稻草不同还田方式对盐渍型水稻土铁形态的影响

Effects of Rice Straw-Derived Biochar on Iron Forms in Coastal Saline Paddy Soil

【目的】探讨适合北方地区的稻草合理还田方式。【方法】采用室内淹水培养方法,研究添加等碳的腐熟稻草(F)、直还稻草(Z)、稻草生物炭(S)等处理对滨海盐渍型水稻土铁存在形态的影响。【结果】在培养0~180 d中,F、Z处理土壤水溶态铁含量随培养时间呈现先降低再增高后降低的变化;各处理土壤的弱酸态铁含量随培养时间逐渐增加、残渣态铁含量随培养时间先增加后减少。培养90 d后,F、Z和S处理使土壤可还原态铁含量显著高于CK,且Z>F>S。培养180 d后,各处理土壤的水溶性铁和弱酸态铁含量显著高于CK,而残渣态铁含量均显著低于CK;土壤水溶性铁含量大小依次为:Z>S>F;土壤弱酸态铁含量大小依次为:Z>F>S。【结论】此试验条件下,不同稻草添加方式使滨海盐渍型水稻土的残渣态铁向水溶态铁和弱酸态铁转化,Z处理比S和F处理的增加幅度更大。

【Objective】The purpose of this work is to explore the rational use of the northern rice straw and appropriate way of its returning.【Method】A laboratory incubation experiment with the equivalent carbon application was used in this study. This study had three treatments,including F(rotted rice straw),Z(direct return of rice straw) and S(rice straw-derived biochar).【Results】Within the incubation period of 0~180 days,the water soluble iron in the F and Z treatments decreased firstly,then increased,and finally showed a decreasing tendency. The content of weak acidic soluble iron increased,while the content of residual iron increased firstly and then decreased. After 90 days incubation,the re duced iron contents in the F,Z and S treatments were significantly higher than that of CK,with an order of Z>F>S.After the 180 days incubation,both water soluble and weak acidic soluble iron in all treatments were significantly higher than those of CK but the opposite was true for residual iron. The water soluble iron followed an order of Z>S>F. The weak acidic soluble iron followed an order of Z>F>S.【Conclusions】Under the experimental conditions,rice straw addition is favorable to transfer residual iron into water soluble and weak acidic soluble iron in coastal saline paddy soil. The efficiency of Z treatment was better than that of both S and F treatments.