National UK farm trials confirm superiority of soil nitrogen n-min test

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N-Min test predicts exact soil N reserves nearly 80% of the time compared to less than 50% for SMN

Significantly more precise than SMN or RB209 estimates in all cases

 CF N-Min test is the most accurate starting point for optimising N-use efficiency

A series of national farms trials has shown CF N-Min is the most accurate method of measuring soil Nitrogen reserves by a significant margin when compared to simple soil mineral nitrogen (SMN) testing or using RB209.

Carried out by CF Fertilisers, Agrii and Frontier across nearly 50 farms representing more than 20,000ha of UK arable production, the trials show CF’s soil Nitrogen N-Min field test accurately predicts precise soil N reserves in nearly 80% of cases.

This compares to 45% with SMN and just 33% with the RB209 Field Assessment method.

“These are critically important results,” says CF head of agronomy Dr. Sajjad Awan. “At a time when all producers are being asked to be as responsible as possible with their Nitrogen use, accurate assessment of what N is in the soil to start with is essential.

“Without this, inadvertent over-application is a real possibility and, in addition to the obvious environmental concerns associated with this, efficient N use is more important than ever when fertiliser prices are high.

“Looking at Nitrogen take-off in the crop and the amount left in the soil after harvest, N-Min was 100% accurate nearly four out of five times and significantly more precise than either SMN or RB209 estimates in all cases.

“Bearing in mind N-Min is a field-based test with many variables in play including increasingly volatile weather conditions throughout the growing season, this is an astonishing level of accuracy and one growers can have real confidence in.

“Across the farm, such accuracy represents a significant opportunity for margin improvement, not just from a potential reduction in fertiliser use but also from ensuring high performance crops receive the vital N they need.”

AAN and unique dataset key to N-Min accuracy

The consistency and accuracy of N-Min compared to other assays, lies largely in its prediction of additionally available nitrogen (AAN) underpinned by a unique dataset, he explains.

“An SMN test gives you a snapshot of what N is in the soil at the moment of the test, whereas N-Min test also calculates what has already been taken up by the crop and what N is likely to mineralise in the soil during the season.

“Putting all this together gives you the total soil nitrogen supply (SNS) which is the only way you can reach the correct starting point for calculating the remaining N needed to hit yield and quality requirements.

“Furthermore, N-Min’s final calculations are based on more than 25 years of data which allow it to make the correct adjustments for key factors such as soil type and other specific farm characteristics.”

Financial and environmental benefits

Although the N-Min test costs more than a simple SMN test, the return on investment from the improved accuracy can be substantial, Sajjad Awan adds.

“It’s not just about reducing N inputs, you’ve got to factor in the possible lost farm income from not allowing high performance crops to perform to their full potential or the financial penalties resulting from missing premium market specifications.

“Five years of trials suggest the improvements in margin over purchased fertiliser (MOPF) from using N-Min as a base for planning fertiliser applications average around £210/ha but can be as high as £300/ha.

“But the benefits extend far beyond on-farm financial gains and include several significant environmental advantages as result of optimised N applications. These include reduced losses to the air and water plus a lower carbon footprint.

“The more efficient we can be with Nitrogen applications, the better it is for everybody and, as these results confirm, the best way to start this journey is with CF N-Min.”

Further information of N-Min including how to book tests can be obtained from:




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