Agricultural practise

Agricultural practise

1. soil maintenance

   • shifting cultivation
     • slash and burn
       • 1. forest cleared
       • 2. grow crops
       • 3. abandon after 3 seasons
         • forest cleared (again)
       • 4. forest regen
       • system works if enough resource and sufficient time for regen
     • crop rotation
       • farming
         • root crops
         • cereal
         • grass-clover pasture
           • clover fixes N into soil
           • livestock give manure

2. tillage

   • disturbance of top 20-25cm of soil
   • plant residues buried
   • harrowing
     • makes fine tilth
   • Negative effects
     • decr in worms and fungi
     • SOM inacessible
     • deflocculate clay

3. fertilisers

   • correct nutrient deficiencies and imbalances
   • promote improved growth and quality
   • solutions, suspensions, emulsions, solid
   • N, P, K, S
     • Phosphate
       • superphosphate
         • dissolve rock phsophate
       • triple superphosphate (MCP)
         • in dry soil takes up moisture from atmosphere => saturated salt solution
           • salt = v acidic
             • dissolves soil minerals
               • release Ca, Al, Fe, Mn ions
   • single macronutrient products
     • ammonium nitrate
     • urea
   • multi-nutrient/compound
     • ammonium nitrate
     • MAP
     • DAP
   • components mixed => N:P:K ratio
   • water soluble
     • granulate
   • slow release
     • plants reap benefits esp in sandy
     • mitigate leaching
   • pH

4. liming

   • incr pH
   • acidic if Ca, Mg, K, Na leached faster than released
   • calcium carbonate

5. manures

   • cattle dung and urine + straw
     • low in macronutrients
   • slurry
     • dung and urine + washings (from milk parlour)
       • more dilute
   • compost
   • sewage sludge

6. traditional vs. modern

   • traditional
     • low tillage
     • minimum disturbance
     • plant debris left on surf
       • protect soil from erosion
     • intercropping with tall and short crops
       • minimise bare ground
   • modern
     • minimum disruption in combo with use of herbicides to control weeds
     • direct drilling
       • grow crop and harvest
       • apply herbicide
       • drill seed into soil
       • advantages
         • minimal soil disturbance
         • mulch -> shade
         • reduce water evapotranspiration
         • stabilises temp
         • surf runoff and erosion reduced
         • lower fuel use