No Substitute for Good Agronomy
2011-03-02

When it comes to fertiliser agronomy, timing and spreading are relatively easy to manage but selecting the optimum N rate can be more difficult.

Allison Grundy, GrowHow Arable Agronomist

As ADAS has recently pointed out, the cold winter is likely to have delayed mineralisation of nitrogen from the soil this year. Because of this, ADAS has warned that the results from standard Soil Mineral Nitrogen tests will need to be viewed with extra caution this time as there may be more N mineralising from the soil than usual.

All this suggests that calculating the correct rate will be more of a gamble than ever, but, according to Allison Grundy, GrowHow Arable Agronomist, that need not be the case. “Farmers who use the GrowHow N-Min & N-Calc service do not need to worry about delayed mineralisation. This proven system is designed to measure the N in the sample now and the N which will become available to the crop from the soil over the entire growing season.”

And there is still time to get out and take those soil samples. “Soil samples can be taken now provided no Nitrogen has yet been applied to the crop,” she says. “Any necessary adjustments to application rates can be made at the second split so there’s no need to hold off with the spreader once the samples have been taken,” she adds.

The GrowHow N-Min soil test is part of the proven Nitram plus system which improves farm profitability, provides evidence of good practice and compliance and is good for the environment.

At this time of year everyone tends to review their fertiliser management strategy, but in reality it all boils down to simple, sound agronomy coupled with the right product choice. “This is the blueprint for profit and the environment,” adds Allison.

When it comes to nitrogen product choice, there are different options available such as AN, urea, urea plus inhibitor or UAN. Allison reminds us: “Defra research firmly concluded that an ammonium nitrate fertiliser, such as Nitram, is by far the most effective product under UK climatic conditions.”

She continues: “If you’ve always used urea then using a coated product will reduce the risk of nitrogen losses but beware, depending on what the weather throws at you, these can still be as high as 17%. If you’re an AN user, switching to a coated urea would be a backward step.”

Let’s not forget that all the research on the comparative efficiencies of nitrogen fertilisers was conducted on crops that were managed according to good agronomic principles. “Bad agronomy – in other words the wrong rates, bad timing and poor spreading – will reduce the cost effectiveness of all nitrogen fertilisers,” she concludes.

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