PHOTO: HENK RISWICK PHOTO: RONALD HISSINK
FERTILISER TECHNOLOGY ▶▶▶
6 steps to improve your fertiliser use efficiency
I BY RICHARD ALLISON
n a normal season, most farmers will achieve a nitrogen use efficiency of some- where around 60%, says Frontier national crop technical manager Edward Downing.
However, research has shown that 80% is achievable. he believes this is what farmers should be aiming for. So what does 60% effi- ciency look like? Take a wheat crop yielding 8 t/ha with a grain protein of 10.8%. This crop could have typically received 200kg/ha of N fertiliser. “This crop has taken up 190kg/ha to support this level of output and if you as- sume about 70kg/ha is supplied from soil, that leaves 120kg/ha coming from fertiliser,” he says. This equates to 60% of the total ap- plied. Looking at the benefits of improving efficiency, in a situation where nitrogen is lim- iting yield, it will lead to increased output. “If a farmer can increase uptake to get up to 9t/ ha, the efficiency rises to 72% and it brings £160/ha extra margin.” If nitrogen is not limit- ing, improving efficiency to 70% means the farmer can save on fertiliser and apply only 171kg/ha for the same yield and protein. Here are six areas where farmers can improve their fertiliser use efficiency.
1. Other nutrients and soil pH A deficiency in another nutrient can lead to a lower nitrogen use efficiency. One example is sulphur, which has an important role in protein synthesis. A shortage in this macronutrient is linked with poorer nitrogen uptake, Mr Down- ing says. Phosphate is also important for root- ing, and having a good, extensive root network is important for maximising nutrient uptake. “Don’t forget soil pH, as this also affects root development too,” he says. Mr Downing points to lime use in the UK, which has been declining over the past 14 years, and if this trend continues there will be zero use by 2040.
2. Reduce losses as ammonia Another factor hitting fertiliser efficiency is
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Modern sensor technology can measure what the N-requirements of a crop are, or how much N is removed by, in this case, collecting grass.
▶ FUTURE FARMING | 24 May 2019
An average of 40% of the nitrogen fertiliser applied to crops isn’t utilised and could be lost. However, by making small changes to fertiliser use, farmers can reduce these losses and boost margins.
losses from soil. There are two key processes at work here: ammonia volatilisation from ap- plied urea and nitrate leaching. Aside from the environmental benefits of reducing ammonia, Mr Downing believes tackling these losses can potentially save tens of kilograms of fertiliser, which can be a substantial saving. Switching from urea to ammonium nitrate fer- tiliser is one way to eliminate ammonia loses, as it does not volatilise. “Another option is to incorporate urea in soil, but I can’t see this be- ing practical,” he says. Timing is important and farmers should avoid warm, dry conditions when applying urea, as this favours volatilisa- tion. However, urease inhibitors can virtually eliminate this problem, by controlling the
conversion of urea to ammonium. “Perhaps farmers should consider using an additive when applying urea in more challenging con- ditions.” He highlights Adas data showing a 75% reduction in ammonia losses when using an enhanced urea product instead of straight urea. In one Frontier trial, there was a nitrogen use efficiency of 62% with liquid urea-ammo- nium nitrate (UAN). Two different urease in- hibitors were being tested and both increased efficiency to 70%.
3. Reduce nitrate leaching Although nitrate is a very mobile form of nitro- gen, if there is a growing crop present, it will take up the nutrient. Mr Downing says the
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