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Blue Bags Grow Better Crops

Forage Maize

Are you applying the correct amount of fertiliser to your forage maize?


With the nutrient value of organic material varying in its contribution to forage maize, careful consideration should be given to the additional fertiliser added.  Over- supply can impact on the environment and profit margins whilst under- supply may compromise yield and crop quality. 

Take the guess work out of your fertiliser program and use The N-Min® service to provide you with a detailed analysis of the Nitrogen available for your crop throughout the growing season.

Use our fertiliser selector below to find out which fertiliser will best suit your crop and soil needs and access a blueprint for growth.

Start your CF Fertilisers journey today…


pH Level


A pH range of 6.5 to 7.0 is the optimum to cover availability of nutrients in an arable rotation. The field should be limed if the pH is 6.0 or lower. In the diagram below, the wider the band in each nutrient, the greater the availability.


Nutritient Uptake


P, K, status


Soil analysis should be conducted on a rotational basis so that 25% of the farm is sampled each year. Target Index at which crop removal rates of P & K should be made are :

  • Phosphate (P) Index 2
  • Potassium (K) Index 2-

For indices higher or lower than target, adjust rates accordingly as shown in the Fertiliser Manual (RB209)

Once soil index is know use our fertiliser selector to access the best fertiliser system for your needs.


Crop Uptake


To produce a healthy and high yielding crop, maize needs to grow rapidly after germination. To support this rapid growth, it has a large demand for nutrients and any shortage will restrict early growth and final yield. At P index 2, slurry nutrients will not be sufficient, so seedbed P is needed. 





Nitrogen is a key contributor to yield and quality.  It is supplied from:

  • Soil Mineral N (SMN)–soil Nitrogen available for plant uptake
  • Additional Available Nitrogen (AAN) – organic Nitrogen which needs to be mineralised before it becomes available for crop uptake
  • Organic manures – supplying both readily available and organic Nitrogen which requires mineralising before crop uptake.
  • Minor amounts provided by wet and dry deposition
  • Additional fertiliser Nitrogen


Soil Nitrogen supply =

soil mineral N + N likely to be mineralised during the growing season. + Spring Crop N

Nitrogen is the key nutrient for obtaining maximum yield and quality, but calculating the optimum crop requirement can be difficult due to most forage maize crops receiving large amounts of organic manures.  The CF Fertilisers N-Min® service can be used in the maize crop to analyse soil Nitrogen contribution, remove uncertainty and help calculate crop N requirement.

The most efficient form of Nitrogen in the UK climate is Ammonium Nitrate (Nitram®) as proven in the most extensive trial carried out in recent times by Defra in 2004/5.  This NT26 trial series is recognised across Europe as the most credible data on Nitrogen use efficiency and went as far as to state that;

AN remains the best option for UK agriculture and early application of urea did not guarantee reduced ammonia losses.

Defra NT26


Phosphate and Potash

Phosphate and Potash have major functions in crop production, heavy clay soils typically being more Phosphate deficient and medium / lighter soils being more Potash deficient. Potash is the nutrient required in the greatest amount by maize.


Peak uptake of Potash in maize for a 40t/ha crop can exceed 360kg/ha requiring adequate soil reserves and significant Potash application. During maximum periods of growth the maize plant will contain more K than N.




With atmospheric Sulphur deposition now less than 10% of the 1980 levels and most of the UK now getting less than 10kg S03/ha/year from this source, additional fertiliser sulphur now essential in virtually all cropping.

The most available form of Sulphur is ammonium sulphate.  Straight ammonium sulphate contains 21%N, 60% Sulphate and (SO3) is unbalanced in N : S ratio.

  • Applying 50kg Sulphate would only apply 17kg N
  • Applying 40kg N would apply well over twice the Sulphur requirement for maize.

Sulphur has to be applied annually to crops in Spring, as it is subject to overwinter leaching. CF Fertilisers have a range on N:S analysis to suit ratios required.

Whilst maize requires Sulphur in modest amounts, it can be beneficial. Recent CF Fertilisers trials suggest that 20-25kg SO3/ha improves both yield and N uptake. Using a product such as SingleTop 27-0-0(12SO3) at a rate of 200kg/ha is ideal, supplying 54kg N/ha and 24kg SO3/ha.




While still a major nutrient, Magnesium is not typically in deficient supply, but in some regions where Magnesium applications are required and particularly where root crops are in the rotation, Calcined Magnesite is the usual source.

Magnesium is essential for chlorophyll production and hence for photosynthesis. Crop removal is 40kg/ha MgO.

The total amount supplied to maize should be related to the Mg level in the soil and additional Mg is only justified at soil index 0 when 50-100kg MgO/ha should be applied every 3-4 years.

For more information or advice please contact our Crop Nutrition Team on +44 (0)151 357 5758 or email 


How do I arrive at profitable Nitrogen rates?


CF Fertilisers have had 30 years of experience with Nitrogen recommendations.

Our customers who use our advice and services achieve above average yields and if applicable, are able to achieve this extra yield without compromising crop quality.


N-Min® and N-Calc service


Assessing the amount of Nitrogen the soil will contribute to the growth of the Maize crop during the growing season is key to assessing the optimum rates to apply.

A patented analysis makes N-Min® service unique in accuracy of Nitrogen recommendation.

Don't just take our word for it, these farmers have had great results year on year.

A sulphur recommendation will also be provided in a product to suit your system.


So get in touch today to unlock the potential on your farm +44 (0)151 357 3738 or email


Each field on your farm is individual with its own characteristics and nutritional requirements. Follow our step by step guide and unlock the potential on your farm today.

  1. Identify crop to be grown, intended market and crop quality requirement.

  2. Annually use the N-Min® analysis and Nitrogen Calculator (N-Calc) to understand the Soil Nitrogen Supply.

  3. Sample ¼ of the farm each year and analyse for soil pH, P, K and Mg.

    Target Values to maintain in arable rotations  
     Soil pH 6.5 (5.8 on peat soils) 
     Soil P  Index 2
     Soil K  Lower Index 2(2-)
     Soil Mg  Index 2
  4. The N-Min® analysis is the only test that measures both Soil Mineral Nitrogen (SMN) and Additionally Available Nitrogen (AAN) to accurately quantify the Total Nitrogen available during the growing season.

  5. Annually review Phosphate and Potash applications to ensure that optimal levels are maintained. It is important to allow for any surplus or soil deficit situations due to the under or over application of phosphate or potash to previous crops in the rotation.

  6. Use N-Calc to work out the N requirement of Cereals and Oilseed Rape.

  7. Annually check that the fertiliser spreader is in good working order and is calibrated to specific spreading width.

  8. Ensure that accurate records are kept of any fertilisers and organic manures applied.

Contact us for fertiliser advice, our expert team of FACTS qualified advisers are on hand to provide you with the latest advice in fertiliser management and nutrient plans.