免耕和秸秆覆盖对黑垆土磷素形态组分的影响

目的]探究免耕及添加秸秆条件下黑垆土土壤磷组分特征及其与AM真菌侵染的关系,了解雨养农业区农业系统磷素利用效率。方法]在陇东黄土高原黑垆土区域,测定传统耕作、传统耕作+秸秆覆盖、免耕和免耕+秸秆覆盖4种处理小麦—玉米—大豆轮作系统中玉米阶段土壤全磷、速效磷组分及AM真菌菌根侵染率。结果]水土保持耕作处理实施9a后,免耕和秸秆覆盖处理下0—5cm土壤磷素含量显著提高,活性磷组分H2O—Pi,NaHCO3—Pi,NaOH—Pi分别比对照提高84.6%,85.2%和56.6%;活性无机磷(H2O—Pi,NaHCO3—Pi之和)和潜在活性磷(NaOH—Pi)分别占总无机磷的11.4%和4.5%,全磷含量与磷组分、速效磷与磷组分呈显著正相关,2个免耕处理菌根侵染率分别比对照增加20.8%和16.5%。结论]免耕和秸秆覆盖显著提高了土壤磷含量,免耕对AM真菌菌根侵染率有积极影响。

Effects of No-till and Stubble Retention on Phosphorus Fractions of Heilu Soil

Objective] The objectives of the study are to investigate the characteristics of soil phosphorus fractions on Heilu soil and its relationships with AM fungi colonization under no-till and stubble retention, in order to understand the phosphate use efficiency in rain feed agricultural system.Methods] Total phosphorus, available phosphorus and phosphorus fraction and arbuscular mycorrhizal(AM) fungi colonization were determined using classical methods for maize crop under 4 tillage managements:conventional tillage, tillage +stubble retention, no-till, no-till +stubble retention in the Loess Plateau.Results] After nine-year conservation tillage implementation, the content of P in soil layer of 0-5 cm increased. Compared to conventional tillage, the fraction of H₂O-P, NaHCO₃-P_i and NaOH-P_i was increased by 84.6%, 85.2% and 56.6%, respectively, under conservation tillage. Labile phosphorus(H₂O-P_i, NaHCO₃-P_i) and potential labile phosphorus(NaOH-P_i) accounted for 11.4% and 4.5% of total inorganic phosphorus. The total phosphorus showed a significantly positive correlation with available phosphorus and phosphorus fraction. Compared to conventional tillage, the AM fungi colonization increased by 20.8% and 16.5% under no-till manage ment.Conclusion] The content of soil phosphorus was significantly improved under no-till and stubble retention, and the AM fungi colonization had a positive response to no-till.