There has been a lot of talk lately about emissions and while on the one hand Ireland has been somewhat vilified for falling behind EU targets, new research on maximising nitrogen efficiencies seems to point towards a solution.
A European Parliament report last week found Ireland's agri-sector to be the largest contributor of greenhouse gases amongst European farmers with “highest level of greenhouse gas emissions per euro of agricultural output of 28 member states”. While this has something to do with the way in which the study was conducted, it is also an undeniable reality that we will need to face.
Last year, as the Paris climate talks approached, Irish representatives tried to get a deal for offsetting farming emissions with new forestry schemes. This was turned down on the basis that Europe expects every sector to increase its efficiency and reduce its greenhouse gas emissions. At that time Commissioner Miguel Arias Canete said “The message from the Commission is that all the sectors should contribute. It’s up to the member state to establish the balance according to the possibilities and the mitigation potential of each sector.”
The study did acknowledge that Ireland is managing to increase productivity while keeping emissions from rising, and that our investment in agricultural research and development is the highest per capita in Europe. A spokesperson for Department of Agriculture tried to play down the significance of the report's findings: “While greenhouse gas productivity per euro is a widely-accepted indicator at international level to monitor green growth, it is not a measure of a typical carbon footprint per unit of agricultural output, and so should not be interpreted to mean we are the least climate efficient.”
Europe wants to cut total emissions by 40% by 2030. At present, Ireland's farming sector is on track to maintain current emissions levels at best, with a slight rise more likely. As pressure increases to find ways of reducing the carbon footprint of Ireland's agri-sector, new technologies are going to play a central role in any success we achieve.
Reducing Nitrogen Waste
A paper published last year investigates the possibility of reducing nitrous oxide emissions from slurry and fertilizers. According to its authors, nitrogen uptake by plants in laboratory conditions can be 45-65%, while on-farm uptake is often below 40%. Scientists are trying to discover why there is such a difference in uptake, as by bridging this gap they know farmers can reduce their fertilizer costs, as well as emissions from harmful nitrous oxide gases.
One of the ways in which this can be done is by pin-pointing plant needs and offering only the nutrients required, as quickly as possible. Timing is therefore the key here. The 4Rs nutrient stewardship principle is applied here, which means using “the right nutrient source, at the right rate, right time and in the right place to achieve the basic economic, social and environmental elements of sustainability.”
Using technology in the field is becoming more and more common. GPS and GIS are now standard tools on modern machinery, and they provide a technological platform from which more efficient systems can be built. US researchers have achieved remarkable results using nitrogen sensors from which they reduced the need for nitrogen application on maize by 10-50kg/ha. Indeed Yara's N-Sensor is already used on over 1.2m hectares of EU cropland.
Cover crops are another method of reducing nutrient loss and balancing emissions. Winter cover will minimise erosion, build organic DM, boost worms and may trap excess nitrogen, but some studies have suggested limitations and variabilities in their effectiveness, depending on conditions and soil type. So a tailored approach may be needed.
Another problem farmers currently suffer are losses in nitrogen content of slurry from a phenomenon called volatilisation of ammonia, by which slurry, manure or urea evaporates on warm days. Teagasc have also investigated this problem and concluded that “Volatilisation represents a loss in terms of soil fertility and causes negative environmental impacts by contributing to eutrophication and acidification of water bodies.”
The important lesson is that no single solution will work alone. It will take a combined application of better practice, broader awareness and informed use of slurry and nitrogen to increase overall efficiency and reduce emissions.