Fixed Ammonium in Major Types of Paddy Soils in Hunan Province,China

ZHANG YANGZHU; LIAO JIPEI; SUN YUHUAN; FENG YUEHUA; HUANG YUNXIANG

摘要

The contents, affecting factors, seasonal changes and availability of fixed ammonium in major types ofpaddy soils derived from different parent materials in Hunan Province, China, were studied using the Silva-Bremner method by laboratory and pot experiments. Results showed that the content of fixed ammoniumin the plough horizons ranged from 88.3 mg kg-1 to 388.1 mg kg-1, with 273.2 ± 77.7 mg kg-1 on average,accounting for 11.2% of total soil N on average. Content of fixed ammonium decreased in the order of newlylacustrine clayey paddy soil ＞ alluvial sandy paddy soil ＞ purple clayey paddy soil ＞ newly alluvial sandypaddy soil ＞ yellow clayey paddy soil ＞ reddish-yellow clayey paddy soil ＞ granitic sandy paddy soil. Therewere four distribution patterns of fixed ammonium in the profiles to 1-m depth, i.e., increase with the depth,decrease with increasing depth, no distinct change with the depth, and abrupt increase or decrease in somehorizon. Percentage of fixed ammonium in total N increased with the depth in most of the soils. Fixationof NH4+ by soil was higher at 30 ℃ than at 20 ℃ and 40 ℃, and continuous submergence benefited thefixation of NH4+ in newly alluvial sandy paddy soil, purple clayey paddy soil and alluvial sandy paddy soil,while alternating wetting and drying contributed to the fixation of NH4+ in yellow clayey paddy soil mostly.Fixed ammonium content in the test paddy soils was significantly correlated with ＜ 0.01 mm clay content(P ＜ 0.05), but not with ＜ 0.001 mm clay content, total N, organic N and organic matter. Fixed ammoniumcontent varied with rice growth stages. Application of N fertilizer promoted fixation of NH4+ by soil, and Nuptake by rice plant promoted release of fixed ammonium from the soil. Recently fixed ammonium in paddysoil after N fertilizer application was nearly 100% available to rice plant, while native fixed ammonium wasonly partly available, varying with the soil type and rice type.

机译：通过席尔瓦-布雷姆纳方法，通过实验室和盆栽试验研究了湖南省不同母体来源的主要类型水稻土的含量，影响因素，季节变化和固定铵的有效性。结果表明，耕层中固定铵的含量范围为88.3 mg kg-1至388.1 mg kg-1，平均为273.2±77.7 mg kg-1，平均占土壤总氮的11.2％。固定态铵的含量按新湖相粘土质水稻土＞冲积沙质水稻土＞紫色质朴水稻土＞新冲积沙质土壤＞黄黏土质水稻土＞红黄黏土质水稻土＞花岗质沙质水稻土。分布在1m深度的固定铵分布有4种分布模式，即随深度增加，随深度增加而减小，随深度没有明显变化以及某水平的突然增加或减少。在大多数土壤中，固定氮在总氮中的百分比随深度的增加而增加。在30℃下土壤对NH4 +的固定高于在20℃和40℃下的固定，连续淹没有利于NH4 +在新冲积沙质水稻土，紫色黏土水稻土和冲积沙质水稻土中的固定，而交替的湿润和干燥有助于固定。黄壤性水稻土中的NH4 +含量最多。试验稻田中固定的铵含量与＜0.01 mm粘土含量显着相关（P ＜0.05），而与＜0.001 mm粘土含量，总氮，有机氮和有机质则不相关。固定铵含量随水稻生长期而变化。氮肥的施用促进了土壤对NH4 +的固定，水稻植物对氮的吸收促进了土壤中固定铵的释放。施用氮肥后，稻田土壤中的固定铵态氮近100％可用，而天然固定铵态氮仅部分可用，随土壤类型和水稻类型的不同而不同。

Fixed Ammonium in Major Types of Paddy Soils in Hunan Province,China

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