The Straw Incorporation Measure has brought straw chopping and carbon sequestration on tillage farms into sharp focus. So, not surprisingly, it was the theme of this year’s Irish Tillage and Land Use Society (ITLUS) summer field event which recently took place virtually at the start of the month. The meeting was a mix of pre-recorded farm walk videos with growers and live presentations, along with questions and answer sessions. The event can be watched back in full on the ITLUS YouTube channel. Growers John Monahan from Carlow and John O’Neill from Waterford gave their experiences of chopping straw on their farms over many years.
Chopping out of necessity since 2000
John Monahan farms alongside his two brothers and nephew in Castletown, Co Carlow, where they grow winter wheat, winter oats, spring wheat and spring beans.
John explained to ITLUS council member John Dunne, who visited the farm last month, that he initially decided to chop straw back in the early 2000s.
Problems in the straw market at the time precipitated that decision and he hasn’t looked back since.
The process wasn’t without its problems, however.
The few years of straw incorporation made the transition to min-till establishment easier and it also suited chopping straw
In the first few years, he said he would often see patterns in the crop where straw had been chopped, particularly in the autumn.
He attributed this to nitrogen lock-up and spread some chemical nitrogen on to the chopped straw for a few years to help combat this. However, he also commented that, most of the time, the yellowing in the autumn would disappear by the spring.
Some years later, he made the move from a plough-based system to minimum tillage. The few years of straw incorporation made the transition to min-till establishment easier and it also suited chopping straw.
John farms on heavier ground and he found that after a number of years of minimum tillage and straw chopping, the soil structure in his fields improved considerably.
Improved soil structure has many advantages, not least of which is that the soil becomes easier to work. This was most evident one night when John pulled into a new field to cultivate it but forgot to change down from the road transport gear on his tractor.
Even when these cover crops are only in the ground for a short period of time, John believes that they help straw breakdown
The ground had become so workable that he could easily till it at 15km/h.
He stopped spreading nitrogen on the chopped straw to aid its breakdown after a few years and now aims to establish a cover crop as soon as the field is cleared. This system is working well for him because he can plant immediately post-harvest as the straw does not have to be baled and gathered.
Even when these cover crops are only in the ground for a short period of time, John believes that they help straw breakdown.
John quickly noticed a considerable increase in earthworm numbers and also in general soil health, and he puts both benefits down to his system. However, the many other soil-friendly decisions that John makes on his farm also go a long way towards this.
One good example of this is how he treats his headlands. John would often leave the turning headlands until last to harvest, opting instead to park the trailer further in the field. This is to save the headlands from harvest compaction.
Indeed, he said that he might use the middle of the field to unload grain where the runs were very long, again to save the headlands.
In terms of soil fertility indices, he noted that his potash (K) levels have increased across the farm since the 2000s.
His land was traditionally low in K and high in P, but the system now seems to have struck a better balance.
Grower John O’Neill farms in Knockanore, Co Waterford. Like John Monahan, his decision to chop straw was out of necessity.
John says that demand for straw in his area was low, and it became a challenge for him to deal with it. Initially, he tried a number of methods of chopping straw including using a trailed forage harvester.
However, it was only when he bought a combine with a straw chopper that things began to go smoothly for him. Now, 23 years later, he is still chopping most of his straw.
John farms on light land, some of which is on the banks of the River Blackwater, and he runs a plough-based system.
The regular chopping of straw has helped improve the quality of his soil considerably and, in particular, it has helped to improve the water holding capacity in the ground.
John never applied chemical nitrogen on to the chopped straw in the early years, but instead used pelleted sewage sludge from Cork County Council
This was very evident in the drought of 2018 when some of the crops on his driest ground yielded quite well, despite the dry conditions. However, he also acknowledged that a few “lucky” rain showers may also have played a part in the performance that year.
John never applied chemical nitrogen on to the chopped straw in the early years, but instead used pelleted sewage sludge from Cork County Council.
He thinks this may have helped aid the breakdown of the straw and prevent nitrogen lock-up. It may also have helped the soil itself in terms of structure, fertility and health.
Tighten it up
One of the strongest tips that John gave was to roll the land following incorporation of the straw. He uses a disc cultivator with a crumbler roller to incorporate the chopped straw. But he finds that rolling again soon after with a Cambridge roller greatly speeds up the rate of decomposition.
“We found the disc was leaving it a bit loose but rolling it made it breakdown quicker. The straw can lose 50% of its volume within three weeks if it is making good contact with the soil,” John said.
We didn’t have a strong demand for the straw in the first place
Overall, he feels the land quality has improved as a result of long-term straw chopping. Much of his land was worn and he has noticed a gradual increase in soil indices, particularly K. “Land that was well worn was rejuvenated and given new life,” John said.
He also said that water seems to drain away quicker in wet years, especially on headlands.
When asked about the loss of income from straw sales, he made the following reply.
“We didn’t have a strong demand for the straw in the first place. What you don’t have, you don’t miss. It’s a byproduct, but it has a value to me in the soil.”