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Growers are being advised to plan soil nitrogen sampling earlier in the season in light of changing conditions brought into sharp focus by the... New emphasis on accurate soil nitrogen analysis

Growers are being advised to plan soil nitrogen sampling earlier in the season in light of changing conditions brought into sharp focus by the 2019/20 growing season.

Climatologists agree growers can expect more extreme weather and variable growing conditions – making accurate and timely analysis of soil nitrogen an increasingly important element of on-farm risk management planning.

While 2020 saw the worst harvest of the last 25 years, the UK Centre of Ecology and Hydrology says the extreme conditions behind it are likely to become more commonplace in the UK over the coming years.

“Soil nitrogen content varies widely year on year depending on the weather,” says Ross Leadbeater, of CF Fertilisers.

“Accurate analysis of this is a vital starting point in planning fertiliser applications accurately so nitrogen utilisation and cost efficiency of production are maximised and potential environmental impacts minimised.”

Many variables

At a time when farm inputs are under the spotlight, Mr Leadbeater says standard general assumptions are increasingly invalid. Accurate soil testing is the only way of ensuring fertiliser is being used responsibly, he argues.

“This is also of growing importance in light of the use of organic materials and manures now being used more in arable production systems which throw another variable into the crop production mix.”

Relying on Soil Mineral Nitrogen (SMN) is insufficient to plan fertiliser applications accurately, says Mr Leadbetter. Instead, measuring total Soil Nitrogen Supply (SNS) is a more suitable assessment.

“SNS takes into account nitrogen that will be mineralised and made available to plants as the season develops whereas SMN is just a snapshot of nitrogen in the soil at the time of the test.

“Without taking into account this extra soil nitrogen, growers risk applying too much or too little fertiliser and in the modern world of responsible crop production and fertiliser use this is simply unacceptable.”

Other improvements include a partnership between CF Fertilisers and agri-environment research specialists Envirofield to create a nationwide network of technicians to plan programmes with farmers and carry out any necessary testing.

“We want to make the N-Min test as simple and widely accessible to as many people as possible so our new service takes the responsibility for sampling away from growers and puts it in the hands of specialists with professional soil sampling kit.”

To encourage growers to take advantage of the new service, those booking tests with CF Fertilisers before the end of the year will be able to save money by getting four tests for the price of three.

Cost-effective service

“Considering our trials over the last few have shown increases in Margin over Purchased Fertilisers (MOPF) ranging from £60 to £280/ha from the improved fertiliser utilisation resulting from N-Min, this makes the service more cost-effective than ever.”

Further developments include the addition of a new protein prediction test. This is designed to allow premium wheat growers to fine-tune their final fertiliser applications and maximise yields without sacrificing milling quality.

“Protein levels can be diluted as yields rise and this can be an issue with modern high yielding milling wheats,” says Mr Leadbetter.

“The new test – developed and provided by Hill Court Farm Research – identifies the amount of protein likely to be contained in grain at harvest so final nitrogen applications can be fine-tuned to meet quality and yield targets.

“The beauty of the new test is that you can sample as late as mid May to mid June and then be able to adjust final fertiliser application to make up any potential quality shortfall identified or cut it out and save money if all is looking good.

“It’s proven to be highly accurate and reliable in the last three years of trialling and will now become widely available to UK growers in 2021. All in all, it means there are significant advantages to planning your new season soil N-testing early.

“With soil nitrogen testing usually taking place in late January and February, growers really need to start making plans for these well before Christmas rather than rushing things in the new year.”

Arable producers wishing to find out more about CF N-Min and the range of CF Fertilisers Nitrogen management services can find out more by visiting the CF Fertilisers UK website at