Advantages of fertilizers over Manures
Chemical fertilizers have many advantages over the manures as given under:
1. Chemical fertilizers have smaller bulk and hence are easy to store, transport and apply.
2. Chemical fertilizers are nutrient specific. Thus for supplying a particular nutrient we can select some specific chemical fertilizer. For example, super phosphate is used in case the soil is deficient in phosphorus.
3. Chemical fertilizers are soluble in water and hence are easily absorbed by plants.
Disadvantages of Fertilizers over Manures
Chemical fertilizers when used in proper amounts promote the growth of plants and boost the crop yield. However, the excessive use of fertilizers has many serious disadvantages. Some of these are discussed below:
- The excessive use of nitrogenous fertilizers concentrates nitrates in the soil and water. Nitrate rich water is unfit for drinking, and is rather difficult to treat. When nitrate rich water is carried off into surface water bodies such as ponds, rivers and lakes it proliferates (accelerates) the growth of alga. These algae consume dissolved oxygen from water and thus deplete the water of its oxygen content leading to the death of useful aquatic life such as fish. Such an increase in the growth of algae in the lakes, ponds etc. resulting in the reduction of oxygen content in water is called EUTROPHICATION. Eutrophication thus destroys the life supporting environment in lakes and ponds.
- Excessive use of fertilizers over a long period may affect the alkalinity or acidity of the soil and may adversely affect the crop production.