Majken Deichmann


Majken Deichmann


Title: Changes in the N-cycle and wheat N-uptake during waterlogging under Chines and Danish climate conditions


Climate changes predictions indicate an increase and changes in the current precipitation patterns globally, where areas already receive large amounts of precipitation are more likely to receive even more rain in the future. Global wheat production reached 749 million tons in 2016 making wheat one of the main crops worldwide, with an expected increase in the production area. Accordingly, wheat production often suffers from waterlogging and flooding resulting in global reports of wheat yield decreases in the range between 10-50%. The large reduction in yield for wheat alone indicating that waterlogging currently presents a serious challenge to the agricultural production.  Even more so when climate predictions indicate that even more precipitation is expected in many of these areas. Thus flooding and waterlogging is and continually will be a larger challenge for crop production.

In both China and Denmark, wheat is one of the major crops representing respectively 23% (12620.8 104 ton) and 50 % (502.9 104 ton) of the total cereal production, and both China (The Yangtze river delta) and Denmark already receive large amounts of precipitation of respectively 1102 mm year-1 and 712 mm year-1 making these areas vulnerable to waterlogging. In the Yangtze delta of China, there have already been reported decreases of winter wheat yield due to waterlogging. However, this is not the case in Denmark at the moment, but with the climate predictions and the introduction of new nitrogen (N) management tools like controlled drainage, which increases the water table in fields, it enhances the probability that waterlogging can occur. Therefore, it is necessary to evaluate how waterlogging and flooding will affect plant development both now and in the future for both countries.

But while waterlogging have an adverse effect on yields, it has also been reported to affect the soil N-dynamics, as anoxic soil conditions can enhance denitrification and thereby lower the amount of available N in the soil for plant uptake. So not only do waterlogging and flooding affects plants directly, but it can also have long-term effects on the environmental conditions which should be taken into consideration during N-management in fields. It is therefore necessary to evaluate how waterlogging affects N-uptake in plants, but also the long-term effects which might follow from it. 

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