To investigate potassium and lime responses and effects on lime and potassium requirements.

Barley yields exceeded 5 t/ha with strong responses to lime and potassium fertiliser.

The 1.0 t/ha response to potassium (K) was not as strong as in the previous two wheat crops (1.4 t/ha in 2013 and 2.4 t/ha in 2014). This was probably partly due to better control of ryegrass in plots without K fertiliser compared to previous years.

The response to lime applied in 2011 and 2014 was also 1.0 t/ha. This followed a 0.35 t/ha response in 2014 wheat. Like 2014, lime did not affect response to K.

Compared to topdressing potash, banding K increased early crop vigour, but 140 kg/ha K-Till Extra (15K) did not supply enough K to satisfy demand of the high yield potential.

This trial has highlighted the importance of maintaining K inputs (if required) when undertaking liming programs.

Ongoing responses to lime are likely to increase future demand for K because soil reserves will be depleted at an increasing rate.