Sulphur is sometimes overlooked when it comes to crop nutrition, with some viewing it as less essential than the “main three” nutrients, NPK. This approach is a mistake; sulphur is a vital building block of plant proteins and is a critical component in the delivery of both yield and quality. When applying the correct rates at the best timings, sulphur reveals itself to be indispensable to crop nutrition, and should be integrated properly in every nutrient management programme.
“Sulphur behaves in a very similar way to nitrogen in the soil,” says Natalie Wood, Country Arable Agronomist at Yara. “You’ll see leaching of the sulphate form just as you would with nitrates, so it’s sensible to treat sulphur the same as you would nitrogen. You wouldn’t apply all your nitrogen in one go and expect it to fulfil the crop requirement through the growing period. Sulphur is no different.”
When applying sulphur in just one large application, it’s likely that a significant amount will leach away through the soil profile and become unavailable to the crop. Applications should therefore be little and often – as with nitrogen – to ensure availability to the crop throughout the growing season.
Sulphur also has a very close relationship with nitrogen. Without a sufficient supply of sulphur, nitrogen cannot be taken up and utilised effectively by the crop. “Increasing nitrogen use efficiency (NUE) on farm is becoming more and more important,” says Natalie Wood. “Using sulphur effectively is an easy way to do that. With sufficient nitrogen and sulphur at each application, the two nutrients will work together… a better result for the crop, the environment, and your wallet.”
Yield responses to sulphur can vary from season to season. 0.2-1.9t/ha have been the responses seen in recent years, but the type of sulphur applied makes a difference. “If applying elemental sulphur, it can take a long time (up to 8 weeks) for this to convert into sulphate within the soil,” adds Natalie. “The plant requires sulphate, so might present an unacceptable delay. By applying a product which contains sulphur already in that sulphate form, you can immediately guarantee availability in the soil. That product should also contain nitrate (as ammonium nitrate) because both nutrients are necessary for optimal results.”
“Don’t get caught out – sulphur should be a cornerstone of your crop nutrition plan to ensure the highest yields and quality possible.”