Polysulphate autumn application increases nutrient efficiency

Reducing greenhouse gases and producing more food with less inputs is the major challenge facing UK farmers over the next decade. This means increasing nutrient use efficiency and ensuring crops have an adequate supply of all the nutrients they need that are essential to optimise yields.

Increasingly, farmers will need to focus on making the most efficient use of nutrients for both arable and grassland production. That means making the most of nutrients in the soil through regular soil testing, as well as those applied as fertilisers or manures.

Efficient nutrient use brings the benefits of improved crop yield and quality and reduces the risk of losing nutrients through leaching or gaseous emissions, and importantly will reduce annual fertiliser bills. Improving nutrient use efficiency requires a balanced approach. Inadequate supplies of any single nutrient can result in plants being unable to properly utilise others that are in adequate supply. The timing of when and how nutrients are applied is also important.

Balanced nutrition the key to utilising nitrogen

Liebig’s law of the minimum dictates that the yield of plants is not dictated by the total resources available, but by the scarcest one.

Sulphur has more often become the nutrient most deficient. As atmospheric deposition of sulphur has declined over the past 50 years, so UK soils have become increasingly deficient. Independent soil analysis experts estimate that in 2019, some 85% of UK arable land was deficient in sulphur and in grassland it was 88%. The need for sulphur fertiliser applications is essential.

Both sulphur and potassium are vital to achieve maximum nitrogen use efficiency, even in autumn where residual nitrogen from the previous crop is present within the soil; mineralised nitrogen also occurs due to natural breakdown within the soil profile. Both sources can be used to support early crop growth in autumn sown crops, provided there is sufficient potassium and sulphur.

With insufficient potash and sulphur, valuable nitrogen will be lost – this is both an economic loss and will harm the environment as nitrogen is volatilised or leached. Autumn applications of ICL’s Polysulphate based products will supply essential potassium and sulphur over a prolonged period of time – 50 days on average. Plants have more opportunity to take up available nutrients available and less are wasted.

Use Polysulphate to increase uptake of nutrients in autumn soils

In trials, conducted in 2020/21 on winter wheat and barley, an application of 100kg/ha of Polysulphate resulted in a 28% increase in nitrogen uptake by the crops and a 41% increase in phosphate too. This represents a significant increase in the nutrient use efficiency for all key elements during the autumn period.

The results can be observed in crops as stronger, healthier plants with a significantly enhanced biomass. Plants that enter the winter dormant period in a healthy state will emerge faster and stronger once growth recommences in spring.

Polysulphate-based fertilisers are the ideal solution to meeting the autumn requirement for sulphur. These products offer a prolonged release of nutrients which is particularly valuable for sulphate, a nutrient prone to leaching.

Polysulphate, which contains 48% sulphur, 14% potash, 17% calcium and 6% magnesium all in a water-soluble form, can be applied as a straight fertiliser or be incorporated into an autumn programme.

Paul Hogarth, who farms near Goldsborough in North Yorkshire has certainly seen the advantages of autumn treatment on his arable farm where crops include oilseed rape, wheat, barley and potatoes:

“You can really tell the difference especially with the OSR, with a noticeable difference between the sizes in plants. Also a big difference in root mass – at least a 15% increase.

“Applied at the back end of last year for establishment for the first time and doing the same this year using a standard spreader with straight potash and then in the spring with nitrogen.”