AGP - Conservation Agriculture
 

Climate change is becoming increasingly important for agriculture. Extended drought periods and heavy rainstorms are becoming common features of the weather not only in the tropics. CA can help to adapt to these changing and less stable climatic conditions. The increased water infiltration allows soils to absorb most of the rain water even during extreme rainfall events, reducing the risk of erosion and flooding. Increased organic matter levels and a better rooting environment in the soil improve water holding capacity of the soils and the ability of plants to survive during drought periods. Yield variations between dry and wet years are less pronounced under CA than under conventional farming practice.

In addition, agriculture can also help mitigate climate change by reducing the emissions of green house gases into the atmosphere. Since 40 per cent of the world’s land surface is under agricultural use, the contribution of agriculture to climate change mitigation could be significant. CA can reduce the emissions of fossil fuels compared to conventional agriculture by up to 60 per cent. In addition to this, the use of fertilizer and agrochemicals can be reduced in the long term by 20 per cent. Even the capital investments into heavy machinery such as tractors can be reduced by 50 per cent. This would reduce the emissions resulting from the production of these inputs. However, the largest contribution to mitigate climate change with CA can be obtained from carbon sequestration and the storage of atmospheric carbon in the soil. The levels of carbon to be captured in the soil vary depending on climate and production system. On average under humid temperate conditions, 0.1-0.5 t.ha-1.y-1 of organic carbon can be captured. Under semi arid or tropical conditions, these levels decrease to about 0.05-0.2 t.ha-1.y-1. This process continues for 25-50 years before a new balance is reached. Even the emissions of other green house gases such as methane and nitrous oxides can be positively influenced by a change of the cropping practices to CA. These gases occur in smaller volumes but have a much stronger effect as green house gases than carbon dioxide. Methane is for example released from rice fields under anaerobic conditions. CA would change the rice soils into a more aerobic environment without permanent flooding, which would reduce the methane emissions.  Similar effects can be achieved for nitrous oxides as a result of changes in the nitrogen fertilizer and the soil water management. Suitable selection of fertilizers and placement in the soil can reduce the emissions also under conditions of zero tillage.

 

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