IRTG 1070: SP 1.2 Optimisation of soil organic matter management under intensive cropping in the North China Plain

Intensive maize-wheat double cropping is a common plant production system at the North China Plains. More than 600 kg N/ha as mineral N fertiliser are applied annually while only 300 to 350 kg N/ha are removed with plant products. Despite of this extraordinarily high level of N-fertilisation, the yield potential in the common wheat-maize cropping system is by far not fully taped yet. Beside low N utilization efficiencies (partly < 30%), frequent lodging and environmental pollution including leaching and gaseous losses of N are the results of the excessive use of fertiliser-N.

Within this study, different N-fertilisation, tillage and cropping strategies shall be investigated with their potential to maintain high levels of SOM and to guaranty high and stable yields in the long term in the North China Plain. Future developments like climate change and increasing demand for energy production from plant residues shall be considered. Special emphasis will be put on the fate of (fertilised) N which preferably should be available for plant uptake and built up of organic matter but may also disappear by leaching and gaseous losses. A combination of lab experiments, existing and newly established long term field experiments combined with computer modelling shall be used to extrapolate short and medium term findings into the future and up to a regional scale.