MOULD

A mycelial micro-fungus or a visible growth of such a fungus is called mould. A blue mould or a green mould is caused by Penicillium spp., a grey mould by Botrytis cinenu, a sooty mould by one of the members of family Capnodiaceae
The term is, however, sometimes used incorrectly for the growth of Cludosponzun spp. and other fungi giving black powdery appearance on foliage.
Movement of fertilizer
The relative mobility of a nutrient in soil is of prime importance. N, S, B and Cl are considered to be mobile in soils.
Nitrogen is mobile in soil but can easily be lost from the root zone. Phosphorus is considered relatively immobile in soils. It is subjected to a number of reactions and transformations that can reduce its availability to plants. Placement techniques of phosphorus-containing fertilizers can minimize the effects of these transformations, enhancing the phosphorus availability. Nutrients reach the roots by mass flow, by diffusion and/or by the root interception.
The movement of soluble fertilizer salts from the point of application differs from one salt to another. Soil properties and climatic conditions influence the movement. The movement of phosphorus is generally limited since the H₂PO₄⁺ ion is only slightly mobile in soil. The nitrate ion moves more readily than nitrogen in the ammonium ion (NH₄⁺) form. Potassium is also relatively immobile because, like ammonium, it is adsorbed on the soil colloidal complex. As the soil dries out, the soil water moves upward and deposits salts on the surface. The soluble salts move downward with rains.
Soluble salts in excessive concentration can be injurious to plant roots and germinating seeds. This occurs through plasmolysis, which is the contraction and leakage of the protoplast of a plant cell consequent upon the loss of water from the cell. Plasmolysis results in a limited moisture availability or actual toxicity, known as fertilizer burn. Free ammonia, urea, DAP, ammonium carbonate [(NH₄)₂CO₃] and ammonium hydroxide (NH₄OH) may cause more damage than MAP, ammonium sulphate [(NH₄)₂SO₄] and ammonium nitrate (NH₄NO₃).
Broadcast application or fertilizer placement is effective in avoiding salt injury. Potential problems related to fertilizer salts are the greatest in coarsetextured soils.