Blue Bags Grow Better Crops


Farming businesses can achieve higher yields and maximise financial margins by choosing the most effective form of Nitrogen for UK growing conditions, and optimising its application, according to CF Fertilisers Ltd.



ISARIA precision fertilizer application


While fertiliser remains a significant crop expense, it also offers the greatest response and therefore potentially the highest return on investment. But to achieve optimum yields and financial margins a number of key factors must be considered, says Allison Grundy, an agronomist for CF Fertilisers UK Ltd.

"It is vital to apply the right Nitrogen type, in the right amount, at the right time, in the right place. The starting point is to choose the most effective form of Nitrogen, which is often an area for confusion. With UK farming businesses under increasing pressure due to low output prices some will be tempted to choose the cheapest source of Nitrogen, but basing this key decision purely on price is likely to be a false economy.

The Defra NT26 project, which investigated a range of Nitrogen sources, proved beyond doubt that UK farmers benefit significantly from choosing Ammonium Nitrate (AN) over urea because the ammonia lost through volatilisation following urea application reduces the amount of Nitrogen available to the crop by an average of 24%, but by up to 43% in arable situations and 58% on grassland.




The researchers calculated that to maintain yields and quality, the optimum N rate when using urea would have to be, on average, 20% higher than for AN.  Because it is impossible to predict N losses from urea exactly, as this depends on factors which are largely outside farmers’ control, using it creates the potential for multiple risks, including loss of yield, lower protein levels, lodging, negative environmental impact and compliance issues in respect of NVZ regulations, negating any apparent 'cost saving'.

Farmers and their agronomists go to great lengths to calculate Nitrogen rates that are specific to individual crops and farm conditions. Newer varieties, such as Skyfall, which have a high potential for yield and quality, require the correct Nitrogen rates, which are potentially above standard levels. Most important is the predictable availability of Nitrogen to the crop, which can only confidently be achieved with Ammonium Nitrate.  Using urea, which is highly weather dependent, is therefore completely at odds with modern Precision Farming systems.


Nitram fertilizer verus Urea



Another issue is the question of Sulphur application. Farmers who use urea to supply the crop’s Nitrogen requirements may have difficulty in applying the correct amount of Sulphur. Some will use Ammonium Sulphate (21N 60SO3) to supply this nutrient, but the balance between Nitrogen and Sulphur is disproportionate. If, for example, you are looking to apply 40kgN/ha as a first Nitrogen application in wheat, then the 114kgSO3/ha Sulphur applied with this product would be way above recommended rates. Conversely a recommended Sulphur rate of 50kgSO3/ha would lead to the under application of Nitrogen, just 17kgN/ha.

Products such as CF DoubleTop® (27N 30SO3) or SingleTop® (27N 12SO3) offer a range of treatments to supply timely crop needs in the correct ratio and to suit your farming system.


Calculating the right fertiliser application rate

A key element in applying Nitrogen is to put on the right amount, which is why following a blueprint of technical advice, products and services represents the way forward for growers looking to achieve optimum results.

While farmers rightly tailor the application of crop protection products to individual farm and crop conditions, when it comes to fertilisers they tend to rely on standard rates from the Defra Fertiliser Manual (RB209). This generalisation is compounded by the fact that fertiliser tends to be sold as a commodity, on a lowest-cost basis and without specialist advice. As a result, famers often end up applying too little or too much of a product , which increases their variable costs without improving yields.

A better approach is to discuss their fertiliser requirements with a FACTS-qualified adviser who is trained to use CF Fertilisers' unique, patented N-Min® Soil Nitrogen Analysis Service. This allows the exact rate of Nitrogen required to be calculated so that it can be applied precisely to maximise crop performance and profitability.

Calculating the optimum level of Nitrogen to apply is complex because it depends on numerous factors, including soil type, organic matter, soil temperature, previous cropping and winter rainfall. Other considerations include current crop, yield and quality expectations, the amount of Nitrogen already taken up by the crop in the spring and many others.

N-Min is particularly recommended for new fields, those with an unknown history, where organic manure has been applied, where the soil contains a high level of organic matter, on farms with diverse soil types and in fields that have grown crops which are known to leave behind large residues of Nitrogen. The best time to take N-Min samples is in the spring, before the first fertiliser is applied and at least six weeks after the last manure has gone on.

