Studies examining the impact of cultivation methods on crop yields have found that no-till systems do not increase soil carbon store any more than plough-based systems.
Presenting the findings at the AHDB Agronomy West Conference in Malvern, Dr Blair McKenzie of the James Hutton Institute said: “If you’re going to move from a ploughed system to a no-till or min-till system do not do it expecting that you are going to see big increases in the amount of soil carbon over the whole profile.”
The studied reviewed deep non-inversion tillage, minimum and non-inversion tillage, and mouldboard ploughing at three sites across England and Scotland with differing soil types.
Dr McKenzie said: “We’ve done this across multiple sites and after multiple years of no-till, if you consider the total depth of the profile, we don’t find any more carbon than in a ploughed system.”
Studies in Finland have seen the same results, according to Dr McKenzie. “If you just take the surface soil, you might see accumulations of carbon, but not if you take the whole depth of the profile.”
The Scottish site saw soil carbon levels increase with a plough-based system.
The study also found spring barley yields in non-inversion systems were lower than in inversion yields in every year, and that cover crops gave varying levels of success in different tillage systems.
“Where we had ploughed, often the response to cover crop was negative, and it was rare that they got a positive response to the cover crop. If you look at the min-till or shallow cultivations systems, that was where the benefits to the cover crop seemed to be, so there is something that says perhaps we need to match cover crops to systems.”