Benefits of using an inhibitor when applying digestate

Farmers applying ammonium-rich fertilisers such as digestate should consider using a denitrification inhibitor to make the most of the nitrogen applied.

Digestate is increasingly seen as a valuable nitrogen fertiliser replacer and is applied in spring to crops including winter cereals, grass leys and maize.

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However, Agrovista crop nutrition specialist Chris Martin explained that 90% of the nitrogen in digestate is in the ammonium form.

While it is an efficient form for crop uptake, it can easily break down and be lost as nitrates through leaching and as nitrous oxide emissions.

By using an inhibitor such as Instinct, farmers can keep the nitrogen in soil for longer, offering a longer-term nitrogen supply supporting stronger growth.

How it works

Instinct is a micro-encapsulated nitrogen stabiliser containing nitrapyrin. It slows down the nitrification process – delaying the conversion of ammonium into nitrate for eight to 12 weeks. This stabilises nitrogen in the root zone, reducing losses and improving the timing of nitrogen availability.

Therefore, Chris believes growers using digestate should consider applying Instinct to get the most out of the organic nitrogen source.

Another part of crop nutrition where farmers can make savings is with phosphate, by making use of the huge reserves in soil.

He highlighted that grain analysis at the site, like many other farms, showed P levels are below the critical 0.32% despite soils being well above the 16ppm guideline level with the Olsen test. “There is plenty in soil, but it is not getting into the grain.

P reservoir

The problem is that phosphate is immobile and is incredibly reactive, becoming fixed with metal cations like calcium. Many farmers will apply fresh phosphate, but there is a huge reservoir in soils like that at Lamport.

Calculations based on soil analysis suggest there is 4,744kg/ha of P in the top 15cm. With TSP priced at £598/t, this equates to about £6,168. Yet farmers will apply imported phosphate, which quickly becomes unavailable.

Therefore, Chris advises using Phosphorus Liberator in the autumn to release this locked up P to establishing crops.

It is a soil-applied biostimulant designed to dissolve and release phosphorus and manganese that are naturally locked up in the soil, making them immediately available to crops.

Based on carboxylic acid, it breaks down the calcium phosphate bonds and keep the nutrients in a highly accessible solution. Then in spring, farmers can use a foliar product like Luxor, which is formulated to get into the leaf.

He says by taking this approach, farmers can save around £70/ha over the traditional use of TSP.