Samples are sent to Hill Court Farm Research near Tewksbury where they are analysed for Soil Mineral Nitrogen (SMN) content and incubated to establish the level of Additional Available Nitrogen (AAN). Total AAN is adjusted to account for Nitrogen supplied from the soil at a depth of 60cm to 90cm and allowances made for leaching losses, deposition and uptake efficiency. CF Fertiliser's N-Calc System then uses the Soil Nitrogen Supply (SNS) which includes the N-Min result plus spring crop N, to calculate the optimum Nitrogen input for the target yield which growers are aiming to achieve from cereals and oilseed rape crops.

Measurable Benefits


Drew Smith- N-MinDrew Smith- N-Min


Using CF Fertilisers' N-Min® Service to measure Soil Mineral Nitrogen (SMN) and Additional Available Nitrogen (AAN) has enabled A. W. Smith & Sons Ltd at Withcall near Louth to tailor the application of bagged Nitrogen precisely, producing optimum crop yield and quality as well as reducing fertiliser costs and improving the farm's environmental credentials.

“Since starting N-Min testing in 2013 the benefits have become apparent in terms of making the best use of applied Nitrogen and improving yields," says Drew Smith, who farms just over 1000ha of predominantly silty clay loam over chalk with his brothers Nik and Martyn. "For example, having an accurate analysis of Soil Nitrogen has allowed us to increase the amount of Nitrogen applied to winter barley from 130kg/ha up to 170kg/ha, the additional gross margin being worth £30/ha.

“N-Min is very reassuring because it provides us with the confidence that applying higher rates of Nitrogen will not cause the crop to lodge or increase grain Nitrogen above the level specified by Gleadell Agriculture, who market our grain.

“Although Mother Nature still plays a big part in achieving optimum yields our aim is to give the crop the best possible opportunity to deliver its full potential. N-Min is now a key part of a much more scientific approach to crop management, providing us with a much more accurate picture of soil nutrient status and enabling Nitrogen to be applied much more accurately and cost-effectively.

“By using N-Min we have been able to move from industry-standard fertiliser manual (RB 209) figures to more precisely-tailored Nitrogen applications that are specific to our situation. It has allowed us to take another step forward, given us the confidence to tailor application rates more precisely and both  financially and environmentally it is the right thing to do.


Optimising Application


Neil Wellburn ISARIA user


ISARIA, the latest in variable-rate fertiliser application technology, helps North Yorkshire producer Neil Welburn to optimise the use of fertiliser, increase yields significantly and produce much more even arable crops by automatically varying Nitrogen application. The machine uses two infra-red sensors to scan the crop ahead of the tractor, calculates the optimum application and automatically varies the amount of fertiliser which the spreader puts on.

One of the first farmers in the UK to use the technology, Neil trialled it in 2014 on 250 hectares of owned, rented and share-farmed land across a 10 mile radius. He also carried out a further 1000ha of contract spreading. He states:

“I appreciate the benefits of variable-rate technology and have been varying seed rates by manually adjusting our drill for 20 years. ISARIA is a natural extension of that approach and will have great implications because it does the job automatically.

"The aim of ISARIA is not necessarily to use less Nitrogen but to use it more effectively by applying it to areas where it will produce the greatest benefit. I have been amazed how accurate, versatile and easy to use the system is, and by the results.  There is no doubt that it represents the way forward.”

The ISARIA machine comprises a 6.9m-wide boom which is carried on the tractor’s front linkage and incorporates two infra-red sensors, each of which scans a 50cm-wide strip of crop and measures reflectance within the leaf, regardless of crop type or variety. Once the correct boom height is achieved the in-cab display shows two green bars, which turn red if the boom height falls out of its pre-set range, approximately 1m above the crop. Data from the ISARIA sensing heads is transmitted to a tablet computer in the cab via Bluetooth, thereby avoiding the need for cables running along the side of the tractor and into the cab. This information is then used to automatically control a fertiliser spreader or sprayer which is equipped with a variable-rate facility, via the tractor’s ISOBUS system.