Soil Science and Fertilizers

Manure is organic fertilizer created through the biological decomposition (breakdown by microorganisms) of animal waste (excreta, dung) and plant residues. This decomposition process converts raw waste into nutrient-rich humus that improves soil structure and fertility. Chemicals would not create organic manure, aeration adds oxygen, and denitrification removes nitrogen.

Manure consists primarily of organic matter - decomposed plant and animal material that contains carbon compounds. This organic content improves soil structure, water retention, and nutrient availability. Chemicals refer to synthetic substances, inorganic matter lacks carbon-hydrogen bonds, and physical matter is a meaningless category in this context.

Bio-agents are organic agents used in fertilisers. For example, culture of blue-green algae. Cultures of neem leaves or turmeric are used in grain storage as bio–pesticides because grains, during storage, cannot be sprayed with pesticides. So, during that period, cultures of neem leaves are placed with them. Culture of earthworms, used in making compost (rich in organic matter and nutrients), hastens the process of decomposition of waste. Culture of mushrooms cannot be used as mushrooms themselves are capable of extracting the nutrients from fertilisers.

Anabena and Nostoc are very useful for agricultural as they enrich the soil with nitrogen.

The slurry left behind in a biogas plant contains nitrogen. 

Nitrates are useful for maximizing production of food. Yet, the extra nitrates we utilize in the fields mixed with drinking water results in converting nitrates into nitrites in stomach, which mixes with haemoglobin, decreasing oxygen carrying process. This results in methaeglobinaemia where methemoglobin is present higher than its normal level in blood.

Fertilizer refers to products added to a plant’s soil or sometimes sprayed onto its leaves which are supposed to help the plant to get all of the nutrients it needs to grow big and strong. Fertilizer is rich in Nitrogen, which is the main component for the the growth of the plant.

Humus is the organic part of the soil because soil is made of rotten leaves and decayed bodies of plants and animals. Humus increases the soil fertility.

It is not a type of manure. Manure is partially decomposed organic matter derived from plant and animal wastes.

This is the correct option. It is not a correct statement. It is very bulky and therefore, not easy to handle, store and transport.

Weathering causes the disintegration of rock near the surface of the earth. Plant and animal life, atmosphere and water are the major causes of weathering. Weathering breaks down and loosens the surface minerals of rock, so they can be transported away by agents of erosion such as water, wind and ice.

This is the correct option. Sun, water, wind and living organisms are the factors that help in the formation of soil.

This is the correct answer as these statements are correct. Lichens grow on the surface of rocks and while growing, they release certain substances that cause the rock surface to powder down and form a thin layer of soil. Mosses grow on this surface and they cause the rock to break up further. Bits of decayed living organisms in the soil are called humus.

Azolla (genus) is an aqueous fern which is capable of nitrogen fixation, so that it is used as a biofertiliser in agriculture.

All the given factors affect soil corrosivity. With the increase in acidity of soil, corrosion rate increases. Since corrosivity is associated with electrochemical reactions in soil, high soil resistivity slows down the corrosion reactions. Concentration of chlorides and sulphides in soil plays an important role in soil corrosivity.