The choice of method and time of fertilizer application depends on the form and amount of fertilizer, convenience of the farmer, the efficiency and safety of fertilizer application.
I. Solid Form
1. Broadcasting – The manures and fertilizers are scattered uniformly over the field before planting the crop and are incorporated by tilling or cultivating.
2. Drilling and placement – Fertilizers are placed in the soil furrows formed at the desired depth. Placement can be done by the following ways.
(i) Plough sole placement – In this method of fertilizers are applied or dropped in the plough sole, which will be covered by the plough during the opening of adjacent furrow.
(ii) Deep placement – Fertilizers or manures are placed at the bottom of the top soil at a depth of 10-12 cm, especially in the puddle rice soil.
(iii) Sub soil application – Fertilizers are applied in the subsoil especially for tree crops and orchard crops at a depth above 15 cm.
3. Location or spot application – Fertilizers are placed in the root zone or the spot near the roots from which roots can absorb easily.
(i) Contact of drill placement – Fertilizers or manures are placed at the time of drilling for placing the seeds. Fertilizers or manures will have good contact with the seeds or seedlings.
(ii) Band placement – This is the placement of manures or fertilizers or both in bands on the side or both sides of the row at about 5 cm away from the seed or plant in any direction. Such band placement is of three types.
(a) Hill placement – In widely spaced crops, like cotton, castor, cucurbits fertilizers or manures are applied on both sides of plants only but not continuously along the row.
(b) Row placement – In widely spaced crops between rows (Example–Sugarcane, maize, tobacco, potato) manures or fertilizers are placed on one or both sides of the row in continuous bands.
(c) Circular placement – Application of manures and fertilizers around the hill or the trunk of fruit tree crops in the active root zone.
(iii) Pocket placement – Application of fertilizers deep in soil to increase its efficiency Especially for the sugarcane pocket placement is done. Fertilizers are put in 2 to 3 pockets opened around every hill by means of a sharp stick.
(iv) Side dressing – It refers to hill and ring placement of manures or fertilizers. It consists of spreading the fertilizer between the rows or around the plants.
(v) Pellet application – Nitrogen fertilizers are pelleted like mud ball or urea super granules (USG) and placed deep (10 cm) into the saturated soils (reduced zone) of wet land rice to avoid nitrogen loss from applied fertilizers.
Generally placement of fertilizer is done for three reasons.
• Efficient use of plant nutrients from plant emergence to maturity.
• To avoid the fixation of phosphate in acid soils.
• Convenience to the grower.
II. Liquid form
Foliar application: It refers to spraying of fertilizer solution on the foliage of plants for quick recovery from the deficiency (either N or S).
Fertigation: It is the application of fertilizer dissolved in irrigation water in either open or closed system i.e., lined or unlined open ditches and sprinkler or trickle systems respectively.
Starter solutions: They are solutions of fertilizers prepared in low concentrations which are used for soaking seeds, dipping roots, spraying on seedlings etc., nutrient deficient areas for early establishment and growth.
Direct application to the soil: Liquid fertilizers like anhydrous ammonia are applied directly to the soil with special injecting equipments. Liquid manures such as urine, sewage water and cattle shed washing are directly let into the field.
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