Last week, we explained how soil carbon sampling was undertaken on the Footprint Farmers’ farms. There was huge variation in those samples.
Figure 1 clearly represents the variation in those results. The lowest result was an organic carbon stock of 21.9t/ha and the highest result was 313.9t/ha.
So far, the majority of the samples are from grassland soils, but there are some tillage samples in the mix and the remainder of the tillage samples will be added to the data set once crops are harvested and can be sampled.
The lowest result for soil carbon stocks was on the Irish Farmers Journal’s Tullamore Farm. Some 21.9t/ha of carbon was being stored in one sample taken on the grazing platform which had been in continuous tillage until it was reseeded in 2017. This soil has huge potential to increase soil carbon as animals will graze it and organic manures can be applied.
The grass is also high in clover and this may help with soil biology and structure.
The highest soil carbon level came from a dairy farm. Some 313.9t/ha of carbon was stored on one sampled area of the farm’s grazing platform.
The majority of the tillage land sampled so far is below 60kg C/ha. However, one tillage sample was at 132.9kg C/ha. This sample was from a mixed farm and was the tenth highest carbon sample of the 208 samples taken, so it will be very interesting to see the rest of the tillage results once they are sampled.
It is important to remember that there is only a small number of tillage samples returned, but initial results indicate huge potential to build soil carbon levels through the use of organic manures, cover crops and straw incorporation.
Samples from a farmer in west Limerick were consistently high and were above 100kg C/ha on peaty, wet soil.
Interestingly, the majority of samples with results below 40kg/ha were on tillage land or grassland converted from tillage.
Results from the sheep farm ranged from 54kg C/ha to 76kg C/ha.
Getting a baseline soil carbon level allows soil carbon to be tested again in a number of years to see if the soil carbon level has increased.
If the soil carbon level has increased, then that means that carbon has been stored in the soil and this can offset some of the emissions produced on the farm.
If a farm stores more carbon than it produces, it could be rewarded for offsetting other farms’ or industries’ emissions.
Important to note