In the last issue in December I presented the ongoing slide in cereal area since the famine. However, it is likely that the area decline, from over 1.85m hectares to just over 400,000ha, had much less of an impact on total cereal production. That 1.45mha represents a 78.3% area reduction, but increasing yields and productivity over the period helped to keep total cereal output up at close to 2.5mt per annum.

But the famine was a long time ago, so I am choosing the period since 1980 to look more closely at the falling area and its associated consequences.

The lost hectares

In 1980, there were 634,420ha of the main crops on the island of Ireland. This fell by 232,822ha up to 2019 (Figure 1).

Most the reduction came from lower barley area (-218,557ha), wheat area increased slightly but potato area was down (-44,599ha). However, these hectares were not lost from agriculture and most of the transfer up to 2015 went to beef and sheep, and almost totally to dairy after that.

This area reduction removed the potential to produce an additional 1.5mt of native cereals today. While that would not fill the feed tonnage deficit, it would put a sufficient dent in it to make it easier to verify that our current livestock production is being fed with ‘Irish-produced ingredients’. The importation cost of replacing that grain might be put at €200/t on average, to give an annual importation cost of €300m.

While the livestock sector has been largely indifferent to the loss of this grain as a feed ingredient, it seems more sensitive to the loss of the straw.

This has heightened fodder shortages in some years

Assuming roughly 25 4x4 bales per hectare on average across all cereal crops, the reduction in the area sown to cereals (206,029ha) has reduced straw production on the island by over five million bales per annum today. This has heightened fodder shortages in some years and it has also given rise to the importation of straw, mainly from Britain.

Ironically, this importation of straw, more so than grain, represents an even greater threat to the future of the crop sector on this island. The use of blackgrass-infested straw as dung or compost poses an unquantifiable threat to crop production, with the possible consequence of forcing land out of tillage.

The regional effects

The overall reduction in cropped area did not occur uniformly across the country. A bigger part of the reduction occurred on livestock farms where a tillage crop (mainly spring barley) was grown to supply grain and straw for the farm. This has resulted in a considerable reduction in cropped area in Northern Ireland, in the border counties, midlands and across the west of Ireland. The crop area reduction in NI over this time frame was 44%, compared with 36% in the Republic.

Certain birds like the yellow hammer and lapwing depend on the presence of cereal stubbles for their existence, so they have vanished from parts of the country

The lost area means that more feed must be hauled into these regions where there is higher demand but less local supply. So, haulage has become a bigger factor.

The importation of feeds to replace the 1.5mt of potential native product is also an importation of nutrients on to livestock farms, some of which already have high nutrient loadings.

Many of those regions where crops have vanished have suffered environmental consequences. Certain birds like the yellow hammer and lapwing depend on the presence of cereal stubbles for their existence, so they have vanished from parts of the country.

The straw that is important to livestock farmers must now travel greater distances, with transport being an even greater element of the total cost

The absence of acres in crops has also changed local infrastructure. It is more difficult to get advice or even to purchase inputs in some regions, with fewer merchants geared to supply. And this has become a further reason why those remaining in crop production might exit in the future.

The straw that is important to livestock farmers must now travel greater distances, with transport being an even greater element of the total cost.

Additional GHG obligations

The transfer of land use also has direct consequences in terms of changing national obligations on environment and climate change. Greenhouse gas emissions (GHG) change significantly with land use, as do ammonia emissions. For over three-quarters of these four decades, the bulk of the land exiting crop production reverted mainly to beef, with some to sheep, both of which have higher associated GHG emissions than tillage. It was really only since 2014 that almost all of the land returning to grass went to dairying, which has double the GHG emissions of beef.

Take then that the change of land use was to drystock for 35 of the past 40 years, with dairy being the main change in the last five. For this exercise, I am using the National Farm Survey emissions data and taking 4t/ha of carbon dioxide equivalent (CO2e) to reflect the output of beef and sheep in this change of land use.

While the Teagasc NFS assessment indicated around 2t/ha of CO2e emissions for its mainly tillage farms, it also stated that around 75% of that output comes from the animal enterprises on those farms. This would equate to around 0.5t/ha of CO2e from specialist tillage land. For this exercise, I am using the higher international figure of 1.18t/ha. The figure used for dairy emissions is the NFS figure of 8.7t/ha CO2e.

