Carob-Thyme Intercropping Systems Can Improve Yield Efficiency and Environmental Footprint Compared to Conservation Tillage

Living mulch intercropping systems are considered as nature-based solutions of low environmental footprint for combating weeds, improving biodiversity and agroecosystem sustainability. In drylands, however, they may increase intra/inter-specific competition for water, reducing crop productivity. We tested conservation tillage carob plots with and without irrigation (TLGirr; TLGdry) vs. rainfed intercropping systems of carob and (i) thyme (Thymbra capitata; T-System) or (ii) clover (Trifolium squarrosum; C-System), strategically planted on the south (sun) exposed soil side (SES) of carobs, to reduce soil temperature/evaporation. Carob water relations, productivity and environmental footprints were examined for three years under semi-arid low-weed competition (SKR) and arid high-weed competition (VRY) conditions in Cyprus. Carob yield efficiency (kg/m3) in SKR, was >27% higher for the T-System (p<0.05; SES cover ca. 85%; year-3), matching higher leaf-water content (p <0.001) compared to TLGdry. The T-System reached 28% and 56% of TLGirr yields during very dry and normal rainfall years; TLGdry yields approached zero. For VRY, no negative impacts on carob leaf-water, at 25% SES cover, were found. SKR’s C-System, improved leaf-water content (p<0.05) for only one year. The T-System also outperformed TLGirr and TLGdry in terms of reducing irrigation needs and energy consumption, breaking new grounds for dryland agroforestry.