Most plans for grass and silage focus on nitrogen as key driver for plant growth, but other nutrients need to be considered to understand where improvements in fertiliser use efficiency can be made.

According to Julia Andrews, Scottish nutrition agronomist at Origin Fertilisers, a detailed soil analysis is essential to understand where additional nutrients are required.

“Increasing a plant’s nitrogen uptake is only possible by understanding where the deficiencies in a soil profile are. Nitrogen is vital, but it can’t grow quality grass on its own and a balanced nutrient profile is key to high yielding and nutritious swards,” she says.

Although soil types and profiles vary from field to field, maximising grass growth and quality is key to reducing livestock farmers’ reliance on bought-in feed costs. Regardless of individual soil profiles, giving the plants access to other essential nutrients is paramount, and sulphur plays an essential role in helping other nutrients become more available.

“Sulphur is an essential nutrient and a key part of protein formation, it also helps increase the nitrogen use efficiency, meaning more of the nitrogen applied is available to the plant,” said Ms Andrews.

Sulphur is mobile within the soil and therefore vulnerable to leaching, so applications need to be made each season to ensure adequate plant available levels are maintained. The correct nitrogen to sulphur ratio is 12:1, and this should be a minimum requirement to maintain levels. Ms Andrews added that one application of polysulphate could be all that is required.

“Polysulphate can offer swards their full sulphur requirement for the season and the slow-release characteristics allow the plant access to sulphur up to 55 days after application, which reduces the risk of leaching. Polysulphate also has potassium, calcium and magnesium to boost wider nutrient levels.”

Other nutrients can also directly influence the nutritional value of forage and how swards react to weather extremes, such as some regions experienced last summer with the extended dry spell.

“It is swards that have access to the right nutrients that can withstand heat stress for longer, and good sodium levels mean the grass is more palatable to the animals thanks to increased sugar content. Furthermore, good sodium reserves can also mimic potassium in certain cases where the potassium level is too low, which helps with stress resistance and water regulation,” explains Ms Andrews.

Application rates of each nutrient depend on the soil’s needs, which will vary from farm to farm and be influenced by previous years applications. Getting advice from a FACTS qualified advisor to understand where these deficiencies are, and how to correct them, will allow greater returns from a farm’s fertiliser purchase this season.