| Which of the statements given below are correct with respect to fertilizers? |
| I. Fertilizer-organic or inorganic material containing one or more of the nutrients-mainly nitrogen, phosphorus, and potassium, and other essential elements are required for plant growth. |
| II. Added to the soil or other medium, fertilizers provide plants, nutrients that are naturally lacking or that have been removed by harvesting or grazing, or by physical processes such as leaching or erosion. |
| III. Organic fertilizers include animal and green manure, fish and bone meal, and compost. |
| IV. Micro-organisms in the soil decompose organic material, making its elements available for use by plants. |
| V. Inorganic or artificial fertilizers (also called chemical or mineral fertilizers) are formulated in appropriate concentrations and combinations for various crops and growing conditions. |
A) I, II, III and V
B) II, III and V
C) I and V only
D) All the above
Correct Answer: D
Solution :
In order for a plant to grow and thrive, it needs a number of different chemical elements. The most important are: 1. Carbon, hydrogen and oxygen - Available from air and water and therefore in plentiful supply. 2. Nitrogen, phosphorus, potassium (a.k.a. potash) - The three macronutrients and the three elements you find in most packaged fertilizers. 3. Sulfur, calcium, and magnesium Secondary nutrients 4. Boron, cobalt, copper, iron, manganese, molybdenum and zinc - Micronutrients The most important of these (the ones that are needed in the largest quantity by a plant) are nitrogen, phosphorus and potassium. Without nitrogen, phosphorus and potassium, the plant simply cannot grow because it cannot make the pieces it needs. It's like a car factory running out of steel or a road crew running out of asphalt. In nature, the nitrogen, phosphorous and potassium often come from the decay of plants that have died. In the case of nitrogen, the recycling of nitrogen from dead to living plants is often the only source of nitrogen in the soil. Most fertilizers supply just nitrogen, phosphorus and potassium because the other chemicals are needed in much lower quantities and are generally available in most soils. Nitrogen, phosphorus and potassium availability is the big limit to growth.
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