Fertilizers are organic or inorganic materials of natural or synthetic origin which is added to the soil to supply certain elements required for growth of plants. Manures may be defined as plants and animal materials added to the soil to improve its fertility. Examples of fertilizer are urea, NPK etc. while examples of manures are farm yard manure, compost manure and green manure.
Just like nature, where everything has protocol to be followed for every operations, so also the application of manure or fertilizer has its own methods. Applying fertilizer or manure may look easy but technical. There are various methods of apply fertilizer or manure to plants, these methods will be discussed below;
1. Broadcasting : This is the easiest method of applying fertilizer or manure. The fertilizer or manure is evenly spread on the farm and is immediately incorporated to the soil. In case of manure, the depth to which it should be buried depends on the type of soil and climate. Under dry condition, placement should be deep enough to avoid loss through volatilization . Shallow placement is advised under wet conditions and in heavy soil. On sandy soil, because of maximum aeration, decomposition, volatilization and leaching are rapid, deep placement is advised. Broadcasting is necessary to ensure an even distribution of fertilizer or manure. Broadcasting fertilizers needs a lot of caution because most fertilizer are hygroscopic in nature and are of relatively smaller sizes, because if a particle of fertilizer drops one the leaves of plant, it will scorch the plant and turns the leaves yellow. However it is advised to broadcast fertilizer before wetting so that the water will wash down the fertilizer if it accidentally falls on the leaves.
2. Row application: this places the fertilizer or manure within the immediate reach of the root hairs of the crops. The fertilizer or manure is placed in between the space between two plants. This method is very suitable but can only be used on small garden because of lack of adequate machinery to handle it.
3. Top dressing: This is the method used when the crop are already growing. Manure applied in this way tends to loose much of its nutrient through leaching and volatilization. But it serves a more useful purpose as a mulch material by conserving moisture and controlling erosion. The manures are made to spread on the surface of the soil.
4. Ring method: This is applicable to both fertilizer and manure. To do this, a hole is made round the root of the plant at a radius of 4-8cm, the fertilizer or manure is inserted inside this hole and covered. The nutrient is released in the soil and the plant traps it through the root hairs.
5. Basal placement: This is the application of fertilizer or manure during sowing, the fertilizer or manure is placed together with the seeds.