How Do Manure and Fertilisers Improve Soil Fertility?
The only organic fertiliser that is free of synthetic chemicals is manure. Animal dung and fragments of decomposing plants are used to create manure. As a result, it is abundant in potassium, phosphorus, nitrogen, and other nutrients. Due to all these nutrients are necessary for plant growth, employing dung as fertiliser in fields gives crops all the growth ingredients they need.
Additionally, different kinds of bacteria found in manure increase the organic content of the soil, increasing its fertility. It is also reported to provide humus to the soil. The freshly prepared manure is more effective than the composted manure. One of the limitations of manure is as it is prepared in the field, they are difficult to store and transport.
The fertilisers, on the other hand, are mostly chemical in nature, are prepared in factories and are easily stored and transported. Bio fertilisers are a feasible and sustainable alternative to chemical fertilisers, and it is used to increase crop yield and also improve soil fertility, promoting the growth of plants.
What are Manure and Fertilisers?
To boost crop output, dead plants and animals are introduced to the soil on agricultural land as their carcasses decay. The decomposing bodies are a very affordable and natural source of fertiliser. Along with livestock dung, which is rich in nitrogen, phosphate, and potassium as well as other crucial minerals that improve the condition of the soil, farmers also employ human and animal excrement as manure.
A fertiliser is a substance that can be natural or artificial, are applied to soil or plant tissues to provide plant nutrients. Both naturally occurring and artificial sources of fertiliser are available. The three main macronutrients, nitrogen (N), phosphorus (P), and potassium (K), serve as the foundation for modern agricultural techniques. These fertilisers are applied by farmers using a variety of techniques, including hand tools, large agricultural equipment, and liquid, dry, and pelletised application processes.
Advantages of Fertilisers
Adding fertilisers to the soil helps replenish the nutrients lost by crops in the soil, which would otherwise hamper crop yield.
The main advantages include-
Mineral fertilisers help in escalating the level of nutrients and minerals in the soil absorbed and utilised by plants without any difficulty.
The fertilisers are inorganic substances that do not provide humus to the soil but are rich in plant nutrients. Fertilisers are loaded with soil nutrients like nitrogen, phosphorous, and potassium.
Fertilisers are used to improve the quality of our food and increase crop yield, it is also reported to balance the nutrients.
Fertilisers are easily absorbed by plants.
Disadvantages of Manure
Manure is an organic substance obtained naturally by decomposing plant and animal wastes. The process of decomposition is done majorly by microbes and earthworms. The manures are reported to provide fewer nutrients to plants, and they are unable to provide high-yielding crops. Manures are slowly absorbed by the plants, and they add a lot of humus to the soil. They are made in fields, so transportation is difficult for manures. Manures can be obtained from different sources.
Manure example includes cow dung, wastes from human such as human urine, sludge, sewage, and domestic waste. The droppings of goats and sheep are also considered good manure. Some by-products of agricultural industries and crop wastes can also serve as manures.
Examples of Manure and Fertilisers
The most popular examples of fertilisers include:
Micronutrient fertilisers are present in the tissues of plants and are absorbed in lesser quantities. The micronutrients are required as cofactors for enzymes that are essential for the metabolism of plants. Examples include boron, zinc, molybdenum, iron, and manganese.
Nitrogen Fertilisers are prepared from ammonia that is produced by the Haber-Bosch process. Ammonia is needed as feedstock by all nitrogen fertilisers, such as anhydrous ammonium nitrate and urea.
Phosphate rock, which contains the phosphorus-containing minerals fluorapatite and hydroxyapatite, is used to make phosphate fertilisers. These minerals become water-soluble phosphate salts after being treated with sulfuric or phosphoric acids.
Potash is a mixture of potassium minerals used to produce potassium fertilisers. Due to its water-soluble nature, extraction of this nutrient requires several stages of purification. Examples include potassium chloride, potassium sulfate, and potassium nitrate.
Bio fertilisers are reported to supply nutrients to plants through the process of nitrogen fixation and phosphorus solubilisation. Bio fertilisers use microorganisms to reinstate the soil's natural nutrient cycle.
Popular examples of manure include animal poop, cattle dung, and the dropping of goats. Other examples are urine and waste obtained from the slaughterhouses, such as bones, meat and fish waste.
Application of Manure and Fertiliser
One or more of the important elements, such as nitrogen, phosphorus, potassium, calcium, magnesium, etc., are present in manures and fertilisers. They are sprayed on the soil to promote crop development. The amount of manures and fertilisers to be added is determined by analysing the soil or plants. Applying manure to cropland can help maintain or increase the levels of soil organic matter, improve soil tilth, soil structure, water infiltration, nutrient and water holding capacity, and reduce soil erosion.
An appropriate amount of fertiliser is applied equally throughout the garden and thoroughly incorporated into the soil to a depth of 3 to 4 inches. This approach typically works best for backyard gardeners since it poses the lowest risk of causing plant damage.
