Carbon capture and soil biological activity in fruit tree orchards

Climate changes (mainly increased temperature and precipitation changes) will have agricultural consequences due to the interrelations between climate and soil degradation, land and water use, landscape changes. At the same time, conservation agriculture offers new chances to adapting and mitigating climate change. In sustainable agro-forestry systems, management practices are able to increase carbon inputs into soil and possibly reduce GHGs emissions due to some revised field operations (e.g. irrigation, pest and disease, fertilization, soil and plant management). Carbon enrichment increases biological activities by changing (improving) soil structure as well as the soil moisture and nutrient contents which are beneficial to plant growth and production. This paper reports results on the effects of changed soil management practices from conventional (soil tillage, mineral fertilisers, burning of pruning residues) to sustainable (no-tillage, pruning residues and cover crop retention, compost application) on soil microbial biomass and organic carbon (SOC). Results show that a 7-year period of changed practices significantly (including carbon input at a mean rate of 8-9 t C ha-1 y-1) increased SOC concentration (from 1.3% up to 1.8%, early top 10 cm) proving the potential role of that orchards for carbon capture. The paper shows the beneficial effects of sustainable practices on yield which was improved by 30-50% as compared with conventional managed orchards. The effects of carbon addition on reserves of soil nutrients (N, P, K, Ca, Mg) and on CO2 soil emission are discussed.