Biomass of alternative species for traditional cereal crops in Latvia and their potential impact on the carbon cycle

Abstract

Sustainable agroecosystems with systematic crop rotation and crop diversity can promote the maintenance of soil fertility and sustainable carbon cycling including CO 2 sequestration from the atmosphere and formation of organic matter. To contribute to the implementation of the goals of the European Green Deal course, it is necessary to assess CO 2 uptake capacity for the widest possible range of agricultural crops grown in a certain region. This study determined the amount of above-ground (Resid AG ) and below-ground (Resid BG ) residues of plants and the content of C and N fixed in them looking for relationships with the yield for six alternative crops for cereals grown in Latvia: winter rape (WRa), buckwheat (BW), peas (P), potatoes (PO), maize (M), and green fallow (GF) compared to cereals in two different regions of Latvia over a three-year period. Significant differences were found between alternative species in the amount of total (AG + BG) plant residues (g m −2 DM) left in the field: 1840 ± 67.8 for winter rape, 740 ± 30.7 for buckwheat, 767 ± 54.7 for peas, 323 ± 11.2 for potatoes, 172 ± 5.2 for maize, and 470.2 ± 30.9 for green fallow. The results showed that the winter crops – rape, triticale (WT), and rye (WR) – left the most total plant residues in the field with the most C content exceeding 80 g m −2 C in Resid BG and 600 g m −2 C in Resid AG . A significant variation in the amount of plant residues within the species depending on the year, cultivar, fertilisation, and soil properties was found, so for more accurate calculation of C and N inputs, the data set should be enlarged, or average statistical data be used.