 8 to July 15 and the second was August 8 to October 15.The results showed that dry matter weight of wheat under added BC treatments were significantly higher than that under CK.There were no significant differences among the three types and three application rates of biochar in terms of the first-season wheat dry matter weight.However,the second-season wheat dry matter weight was significantly affected by biochar qualities,application rates and the interaction of them.The highest wheat dry matter weight was under BC750 with an application rate of 20 g·kg-1.Soil total organic carbon increased with increasing biochar pyrolysis temperature and application rate.Soil total organic carbon under BC450,BC600 and BC750 was 2.11,3.32 and 4.19 times of CK,respectively.Soil readily oxidizable carbon content was significantly higher under biochar treatments than the control.Water-soluble organic carbon was significantly higher under biochar treatments at 5 g·kg-1 and 10 g·kg-1 application rates than the control.However,there was no significant difference between 20 g·kg-1 biochar treatment and the control.Microbial biomass carbon increased significantly under biochar treatment,except for BC750 biochar at 5 g·kg-1 application rate.Readily oxidizable carbon and microbial biomass carbon contents of soil changed in the following order of BC450 > BC600 > BC750.However,soil water-soluble organic carbon content was not affected by biochar pyrolysis temperature.The order of influence of different biochar application rates on readily oxidizable soil carbon was 10 g·kg-1 ≈20 g·kg-1 > 5 g·kg-1,and that of water-soluble organic carbon was 5 g·kg-1 ≈10 g·kg-1 > 20g·kg-1.For soil microbial quotient,BC450 and BC600 at 5 g·kg-1 application rate were higher than CK.Also BC450 at 10 g·kg-1 and 20 g·kg-1 application rates were not significantly different from CK.Other biochar treatments were as well lower than CK.These results suggested that application of biochar as soil organic amendment was an efficient way of increasing soil carbon reserve,changing soil organic carbon fraction and promoting soil productivity.