生物炭调节盐化水稻土磷素形态及释放风险研究

为探明生物炭施用对盐化水稻土磷素形态及释放风险的影响,以滨海草甸盐化水稻土为基础,结合室内分析,研究了不同用量生物炭还田方式(CK:0 t·hm~(-2);B1:20 t·hm~(-2);B2:40 t·hm~(-2))条件下土壤磷含量、组分特征及磷素释放风险。结果表明:生物炭能提高土壤全磷、有效磷、总有机磷和总无机磷含量,提高幅度分别为:11.40%～35.70%、28.96%～46.63%、11.30%～29.19%和10.54%～25.98%。生物炭提高了土壤NaHCO_3浸提态磷(Ca_2-P)、NH_4AC浸提态磷(Ca_8-P)和NH_4F浸提态磷(Al-P)含量,随着施炭量的增加而增大,且各处理间差异显著;当施炭量为20 t·hm~(-2)时,土壤NaOH-Na_2CO_3浸提态磷(Fe-P)和闭蓄态磷(O-P)含量显著高于其他处理;施用生物炭对H_2SO_4浸提态磷(Ca_(10)-P)无显著影响。生物炭显著提高了土壤活性有机磷(LOP)和中等活性有机磷(MLOP)含量,但显著降低了土壤中等稳定性有机磷(MROP)含量,当施炭量为40 t·hm~(-2)时,土壤高等稳定性有机磷(HROP)含量最小,且显著低于其他处理。本试验中土壤的活性AlAl(ox)]和活性FeFe(ox)]均处于较高水平;施用生物炭显著提高了土壤磷吸持指数(PSI),增加了土壤固磷能力;土壤磷吸持饱和度(DPSS)为6.81%～8.34%,土壤磷释放风险指数(ERI)为54.55%～61.67%。综上所述,在本文试验条件下,施用生物炭可以改善盐化水稻土磷素状况,且不会增大土壤磷素释放的风险。

Regulation of phosphorus fractions and release risk upon biochar application in saline paddy soil

In order to investigate the effect of biochar application on phosphorus fractions and release risk of coastal meadow saline paddy soils, a field experiment was conducted to investigate soil P content, characteristics of P fractions, and P release risk under different biochar application rates(CK:0 t·hm^-2;B1:20 t·hm^-2;B2:40 t·hm^-2). The results showed that biochar could increase the content of total P, Olsen-P, total organic P, and total inorganic P in soil by 11.40%~35.70%, 28.96%~46.63%, 11.30%~29.19%, and 10.54%~25.98%, respectively. Biochar increased the content of NaHCO₃ soluble P(Ca₂-P), NH₄AC soluble P(Ca₈-P), and NH₄F soluble P(Al-P) in soil, and there was a significant positive correlation with biochar dosage. When biochar application was 20 t·hm^-2, the content of NaOH-Na₂CO₃ soluble P(Fe-P) and occluded P(O-P) in soil reached the highest values. The application of biochar had no significant effect on H₂SO₄ soluble P(Ca₁₀-P). Biochar significantly increased the content of soil labile organic P(LOP) and moderately labile organic P(MLOP), but significantly reduced the content of moderately resistant soil organic P(MROP). When the amount of biochar was 40 t·hm^-2, the content of highly resistant soil organic phosphorus(HROP) reached the lowest value. In this experiment, soil Al_(ox) and Fe_(ox) were at a high level and the application of biochar significantly increased soil P sorption index(PSI) and increased the fixation capacity of soil P. Soil P adsorption saturation(DPSS) was only 6.81%~8.34%, and soil environmental risk index(ERI) was 54.55%~61.67%. In conclusion, the application of biochar can improve the P availability of salinized paddy soil, but do not increase the risk of soil P release under the conditions of this study.