SOIL APPLICATIONS - ORGANIC SOIL CONDITIONERS
Importance of Organic Soil Conditioners
As fresh organic matter decomposes, the nutrients it contains are released in inorganic form for use by plants. A portion of the nutrients is utilized by the soil microorganisms, but when they die and decompose the nutrients are again released. Organic matter, therefore, is an important source of nutrients for growing plants, especially those which would otherwise be leached from the soil. Decomposing organic matter supplies most of the nitrogen and sulfur, about half of the phosphorus, and appreciable amounts of the other plant nutrients. In addition, organic acids released during decomposition of organic matter help to release nutrients from the mineral portion of the soil.
As organic matter decomposes, it becomes chemically altered. This change gives it a negative electrical charge that attracts and holds inorganic elements such as potassium, calcium, magnesium, and several of micronutrients in forms that make them readily available to growing plants. Rain cannot easily wash away elements 'held' by organic matter. Organic matter helps improve the physical condition of clay soils. Microorganisms secrete sticky glue- like materials which bind individual microscopic clay particles into larger, more stable clumps, called aggregates. These aggregates do not break down easily when wet or when the soil is tilled, and they resist compaction. Pore size is small within aggregates, enabling them to retain moisture. Spaces between aggregates are larger, thus improving infiltralion, drainage, and aeration. Such a soil is said to have good structure. Roots develop better in a well- structured soil.
Organic matter increases the moisture holding capacity of soil because organic particles absorb water like a sponge. Plants can use some of this water - an important consideration for sandy soils. In short, organic matter improves nutrient supplying power of the soil, soil structure, and moisture holding capacity.