不同耕作方式下土壤氮素矿化和硝化特征研究

为探讨长期定位试验田不同耕作方式下土壤氮素矿化和硝化特征，采用室内恒温通气培养法，保持土壤田间持水量在65％条件下，测定不同耕作方式下表层土壤（0～20cm）在不同温度下的NH4^＋和NO3^-含量，并计算氮素矿化量和硝化率。结果表明，随着温度的升高，土壤氮素矿化和硝化作用均增强，几种耕作方式下土壤氮素矿化和硝化作用均表现为35℃〉30℃〉25℃。保护性耕作与水旱轮作和常规平作之间的矿化量存在显著的差异，垄作免耕〉厢作免耕〉水旱轮作〉常规平作。土壤氮素最终硝化率达到了60％～80％，表现为常规平作最高，水旱轮作次之，厢作免耕最低。矿化率与土壤有机质、碱解氮和速效磷对数均成显著正相关，相关系数分别为r^2=0．99，r^2=0．97，r^2=0．96，pH是影响硝化作用的重要因素，硝化率与土壤pH成显著正相关，r^2=0．991。

Study on the characteristics of mineralization and nitrification in different cultivation modes

To explore the difference of soil nitrogen mineralization and nitrification between the no-tillage and conventional tillage soils in long-term experimental fields, an indoor heated aerobic incubation experiment was conducted to investigate the NH_4~+ and NO_3~- of the protection of surface soil (0～20 cm) at different temperatures, with 65% water holding capacity, and also calculate the nitrogen mineralization and nitrification rates. Result showed that with the increasing of temperature, soil mineralization and nitrifi-cation were increased. Soil mineralization aad nitrification were expressed as 35 ℃> 30 ℃> 25℃.At the same time, there was sig-nificantly difference between conservation tillage and farming methods in soil mineralization, no-tillage and ridge culture > no-tillage and plain culture > Paddy-Upland rotation > conventional flatten culture. The final nitrification rate reached 60%～80%, conventional flatten culture > Paddy-Upland rotation > no-tillage and ridge culture > no-tillage and plain culture. Mineralization rate of soil was significantly related to soil organic matter content, soil mineral N content and soil available P, r~2 = 0.99, r~2= 0.97, r~2 = 0.96, soil pH was an important factor to influence soil nitrification, nitrification rate of soil was significantly correlated with soil pH, r~2=0.991.