Soil Carbon
Soil carbon improves the physical properties of soil. It increases the cation exchange capacity (CEC) and water-holding capacity of sandy soil and it contributes to the structural stability of clay soils by helping to bind particles into aggregates. Soil organic matter, of which carbon is a major part, holds a great proportion of nutrients, cations and trace elements that are of importance to plant growth. It prevents nutrient leaching and is integral to the organic acids that make minerals available to plants. It also buffers soil from strong changes in pH. It is widely accepted that the carbon content of soil is a major factor in its overall health.
Carbon, as it relates to the organic matter of soils, is a major component of soil and catchment health.
Fertilizer and Salinity
The frequency of applying fertilizer has a direct effect on the concentration of total salts in the soil.
Water logging causes three problems:
(1) A shallow water table and lack of oxygenation of the root zone reduces the yield of most crops.
(2) It leads to an accumulation of salts brought in with the irrigation water as their removal through the aquifer is blocked.
(3) With the upward seepage of groundwater more salts are brought into the soil and the salination is aggravated.
(2) It leads to an accumulation of salts brought in with the irrigation water as their removal through the aquifer is blocked.
(3) With the upward seepage of groundwater more salts are brought into the soil and the salination is aggravated.
Salt Index Definition (An index used to compare solubilities of chemical compounds used as fertilizers.)
Most nitrogen and potassium compounds have high indexes, and phosphorus compounds have low indexes. When applied too close to seed or on foliage, the compounds with high indexes cause plants to wilt or die. The lower the salt index, the lesser the risk of crop injury with localized placement of fertilizers.