Getting the most out of nitrogen has seldom been more important – especially given the cost of fertiliser and low commodity prices.
In simple terms, Nitrogen Use Efficiency (NUE) describes how well available nitrogen is converted into grain yield.It’s fast becoming one of the most important metrics in agriculture, says Tom Land, national fertiliser manager for Agrii.
“NUE from conventional fertiliser practices is typically in the region of 50-60% but there are many ways this can be improved with 70-80% being a realistic target on many farms.”
Profound effect
In most production systems, most nitrogen taken up by crops comes from the soil – which canhave a profound effect on NUE, says Mr Land.
“Compacted soils make root development difficult, poor drainage can contribute to soil pH changes and poor overall nutrient status can interfere with the soil biome and its ability to make nitrogen available to plants.
“Increasing organic matter, for example, can have a massive effect on nutrient uptake and judicious use of organic inputs such as farmyard manure can play a leading role in this, but be mindful of the government’s Farming Rules for Water.”
Cover crops can help improve soil structure and rooting performance through encouraging greater root depth and mass in the short term but longer term they can add vital nitrogen fixing capability, build organic matter significantly and reduce nitrate leaching, says Mr Land.
“Paying attention to field drainage and soil pH and remedying where necessary, is also important.”
Crop choice has a massive effect on fertiliser need so if reducing nitrogen requirement is a key commercial objective, it might be worth revisiting rotations to see if changes can be made to facilitate this, he points out.
“If nitrogen levels are sub-optimal, tiller loss may result which can severely compromise yields subsequently. Seed numbers can be increased to address this and Rhiza/Contour can help in determining the correct rates to use.“
Root boost
“In such situations it’s also worth considering root-boosting agronomic interventions such as early PGRs, foliar nutrition and the urease and nitrogen stabiliser Liqui-Safe.
“Liqui-Safe has been shown to improve NUE by 15% through reducing nitrogen losses to the air and preventing leaching. In recent trials, Liqui-Safe added nearly a tonne to winter wheat yield over UAN by itself – and produced an return on investment of over £170/ha.
“Agrii-Start Release can also improve the efficiency of your fertiliser use by helping prevent phosphate lock-up and making other nutrients more available at the same time.
“Use of AgriiStart Enhance granular urea to ensure nitrogen is protected and stabilised so volatilisation, leaching and nitrification are reduced, will also help improve NUE.
“It’s also important to ensure potassium is balanced with nitrogen to allow maximum affect from applied nitrogen. Sulphur is important in the NUE equation too, with polysulphate being a good source of both sulphur (48% S03) and potassium (14% K2O) alongside calcium and magnesium.”
Strategic use of Biosolutions as part of an integrated agronomy programme can help increase NUE through enhancing the plant’s response to macro nutrition, fungicides and PGRs while enabling the plant to search out available nutrition more efficiently, adds Mr Land.
Building yield
“Biosolutions can stimulate plants to use nutrients to build yield and quality at the same time as alleviating stress responses. They can also help boost Green Area Index – trapping nitrogen reducing fertiliser requirements and boosting return on investment.
“Humic acid-based seed treatments, for example, have been shown to deliver £3 back for every £1 spent due to improved nutrient uptake, enhanced levels of chlorophyll and better tolerance to abiotic stresses.
“Nutriphite PGA and Quark also stimulate similar responses in crops along with other agronomic benefits while Physiocrop, a mineral based fertiliser based on vegetable-derived amino acids, has also proved very valuable in this regard.”
Growth and health
Improving rooting is key to maximising NUE and fungicides such as strobilurins and SDHIs have a well-documented effect on plant greening, growth and health, he says.
“Pyroclostrobin is particularly effective and now Architect, for example, takes this a stage further in rape with well-researched benefits to root growth. Trials with Architect have, in fact, shown a doubling of root mass over untreated in rape crops and this has been replicated in the field with root mass and rooting depth being significantly improved.
“Early season PGR use in cereals can also improve NUE with Alatrin, with Evo showing particularly strong performance in cold conditions.”