BIO220H1 Lecture Notes - Lecture 20: Norman Borlaug, Herbicide, Soil Texture
38
BIO220H1 Full Course Notes
Verified Note
38 documents
Document Summary
Bio220: lecture 20 ecology of ancient and modern food production. Early humans evolved and migrated as hunter/gatherers. Ancient technical innovations: fishing by net, irrigation channels, domestication of cattle, sheep, poultry, crop rotation/draft animals, humans went from wandering hunter gatherers to being stationary. Limitations of primitive cropping systems: crops were limited by areas that weren"t suitable for growth, overall structure of soils (deep, sandy, oil, pathogens. Repeated crop harvests known to exhaust soils (nutrients removed rather than recycled) Add animal poop to soil known since forever. Main chemical benefits are n, p, k. other benefits come from organic matter improving soil texture and water retaining capacity. Lawes: dramatic growth responses to chemical fertilizers, especially grasses. Haber-bosch process: can take natural gas + aerial nitrogen into ammonia (plants can take it up: developed for fertilizer and explosives. Life history theory: plants have to allocated resources to growth, competition, defense, reproduction, dispersal (finite amount of resources)
