Only 15% of Irish dairy farms had optimum soil fertility levels in 2017 and 47% of grassland farms required lime.

Where soil fertility is improved, more grass can be grown. According to Teagasc, soils in index 1 and 2 for phosphorus (P) and potassium (K) are producing approximately 3t/ha/year less grass than soils with optimum soil fertility.

Grassland Agro and Cork Grassland Services have teamed up to combat this problem. Speaking to AgriLand, John O’Loughlin of Grassland Agro, said: “Rectifying soil fertility can have a big impact on yield.

One of the main things we noticed from the soil fertility conference was that there has been no change in the soil fertility status over the past number of years.

“To counteract this, Grassland Agro and Cork Grassland Services are going to work together to use grass measuring data to work out under-performing fields and put in bespoke fertiliser plans specific to each field, so that farmers can rectify their soil fertility status and increase productivity.”

Grass measuring is becoming increasingly popular and availing of a grass measuring service takes some of the load away from the farmer, it also allows data to be uploaded to Pasture Base efficiently.

“It’s important to get that soil fertility message out there. Grass yield and soil fertility are heavily inter-linked. Some farmers are great grassland managers and are great at measuring grass, but their soil fertility might be poor,” John explained.

If a farmer is measuring grass every year, there is a great opportunity to use this, together with soil and fertiliser information to improve grass growth.

Linking soil and grass growth

“Farmers who take advantage of this partnership will have an opportunity to have their grass growth data assessed, side-by-side with their soil and fertiliser situation, to see how better progress can be made to grow more grass.

“We’ll almost be going into precision agriculture territory. We’ll be taking soil samples for each paddock and treating them individually with a specific programme to lift the P and K index.

Fertiliser, Fertiliser Spreader

Image source: Shane Casey

“We’ll be able to use the farmer’s data at the end of the year to see what didn’t perform and what the underlying issues are.”

John added that they will be able to calculate P and K offtakes by knowing how much grass was produced and how much fertiliser was utilised.

In grassland, what’s actually used can sometimes be up in the air. We’ll be getting into the nitty-gritty of that, which will be a high point.

Working on improving soil fertility and matching inputs to grass productivity can also result in the sustainable use of fertiliser. If a farm’s lime requirement is right, it can have a big impact on efficient fertiliser use.

John explained that it’s also important to be proactive and reactive to weather conditions. Farmers who sign up to the plan will work closely with their Grassland Agro advisor to do this.