URSUS- Main 2


Agriculture Investment

Dr Erik Adriaanse, Manager: Product Development and Technical Support

The quantity of measurable inorganic N that should be in the soil throughout the growing period for maximum yield does not differ between El Nino (dry) or La Nina (wet) or average rainfall seasons but the actual yield, profitability and risk will differ to a large extent between these conditions.

Nitrogen (N) is normally more efficiently utilised when applied 4 to 8 weeks after planting under high rainfall conditions compared to pre-plant applications (Grove et. al., 1980). In contrast, most N applied 2 weeks after planting showed higher yields than later applications at 5 and 9 weeks after planting under relatively dry conditions (Adriaanse and Human 1993).

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Volatilisation of applied nitrogen is primarily in the form of ammonia (NH3), although losses in the form of atmospheric nitrogen (N2 en N2O) may also occur when soils are waterlogged.



Inorganic nitrogen (N) dissolved in groundwater could be lost for crop production through downward and sideway movements of groundwater, resulting in lower yields and profit margins above costs. Differences in leaching between N sources can effectively be utilised to reduce the risk of N leaching.


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