摘要
根据钾素在土壤中对作物的有效性 ,可将其分为速效钾、缓效钾和无效钾。各种形态钾素之间存在着渐变性 ,并处于一种动态平衡 ,其中 ,土壤钾素固定与释放对这一平衡产生重要影响 ,进而影响钾素的有效性。富含 2∶1型粘土矿物的土壤 ,不仅有丰富的缓效钾储量和较强的供钾能力 ,而且固钾能力也较强。在淋溶性较强的砂质土壤上 ,固钾作用可使钾素免受淋失 ,有利于保存肥力和提高肥效。但是 ,对于多数土壤来说 ,将使施入土壤的大部分钾素转化为非交换性钾 ,其中 ,只有小部分可被当季作物利用。在集约农业条件下 ,土壤的固定已成为提高钾素利用效率的主要障碍因素。系统阐述了钾素释放与固定的概念与过程 ,综述了影响钾素固定与释放的主要因素 ;系统分析了粘土矿物类型及其结构、土壤铵态氮肥和磷肥水平、土壤水分状况、有机物和羟基铝影响钾素固定、释放过程的作用机理 ;
Potassium, one of three main nutrient elements necessitated for plants, is usually divided into fast available potassium, slowly available potassium and invalid potassium according to its availability for crops in soils. The three type of potassium lay in a mobile equilibrium in soils, which can be affected by potassium fixation and release, thus exerts impact upon the availability of potassium. The soils, rich in 2∶1 clay minerals which have great mounts of specifically adsorptive sites, are not only abundant with reserves of slowly available potassium and high with potential of potassium supplying ability, but also show higher potassium fixation capacity. To a certain extent, this kind of fixation could alleviate potassium from being leached in sandy soils, preserve the fertility and enhance the fertilizer efficiency. Large parts of available potassium input in the soil, however, will turn into non exchangeable K in most other kinds of soils as a result of the fixation, thus only can a little of applied K fertilizer be utilized by current crops. The potassium fixation in soil has become a main impediment factor in increasing the efficiency of K fertilizer under the condition of modern intensive agriculture. The conceptions of the three type of potassium and the processes of potassium fixation and release in soils are expatiated respectively in this paper. The mechanism of potassium fixation and release is summarized. The authors put forward that the types and structure of clay minerals are main factors influencing the capability of potassium supplying and that the tri octahedral clay minerals assume the stronger capacity of potassium fixation after comparing the performance of different type of clay materials. The levels of NH + 4 and phosphor, the status of soil water, as well as the contents of organic matter and hydroxy aluminum, lay important influence upon the fixation and release of potassium in soil. The status and progress in the field of potassium fixation and release are also reviewed.
出处
《地球科学进展》
CAS
CSCD
2002年第5期679-684,共6页
Advances in Earth Science
基金
国家自然科学基金项目"腐殖质对土壤固钾与释钾作用的影响研究"(编号 :40 0 710 5 2 )资助
