Scottish farmers sweetening, with sodium for better silage

Nutrition agronomist at Origin Soil Nutrition, Abby Kellett, says low sugar content in grass can be one of the main reasons for reduced consumption, especially in later cuts which can become more fibrous and unpalatable. With the majority of first-cut silage under way or gathered in, focus will turn to replacing nutrient off-take and ensuring subsequent cuts are the highest quality possible.

She said: “Improving the palatability of grass means getting the right nutrition into the growing crop so it has time to take up the nutrients and improve second-cut quality.

“It’s also important to remember grazing ground, as sodium inputs will increase palatability, meaning animals will eat more homegrown grass and reduce the requirement for bought-in supplements.”

With prices of bought-in nutrition high, Abby says farmers should be applying a prescriptive blend of nutrients to stimulate regrowth, improve quality, and cater for any nutrient deficiencies in the soil profile. Applying straight nitrogen fertiliser – or even standard silage grades containing just nitrogen and potash – isn’t going to significantly improve grass quality alone.

Sodium has a vital role to play in this, she said.

“Sodium optimises sugar content and improves palatability, making grass more attractive to cows thereby promoting intakes. It’s like us adding salt to our food to improve the flavour, the sodium salts increase the sugar content in grass, encouraging cows to eat more of it.”

Adding it up

Applying sodium following cuts can also benefit farmers who are applying an additive at grass harvest. Grass that is clamped or baled converts sugars to acids to improve fermentation, and a lower grass sugar content means the performance of any additive, regardless of how good it’s claimed to be, will be compromised.

Ms Kellett said: “A higher sugar content in the grass at harvest will improve fermentation by speeding up acidification and reducing losses, making any additive that is applied more effective.

“Farmers might be concerned that adding sodium to a granular grade could cost more at a time when budgets are stretched. However, considering that cows could consume more homegrown forage, which contains essential nutrients, this could reduce the need for supplementation.

“Furthermore, reduced additive performance can affect the return on investment.”

Origin’s Sweet Silage tailored grassland fertiliser contains several grassland essential nutrients for improving yield and quality, including nitrogen and potassium for growth and DM yield, sulphur to support nitrogen uptake, and sodium for silage quality.

Additives are likely to cost farmers £1/t of silage produced, whereas adding sodium to a silage fertiliser in the form of Sweet Silage costs 28p per tonne of silage (based on a 17t/ha yield).

The addition of sodium can also avoid grass becoming sour following slurry applications post-harvest, especially if farmers plan to graze the cut ground after spreading.

Avoiding pica

Sodium inputs now will also feed through to better quality late season grazing, which can often become unpalatable due to a lack of quality. Cows with reduced sodium in their diet can often be seen licking fence posts, or eating stones, a condition known as pica, which can be mitigated by increasing sodium content in the grass.

“Sodium deficiency is one of several causes of pica and, while salt licks can be a way to offset the impact, it’s a reactive solution to a problem that can be solved with a proactive grassland nutrition approach to address the sodium shortfall.

“Ensuring sodium is available to grass for uptake can support better quality grass and will be vital for second and third cuts this season,” added Ms Kellett.