Why grassland farmers could be applying lime to the wrong fields

Grassland farmers are being advised to prioritise better-performing leys when liming to ensure they yield the highest return on investment.

There is a misconception that rebalancing low pH levels should begin with liming a farm’s poorer fields, according to independent grassland specialist Chris Duller.

He advised that return on investment is highest in fields where ryegrass is strongest.

“The response to lime is going to be highest in a field that was reseeded a few years ago, not the worst field on the farm,’’ he said.

“Unless you have won the lottery you can’t lime the whole farm in one hit. Pick your best fields: lime will give you big and punchy ryegrass in those fields.’’

See also: How to manage soil and grassland for an early turnout

Short of sulphur

Most farms in the UK were not only deficient in lime but in sulphur too, Mr Duller warned delegates at Farmers Weekly‘s Grassland Management event at Carnbwll Farm, Four Crosses, Powys, last week (13 March).

Farmers are reluctant to apply sulphur because it has the potential to lock up copper and this has consequences for livestock fertility, but this chemical element is vital for helping grass plants use nitrogen.

Targets for sulphur and lime

Mr Duller recommended applying 80-100kg/ha of sulphur a year.

He calculates that applying 30kg/ha of phosphate every year for five years will raise the P index from 1 to 2.

“If you are paying 65p/kg for phosphate at current prices, that works out at £100/ha over five years – a small investment when you are increasing grass production by more than a third.”