NEET BIOLOGY

Detailed explanation-1: -Due to their close proximity to plant roots, soil microbes significantly affect soil and crop health. Some of the activities they perform include, nitrogen-fixation, phosphorus solubilization, suppression of pests and pathogens, improvement of plant stress, and decomposition that leads to soil aggregation.

Detailed explanation-2: -Bacteria, actinomycetes, and protozoa are hardy and can tolerate more soil disturbance than fungal populations so they dominate in tilled soils while fungal and nematode populations tend to dominate in untilled or no-till soils.

Detailed explanation-3: -Micro-organisms like bacteria and certain fungi decompose excretory products and remains of dead plants and animals into simpler substances. This increases the organic content of the soil, thereby increasing its fertility.

Detailed explanation-4: -Bacteria perform important functions in the soil, decomposing organic residues from enzymes released into the soil. Ingham (2009) describes the four major soil bacteria functional groups as decomposers, mutualists, pathogens and lithotrophs. Each functional bacteria group plays a role in recycling soil nutrients.