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Smarter fertilising results in lower costs


Photo: Trond Henriksen

In recent years fertiliser prices have risen dramatically. Each farmer must make use of good agronomy to keep the costs down and production up.

To take advantage of the yield potential in grain fields, it is important to make good use of mineral fertiliser and organic fertiliser in addition to crop rotation, integrated plant protection, good soil structure, the right pH, and the composition of topsoil.

NIBIO has investigated the effect of nitrogen on oats and barley by adding the entire amount of nitrogen in spring versus split application where some nitrogen is given in the spring and the rest as partial fertilising. The researchers recommend 8–9 kg of nitrogen per acres in the spring and the rest as partial fertilising. This makes it possible to adapt fertilising to the growing conditions beyond the season.

The results show a yield increase up to 12 kg of nitrogen per acres, but no noticeable yield increase when fertiliser amount increased to 16 kg nitrogen per acres. This means that 12 kg was enough, even at a yield level of over 600 kg of grain per acres. This matches well with the fertiliser standards in NIBIO’s fertilising handbook.

There are big savings to be made by taking advantage of the soil’s stored phosphorus resources. If the soil is rich in nutrients and loamy, you can under-fertilise with phosphorus for a year. This is positive in terms of economy and the environment. At the same time, you should aim for a high humus content in the soil which provides good conditions for root growth and nutrient uptake.

NIBIO has also investigated organic waste to see how the nitrogen becomes available for the plants. The studies show that in solid waste the nitrogen was present in organic compounds, while as ammonia in liquid waste. The amount of nitrogen that is released from different types of waste varies considerably, but they all have in common that the rapidly available nitrogen fraction is released after 10–20 days.