层表面的土壤含有最高的数字和各种微生物。这些微生物在土壤中分解的重要作用,有机和矿物材料部分通过酶作用,部分通过进一步的材料作为营养和代谢。大部分的故障产品所使用的植物营养流失或进入土壤环境。然而,剩下的这些用于生成腐殖质分解材料。腐殖质中发挥着积极的作用,进一步加强土壤性质,如能提高土壤的持水能力,使更多的水提供给植物,为植物提供营养,增加矿物的吸附,导致土壤聚合。此外腐殖质增加土壤缓冲能力和稳定土壤的pH值,进一步帮助植物矿质营养。此外,它更深的土壤颜色增加了土壤的吸收太阳能 此外,植物和动物组织的分解微生物可以回收能源和营养物质转化为形式,用于植物。此外,非常重要的是,微生物在自行车扮演重要角色的硫、磷、铁,许多微量元素微量元素。元素来描述各种形式的转换周期。在碳循环中,微生物把植物和动物残留物变成二氧化碳和土壤有机质称为腐殖质。氮循环,氮是植物,只有当它是转化为氨(NH3)通过土壤细菌如(N2固定)或由人类如(制造肥料)土壤细菌也可以返回到大气中的氮转化NO3 N2或气体(一氧化二氮) 另一个非常重要的元素在土壤磷,这对提高土壤肥力是至关重要的(13 - 14日),因此增加了森林和农业生产。无花果所示:1.1磷通常是发现在岩石风化后,就可用于植物和土壤水溶解。然后被植物吸收,然后被转移到动物,动物和植物残留物包含这个可以再次回收磷微生物。此外,化肥也是一种土壤中磷的重要来源.
The surface layers of soil contain the highest numbers and variety of microorganisms . These microorganisms in soil play the important role of breaking down both, organic and mineral materials partly by enzymatic action and partly by taking the materials in as nutrients and metabolizing them further. Most of the breakdown products are used by the plants as nutrients or are lost into the soil environment. However, the rest of these breakdown materials are used to generate humus. Humus plays an active role to further enhance soil property, e.g. it improves the water-holding capacity of soil which makes more water available to the plants, a supply plant with nutrients, increases the adsorption of minerals, and contributes to soil aggregation . Moreover humus increases the soil buffering capacity and stabilizes the soil's pH to further help the plants to take up mineral nutrients. Additionally, it darkens the soil color which increases the soil's absorption of solar energy
In addition, the decomposition of the plant and animal tissues by microorganisms can recycle energy and convert nutrients to forms that are usable for plants. Also, very importantly, microorganisms play vital roles in cycling of sulfur, phosphorus, iron, and many micronutrient trace elements . The transformations of elements to various forms are described as cycle. In the carbon cycle, microorganisms transform plant and animal residues into carbon dioxide and the soil organic matter known as humus. In the nitrogen cycle, nitrogen is made available to plants only when it is transformed to ammonia (NH3) either by soil bacteria such as (N2 fixation) or by humans such as (manufacture of fertilizers) Soil bacteria also can return the nitrogen to the atmosphere by transforming NO3- to N2 or (N2O) gas
Another very important element found in soil is Phosphorus, which is critical for improving the soil fertility [13-14], thus increasing the forest and agriculture production. As shown in fig: 1.1 Phosphorus is usually found in rocks and it becomes available for plant after weathering and dissolving in the soil water. It is then absorbed by plants and then gets transferred to animals, the animal and plant residues containing this phosphorus can be recycled again by microorganisms. Additionally, fertilizers are also an important source of phosphorus in the soil