www.sare.org publications building-soils-for-better-crops-3 organic-matter-distribution-in-soil Organic Matter Distribution in Soil With Depth in the Soil In general, more organic matter is present near the surface than deeper in the soil (see figure 3.5). This is one of the main reasons that topsoils are more productive than subsoils exposed by erosion or mechanical removal of surface soil layers. Some of the plant residues that eventually become […]
www.sare.org publications building-soils-for-better-crops-3 human-influences Human Influences Loss of topsoil that is rich in organic matter by erosion has dramatically reduced the total amount of organic matter stored in many soils after they were developed for agriculture. Crop production obviously suffers when part of the most fertile layer of the soil is removed. Erosion is a natural process and occurs on almost […]
www.sare.org publications building-soils-for-better-crops-3 natural-factors Natural Factors Temperature In the United States, it is easy to see how temperature affects soil organic matter levels. Traveling from north to south, higher average temperatures lead to less soil organic matter. As the climate gets warmer, two things tend to happen (as long as rainfall is sufficient): More vegetation is produced because the growing season […]
www.sare.org publications building-soils-for-better-crops-3 summary-and-sources Summary and Sources Summary Soil organic matter is the key to building and maintaining healthy soils because it has such great positive influences on essentially all soil properties—helping to grow healthier plants. It also plays a critical role in the water, nitrogen, and carbon cycles. Organic matter consists mainly of the living organisms in the soil (“the living”), […]
www.sare.org publications building-soils-for-better-crops-3 organic-matter-and-natural-cycles Organic Matter and Natural Cycles The Carbon Cycle Soil organic matter plays a significant part in a number of global cycles. People have become more interested in the carbon cycle because the buildup of carbon dioxide in the atmosphere is thought to cause global warming. Carbon dioxide is also released to the atmosphere when fuels, such as gas, oil, and […]
www.sare.org publications building-soils-for-better-crops-3 why-soil-organic-matter-is-so-important Why Soil Organic Matter Is So Important A fertile and healthy soil is the basis for healthy plants, animals, and humans. And soil organic matter is the very foundation for healthy and productive soils. Understanding the role of organic matter in maintaining a healthy soil is essential for developing ecologically sound agricultural practices. But how can organic matter, which only makes up […]
www.sare.org publications building-soils-for-better-crops-3 a-larger-view A Larger View In this book we discuss the ecological management of soils. And although the same basic principles discussed here apply to all soils around the world, the problems may differ in specifics and intensity and different mixes of solutions may be needed on any particular farm or in any ecological zone. It is estimated that close […]
www.sare.org publications building-soils-for-better-crops-3 how-do-you-build-a-healthy-high-quality-soil How Do You Build a Healthy, High-Quality Soil? Some characteristics of healthy soils are relatively easy to achieve—for example, an application of limestone will make a soil less acid and increase the availability of many nutrients to plants. But what if the soil is only a few inches deep? In that case, there is little that can be done within economic reason, except […]
www.sare.org publications building-soils-for-better-crops-3 how-do-soils-become-degraded How Do Soils Become Degraded? Although we want to emphasize healthy, high-quality soils because of their ability to produce high yields of crops, it is also crucial to recognize that many soils in the U.S. and around the world have become degraded— they have become what many used to call “worn-out” soils. Degradation most commonly occurs when erosion and decreased […]
www.sare.org publications building-soils-for-better-crops-3 the-nature-and-nurture-of-soils The Nature and Nurture of Soils Some soils are exceptionally good for growing crops, and others are inherently unsuitable; most are in between. Many soils also have limitations, such as low organic matter content, texture extremes (coarse sand or heavy clay), poor drainage, or layers that restrict root growth. Iowa’s loess-derived prairie soils are naturally blessed with a combination of silt […]