三种典型土壤固定态铵及其释放研究初探

Preliminary Comparison of Fixed Ammonium and Its Release in Three Typical Soils

通过探究三种典型土壤(黑土、潮棕壤、红壤)的固铵潜力,及其达到最大固铵量后的释放状况,比较了三种土壤固定态铵库在土壤养分管理中的重要性。结果表明:随着氮加入量(NH4Cl)的增大,黑土和潮棕壤的固定态铵含量随之提升,当NH4Cl加入量(以N量计)达到3000mg kg^(-1)时,黑土和潮棕壤达到最大固铵量,此时两种土壤分别新固定铵140.2和162.0 mg kg^(-1);然而,红壤的固定态铵含量不随加氮量的增加而提高。在连续振荡淋洗实验中,黑土新固定铵的释放率为14.8%,潮棕壤新固定铵的释放率为29.9%,红壤的固定态铵含量没有明显变化。综上,不同土壤对加入铵的固定能力不同,潮棕壤固铵能力高于黑土,且更易释放出来供植物吸收利用,该过程对农业生产具有重要意义;而红壤几乎不固定加入的铵,且原固定态铵也较难释放出来,故在此类土壤上氮素的保存与供给应更依赖于生物过程。三种土壤固定态铵库在氮素养分管理中的重要性为:潮棕壤>黑土>红壤。

The maximum fixation capacity of NH4^＋ in three typical farmland soils in China, i.e. Black Soil, Aquic Brown Earth and Red Soil, was analyzed in the present study.Subsequently, the release of fixed NH4^＋ was studied with the sequential elution method.The significance of fixed NH4^＋ pool in nutrient management was compared in the test soils.The results showed that the fixed NH4^＋ increased with the increasing application rates of NH4Cl. Underthe concentration of NH4Cl at 3000 mg kg^-1, the recently fixed NH4^＋ reached the maximum of 140.2 and 162.0 mg kg^-1 in Black Soil and Aquic Brown Earth, respectively. On the other hand, no significant change of fixed NH4^＋ was observed in Red Soil with the NH4Cl addition. After sequential elution, 14.8% and 29.9% of recently fixed NH4^＋ released in the Black Soil and Aquic Brown Earth, respectively; whereas little fixed NH4^＋ released in the Red Soil. Therefore, the capacity of NH4^＋ fixation varied with different soil types. Compared with Black Soil, the higher capacity of fixation and release of NH4^＋ in Aquic Brown Earth implied the greater importance of fixed NH4^＋ pool in agricultural production.However, fixed NH4^＋ pool was stable in Red Soil, indicating there was little recently fixed NH4^＋ and its release, and conservation and supply of fertilizer N relied more on biotic process in this soil. In general, the importance of fixed NH4^＋ pool in nutrient managementofthe three soils followed the order of Aquic Brown Earth Black Soil Red Soil.