Climate & Agriculture. Agricultural has evolved into a highly technical field.
Dramatic changes occurred in the 20th century: genetics, improved fertilizers, increased disease resistance, and the substantial input of energy into farming methods has dramatically increased on productivity. However
The prevailing climate of a region still places distinct limitations on what crops can be grown and, in part, determining the hazards to which the crops are exposed.
Example: bananas will not grow in Wisconsin; Deciduous fruit trees will not fruit in tropics; Climate has impact on quality (protein content) of wheat. Highest protein content wheat is in wheat belts of North America and black-steppe area of the former U.S.S. R. (mid-lat grassland biomes of the world); But hazards for wheat are still problems: hailstones. Example: a single storm in Nebraska destroyed 3 million bushels of standing wheat.
Energy input: sunlight, fuel for tractors, food for the farm workers
Pro: maximize the benefits of this energy supplant and obtain highest yield for all input.
Con: it contrasts to climax ecosystem, where diversity is a key to the maintenance of the system
Example: Boll Weevil problem in the cotton belt of southern US
Potato famine of Ireland and Europe, 1840s (potato blight led to 2 million death).
Due to the weather-related risks in agricultural practices, some adaptations have been made to ease the vulnerability:
Banana is native to SE Asia, now spread into tropical America
Potato originated in America, now in Europe
Sugar cane from SE Asia, now in tropical America
Rubber trees from equatorial rainforest in Amazon basin, now are in plantations in SE Asia.
Relocation results in better yields:
1. Frost protection
Radiation frost occurs
at local area; Advection
frost is caused by cold air
flowing into region and covers a wider areas (cP air from North)
2. irrigation some adaptations have been made to ease the vulnerability:: water required by a plant to function at its maximum capacity (PE) design irrigation system using water budget.
Three areas need augmentation of precipitation:
If P>PE, AE=PE
If P<PE, AE=P+ absolute value of storage change
4. Deficit occurs when AE<PE
5. After deficit period, (when P becomes >PE), excessive water will recharge soil to capacity before surplus (or runoff) occurs
Climatic water budget for Wilmington, DE (using handout soil moisture table)
(1)Photosynthesis: carbon+water+solar energy=hexose sugar+oxygen (sun light determine the rate of photosynthsis)
(2) Photoperiodism: plants response to the length of the daylight hours
Long-day plants: flower only when daylight is greater than 14hours
Short-day plants: flower only when daylight is less than 14hours
Day-neutral plants: bud under any period of illumination
Intermediate plants: flower with 12 to 14 hours of daylight but not outside these limits
(2) Temperature moisture table)
Tropical plants: 20-30C(68-86F)
Mid-latitude plants: 15 to 20C (59-68F)
Growing degree days (GDD): degrees accumulated above a certain baseline (depending on plants)
Sunflower and potatoes: 45F; corn and soybeans 50F;