Growers applying slurry or liquid digestate ahead of spring-sown crops, such as maize, have a new option for improving the efficiency with which crops take up and use this valuable source of nitrogen.

Vizura is a nitrification inhibitor designed for use with slurries or digestate and is available exclusively through knowledge and input suplly company, Hutchinsons, this season.

It works by delaying the natural conversion of ammonium to nitrate, thereby keeping nitrogen in a more plant-available form for longer, and reducing potential losses from nitrate leaching and nitrous oxide emissions to the atmosphere.

According to manufacturer, BASF, it takes around six weeks for ammonium to be converted into nitrate at low soil temperatures (5°C), but just one week at 20°C. However, Vizura can extend these conversion periods to 10-14 weeks and 4-6 weeks, respectively.

This gives more time for young plants to directly assimilate the ammonium form of nitrogen for protein synthesis and other vital plant functions, without having to use valuable energy converting nitrates back into ammonium inside the leaf.

Hutchinsons crop nutrition manager, Tim Kerr, pointed out that this improves overall nitrogen use efficiency (NUE), which in turn benefits yield. Trials in maize have found a typical yield increase of 5-7% is possible from using Vizura, giving an average return on investment of 3:1. One Hutchinsons trial in 2019 showed a yield increase of 2.5 t/ha of dry matter.

He stressed the particular importance of maximising the nutritional benefits from slurry, or digestate applications in maize given the N-Max and RB209 guideline of 150 kg/ha is considered to be insufficient for modern high-yielding varieties.

“Also, maize requires more than half of its nitrogen post-flowering, yet late fertiliser applications are difficult without damaging the crop or using specialist equipment, therefore it is vital to get as much value as possible from earlier applications.”

The ability of Vizura to reduce leaching risk has obvious environmental as well as financial benefits and is likely to be particularly important where high amounts of nitrogen are applied early onto light soils or where ground may become saturated – often an issue in wetter maize-growing parts of the country.

Mr Kerr added that maximising the uptake efficiency of ammonium fertiliser can have other key benefits. These include lowering the pH around the roots which improves availability of phosphate and micronutrients; encouraging root growth; and increasing the plant’s resistance to stress.

Vizura is available through Hutchinsons in 10-litre cans and should be metered into the spreader or out of the storage facility via a dosing pump. It has been formulated for a low application rate of typically two litres per ha.