Why winter-worn crops will be exceptionally hungry for nutrients this spring

Another cold wet winter is again putting the emphasis on ensuring autumn sown cereal crops have adequate nutrition going into the spring period with growers urged not to forget the importance of sulphur in the equation.

Growers must prioritise overall crop nutrition this spring following another cold, wet winter with potentially low levels of sulphur and other key nutrients available to stimulate critical root and plant growth, says ICL Growing Solutions agronomist Scott Garnett.

In particular, arable producers applying nitrogen to boost depleted soils reserves in the next few weeks must make sure they have sufficient sulphur in place to optimise nitrogen use efficiency (NUE) and ensure every kg N/Ha works as effectively as possible.

“It’s been a challenging winter for autumn-sown cereal crops with many drilled into less than optimal soil conditions followed by high levels of rainfall across the country since,” he explains.

“Many growers that managed to avoid the worst of January’s waterlogged fields, still face the problem of thin, backward crops with poorly developed root systems, sitting in wet soils and vulnerable to pests and diseases.

“Tiller numbers are also likely to be lower than usual and where slug damage has occurred, potential green area index (GAI) will be reduced.

“This year more than ever, slow growing crops will really benefit from a multi-nutrient boost to kickstart them and pull them out of the winter.

“Calcium, magnesium, phosphate and potassium are all important alongside appropriate applications of nitrogen, but sulphur must not be overlooked either.

“Like nitrogen, sulphur can leach easily from the soil, reducing availability for plants and this has been compounded by steadily reducing levels of atmospheric sulphur over the last 20 years that used to replenish this.

“Independent soil analysis suggests some 85% of UK arable land is now deficient in sulphur and unless corrected this can have a serious effect on plant growth, final yields and grain quality, particularly with regard to protein content.

“With an exceptionally high sulphur content, naturally occurring Polysulphate is a proven and reliable means of ensuring nitrogen is used as efficiently as possible and NUE is maximised.

“Plus, its unique composition of 48% SO₃, 14% K₂O, 17% CaO and 6% MgO means it also provides many of the other the essential building blocks required for optimum plant growth and health.”

Simple application

Polysulphate can be applied to cereal crops from February through to April at a recommended rate of 100 – 150kg/ha of product and it is also suitable for use in a range of other crops including brassicas, legumes, grassland, maize and potatoes, Scott Garnett points out.

“UK trials with Polysulphate have consistently shown yield lifts of over 5 – 8% in winter wheat and as much as 33% in oilseed rape with a clear 0.5t/ha advantage over the commonly used NS products.

“It’s a naturally occurring multi-nutrient sulphate fertiliser mined from under the North Sea and processed into an easy-to-apply product with excellent physical properties and performance right up to the widest spreading widths of 36.0m and more.

“It’s got vital prolonged release characteristics, too, with University of Nottingham trials showing over 50% of the sulphur contained is available in the first 12 days after application with the remainder released over the following 6 – 8 weeks.

“This matches nutrient availability precisely to crop needs through the growing cycle, which is in contrast to traditional NS products, where 100% of the sulphate is released within just 5 – 6 days after application.

“This sudden release not only means many of the applied nutrients will never be taken up by crops, it also increases the possibility of soil nutrient loss and potential environmental problems.

“Compared to NS products, Polysulphate also gives growers the opportunity to separate sulphur out from their nitrogen applications. In NS products, both nitrogen and sulphur are locked together in a fixed ratio and this can be a problem.

“If you want to meet the crop’s sulphur requirements using NS products, for example, you’re often also applying a sizeable amount of nitrogen which may not be desirable, especially in the current very wet soil conditions, when leaching can be an issue.

“Applying Polysulphate means you can apply the sulphur you need with the precise amount of nitrogen required, which is better for both the environment and overall production efficiency.”

“Polysulphate can be applied by itself or blended with nitrogen fertiliser to provide the precise N:S ratio for an individual growing situation and to help arable farmers achieve ‘little and often’ applications.”

Low carbon footprint

Polysulphate’s environmental credentials have been further improved by ICL reducing the carbon footprint of the product by 90% in the last five years, says the company’s Richard Ward.

“The reduction to 0.0029 per kg of CO₂ e gives users of Polysulphate even greater opportunities to decarbonise their production as well as having wider food supply chain implications,

“This reduction demonstrates ICL’s ongoing commitment to playing a key role in a food and farming industry that is increasingly focused on meeting sustainability and carbon targets.

“Imported sulphur fertilisers combining both nitrogen and sulphate are increasingly under the spotlight due to the significant carbon footprint contribution they make to the food supply chain.

“But with UK produced Polysulphate containing no nitrogen, growers can choose low carbon N options to apply with it and manage their overall N use far more accurately.”