Fertilizers & Manures

Fertilizer

fertilizer or fertiliser (in British English) is any material of natural or synthetic origin (other than liming materials) that is applied to soils or to plant tissues (usually leaves) to supply one or more plant nutrients essential to the growth of plants. This also depends on its soil fertility

Fertilisers enhance the growth of plants. This goal is met in two ways, the traditional one being additives that provide nutrients. The second mode by which some fertilisers act is to enhance the effectiveness of the soil by modifying its water retention and aeration.

Manure

Manure is organic matter, mostly derived from animal faces except in the case of green manure, which can be used as organic fertilizer in agriculture. Manures contribute to the fertility of the soil by adding organic matter and nutrients, such as nitrogen, that are trapped by bacteria in the soil. Higher organisms then feed on the fungi and bacteria in a chain of life that comprises the soil food web. It is also a product obtained after decomposition of organic matter like cow dung which replenishes the soil with essential elements and add humus to the soil.

Plants need nutrients for healthy growth. These nutrients are available to plants through water-soluble minerals from the ground. If these nutrients deplete from the soil, they can be supplemented by applying organic manures like farmyard manure, green manure, leaf mould, oil cake, earth worm compost, fish / bone meal, sheep droppings and poultry litter. Alternatively the nutrients can be supplied to plants by applying inorganic fertilizers, which are also called as chemical fertilizers. The nutrients are divided in two groups, namely – macro nutrients and micro nutrients. The plants need macro nutrients in larger quantity than the micro nutrients. Macro nutrients are nitrogen, phosphorus and potassium (N = nitrogen, P = phosphorus, K = potassium). Calcium, magnesium, iron, and sulphur are micro nutrients. There are some other nutrients, which are needed by plants in very minute quantities. Such nutrients are called as ‘Trace elements’. Zinc, manganese, copper and boron are the trace elements.

Organic Manures : Organic manures not only supply nutrients to plants but also help in aeration of soil. They help excess water to drain out fast, but at the same time help to retain the moisture in the soil. By using the organic manures soil remains friable and thus encourages growth of hair roots. Organic manures are not water soluble; thus, the plants can not use these by themselves. Certain bacteria work upon these organic manures and gradually turn them to water soluble minerals. As this conversion process is slow and prolonged, the organic manures once applied will continue to provide nutrients to plants for quite some time.

Chemical Fertilizers : Chemical fertilizers are water soluble minerals. So, as soon as they are applied to plants and water given, they dissolve in water and are absorbed by the plants. Thus, a slight overdose of a chemical fertilizer could damage the plant or may even kill it. Due to their water solubility, the chemical fertilizers are easily washed out of soil. This too makes them unavailable to plants. When used with caution and along with organic manures, chemical fertilizers can give good results.

Symptoms of Nitrogen Deficiency (Chlorosis) : Nitrogen encourages growth of chlorophyll and proteins. This helps plants to produce more food. Due to nitrogen deficiency plants get stunted, leaves turn yellowish. Normally lower leaves turn yellow first.