What are the desirable agronomic characteristics for crop improvements?

What are macro-nutrients and why are they called macronutrients?

Compare the use of manure and fertilizers in maintaining soil fertility.

Which of the following conditions will give the most benefits? Why?

(a) Farmers use high-quality seeds, do not adopt irrigation or use fertilizers.

(b) Farmers use ordinary seeds, adopt irrigation and use fertilizer.

(c) Farmers use quality seeds, adopt irrigation, use fertilizer and use crop protection measures.