Using these base figures, the area that moved from tillage to drystock increased GHG emissions by 4 - 1.18t/ha, or 2.82t/ha. The land that swapped to dairy increased GHG emissions by 8.7-1.18t/ha, or 7.52t CO2e higher than tillage. Combined, these land use changes are now adding 793,341t of CO2e to GHG emissions on the Island of Ireland.

These higher numbers increase the reduction obligations being imposed on agriculture. Valuing carbon at €30/t, these additional emissions would add over €23m in fines if we fail to meet our emissions obligations.

More ammonia too

A similar situation pertains to these land use changes and their implications for ammonia emissions on the island. However, for both CO2e and ammonia, the significance of the land use changes is even greater in Northern Ireland, because the overall fall in tillage area was proportionally greater and there is a far greater proportion of intensive livestock systems there.

I am using similar methodology for the implications of the land use change on ammonia emissions. Again, taking the NFS sustainability data, I use a figure of 20kg/ha for ammonia emissions for the switch to beef/sheep and 48kg/ha for dairy.

The figure to use for tillage is more complex. The NFS data indicates an average output from specialist tillage farms of 8.48kg/ha of ammonia, but it also says that 73% of this relates to the cattle enterprises on these farms. This would suggest an output from tillage-only land at 2.29kg/ha, but to not overstate the case, I am using the full figure of 8.48kg/ha in these calculations.

So, the swap to drystock increased ammonia emissions by 11.52kg/ha (20-8.48) and the switch to dairy increased this by 39.52kg/ha (48-8.48). Together, these numbers add up to 3,497t of additional ammonia emissions, which must now be counteracted by other measures to try to reduce emission levels. Again, the ammonia challenge is far greater in Northern Ireland.

Environmental issues

In any given region, a loss of land use is also a loss of biodiversity. I mentioned previously about specific bird species being reliant on the presence of tillage – many of these have now disappeared from parts of the country.

Tillage crops have much higher nutrient utilisation efficiency (NUE) than grassland, especially intensively managed grassland. So, having a proportion of tillage in an area improves the overall efficiency of nitrogen and phosphorus use.

This should help reduce the losses of these nutrients to water and/or air in that region.

The option to grow leguminous crops without nitrogen in tillage, like beans or peas, removes the need for nitrogen on that area of land in that year and it further reduces the requirement for N in the following crop – a saving for the local environment.

Anything that reduces the intensity of nitrogen use helps to decrease losses of nitrates to surface and ground water, as well as decreasing the overall pressure for ammonia loss.

In general, having more tillage in an area should help to reduce local pressures on surface water in terms of N and P pollution.

Not all positive

While having a proportion of tillage in an area can have many advantages, there are also some additional environmental risks. These relate mainly to management that makes the loss of soil from land to surface water easier or more likely. Loose cultivated soil is more likely to be subject to water erosion, which can carry nutrients, especially N and P, and silt to drains and rivers. Silt is a pollutant in itself and tillage farmers should do all they can to prevent the loss of ‘brown water’ from land.

This is best done by having plants growing on the land during risk periods like winter.

While not confined to tillage, the use of pesticides is more intense on cropped land. This can give rise to product getting in to water, but there are mechanisms now to help minimise this. These revolve around choice of product and low-drift nozzles.

All in all, the move away from tillage over past decades was partly driven by the relative profitability of other enterprises in more marginal areas, partly driven by the cost of mechanisation – especially for smaller farms – significantly driven by bad weather years and helped by what appeared to be low grain and straw prices.

While we can do little about the weather, any drive to an increase in area is unlikely unless it is incentivised in some way. While the EU built in mechanisms to prevent the erosion of its area under permanent pasture, Ireland must begin to act to protect its area under tillage.

In short

  • The ongoing decline in the area of tillage on the island has seen over 230,000ha return to grass since 1980.
  • This resulted in a drop in cereal area of over 206,000ha, which equates to around 1.5mt of grain production.
  • The area swap has added almost 800,000t of CO2e to our emissions reduction for climate change requirement on the island of Ireland, plus at least 3,500t of ammonia emissions.