Effect of tillage minimisation on the carbon balance in the soil in the forest-steppe of the Novosibirsk Ob region

Abstract

The study aimed to assess the carbon balance in leached chernozem when used in a long-term field experiment in 2 variants: with annual ploughing to a depth of 25 – 27 cm and surface treatment by 6 – 8 cm. In the experiment, spring wheat was grown using intensive technology in a crop rotation, pure fallow - wheat - wheat. The variants of the experiment differed in the number of plant residues: straw was removed from half of the fields, and on the other half, it was planted and crushed into the soil after harvesting. The authors estimated the carbon balance based on the element’s input into the ground with plant residues (straw and roots) and its losses in the form of CO2 from the soil’s organic matter during the growing season. The total loss of С–СО2 for the period May – September was calculated based on the average daily rate of production of СО2 , which was determined in the field of pure fallow once a week by the absorption method. Minimization, the transition from ploughing to surface tillage, did not significantly impact the average annual wheat yield (2.49 – 2.60 t/ha) and the number of plant residues (1670 – 1818 kg C/ha of arable land). Also, between these treatment backgrounds, no significant differences were found in the average annual mineralization of organic matter and the carbon balance in the soil. These indicators depended only on the amount of plant matter (straw and roots) entering the ground. The poor credit of carbon in the land (-752 kg C/ha of arable land) was registered when straw was alienated from the field. When it was left on the field, the balance of the element became much more favourable (-88 kg C/ha of arable land), approaching a deficit-free state. The authors concluded that a carbon balance close to a deficit-free one was ensured, regardless of the primary tillage with an average annual wheat yield in a 3-field grain-fallow crop rotation of about 2.5 t/ha of grain and the incorporation of the entire non-marketable part of the crop into the soil in the leached chernozem.