CF Fertilisers Advice self auditing is helping keep Nitrogen applications in line with crop requirements so farmers can have confidence in the advice they receive, says Senior Farm Adviser Dave Towse.
Have you reached your targeted yield and quality this season? It’s an important question. Factors outside farmers’ control will always play a part – such as the hot dry period we experienced in late June this year, but that just makes it more important than ever to get the things you can control right.
Knowing exactly how much Nitrogen to apply is key. That’s why we’ve been putting so much time and effort into checking the advice we give is as accurate as possible.
Just ahead of the combine, our Advisers around the country were busy taking crop samples. We revisited a number of N-Min fields, which were soil sampled for Nitrogen in January/February and the results used in the CF Fertilisers Nitrogen Calculator to calculate the optimum application rate. What we were looking to do this time was to take a representative sample of the whole crop so that we can understand exactly how much Nitrogen it contained. “This is the last piece in the N balance jigsaw needed to check the accuracy of our recommendations” says Dave Towse, Senior Farm Adviser (North & East).
During the N-Min season, the CF Fertilisers N-Min Service measures upwards of 3000 soil samples from all across the country. This gives us valuable information on how much Nitrogen is available and what will become mineralised through the breakdown of organic matter during the spring. This information is then used within our N-Calculator and EnCompass planning software to calculate the crop’s fertiliser requirements by taking account of target yields, end market requirements and any additional nutrient contributions from applied organic manures.
“By sampling the crop at harvest time and analysing crop N uptake we can calculate how much N has been removed in total from the system. We know how much was in the “crop and soil”, how much fertiliser was applied in the spring, and how much N the crop used at harvest. A simple balance calculation can be made which informs us of the accuracy of the recommendation” says Dave.
CF Fertilisers began this self-auditing exercise back in 2005 to improve the advice and interpretation of the N-Min service. Each season we have used the data to improved our recommendations and learn more about how crops respond to Nitram fertiliser.
Good crop balances depend largely on the supply of Nitrogen to the crop but what CF Fertilisers know is that those crops supplied with the correct balance of nutrients perform the best. The crops most at risk of underutilising N are milling wheat and oilseed rape especially if they don’t receive an annual application of Sulphur. N offtake at harvest can be reduced where Sulphur isn’t applied leaving a supply of N in the soil at risk of leaching. “Nitrogen efficiency is much improved when Sulphur is applied, because both N and S are major constituents of protein, a lack of one or the other reduces the crops ability to build yield and achieve grain protein specifications” says Dave.
The deposition of Sulphur from the atmosphere has reduced by more than 90% over the last 40 years and at the very most amounts to around 25kg SO3/ha. Therefore we have to make an annual application to make up the shortfall. However in a recent study it was found that nearly one third of farmers are still not applying Sulphur to oilseed rape and nearly half of those growing wheat.
Alli Grundy, CF Fertilisers Agronomist reminds us that, “Sulphur is an essential element which increases and protects yield whilst promoting crop quality and therefore it is important to be aware that Sulphur deficiency only affects the youngest leaves”. Mistakenly applying more Nitrogen in an attempt to correct the problem will only make the deficiency more severe, so it is important to make a correct diagnosis. To make the correct diagnosis it is recommended to use the Malate Sulphate tissue test in spring. Sample 15-20 youngest leaves when the crop is actively growing but early in spring to understand the status of the crop.
Soil type can be an easy indicator to the risk of being Sulphur deficient, the table below shows the likely risk of different….
There are a couple of ways which Sulphur deficiency can be corrected:
- Always in the spring
- Applied in the most available form
- Using one product strategy such as SingleTop – applying little and often
- Use DoubleTop in combination with Nitram in one application
- Use SulphurGold in combination with Nitram in two application.
For more fertiliser advice contact our Crop Nutrition Team.