Soil matter, water-holding capacity

The soil is involved with all the essential elements. Most are present as ions in the soil solution and flow into the plant as it absorbs water. Plants obtain hydrogen, carbon, and oxygen from water and air, but soils provide water-holding capacity, provide pore space for O2 and CO2 movement between plant roots and the atmosphere, and supply CO2 to the atmosphere through the decay of organic matter by soil microorganisms. 

At the boundary between uplands and wetlands there is, in some circumstances, an interaction between organic matter accumulation in sediments and the development of wetland conditions. Some level of organic matter accumulation is required to drive anaerobic metabolism. But also, because, in general, well-decomposed organic matter improves the water holding capacity of mineral soils, particularly in medium to coarse texmred sediments, and particularly if the clay mineralogy is dominated by low activity kaolinitic clays, there is a feedback between organic matter accumulation and the extent and duration of water saturation. 

Soil Dry Matter Content and Water-Holding Capacity.253... 

Organic matter also plays an important role in water-holding capacity, neutralizing acidity and enhancing workability of tropical soils. 

The calibrated adsorption partition coefficient was 0.50 in the top 15-cm zone for North Carolina, and 1.00 in the top 15-cm zone in Wisconsin. These are higher than would be calculated based upon the koc aldicarb and the soil organic matter of these field sites, and higher than has been used in published aldicarb modeling exercises. However, the observed data of these and other aldicarb field studies indicate that aldicarb, in fact, does stay near the surface more than would be surmised based on a calculated partition coefficient. The reasons for this are unclear, but four possible explanations were offered 1) Top soil water percolation is overestimated due either to an underestimation of water holding capacity of the soil or an underestimation of surface runoff. 

Humus also absorbs large quantities of water. The fully synthesized humus of a mineral soil contains as much as 80 to 90% water by weight. Additionally, micropores within larger soil aggregates hold available water for plants. This increase in plant-available water-holding capacity is a major benefit of organic matter additions to sandy soils. 

Peat or muck is used in mixture with soil for the following chief reasons (1) improvement of the physical conditions (tilth) (2) increasing the water-holding capacity (3) as a humus and nutrient source and (4) to provide a better rooting medium. The benefits to be derived from the use of such a material depend very much on the properties of the soil, especially on its texture and natural supply of organic matter. Usually the greatest benefits follow the addition of peats to very sandy soils and to very impervious clays the least benefits are realized from use in mixture with loams that are already well-suppUed with organic matter. 

More information is needed to determine the impact that increased utilization will have on site quality such as soil organic matter content, water holding capacity and fertility levels. (53) It appears that the more intensive the harvest, the greater the opportunity for soil deterioration. The increased... 

Soil texture, structure and organic matter content give soil a certain water-holding capacity which has a strong influence on the selection of microorganisms humidity promotes the formation of bacterial colonies whereas dryness promotes fungal... 

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