Tag: role of organic manures in soil management

Crop rotation helps the farmers to maintain the fertility of the fields by growing alternate crops. A particular crop with one type of nutrient sown in one season restricts the cultivator to sow the other crop with another type of nutrient  in the next season, which is most beneficial for the field e.g., gram is nitrogen rich crop and rice is sugar rich crop, so, their alternate cropping can give different nutrients to the field and thus, reduces the use of chemical fertilizers.

The rice paddy field contains the Azolla weeds with the nitrogen-fixing cyanobacteria which can help in the conversion of the atmospheric nitrogen to nitrates. This nitrate can be used for the growth of the plants without the introduction of nitrogenous manures externally. These organisms help increase the yield of the rice plants. 

• Azotobacter, Azolla, Mycorrhiza, and Nostoc are manure yielding biofertilizers. Biofertilizers are organisms that enrich the nutrient quality of the soil. The main sources of biofertilizers are bacteria, fungi, and cyanobacteria.
• Azotobacter is bacteria that can fix atmospheric nitrogen while free-living in the soil, thus enriching the nitrogen content of the soil.
• Azolla is a water fern. It lives in a symbiotic relationship with a cyanobacteria Anabaena azollae which fixes nitrogen. It is used as an excellent fertilizer in the rice field.
• Mycorrhiza is a symbiotic relationship of fungi with roots of higher plants. The fungal symbiont absorbs phosphorus from soil and passes it to plants. Plants having such associations show resistance to root borne pathogens, tolerance to salinity and drought, and an overall increase in plant growth and development.
• Nostoc is a cyanobacterium. It can fix atmospheric nitrogen. It also adds organic matter to the soil and increases its fertility. 

Manure is an organic substance produced by the decomposition of plant and animal wastes in the presence of microorganism and used as fertilizers. Farmyard manure, compost and green manure are the most important and widely used bulky organic manures. Farmyard manure is the decomposed mixture of excreta of farm animals along with litter and leftover material from fodder fed to the cattle. Green manure and compost are the decomposed substance of crop. It is helpful in maintaining soil form, aeration and hydration. 

• Aerial application, or crop dusting, involves spraying crops with crop protection products from an agricultural aircraft. Agricultural aircraft are highly specialized and used for the application of agricultural materials.
•  It was used by John Chaytor in 1906 to spread seed over a swamped valley floor in Wairoa, New Zealand. Therefore, the correct answer is option D.
  

Manure is an organic substance produced by the decomposition of plant and animal wastes in the presence of microorganism and used as fertilizers. Thus, the fresh manure contains decomposing bacteria along with active digestive enzymes. These enzymes contribute to the faster heating of the manure which accelerates the decomposition of organic materials by the soil microorganisms. Manure generates heat as it decomposes, and it is possible for manure to ignite spontaneously if stored in a very large pile. 

• Fertilizer can cause burn in the plants when too much fertilizer is applied. It is a chemical compound that can dry out the leaves and damage or even cause the death of the plant. 
• Fertilizers vary in their tendency to burn roughly in accordance with their salt index. 

• Manure is an organic substance produced by the decomposition of plant and animal wastes in the presence of microorganisms and thus, produces an unpleasant odor. 
• To prevent such odor they are usually knifed (injected) directly into the soil. Manure from pig and cattle is usually spread on fields using a manure spreader. 

• Fertilizers, chemically synthesized substances that are rich in plant nutrients such as NPK. They are artificially made but have a rapid response. Overuse of fertilizers can cause negative effects such as decreased soil fertility.
• Fertilizers are classified according to whether they provide a single nutrient (say, N, P, or K), in which case they are classified as straight fertilizers. Multinutrient fertilizers (or complex fertilizers) provide two or more nutrients e.g., N and P. 
• Fertilizers are also sometimes classified as inorganic and organic on the basis of molecular structure. Organic fertilizers are derived from plant or animal sources, whereas inorganic fertilizers contain minerals and synthetic chemicals.
• Therefore, the correct answer is option D.

Bulky organic manure contains large quantities of organic matter and small quantities of nutrients. It increases the water holding capacity of sandy soil. This makes more water available to plants. It prevents the environment pollution, because it recycles the animal excretory waste. Therefore, option B is correct.