- Yara’s Agronomy Operations Manager Natalie Wood advises the early application of nitrogen and other nutrients is essential for autumn grown crops
It was a wet and very cold end to 2022 for many areas across the country. With rainfall figures as much as 20-30% above average for the time of year, many UK farmers have had to contend with waterlogging. The potential for waterlogging-related plant root rot and nutrient loss is a serious risk in the current economic climate. That’s why the early application of nitrogen and other nutrients is essential for Autumn grown crops.
Yara’s Agronomy Operations Manager, Natalie Wood explains, “The problem with rainfall is that when you’ve got crops sitting in that anaerobic wet environment, you do start to lose some root mass. So the secondary roots, or the seminal roots, start to rot and die away and you are left with the adventitious roots which are the more shallow ones. If we’re left with just the shallow roots, it will affect that crop’s ability to take up nutrition and water further down the line.”
If crops have suffered waterlogging, it’s likely their roots won’t be long enough to take up moisture from the soil in the event of a dry Spring. According to Natalie, early application of nitrogen is key to helping the plants’ root system recover.
“Nitrogen is the first port of call for trying to recover that root system. Applying the right rates of nitrogen early will also replace lost nutrients from the soil.”
Natalie recommends applying a higher rate of nitrogen (between 70 and 100kg) for the first application in mid-February if conditions allow.
However, it’s not just nitrogen that has a role to play in healthy root development and healthy crop growth. Phosphate and sulphur are also key components in crop nutrition.
Phosphate is important for root development and for energy transfers within the crop. Every plant process requires energy and phosphate is part of that. Given that phosphate availability is fairly poor in cold, wet conditions, an application of the nutrient in an NPKS fertiliser for example gives the crop an immediately available source to help rebuild the root system.
Sulphur is also key – it has a close relationship with nitrogen, and without a sufficient supply of sulphur, there won’t be an efficient uptake of nitrogen.
For farmers who aren’t sure to what extent their crops have been affected by waterlogging, Natalie believes there’s no substitute for getting out into the field and looking at the situation.
“If the roots are white and fresh, that root is actively growing and you know that it’s healthy. If they are a dull colour, off-white, or brown, it’s a sign that they probably have been affected by waterlogging.”
Given the current cost of crop production, losing nutrients through leaching or run-off is something every farmer wants to avoid.
As well as ensuring good nutrition for crops, building up organic matter can help the soil retain moisture and nutrients. It also gives it a better structure overall, which helps with conditions like compaction.
However Natalie emphasises this is not a quick process. “Even with repeat applications year on year, building up organic matter can take as long as ten years. With the predicted climatic trends, particularly of drier Springs, it’s worthwhile focussing on soil structure to minimise any risk to the crop.”.
“If farmers are using urea or straight nitrogen as their nitrogen source, there’s the question of how they are going to ensure crops are getting enough sulphur, not to mention phosphate and potassium,” adds Natalie.
With urea use, there are also environmental considerations. In terms of emissions, urea is the highest emitter of ammonia which is associated with damage to plant and animal life, as well as to human health. Come 1st April 2024, it will be mandatory to use an inhibitor with any kind of urea product to reduce emissions. Natalie says that ultimately, the best way farmers can ensure adequate nutrition and a healthy crop yield is to try things and see what works for them and their farm.
“What we don’t want to do in a year when the economy is like this, is start experimenting with other potential sources of sulphur that you might not be used to, or potentially other products like bio-stimulants. I’m not saying don’t try them, but it’s not a year to go full farm scale with those. Just test them, because what we don’t want to do is reduce yield.”