Can reduced soil tillage mitigate nitrogen losses and increase carbon sequestration in arable cropping systems?
Soil systems play an important role in the global fluxes of greenhouse gases (GHGs), especially of carbon dioxide and nitrous oxide (N2O) and their carbon and nitrogen cycles are tightly connected. Soil tillage in agricultural systems is a central factor in determining the net contribution of GHGs, but also in determining soil organic carbon sequestration, risk of soil erosion, soil fertility, nutrient leaching, decomposition of pesticides, water quality and infiltration, fossil energy consumption and crop yields. It is hypothesized that soil tillage enhanced carbon sequestration have significant effects on nitrogen use and losses in agroecosystems. Consequently, it is essential to understand these relationships to be able to counterbalance unwanted effects. The objectives of this study is to determine the effect of a shift from conventional tillage using ploughing to reduced (shallow) tillage with only surface incorporation of crop residues during 18 years on the emission of N2O, the recovery (and loss) of 15N-labelled nitrogen fertilizer in crops and soil, the soil organic carbon sequestration in the profile, the soil physical quality parameters and crop yields within a diverse (6-yrs) arable crop rotation. The project will result in new valuable knowledge on the possibilities for increasing the sustainability of cropping system via reduced soil tillage.
Project responsible Erik Steen Jensen, projectleader: post doc Maria Ernfors.
Measuring N2O fluxes in sugar beet with different tillage systems. Photo Erik Steen Jensen