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25.11.2009 Studies
 
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Low Greenhouse Gas Agriculture

FAO, 2009

Content

  • Literature review for an assessment of organic agriculture against IPCC recommendations on climate-friendly agriculture

Summary of IPPC recommendations

  • Crop rotations and farming system design: improve crop varieties and productivity, feature perennials in crop rotations, use cover crops (between successive crops or between rows of plantations) and avoid bare fallows, adopt farming systems with reduced reliance on external inputs (e.g. rotations which include legume crops).
  • Nutrient and manure management: improve nitrogen-use efficiency (reducing leaching and volatilization, reducing offsite N2O emissions), adjust fertilizer application to crop needs (synchronization), use slow-release fertilizers, apply N when crop uptake is guaranteed, place N into soil to enhance accessibility, avoid any surplus-N applications, manage tillage and residues conservatively, reduce unnecessary tillage using minimum and no-till strategies.
  • Livestock management, pasture and fodder supply improvement: breed and manage dairy cattle for lifetime efficiency, plant deep-rooting species in primary production, introduce legumes into grasslands (to enhance productivity), prevent methane emissions from manure heaps and tanks, utilize biogas as a resource, compost manure.
  • Maintaining fertile soils and restoring degraded land: re-vegetate: improve fertility by nutrient amendment; apply substrates such as compost and manure; halt soil erosion and carbon mineralization by soil conservation techniques such as reduced tillage, no tillage, contour farming, strip cropping and terracing; retain crop residues as covers; conserve water; sequester CO2 by increasing soil organic matter content.

Findings

  • Problem of excessive nitrogen application in conventional agriculture (which is in the is the main source of agricultural greenhouse gas emissions): worldwide only 1/5 of nitrogen produced taken up by crops, efficiency of nitrogen use has been decreasing over recent decades. Organic agriculture uses 60 to 70% less nitrogen than conventional agriculture – and makes better use of manure and slurry in the place of mineral fertilizer
  • Organically managed soils are better aerated, retain more water, have significantly lower mobile nitrogen concentrations, erode less and sequester more carbon.
  • Worldwide conversion to organic farming would mitigate 40% of the world's agricultural greenhouse gas emissions, and by 65% if combined with reduced tillage techniques. This would reduce yields in intensively farmed regions under the best climate conditions by one third that could significantly improve yields of less intensive farming systems.

Comment

  • The study reads as if it had been written by organic farmers - but it is an official FAO document. Will the future of (developing country) farming be organic?