GEO 702 Chapter Notes -Water Cycle, Topsoil, Phosphorus Cycle
11 Oct 2014
School
Department
Course
Professor
Document Summary
Food resources: why should we care: we need a nutritious diet to stay alive and be healthy, population is growing: do we have enough food for everyone, the current food production system has a too high environmental impact. Life on earth is possible thanks to 2 natural processes: energy flow, chemical cycling. The most important chemical cycles are: water cycle, carbon cycle, nitrogen cycle, phosphorus cycle. Soil is composed of eroded rocks, mineral nutrients, decaying organic matter, water, air, and a myriad of tiny organisms. The soil has several levels, the top one being topsoil. Topsoil is a renewable resource but its renewal process is very slow. Soil provides nutrients for living organisms, helps purify water, and helps control the earth"s climate. Types of agriculture relies on the labour of human and animals. Traditional subsistence agriculture practiced by 40% of world"s farmers on 75% of the world"s farmland, yet it only provides.
