HORTICULTURE

Detailed explanation-1: -All plants require nitrogen, phosphorus and potassium as their primary nutrient. Thus oxygen is not considered as primary nutrient for plants.

Detailed explanation-2: -Soil structure influences plant growth by affecting the movement of water, air and nutrients to plants. Sandy soils have little or no structure but are often free draining. With higher clay contents the soil structural strength increases, but its drainage ability often decreases.