Soil formation is a dynamic process that takes place in different environments. It is strongly influenced by the parent material, climate (largely vegetation and temperature and water exchanges), topography (the elevations, depressions, directions and angles of slopes, and other surface features of the landscape), and time.

The parent material is the unconsolidated mass on which soil formation takes place. This material may or may not be derived from the on-site geological substrate or bedrock on which it rests. Parent materials can be transported by wind, water, glaciers, and gravity and deposited on top of bedrock. Because of the diversity of materials involved, soils derived from transported parent materials are commonly more fertile than soils from parent materials derived in place. Whatever the parent material, whether derived in place from bedrock or from transported material, it ultimately comes from geological materials, such as igneous, sedimentary, and metamorphic rocks, and the composition of the rocks largely determines the chemical composition of the soil.

Climate is most influential in determining the nature and intensity of weathering and the type of vegetation that further affects soil formation. The soil material experiences daily and seasonal variations in heating and cooling. Open surfaces exposed to thermal radiation undergo the greatest daily fluctuations in heating and cooling, soils covered with vegetation the least. Hill slopes facing the sun absorb more heat than those facing away from the sun. Radiant energy has a pronounced effect on the moisture regime, especially the evaporative process and dryness. Temperature can stimulate or inhibit biogeochemical reactions in soil material.

Water is involved in all biogeochemical reactions in the soil because it is the carrier of the acids that influence the weathering process. Water enters the soil material as a liquid and leaves it as a liquid by percolation (the slow movement of water through the soil’s pores) and as a gas through evaporation. The water regime—the water flow over a given time—in soil material is sporadic, and in many parts of the Earth is highly seasonal. Water that enters the soil during heavy rainfall and snowmelt moves down through the soil. As it moves, it leaves behind suspended material and may carry away mineral matter in solution, a process called leaching. On sloping land, water distributes material laterally (sideways) through the soil.

Topography is a major factor in soil development. More water runs off and less enters the soil on steep slopes than on relatively level land. Water draining from slopes enters the soil on low and flat land. Thus soils and soil material tend to be dry on slopes and moist on wet on the low land. Steep slopes are subject to surface erosion and soil creep—the downslope movement of soil material, which accumulates on lower slopes and lowlands.

Vegetation, animals, bacteria, and fungi all contribute to the formation of soil. Vegetation, in particular, is responsible for organic material in the soil and influences its nutrient content. For example, forests store most of their organic matter on the surface, whereas in grasslands most of the organic matter added to the soil comes from the deep fibrous root systems. Organic acids produced by vegetation accelerate the weathering process.

The weathering of rock material and the accumulation, decomposition, and mineralization or organic material require considerable time. Well-developed soils in equilibrium with weathering, erosion, and biotic influences may require 2,000 to 20,000 years for their formation, but soil differentiation from parent material may take place in as short a time as 30 years. Certain acid soils in humid regions develop in 2,000 years because the leaching process is speeded by acidic materials. Parent materials heavy in texture require a much longer time to develop into soils because of an impeded downward flow of water. Soils develop more slowly in dry regions than in humid ones. Soils on steep slopes often remain poorly developed regardless of geological age because rapid erosion removes soil nearly as fast as it is formed. Floodplain soils age little through time because of the continuous accumulation of new materials. Such soils are not deeply weathered and are more fertile than geologically old soils because they have not been exposed to the leaching process as long. The latter soils tend to be infertile because of long-time leaching of nutrients without replacement from fresh material.

土壤形成是一个发生在不同环境中的动态过程。母体材料，气候（主要是植被，温度和水分交换），地形（高程，洼地，斜坡的方向和角度以及景观的其他表面特征）以及时间高度影响着它。 ◆母体材料是发生土壤形成的所需的松散块体。这种材料可能是，也可能不是来源于它所在的现场地质基质或基岩。母体材料可以通过风，水，冰川和重力运输并沉积在基岩上。由于所涉及材料的多样性，来源于运输母体材料的土壤通常比来源于母体材料的土壤更肥沃。无论是母体材料，基岩还是运输材料，根本上都是来自地质材料，如火成岩，沉积岩和变质岩，而岩石的组成极大地决定着土壤的化学组成。 气候对决定风化的性质和强度以及进一步影响土壤形成的植被类型影响最大。土壤材料在加热和冷却中经历日常和季节变化。暴露于热辐射下的开放表面在加热和冷却过程中受影响程度最大，而植被覆盖的土壤最少。面向太阳的山坡比远离太阳的山坡吸收更多的阳光热量。辐射能量对湿度状况有显着影响，尤其是蒸发过程和干燥过程。温度可以刺激或抑制土壤物质中的生物地球化学反应。 水参与了土壤中的所有生物地球化学反应，因为它是影响风化过程的酸的载体。水以液体的形式进入土壤材料，并作为液体通过渗滤（水缓慢地移动通过土壤的孔隙）留走以及通过蒸发成为气体消失。土壤物质中的水分状况——就是一定时间内的水流量，是不确定的，在地球的许多地方都有很强的季节性。在强降雨和融雪期间进入土壤的水通过土壤向下移动。当其移动时，会留下悬浮物质，并可能带走溶液中的矿物质，这个过程称为浸出。在倾斜的土地上，水分通过土壤横向（横向）散开。 地形是土壤发育的主要因素。相比较相对平坦的土地上，陡峭的山坡上流出的水更多，进入土壤的更少。水从斜坡排出进入低而平的土壤。因此，土壤和土壤材在斜坡上更加干燥而在低地中更加湿润。地表侵蚀和土壤蠕变影响着陡坡-土壤物质的下坡运动，积聚在较低的斜坡和低地。 植被，动物，细菌和真菌都有助于土壤的形成。尤其是植被，它是土壤中的有机物质，并影响其营养成分。例如，森林将大部分有机物储存在地表上，而在草地中，添加到土壤中的大部分有机物来自深层根系。植被产生的有机酸加速了风化过程。 岩石材料或有机材料的风化以及积聚，分解和矿化需要相当长的时间。与风化，侵蚀和生物影响平衡的发达土壤可能需要2000到20000年的时间才能形成，但与母质的土壤分化可能在30年的短时间内就能发生。潮湿地区的某些酸性土壤在2000年内发展，因为浸出过程由酸性物质加速。由于阻碍了水的向下流动，母体材料质地又较重，需要更长的时间才能发展为土壤。干旱地区的土壤发育速度比湿润地区慢。而无论地质年龄如何，陡坡上的土壤仍然往往发育不良，因为侵高速的蚀使土壤几乎与其形成的速度一样快。泛滥平原的土壤由于新材料的不断积累而保持年轻。这些土壤没有深度风化，并且比地质老土壤更肥沃，因为它们没有长时间暴露于浸出过程。后者的土壤由于长期浸出营养物质，并且没有新鲜物质取代，往往是贫瘠的，不育的。