Agro-ecological System

1. CLIMATE, WATER, SOIL AND HUMAN RESOURCES

A. Climate
• Tropics
 Lies between the Tropic of Cancer in the north and the Capricorn in the south
 Based on the amount of rainfall and temperature
 Divided into ; super humid, humid and dry zone
 Humid and super humid; very high average daily ambient temperature and heavy rainfall – hot and humid throughout the year
 Grow plants

• Temperature
 Neither too warm nor too cold
 Neither too wet nor too dry
 Four seasons are identified; summer, winter, spring and autumn
                                       
 Crops are usually planted I. Spring and harvested during summer
 But during winter, they plant under controlled environment such as glass-house
 For livestock so, temperate climate appears the most suitable for all animals farming

• Tundra
 Very low temperatures and short growing season with little water and sunshine
 Three types ; Arctic, Antartic, Alpine
 Dominant vegetation; grasses, mosses, lichens
 Crops are hardly be grown, but farming is possible but in restricted enclosures with adequate water supply
                           

• Deserts
 Receive very little precipitation <250mm annually
 Extreme diurnal temperature range , very high in the day and very low at night
 Plants: xerophytic type

B. Water
• Needed for seed germination, root development, and subsequent growth
• The earliest civilation started at the river banks : the Nile Valley in Egypt and Tigris-Eupharates in Mesopotamia

C. Soil
Nutrient cycle
• Rain water > ground soaked up by soil > plants > loses to air through evaporation
• Factors of soil formation: parent material, climate, topography, vegetation and time

2. HUMAN RESOURCE

• Need mans with knowledge and skills at different level
• Today’ s agricultural need strong science and technology
• Needs scientist and researcher to do research from production until marketing level
• Also need labor for land  works

3. ENVIRONMENT

• Global agro-ecological zones
- Due to varying soils and climatic conditions, specific sites are only suitable for some commodities, crops or animals.

 Tundra – ( very cold climate, low biotic diversity)
 Grassland ( low fertile land, mild climate)
 Deserts – ( very little precipitation,extreme diurnal temperature barren land)
 Tropics – ( rain and sunshine all year round, rainforest)

                                     

• Impact of climate change

 Global warming
- Extensive use of fuels releases carbon dioxide, carbon monoxide, nitrous oxide and methane which increase the global temperature and caused climatic instability
- Led to hurricanes, floods, droughts
- Melting polar ice cause to lowlands

 Desertification
- Expansion of desert land due to climatic change
- Less arable land for agriculture
• Impact of pollution

 Acid rain

- Sulphur dioxide and nitrogen oxide emitted to atmosphere translate into rain acid
- Low pH of water, leave impact on forest, less water and soil,affecting crops and animal production


 Heavy metals

- Zinc copper and lead that involved in pollution
- They bound to negative charges of some soil particles rendering them less soluble in water

 Pesticides
-excessive use of chemical pesticides led to undesirable health effects and reduces biodiversity

 Nitrates
- Led to excessive enrichment of the water ( eutrophication) , help to rapid algal growth creates an oxygen deficit aquatic ecosystem and killing off aquatic life.