Fertilizer Classification by SaAm1
Table 1 - Fertilizers
Manures
Manures are organic materials added to the soil to increase crop production. They are biological in origin. The organic matter content is bulky and large and the nutrient content is small. They have the following effect on the soil.- They supply nutrients to the soil. Since the manures contain nutrients in small quantities they have to be used in bulk.
- Since the manure contains a lot of organic matter, it increases the water holding capacity in sandy soils and drainage in clayey soils.
- Organic manures provide food for soil organisms like earthworms which are responsible for improving soil quality.
Farmyard manure (FYM)
This is the decomposed mixture of excreta (dung) and urine of farm animals like cow, horse, goat and sheep along with leftover hay and fodder. They are readymade manures and contain nitrogen, phosphorus and potassium. Farmyard manure when collected in the field and stored in an exposed condition over a long period shows considerable loss of ammonia which is a loss of fertilizing value. To prevent this loss the dung is stored in pits which are about a metre deep. When the pits are filled to the top, the surface is sealed with mud slurry. The manure is ready for use in about 4-5 months. Microbes play an important role in decomposing the dung and converting it into manure.
Compost
This consists of a variety of farm wastes such as farm weeds, straw, sugarcane refuse, rotting vegetables, kitchen wastes, crop stubble, groundnut and rice husk. Composting is a biological process in which aerobic and anaerobic microorganisms decompose organic matter. A trench of suitable size 4-5 m long, 1.5 to 1.8 m broad and 1.0 to 1.8 m deep is dug. A layer of well mixed refuse of about 30 cm thickness is spread in the pit. A slurry of cow dung, earth and water is poured over this layer to keep it moist. Another layer of the mixed refuse is spread in the pit till the heap rises to a height of 45 to 60 cm above ground level. Finally the top is covered with a thin layer of mud. Three months later of decomposition the layers are well mixed and covered again. After three months the compost is ready to be used in the fields.
Table 2. Nutrient content of farm and town compost
| Compost | N | P2O5 | K2O |
| Farm Compost | 0.5% | 0.15% | 0.5% |
| Town Refuse | 1.4% | 1.0% | 1.4% |
Green manure
Green manuring is the practice of growing and ploughing in, the green crops, into the soil. It is a cheap and effective method that increases soil fertility as it can supplement farmyard and other organic manures and is more cost effective. Green manures add nitrogen and organic matter to the soil for improving crop productivity. They also improve soil aeration and drainage conditions. Both leguminous and non-leguminous plants are grown for making green manure. The following is a list of plants used as green manure.
Table 3. Plants used as green manure
| English and Hindi names | Botanical Name |
|---|---|
| Sunn hemp (Sanai) | Crotalaria juncea |
| Lentil (Masur) | Lens esculenta |
| Egyptian clover (Berseem) | Trifolium alexandrium |
| Sesbania (Dhaincha) | Sesbania aculeata |
| Cluster bean (Gaur ki phalli) | Cyamopris tetragonoloba |
| Cowpea (Lobiya) | Vigna sinensis |
| Horse-gram | Macrotyloma uniflorum |
| Senj | Melilotus parvifora |
This type of manuring is used in fields in which crops like rice, maize, sugarcane, cotton, wheat etc., which require high nutrient input are raised. There is 30 - 50% increase in the crop yield by using green manure.
The green manure crops are grown in the field for about 6 - 8 weeks and ploughed into the soil during the flowering stage. The plants are allowed to remain buried for about 1 - 2 months. During this period, the plant gets totally decomposed. The soil is then tilled and the next food crop is sowed. By alternating the green manure crop with food crop the nitrogen and organic content of the soil is maintained.
Vermicompost
Vermicompost is a type of soil made by earthworms and microorganisms as they eat through organic wastes. The soil thus produced is mainly worm excreta and finely ground soil. Organic wastes can be collected and fed on by worms so that the end product is the broken down version of the original organic wastes. Worm castings (excreta) in the vermicompost have nutrients that are 97% utilizable by plants. Besides providing nutrients to plants, worms also upturn the soil thus making the soil lighter.
