BSC 196 Lecture Notes - Lecture 25: Nondestructive Testing, Boron, Sustainable Agriculture
Document Summary
Plants obtain most of their water and minerals from the upper layers of soil. Living organisms play an important role in these soil layers. From largest to smallest they are sand silt clay. Soil is stratified into layers called soil horizons. Less organic content (b: mostly rock (c) Topsoil consists of mineral particles, living organisms, and humus: humus is decaying organic material. The organic components include humus that builds a crumbly soil that retains water but is still porous. It also increases the soil"s capacit(cid:455) to e(cid:454)change cations and serves as a reservoir of mineral nutrients. The goal of sustainable agriculture is to use farming methods that are conservation-minded, environmentally safe, and profitable. The primary source of irrigation water is underground water reserves called aquifers. The depleting of aquifers can result in land subsidence, the settling or sinking of land. Fertilization replaces mineral nutrients that have been lost from the soil.
