How to reduce nitrogen losses and boost soil health

Cutting all three sources of farmland nitrogen loss, boosting both soil fungal activity and crop performance, and improving operating efficiencies in one simple, highly cost-effective step?

Far from a pipedream, this is the sustainability-maximising reality of a specialist nitrogen stabiliser for liquid fertilisers proven in extensive UK trials over the past three seasons by
Agrii with Verdesian Life Sciences.

Research at the John Innes Centre, NIAB TAG, Wessex Water and Campden BRI as well as Agrii Technology Centres and iFarms has highlighted marked increases in Nutrient Use Efficiency (NUE) from the stabiliser’s unique combination of urease and nitrification inhibitors. These have led to valuable improvements in crop yield and quality as well as machinery and labour use, and – every bit as importantly – environmental impact.

“The key challenge in farming today has to be to get more from less,” stresses Agrii nutrition technical manager, Tom Land. “Especially so with the imperative of reducing the carbon footprint of our production. We can only do this by understanding the science behind key elements of crop management and applying it in the most effective ways.

“We have been working with the nitrogen-stabilising technology of the Liqui-Safe added to our Agrii-Start fertiliser range this season in a sister product (Enhance) for more than 10 years now.  Replicated trials across a wide range of crops highlighted its value in both increasing the Nitrogen Use Efficiency (NUE) of urea fertilisation – measured in higher yields and milling wheat N contents – and in enabling the number of passes to be manipulated.”

By slowing down the rate at which urea is converted to ammonia in the soil, Liqui-Safe’s urease inhibitor reduces ammonia losses to the atmosphere from standard urea ammonia nitrogen (UAN) liquid fertilisers by as much as 25%.

In parallel, its nitrification inhibitor delays the bacterial conversion of ammonium to nitrate to more closely match crop uptake. This has led to a halving of atmospheric nitrous oxide emissions in some cases, together with reductions of between 14% and 54% in soil nitrate leaching, depending on conditions.

Compared to standard UAN applications, development work has also shown a 10% increase in mycorhizzal fungi colonisation in the soil. What’s more, no adverse effects have been found on earthworms or aquatic organisms even at 10 times the recommended dose rates, and Liqui-Safe naturally degrades to carbon, hydrogen and oxygen in the soil; altogether, an enviable environmental profile.

“Liqui-Safe is unique in bringing both key components of improved liquid urea NUE together to maximise overall benefits,” explains Mr Land. “And it does so with a much better environmental profile than traditional inhibitors thanks to its naturally-based organic acid make-up.

“Our long experience with Enhance and results from hundreds of manufacturer trials – including more than 40 in the UK and Ireland – gave us confidence in the product’s crop and environmental improvement abilities from the outset.

“On top of this, we saw it having even more to offer in enabling liquid fertiliser users to avoid tying-up sprayers during critical fungicide and PGR timings. And, at the same time, reducing the need for fertiliser applications during the window where scorch is more prevalent. So, our most recent trial work has explored the extent to which Liqui-Safe could allow the number of passes to be reduced.”

Conventional three-split application trials undertaken by NIABTAG at Morley in 2019  showed an impressive wheat yield improvement of 7.4% from including the dual-action nitrogen stabiliser, together with an uplift of 0.6 percent in grain protein.

Alongside this, iFarm strip trials found no difference between wheat performance from standard three-application farm regimes and those applying all the N with Liqui-Safe in a single early season pass in either 2018 or 2019.

The results were even more impressive in replicated Agrii field trials with Skyfall in last season’s very dry spring and early summer. Here, there was no discernible yield difference between the same 200kg/ha of nitrogen balanced with sulphur applied in a standard late-March, early April and mid-May programme without Liqui-Safe and at just the first and third timings with it.

However, applying all the nitrogen with the stabiliser at the first timing alone raised yields by over 9% from an average of 10.8 t/ha to 11.8 t/ha. This gave a margin over input costs of more than £110/ha before accounting for any savings in machinery and labour costs.

“All the evidence shows that Liqui-Safe offers really valuable economic and environmental sustainability benefits for liquid fertiliser users,” Mr Land concludes.

“Applied at a standard 0.5% by volume, its improved efficiency of UAN utilisation means an average 4% cereal yield increase can be expected from current nitrogen application strategies, with similar gains in other field crops. Alternatively, of course, it enables yields to be maintained at lower overall levels of N use.

“At whatever fertiliser rate, the full benefit of the product, though, comes from enabling all the season’s nitrogen to be safely and efficiently put on in a single, early-season application.

“Apart from taking the pressure off the sprayer at its busiest time, this cuts labour and machinery costs, ensures sufficient nitrogen is available to crops even if conditions turn dry, and eliminates any scorch risk from later applications. It’s a real winner whichever way you look at it.”