Interesting Facts
The planet could barely feed around half of its population without fertilisers. Crop yields can be doubled with modern fertilisers. For instance, the same land can yield twice as much food when fertilisers are used.
Key Features
Manure contains nitrogen, phosphorus, and other nutrients required for the growth and development of plants. Money can be saved by the farmers if manures are used instead of fertiliser.
Bio fertilisers make atmospheric nitrogen available to plants by fixing it in the soil and root nodules of legume crops.
Bio fertilisers convert phosphates, including tricalcium, iron, and aluminium phosphates that are insoluble into soluble forms.
FAQs on Adding Manure and Fertilisers: Complete Guide for Students
1. Why do farmers add manure and fertilisers to their fields?
Farmers add manure and fertilisers to replenish essential nutrients in the soil. Continuous farming depletes nutrients like nitrogen, phosphorus, and potassium, which are vital for healthy plant growth. Adding these substances, a process called manuring, ensures that the crops receive adequate nutrition for a better yield.
2. What are the primary nutrients supplied by chemical fertilisers?
Chemical fertilisers are designed to provide specific, concentrated nutrients to plants. The three primary nutrients are:
- Nitrogen (N): Essential for leaf growth and giving plants their green colour.
- Phosphorus (P): Crucial for root development, flower, and seed formation.
- Potassium (K): Helps in the overall functioning of the plant, including water regulation and disease resistance.
These are often referred to as NPK fertilisers.
3. What is the fundamental difference between manure and fertilisers?
The fundamental difference lies in their origin and composition. Manure is an organic substance obtained from the decomposition of animal and plant waste. It provides humus and improves soil texture but is less rich in specific nutrients. Fertilisers are inorganic, commercially produced chemicals that are rich in specific nutrients like NPK but do not add humus to the soil.
4. What are the common methods for applying fertilisers to crops?
The main methods for applying fertilisers include:
- Broadcasting: Spreading the fertiliser uniformly over the entire field, either by hand or with a machine.
- Drilling: Placing the fertiliser in the soil near the seeds during sowing.
- Foliar Spraying: Dissolving fertilisers in water and spraying them directly onto the leaves of the plants.
5. Is manure always better than fertiliser for crop production? Explain the trade-offs.
Not necessarily; the choice depends on the goal. Manure is considered better for long-term soil health because it adds organic matter (humus), improves soil structure, and increases water-holding capacity. However, it is bulky and releases nutrients slowly. Fertilisers are better for immediate, targeted nutrient supply as they are nutrient-specific and act quickly to correct deficiencies, leading to faster growth. The trade-off is that overuse of fertilisers can harm soil microbes and cause water pollution.
6. What is green manure and how does it contribute to soil health?
Green manure refers to fast-growing crops, often legumes like sunn hemp or guar, that are grown and then ploughed back into the soil while they are still green. They contribute to soil health by decomposing directly in the field. This process adds organic matter and nitrogen to the soil, as legume roots contain nitrogen-fixing bacteria. It is a natural and effective way to enrich the soil.
7. What are the long-term environmental consequences of overusing chemical fertilisers?
Overusing chemical fertilisers can have serious long-term environmental consequences. The excess chemicals can seep into the ground, contaminating groundwater. When they run off into nearby rivers and lakes, a process called eutrophication occurs. This leads to excessive growth of algae, which depletes oxygen in the water and harms aquatic life. It can also degrade soil quality over time by killing beneficial microorganisms.
8. How does crop rotation help in naturally replenishing soil nutrients?
Crop rotation is the practice of growing different types of crops in the same area in sequential seasons. This helps in naturally replenishing soil nutrients. For example, a farmer might plant a leguminous crop like peas after a cereal crop like wheat. The leguminous plants have root nodules containing nitrogen-fixing bacteria (Rhizobium) that convert atmospheric nitrogen into a usable form in the soil. This naturally restores the soil's nitrogen content, reducing the need for chemical fertilisers for the next crop.
9. What is compost and how is it different from manure?
Both are organic, but their sources differ. Manure specifically refers to decomposed animal excreta (like cow dung) and bedding material. Compost is a mixture of decomposed organic waste from various sources, which can include kitchen scraps, plant leaves, and garden waste, in addition to animal manure. Composting is a more controlled process that creates a nutrient-rich, humus-like substance.
10. Why is it said that manure improves soil texture while fertilisers do not?
Manure improves soil texture because it is rich in humus, a stable organic material. Humus makes sandy soil more capable of holding water and makes clay soil less dense and better aerated. This improvement in soil structure and water-holding capacity is what is meant by improving texture. Chemical fertilisers, being pure salts, dissolve in water to provide nutrients but add no organic bulk or humus. Therefore, they do not contribute to the physical structure of the soil.
