Soil Science and Fertilizers

Microbes are not needed in manufacturing fertilizers is a correct statement. Groundnut and sunflower are a prominent mixed cropping pair is also a correct statement. Thus, this answer is the correct choice.

This is the correct option as aluminium sulphate is not a chemical fertiliser. Ammonium sulphate is a chemical fertiliser.

This is the correct option as this statement is false. The deficiency of plant nutrients and organic matter in the soil is made up by adding manures and fertilisers to the soil. Manures are not very rich in plant nutrients like nitrogen and phosphorus, but are rich in humus.

Urea (CO(NH2)2) has the highest nitrogen content among common fertilizers. It contains 46% nitrogen by weight. Ammonium nitrate has ~34%, ammonium phosphates ~18-21%, and potassium nitrate ~13% nitrogen.

Wheat cannot fix nitrogen from soil or air. Thus, it needs extra nutrition from fertilizers.

The humus is further degraded humification, by some microbes and release of inorganic nutrients occur by the process known as mineralisation.

Soil organisms are the creatures that spend all or part of their lives in the soil. There are several criteria that can be used to classify soil organisms. For example, soil organisms are classified according to their size into: (1) macro-organisms (> 2 mm in width), (2) meso-organisms (0.2 to 2 mm in width), and (3) micro-organisms (< 0.2 mm in width) Arthropods belong to the meso group. They are a diverse group of spiders, mites, pseudo-scorpions and insects. Many arthropods prey on disease causing pests. Others help to shape soil structure and thus, can improve root development, water infiltration, drainage and help in aerating the soil.

 Yes, it is correct. Manures which are decomposed organic matter increase the nutrient content of soil for healthy growth of plants. They are the fertilizers which in long run make the soil less fertile.

"Higher doses" refers to 'greater than normal, in quantity or size'. 

Terai soil, found in the foothills of the Himalayas, is known to be deficient in phosphorus. This nutrient deficiency limits crop productivity in the region and requires phosphorus fertilization for optimal agricultural yields. The deficiency is due to the soil's geological origin and high iron content which binds phosphorus.

In agriculture, leaching refers to the loss of water-soluble plant nutrients from the soil, due to rain and irrigation. Soil structure, crop planting, type and application rates of fertilizers and other factors are taken into account to avoid excessive nutrient loss.

An organic nutrient provider should at least provide C and H.

Plants are biotic (living) components that significantly affect soil fertility through root growth, leaf litter decomposition and organic matter addition. Biotic components include all living organisms like plants, animals and microorganisms, whereas pH and air content are abiotic factors. Fertilizers are human-added substances, not natural biotic components.

Plants are primary producers that create organic matter through photosynthesis rather than decomposing it. Decomposers like fungi, bacteria and earthworms break down dead organic material into simpler substances and recycle nutrients back into the soil. These organisms are essential for maintaining soil fertility and ecosystem balance.

Peat is acidic in nature and can effectively neutralize alkaline soils by lowering their pH levels. It contains organic matter that improves soil structure while reducing excessive alkalinity. Lime and calcium carbonate are used to treat acidic soils as they increase pH, while water alone does not change soil chemistry significantly.