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  • 土壤形成

    Two contrasting soil types side by side: one light and rocky, the other dark and tilled.
     

    How are these two soils different?
    ::这两个土壤有何不同?

    What color is the  soil  on the left? What color is the soil on the right? Which soil do you think is better for growing things? And why are the two soils so different in the first place?
    ::左边的土壤是什么颜色? 右边的土壤是什么颜色? 你认为哪块土壤更适合生长? 为什么这两块土壤一开始就差别很大?

    Soil Formation
    ::土壤形成

    How well soil forms and what type of soil forms depends on several different environmental factors, including terrain,  climate , and biological activity.
    ::土壤形态和何种土壤形态取决于若干不同的环境因素,包括地形、气候和生物活动。

    Soil development takes a very long time. It may take hundreds or even thousands of years to form the fertile upper layer of soil. Soil scientists estimate that in the very best soil forming conditions, soil forms at a rate of about 1mm/ year . In poor conditions, it may take thousands of years!
    ::土壤发展需要很长的时间,形成肥沃的土壤上层可能需要数百年甚至数千年的时间。土壤科学家估计,在土壤形成的最佳条件下,土壤以每年1毫米的速度形成。在条件恶劣的情况下,可能需要数千年时间!

    Weathering
    ::气象天气

    Soil formation requires  weathering . Where there is less weathering, soils are thinner. However, soluble   may be present. Where there is intense weathering, soils may be thick. Minerals and  nutrients  would have been washed out.
    ::土壤形成需要天气。如果天气较少,土壤会变薄,但可能存在可溶解性。如果天气恶劣,土壤会变厚。矿物和养分会被冲走。

    Climate
    ::气候气候 气候

    Climate is the most important factor determining soil type. Given enough time, a climate will produce a particular type of soil. The original   type does not matter. Two rocks of the same type will form a different soil type in each different climate. This is true because most rocks on Earth are made of the same eight  elements . When the rock breaks down to become soil, the soil is the same.
    ::气候是决定土壤类型的最重要因素。 在足够长的时间里, 气候将产生一种特定的土壤类型。 原始类型并不重要。 同一类型的两块岩石将在不同的气候中形成不同的土壤类型。 因为地球上的大多数岩石都是由相同的八个元素组成的。 当岩石破裂变成土壤时, 土壤是相同的。

    The same climate factors that lead to high weathering also produce more soil.
    ::导致气候高温的同样的气候因素也产生更多的土壤。

    • More  rain  weathers minerals and rocks more. Rain allows chemical reactions especially in the top layers of the soil.
      ::雨能产生化学反应,特别是在土壤的顶层。
    • More rain can dissolve more rock. More rain can carry away more material. As material is carried away, new surfaces are exposed. This also increases the rate of weathering.
      ::更多的雨可以溶解更多的岩石。 更多的雨可以带走更多的物质。 随着材料的流失,新的表面会暴露。 这也会增加天气预报的速度 。
    • Higher temperatures increase the rate of chemical reactions. This also increases soil formation.
      ::温度升高会增加化学反应率,也会增加土壤形成。
    • In warmer regions, plants and bacteria grow faster. Plants and animals   material and produce soils. In tropical regions, where   and   are consistently high, thick soils form. Arid regions have thin soils.
      ::在较温暖的地区,植物和细菌生长更快,植物和动物材料和土壤生产,热带地区,土壤密度一直很高,土壤密度一直很高,干旱地区土壤薄。

    Soil type also influences the type of vegetation that can grow in the region. We can identify climate types by the types of plants that grow there.
    ::土壤类型还影响着该区域能够生长的植被类型,我们可以根据生长的植物类型确定气候类型。

    Parent Rock
    ::父摇滚

    The original rock is the  source  of the  inorganic  portion of the soil.   breaks rock into smaller pieces. Chemical reactions change the rock's minerals.
    ::原始岩石是土壤无机部分的来源。 将岩石碎成小块。 化学反应改变了岩石的矿物。

    Soil may form in place or from material that has been moved.
    ::土壤可以原地形成或来自已移动的材料。

