1 / 13

Climate & Agriculture

Climate & Agriculture. Agricultural has evolved into a highly technical field.

engelbert-nathanial
Télécharger la présentation

Climate & Agriculture

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Climate & Agriculture

  2. 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 Monoculture: 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).

  3. Due to the weather-related risks in agricultural practices, some adaptations have been made to ease the vulnerability: • Risk spreading though insurance schemes and cooperative farming schemes • Environmental manipulation (irrigation and fertilization) • Managed diversification (crop rotation and dual-purpose livestock) • Modified farming system (modified crop calendar and improved storage)

  4. Relocation of plants based on climate conditions 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: • Native place, they are integral part of the environment, thus susceptible to pests and the competition of other plants of that origin. Through transportation natural limiting factors are removed • Due to purpose of production, they are treated with special care and afforded much attention.

  5. Extending climate limits 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) • Plant way from cold valley (above inversion) • Heater to mix air • Sprinkling and flooding to increase thermal conductivity, reduce excessive cooling, supply latent heat • Brushing: cover up plants to reduce nighttime radiation loss

  6. 2. irrigation: water required by a plant to function at its maximum capacity (PE) design irrigation system using water budget. Three areas need augmentation of precipitation: • Perpetual drought (desert) • Seasonally water deficit • Periodic drought

  7. Thornthwaite and Mather’s Water Budget Calculation Rules: • When P is larger than PE, excess water will go to recharge soil moisture until it reaches the field capacity, then leftover will be runoff • When PE is larger than P, plants draw moisture from soil and the soil storage falls below capacity • Actual evapotranspiration (AE): 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

  8. Climatic water budget for Wilmington, DE (using handout soil moisture table)

  9. Climate and Crop Yield: light, heat and moisture condition are the most important factors Light (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

  10. (2) Temperature 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; Agriclimatology

More Related