Methods of Applying Manures
The methods of applying manures would depend on the type of manure, i.e.
i) Bulky manures and
ii) Concentrated manures.
Bulky manures like F.Y.M. should be broadcast over the entire area and mixed well with the soil by harrowing. The season of application should be such that the manure is not leached out. In heavy rainfall areas, the manures may be applied after the monsoon; whereas in light rainfall areas, manures can be monsoon.
The Concentrated Manures include organic manures such as oil cakes, blood meal etc. The nutrients in the manures are not available quickly, as they have to be broken down by the action of soil microorganisms and made available to the plant hence, these manures should be applied well in advance before they are required by the trees.
Inorganic fertilizers such as ammonium sulphate urea, super phosphate, muriate of potash etc. are referred to as artificial manures. Nitrogenous manures include ammonium sulphate, ammonium nitrate, sodium nitrate, urea, etc. Nitrogen in nitrate form is easily available to the plant but the nitrogen in ammonia form takes 10 to 15 days for becoming available to the plant. Fertilizers containing nitrogen may be applied in a round strip along the drip of the tree. A light irrigation to dissolve the fertilizer may be given.
Phosphorus, when applied to the soil, gets fixed up at the spot where it is applied even if plenty of water is present in the soil, and as such, the application of phosphorus should be made near the roots so as to make it readily available to the plant. In plants having superficial roots, phosphates may be applied in top 5 to 7.5 cm layer. In case of plants having their feeding roots deep as in mango, a trench round the drip of the branches about 15 to 25 cm deep should be dug and phosphates applied in that trench and trench filled in.
Potash, like nitrogen is readily soluble and is easily available to the plant and, as such, the method of application of potash is similar to that of nitrogen.