    • Residual soil  forms in place. The underlying rock breaks down to form the layers of soil above it. Only about one-third of the soils in the United States are residual.
      ::土壤残余形式就位,下面的岩石碎裂成上面的土壤层,美国只有大约三分之一的土壤是残余的。
    • Transported soil  has come in from somewhere else.  Sediments  can be transported into an area by  ,  wind ,  water , or gravity. Soils form from the loose particles that have been transported and  deposited .
      ::沉积物可经由风、水或重力运入某一地区,由运输和沉积的松散颗粒形成土壤。

    Slope
    ::斜斜度

    Weathered material washes off steep slopes and so does not stay in place to form soil. Soil forms where land areas are flat or gently undulating.
    ::天气物质冲淡了陡峭的斜坡,因此不能留在原地形成土壤,土地面积平坦或平坦的土壤形态。

    Time
    ::时间 时间 时间 时间 时间 时间 时间 时间 时间

    Soils thicken as the amount of time available for weathering increases. The longer the amount of time that soil remains in a particular area, the thicker it will be.
    ::随着气候变暖可用时间的增加,土壤变厚,土壤在特定地区所剩时间越长,土壤就越厚。

    Biological Activity
    ::生物活动

    Biological activity produces the  organic  material in soil.  Humus  forms from the remains of plants and animals. It is an extremely important part of the soil. Humus coats the mineral grains. It binds them together into clumps that hold the soil together. This gives the soil its structure. Soils with high humus are better able to hold water. Soils rich with organic materials hold nutrients better and are more fertile. These soils are more easily farmed.
    ::生物活动产生土壤中的有机物质。从植物和动物的残骸中形成悍马,它是土壤中极为重要的一部分。 悍马将矿物颗粒涂上厚厚,将它们捆绑在一起,形成凝固土壤的块状体。 这使土壤结构得以形成。 高土的土壤更能保持水。 富含有机材料的土壤养分更好,更肥沃。 这些土壤更容易耕种。

    The color of soil indicates its fertility. Black or dark brown soils are rich in nitrogen and contain a high percentage of organic materials. Soils that are nitrogen poor and low in organic material might be gray, yellow, or red ( Figure ). Soil with low organic material is not good for growing plants.
    ::土壤的颜色表明其肥力,黑棕色或深褐色土壤富含氮,含有很高比例的有机材料,氮贫乏和有机材料低的土壤可能是灰色、黄色或红色(图)。有机材料低的土壤不利于植物生长。

    A barren landscape illustrating sandy soil with sparse vegetation and minimal organic material.
     
    This sandy soil shows evidence of very little organic activity. Plants grow, but are far apart and short-lived. This means that little soil can form. The soil that's there has little organic content.

    Summary
    ::摘要

    • Many factors affect soil formation. Some are climate, rock type, slope, time, and biological activity. Differences in these factors may produce different types of soil.
      ::许多因素影响土壤形成,有些是气候、岩石类型、斜坡、时间和生物活动,这些因素的差异可能产生不同类型的土壤。
    • Soil type determines what can grow in a region.
      ::土壤类型决定一个区域能够种植的是什么。
    • Humus is the decayed remains of living organisms. Humus makes soil fertile.
      ::胡穆斯是活生物体腐烂的残骸 胡穆斯使土壤肥沃

    Review
    ::回顾

    1. Why is climate more important than rock type for determining the type of soil that forms?
      ::为什么气候比岩石类型更为重要?
    1. How would you create a very thick, organic-rich soil?
      ::你会如何创造一个非常厚, 有机富饶的土壤?
    1. How would you create a very thin, sandy soil?
      ::你会如何创造一个薄薄的沙土土壤?
    1. Why is time important for soil formation?
      ::为什么时间对土壤形成很重要?

    Explore More
    ::探索更多

    Use the resource below (start at 0:50) to answer the questions that follow.
    ::使用以下资源(从0:50开始)回答下列问题。

    1. What does soil start as? What changes that material?
      ::土壤的起源是什么? 什么改变了这种物质?
    1. What is really important in creating a good soil?
      ::在创造好土壤方面,什么才是真正重要的?
    1. What makes up soil texture?
      ::什么构成土壤质地?
    1. What types of soil holds water? What type holds air?
      ::哪类土壤有水?哪类土壤有空气?
    1. What does a gardener need to do to the soil to make it better for growing plants?
      ::园丁需要怎样对土壤做才能使土壤更好地生长植物?