Orm Blog The effects of stubble on nitrogen tie-up and supply

Take home messages• Cereal stubble should be thought of as a source of carbon (C) for microbes, not as a source of nitrogen (N) for crops. In no-till systems, only approximately 6% of the N requirement of crops is derived from the stubble.• Nitrogen tie-up by cereal residue is not just a problem following incorporation - it occurs in surface-retained and standing-stubble systems and can reduce wheat yields by 0.3t/ha to 0.4t/ha.• Management is reasonably straightforward - supply more N (5kg N for each t/ha of cereal residue) and supply it early to avoid impacts of N tie-up on crop yield and protein.• Deep-banding N can improve the N uptake, yield and protein of crops, especially those in stubble-retained systems.