Which of the following statement(s) is correct?

Fertilisers and manure are both soil amendments, but they differ fundamentally in composition and function. Fertilisers are industrially manufactured or chemically processed compounds engineered to supply one or more specific plant nutrients, typically nitrogen, phosphorus, and potassium, in a concentrated and readily available form. Manure, by contrast, is organic matter produced by the decomposition of plant and animal waste; it supplies nutrients only in small, diffuse quantities but adds bulk organic content to the soil.

Applying this distinction to the statements offered: because fertilisers are manufactured specifically to deliver targeted nutrients in concentrated doses, they are indeed richer in those specific nutrients than manure, which releases nutrients slowly and in much smaller amounts. This is the standard basis on which agricultural science, and the NCERT Class 8 chapter on Crop Production and Management, differentiates the two soil amendments.

• Water-holding capacity improves when organic matter is mixed into soil, which lets soil particles bind more moisture; this comes from manure's bulk organic content, not from a fertiliser, which contains no such organic bulk.

• Humus is the dark residue left behind after microbes decompose organic material. Since a fertiliser is a synthesised chemical compound rather than decomposed organic matter, it contributes no humus to the soil.

• Soil microbes multiply where organic carbon is available as a food source, which manure supplies in abundance. A fertiliser does not add the decomposable organic matter that microbes feed on, so it does not raise the soil's friendly microbial population.

Cross-checking against the standard framing used in agricultural science: manure conditions the soil, improving its structure, humus content, and microbial life, while a fertiliser concentrates specific nutrients. These roles are complementary, and only the nutrient-concentration property belongs to fertilisers, confirming that the statement “fertilisers are richer in specific nutrients than manure” is the correct one.