摘要
【目的】了解湖南耕地土壤的固定态铵状况及其在土壤供氮中的作用。【方法】通过野外采样、室内培养和分析测定等手段,研究了湖南省主要母质发育的耕地土壤固定态铵含量与最大固铵容量及其影响因素。【结果】(1)由于成土母质的多样性以及不同农业生产方式的影响,不同类型耕地土壤固定态铵含量差异甚大。水田土壤变化于(135.4±57.4)～(412.8±32.4)mg·kg-1之间,平均为(304.7±96.7)mg·kg-1;旱地土壤变化于(85.6±25.4)mg·kg-1至435.7mg·kg-1之间;平均为(230.1±89.2)mg·kg-1。不论旱地土壤还是水田土壤,固定态铵的绝对含量主要受成土母质的影响。由湖积物和板页岩风化物发育的土壤固定态铵含量最高,而由花岗岩风化物发育的土壤固定态铵含量最低;但是旱地土壤固定态铵占土壤全氮含量的百分数要高于水田土壤,水田土壤固定态铵占土壤全氮含量的百分数变动在(6.1±3.6)%～(16.6±4.6)%之间,平均为(14.0±5.1)%,旱地土壤固定态铵占土壤全氮含量的百分比变动在(5.8±2.0)%～(40.1±17.8)%,平均为(23.5±14.2)%。(2)不同土壤最大固铵容量的大小顺序与固定态铵含量基本相同,但供试土壤“新固定的”固定态铵占最大固铵容量的比例大部分在20%以下,这与供试土壤的肥力水平较高,土壤的大部分固铵位点已被铵饱和有关。(3)土壤粘粒含量和粘土矿物组成是决定土壤固定态铵含量及最大固铵容量的两个主要因素。研究表明,水田土壤<0.02mm粘粒中2﹕1型粘土矿物以水云母为主,其中,0.02～0.002mm粘粒中水云母含量远高于<0.002mm粘粒中水云母含量。相关分析表明,水田土壤的固定态铵含量(y1)和最大固铵容量(y2)与<0.02mm粘粒中2﹕1型粘土矿物总量(x1)和水云母含量(x2)以及0.02～0.002mm粘粒中2﹕1型粘土矿物总量(x3)和水云母含量(x4)均呈极显著或显著正相关,但与<0.002mm粘粒中2﹕1型粘土矿物总量和水云母含量的相关性不显著,说明供试土壤的固铵基质主要是<0.02mm粘粒的水云母矿物。【结论】以上结果表明,固定态铵是湖南耕地土壤的主要氮素形态和氮素资源,特别是旱地土壤固定态铵占土壤全氮含量的百分数高于水田土壤。所以,在土壤对作物的氮素营养,尤其是对旱地作物的氮素营养中有着重要作用,值得进一步研究。
[ Objective ] To understand the status of fixed ammonium in the tillage soils of Hunan, China. [ Method ] A fixed ammonium content, maximum capacity of fixing ammonium, and their influencing factors in major types of tillage soils were studied with sampling on fields, and in laboratory incubation. [Result] （1） Content of fixed ammonium in the tested soils varied greatly with nature of parent material and soil use pattern. For the paddy soils, it ranged from （135.4±57.4） mg·kg^-1 to （412.8±32.4） mg·kg^-1, with （304.7±96.7） mg·kg^-1 in average while it ranged from （85.6±25.4） mg·kg^-1 to 435.7 mg·kg^-1, with （230.1±89.2） mg·kg^-1 in average for the upland soils. Weather upland soils or paddy soils with their fixed ammonium content varied with the parent materials the soils from which they were derived. Soils derived from limnic material and slate had the highest ammonium content while soils derived from granite had the lowest. The percentage of fixed ammonium to total N in the upland soils was always higher than that in the paddy soils. It ranged from （6.1±3.6）% to （16.6±4.6）%, with （14.0±5.1）% in average for the paddy soils and it amounted to （5.8 ±2.0）% （40.1±17.8）%, with （23.5±14.2）% in average. （2） Like that in cultivated horizon of the tested soils, the maximum capacity of ammonium fixation in the tested soils also varied greatly with nature of parent material and soil use pattern, and had the same order with fixed ammonium in the tested soils. For all the tested soils, percent of recently fixed ammonium to maximum capacity of ammonium fixation was always bellow 20% （most likely because of better fertility and higher saturation of ammonium-fixing site of the soils）. （3） The clay content and clay composition of the tested soils were the two important factors influencing their fixed ammonium content and maximum capacity of ammonium fixation. The results showed that the 2 ： 1 type clay mineral in 〈0.02 mm clay of the paddy soils is predominant in hydrous mica. Of which, the hydrous mica content of 0.02-0.002 mm clay was much higher than that of 〈0.002 mm clay of the soils. [Conclusion] The above results showed that fixed ammonium is a major form of N in the tillage soils in Hunan Province. It would play an important role in N nutrition of crops, especially upland crops, and be worth being further researched.
出处
《中国农业科学》
CAS
CSCD
北大核心
2006年第9期1836-1845,共10页
Scientia Agricultura Sinica
基金
国家"十五"重大科技攻关项目(2004BA520A01)
关键词
湖南
水稻土
旱地土壤
固定态铵
最大固铵容量
Hunan Province
Paddy soil
Upland soil
Fixed ammonium
Maximum capacity of ammonium fixation
