BIO220H1 Lecture Notes - Lecture 8: Soil Texture, Crop Rotation, Middle Ages

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13 Aug 2016
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Agriculture is a very recent phenomenon-especially in the America’s
Primitive diet was likely opportunistic and unreliable
-not adapted for eating leaves, heed higher quality foods that are less defended
-fruits, seeds, nuts, tubers, etc.
-great because they are selected for dispersal, so they’re made to be attractive
-seeds and tubers are designed as energy-storage organs
Most of what we eat and harvest are grasses, legumes, and fruits
-while humans were planting and harvesting…
-net fishing opened up whole new food source
-domestication of domestication of cattle, sheep, poultry
-irrigation development
-plows replace digging sticks very late in the game(5500BP)
-crop rotation and draft animals caught on by the middle ages
-transformed humans from nomadic life to sedentary, stability, and the rise of cities
In the intrinsic growth performance of crops
-plant ranges of tolerance, soil moisture and fertility, soil exhaustion, build up of pests
-limit the growth of crops
-these limits consistently attacked by science
-booming populations in the 1950’s and 1960’s, famines occur
-change human society or change the agriculture?
-couldn’t continue at current rate
Changes in Agriculture-sustainability of these changes is up for debate…
Soil amendments-aka fertilizer
-growing same crop in same place leads to soil decline
-yields decline
-nutrients removed, then products harvested so they’re not recycled
-animal dung/animals to soil has always been known to supply limited nutrients
-higher concentrations of N, P, & K than in plants
-improving soil texture and water retention
-Higher concentrations needed for optimal growth
-N fertilizer used in 1800’s from high-nitrate minerals (mined)
-Haber-Bosch process (game changer)
-natural gas & aerial nitrogen + catalyst and pressure
-ammonia (fertilizer and explosives)
-approximately 3-5% of world’s natural gas goes to this process
-Impact of Synthetic Nitrogen and Human Society
-HALF!! of the world population would not be here w/o haber-bosch
-meat production sky rocketed
-Food & resources are made possible by haber-bosch feeds ½ world pop.
-technology is very useful in evading prior limitations
Green Revolution
-using conventional breeding to evolve high-yield varieties
ex. Rice strain developed that tripled seed yield
-modified to thrive in high-density environments
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