Key Points
- In over thirty years of research in NZ, yield responses of maize grain to K fertilisers have been very uncommon
- In the US, yield responses to starter fertiliser are common, but often the starter fertiliser contains N and even then the increase in yield is often not economic
- Trials to look at economic responses of maize to potassium fertiliser indicate a response is unlikely unless MAF Quicktest K is less than 5
- Growers may spend over $240/ha by applying P and K fertilisers when there is no yield response
- Although considerable research has been completed, further research is needed to define how K starter fertiliser influences plant development, disease susceptibility and standability.