有机物料添加磷素释放动态与土壤磷组分响应

Phosphorus Release Dynamics of Organic Amendments and Soil Phosphorus Fractions Response

【目的】为农业生产中秸秆等的资源化利用及广辟磷源、磷素高效利用提供理论依据。【方法】通过不同物料(紫云英秸秆、油菜秸秆、400℃稻壳生物质炭、700℃稻壳生物质炭、无机磷肥)等磷量添加入土壤,进行18周恒温培养试验;采用土壤颗粒有机质分离法与修正的Hedley化学连续浸提法相结合,研究物料磷素释放动态与土壤磷素形态响应转化机制。【结果】(1)紫云英秸秆添加入土壤腐解后,有最高的磷素释放率,达95.4%;其次为700℃稻壳生物质炭,磷的释放率为77.3%;而400℃稻壳生物质炭与油菜秸秆,磷素释放不显著。(2)等磷量各物料添加对土壤无机磷的提升率由高到低顺序为:紫云英秸秆,700℃稻壳生物质炭,400℃稻壳生物质炭,油菜秸秆,无机磷肥;对土壤conHCl-Po组分的提升率顺序为:紫云英秸秆,油菜秸秆,400℃稻壳生物质炭,而700℃稻壳生物质炭添加与无机磷肥添加,对土壤有机磷组分均无影响;各物料添加对土壤Residual-P组分的提升率顺序为:700℃稻壳生物质炭,400℃稻壳生物质炭,紫云英秸秆,油菜秸秆,无机磷肥。(3)就土壤磷组分而言,外源磷的添加,均以提升土壤Residual-P组分为主,其提升率最高;土壤各无机磷组分中,外源有机物料添加均以HCl-Pi组分提升率最高,而等磷量无机磷肥添加,以Resin-Pi组分提升率最高,HCl-Pi组分次之。外源磷的添加能显著提升土壤磷素有效性;有机物料添加对土壤磷素有效性的提升效果均显著优于等磷量无机磷肥添加。【结论】农业生产中,相对于其他有机物料,紫云英等绿肥作物还田,在土壤磷素有效性及土壤供磷能力提升方面有明显优势。土壤颗粒有机质分离法用于分离土壤与秸秆腐解残余物以监测秸秆腐解动态,经试验验证及物料回收率数据来看,此法在技术上可行,但后续仍需更多的研究加以对比验证。

[Objective]This study aims to supply theoretical foundations for utilization of straw and green manure resources,and high phosphorus(P)use efficiency in agricultural production.[Method]An 18-week soil incubation experiment was conducted to study the P release dynamics of organic amendments(Chinese milk vetch,rape straw,400℃rice husk biochar and 700℃rice husk biochar)and soil P transformation mechanisms by the methods of soil particulate organic matter(POM)separation and modified Hedley chemical sequential fractionation.[Result]After 18 weeks,the chinese milk vetch had the highest P release rate about 95.4%,followed by 700℃rice husk biochar(77.3%);400℃rice husk biochar and rape straw had no significant P release.The sequence of soil inorganic P(IP)increase rates after 18 weeks incubation by organic amendments with equivalent P input was:Chinese milk vetch addition>700℃rice husk biochar addition>400℃rice husk biochar addition>rape straw addition>chemical fertilizer addition;the sequence of soil conHCl-Po increase rates was:Chinese milk vetch addition>rape straw addition>400℃rice husk biochar addition,700℃rice husk biochar addition and chemical fertilizer addition had no significant effects on soil organic P(OP);the sequence of soil residual-P increase rates was:700℃rice husk biochar addition>400℃rice husk biochar addition>Chinese milk vetch addition>rape straw addition>chemical fertilizer addition.For soil P fractions,soil residual-P fraction had the highest increase rates by exogenetic P additions.For soil IP fractions,HCl-Pi had the highest increase rates by organic amendments;Resin-Pi had the highest increase rate by chemical fertilizer addition with equivalent P input,followed by soil HCl-Pi fraction.Compared with chemical fertilizer addition,organic amendments with equivalent P input may significantly increase soil P availability.[Conclusion]Green manure crops such as Chinese milk vetch have the obvious advantage in promoting soil P supply ability and soil P availability.The methods of soil POM separation was successfully employed in separating soil and straw residues to track straw decomposition dynamics,however,more studies are needed for comparative verification.