www.sare.org publications building-soils-for-better-crops-3 the-water-range-for-best-plant-growth The Water Range for Best Plant Growth The limitations to plant growth caused by compaction and water extremes can be combined into the concept of the optimum water range for plant growth—the range of water contents under which plant growth is not reduced by drought, mechanical stress, or lack of aeration (figure 6.12). This range, referred to by scientists as the least-limiting water […]
www.sare.org publications building-soils-for-better-crops-3 consequences-of-compaction Consequences of Compaction As compaction pushes particles closer together, the soil becomes dense and pore space is lost. Notably, the larger pores are eliminated. Loss of aggregation from compaction is particularly harmful for fine and medium-textured soils that depend on those pores for good infiltration and percolation of water, as well as air exchange with the atmosphere. Although […]
www.sare.org publications building-soils-for-better-crops-3 soil-tilth-and-compaction Soil Tilth and Compaction A soil becomes more compact, or dense, when aggregates or individual particles of soil are forced closer together. Soil compaction has various causes and different visible effects. Compaction can occur either at or near the surface (surface compaction, which includes surface crusting as well as plow layer compaction) or lower down in the soil (subsoil […]
www.sare.org publications building-soils-for-better-crops-3 sources-3 Sources Brady, N.C., and R.R. Weil. 2008. The Nature and Properties of Soils, 14th ed. Upper Saddle River, NJ: Prentice Hall. Hill, R.L. 1990. Long-term conventional and no-tillage effects on selected soil physical properties. Soil Science Society of America Journal 54: 161–166. Karunatilake, U., and H.M. van Es. 2002. Temporal and spatial changes in soil structure from […]
www.sare.org publications building-soils-for-better-crops-3 what-comes-from-the-sky-the-lifeblood-of-ecosystems What Comes from the Sky: The Lifeblood of Ecosystems We need to take a short diversion from our focus on soils and briefly discuss climate. Various characteristics of precipitation affect the potential for crop production and the losses of water, sediment, and contaminants to the environment. These include the annual amount of precipitation (for example, arid vs. humid climate); the seasonal distribution and relation […]
www.sare.org publications building-soils-for-better-crops-3 soil-water-and-aggregation Soil Water and Aggregation Processes like erosion, soil settling, and compaction are affected by soil moisture conditions, and in turn affect soil hardness and the stability of aggregates. When soil is saturated and all pores are filled with water, the soil is very soft. (Fungal hyphae and small roots also serve to form and stabilize aggregates deeper in the […]
www.sare.org publications building-soils-for-better-crops-3 infiltration-vs-runoff Infiltration vs. Runoff An important function of soil is to absorb water at the land surface, and either store it for use by plants or slowly release it to groundwater through gravitational flow (figure 5.8). When rainfall hits the ground, most water will infiltrate the soil; but some may run off the surface, and some may stand in ruts or […]
www.sare.org publications building-soils-for-better-crops-3 available-water-and-rooting Available Water and Rooting There is an additional dimension to plant-available water capacity of soils: The water in the soil may be available, but roots also need to be able to access it, along with the nutrients contained in the water. Consider the soil from the compacted surface horizon in figure 5.6 (left), which was penetrated only by a single […]
www.sare.org publications building-soils-for-better-crops-3 water-and-aeration Water and Aeration Soil pore space can be filled with either water or air, and their relative amounts change as the soil wets and dries (figures 5.1, 5.3). When all pores are filled with water, the soil is saturated, and the exchange of soil gases with atmospheric gases is very slow. During these conditions, carbon dioxide produced by respiring roots […]
www.sare.org publications building-soils-for-better-crops-3 summary-and-sources-2 Summary and Sources Soils are alive with a fantastic number of many types of organisms, most of which help to grow healthy plants and protect them from pests. The food for all the soil’s organisms originates with crop residues and organic materials added from off the field. These provide the fuel that powers the underground life that has […]