Changes in chemical properties of organic matter with intensified rice cropping in tropical lowland soil
Changes in chemical properties of organic matter with intensified rice cropping in tropical lowland soil
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DOI：
10.1111/j.1365-2389.1996.tb01403.x
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发表时间：
1996-09
影响因子：
4.2
通讯作者：
D. Olk;K. Cassman;E. W. Randall;P. Kinchesh;L. Sanger;J. Anderson
中科院分区：
文献类型：
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作者：
D. Olk;K. Cassman;E. W. Randall;P. Kinchesh;L. Sanger;J. Anderson
过去30年来，亚洲的水稻种植系统得到了迅速加强，大面积的灌溉低地水稻现在每年种植两到三季水稻。我们的目的是比较土壤有机质（SOM）的化学组成，从四个领域与不同的历史，水稻种植强度和土壤淹没：（i）一个单一的作物灌溉，旱地水稻系统没有土壤淹没，（ii）灌溉水稻和大豆轮作，和灌溉（iii）双或（iv）三季水稻系统中，土壤仍然淹没在一年中的大部分时间。在所有四种土壤中，提取的移动的胡敏酸（MHA）和胡敏酸钙（CaHA）组分经14 C测年为现代组分，约占全N和有机C的20%。与CaHA相比，MHA在所有土壤中富集N和水解氨基酸（AA）。然而，随着灌溉水稻种植频率的增加，有机质中酚类物质的含量有很大的增加。我们推测，较慢的木质素分解所造成的缺乏O2在淹没土壤中导致酚类基团纳入年轻的SOM馏分。这些组分中酚类物质含量的增加可能会影响氮素循环和低地土壤供氮能力。
Summary Rice systems in Asia have intensified rapidly in the past 30 years, and significant areas of irrigated lowland rice are now supporting two or three rice crops per year. Our objective was to compare the chemical composition of soil organic matter (SOM) from four fields with different histories of rice cropping intensity and soil submergence: (i) a single-crop rainfed, dryland rice system without soil submergence, (ii) an irrigated rice and soybean rotation, and irrigated (iii) double- or (iv) triple-crop rice systems in which soil remains submerged during much of the year. In all four soils, extracted mobile humic acid (MHA) and calcium humate (CaHA) fractions were of modern age by 14C-dating, and represented about 20% of total N and organic C. The MHA was enriched in N and hydrolysable amino acids (AA) compared with CaHA in all soils. With increased frequency of irrigated rice cropping, however, there was a large increase in phenolic content of SOM. We speculate that slower lignin decomposition caused by deficiency of O2 in submerged soil leads to incorporation of phenolic moieties into young SOM fractions. The increased phenolic character of these fractions may influence N cycling and the N supplying capacity of lowland soils supporting two or three annual crops of irrigated rice.