Energy balance and carbon dioxide flux in conventional and no-till maize fields in Lesotho, Southern Africa

The capacity of soils to sequester carbon is currently of scientific interest because soil management impacts carbon dioxide flux and can mitigate the effects of climate change. Soil carbon sequestration is also essential in areas with degraded soil where land use is primarily subsistence agriculture because of limited inputs to increase fertility and return soil nutrients removed during crop growth. Agricultural soils under no-till management can increase soil carbon levels compared to soils managed with traditional tillage practices in the long-term (decades); this is hypothesized to be caused by the short-term (i.e., seasonal) flux of carbon dioxide between the terrestrial system and the atmosphere. In order to investigate the potential of no-till agricultural systems to increase soil carbon in sub-Saharan Africa, micrometeorological stations were set up during the growing season in two adjacent fields with soils classified as Phechela series (fine, montmorillonitic, mesic Typic Pelludert). The fields were located near the village of Maphutseng outside of Mohale’s Hoek, Lesotho (lat. -30.213, long. 27.496, 1456 m above mean sea level). The study area is in the lowland agroecological zone of Lesotho, with long-term mean annual precipitation of approximately 800 mm/yroccuring primarily during the warm summer season between October and March. These stations continuously record the environmental components necessary to complete the Bowen’s ratio energy balance equations for the fields, of which both are cropped in maize-soybean rotations, one under no-till management and the other plowed. Comparison of the transfer of energy throughout the two different cropping systems over the course of the cropping cycle may indicate the suspected superiority of no-till systems for maximizing carbon dioxide uptake of agricultural systems over time, but further data collection is necessary in order to establish significant trends.