Impact of tillage crops on the environment

Reducing the impact of tillage crops on the environment largely revolves around the reducing nitrogen inputs. Nitrogen accounts for approximately 80% of all greenhouse gasses (GHG) from tillage production. Where chemical nitrogen can be reduced, then GHG emissions will fall. 

Signpost Programme Targets

The Signpost Farms program has set targets to reduce the greenhouse gas emissions from farming systems. We have to bear in mind the tillage sector is the lowest GHG emitter compared to the livestock sectors. Where GHG reduction can be made in tillage, the overall savings will be small to the national inventories. That being said there are a number of areas where tillage farmers can focus on which include both decreasing the amount of chemical fertiliser applied and also ensuring applied fertilisers are placed accurately and in the right part of the field.

Perhaps it’s fortuitous for the Signpost farms targets that the cost of nitrogen has increased enormously over the past 6 months. This will discourage applications but on the other side of the coin is that the high costs will hit farmers profitability.    

Tillage farmers growing cereal would generally expect a return of close to 12 kgs of grain for every 1 kg of nitrogen applied. Obviously this is a massive return on money but this is not a linear relationship as in crops yields are limited. This means you get a very high return for money spent for say the first say 60 – 70 kgs of nitrogen per hectare where as the return will be much less for the final 40 to 50 kgs of nitrogen per hectare. The calculation as to the returns for nitrogen has changed as fertiliser prices have increased and the return is now closer to 6:1.

Most economic amount of nitrogen

We can calculate the most economic amount of nitrogen to be applied based on trial results comparing yields to increasing nitrogen rates. At the moment when we look at a CAN price of €700/tonne and a grain price of €250/tonne the recommendation is to reduce fertiliser applications to wheat by -26 kg N/ha and barley by -22 kg N/ha. Where the costs of CAN increase to €1,000 per ton, with the same grain price, then we recommend reducing nitrogen on wheat by -53 kg N/ha and barley by -44 kg N/ha. Applying nitrogen above this level will be uneconomic i.e. for every euro spent on nitrogen you only get back the equivalent value of grain. Reducing the nitrogen input will also reduce the GHG emissions from the crop!

Precision application of fertilisers

Precision application of fertilisers is critical both agronomically and also based on costs.  Even application across the crop will prevent lodging and ensure the best utilisation of nitrogen in terms of grain yield. It is also important to ensure the fertiliser is applied to the growing crop only thereby minimising leakage to the field margins. Ensure your spreader is serviced and properly set up. Check the height above the crop, the spreader veins are in good order, and ensure you have the correct machine settings dialled in for the fertiliser you are using. Finally check the deflectors on your spreader to ensure fertiliser spread into field margins are minimised.  Its always good practice, and now more worthwhile than ever to complete a tray test in the field to check for evenness of spread.