• coffee
• cover crops
• weed management

Cover crops are used worldwide, mainly for organic matter supply, erosion control and weed management. The use of live coverages in coffee (Coffea arabica L.) plantations is a practice that was used in Costa Rica during the 1990s and was set aside due to the increased use of herbicides. Nowadays, coffee producers are seriously interested in reducing chemical input use and adopting alternative and more sustainable methods of control.
The objective of this study was to evaluate the establishment of different cover crop species in two kind of experimental conditions located at different altitudes: the Fabio Baudrit Moreno Agricultural Experimental Station (EEAFBM, for its acronym in Spanish) in a middle-low area in Alajuela province (840 m a.s.l.) and a coffee plantation in a middle-high area in Heredia province (1,280 m a.s.l.). Both experiments were performed during the rainy season August - December 2019.
In the trial set at the EEAFBM, six legumes were investigated: Crotalaria juncea L., C. spectabilis Roth, Vigna radiata L., Mucuna pruriens L. (local cultivar), Mucuna pruriens var. enana L. and Canavalia ensiformis L.. As the plot was homogeneous and no blocks were needed, a completely randomized design was assessed.
The second experiment was conducted in a 1-year coffee field (C. arabica var. caturra and C. arabica var. catuaí) with 2.3 x 1.1 m planting layout. It was used a random block with four replicates, consisting of 6 treatments with 2 legume species (V. radiata L. and Pisum sativum L.) and three grass species (Brachiaria ruziziensis Germ. & Evrard, Lolium multiflorum Lam. and Avena sativa L.) + control.
Results show that C. juncea tested at 840 m a.s.l. managed to completely cover the soil (100%) with a reduction in term of weed cover percentage up to 5%, 49 days after sowing (DAS). Among the grass species tested in the higher altitude site, A. sativa and B. ruziziensis were found to be the best adapted to that environmental conditions, despite their slow establishment.
In both trials, V. radiata provided complete soil cover (100%), 35 and 77 DAS in Alajuela and Heredia province, respectively, and the highest difference between its biomass and that of the weeds (dry pre-flowering V. radiata biomass= 498 g*m-2 while dry pre-flowering weed biomass= 24 g*m-2 in EEAFBM; dry pre-flowering V. radiata biomass= 424 g*m-2 while dry pre-flowering weed biomass= 40 g*m-2 in Heredia).
Chemical leaf analysis shows that V. radiata sequestrated 156 kg*ha-1 of N. Considering that a young coffee plantation needs around 150 kg*ha-1*year-1 of N, this cover crop could be of great help to reduce the dose of chemical fertilizer normally used in coffee plantation.
Then, the use of V. radiata as live mulch species may provide a potential alternative strategy for weed management and soil fertility preservation in different environmental conditions. It is, therefore, an interesting specie to consider for future investigations.