Modeling the suitability of the traditional plastic greenhouse for tomato production across Colombian regions
Greenhouse tomato production in Colombia has increased at a rate of 250 t year-1 in the last decade, but yield has remained constant around 106 t ha-1 year-1. The main reasons for this trend is that greenhouses used for tomato cropping are still vulnerable to the high seasonal and intraseasonal climate variability in the Equatorial Zone. To obtain information about the relation between outdoor and indoor environments, we analyzed productive areas with a greenhouse climate model (GCM). The GCM was calibrated, validated and used to simulate the thermal behavior of traditional greenhouses under different climate conditions in Colombia. The input climate variables included global radiation, outside air and soil temperatures, relative humidity and wind velocity recorded at six locations. The locations are situated between 2000 and 3000 m a.s.l. with average temperatures between 10-20°C characterized by unimodal or bimodal rainfall regimes. Automatic weather stations recorded the hourly climate data during tropical wet and dry seasons. The modeled greenhouse was a naturally ventilated plastic one with a floor area of 5670 m2, surface of the cover including side walls of 9610 m2, and maximum roof and side ventilation area of 324 and 370 m2, respectively. The simulations were carried out with the presence of a tomato crop. The simulations showed that traditional structures keep appropriate temperatures for tomato, mainly during the dry season at the six locations. The wind profile for each season explained these results, affecting the efficiency of natural ventilation. The change in the wind profile is due to the meridional migration of the intertropical convergence zone throughout the year. Therefore this atmospheric system is a factor to take into account when designing sidewall and roof ventilation openings. For cold marginal tomato production areas, predictions showed the potential to explore passive heating systems to improve the climate during night hours.
Diaz, D.C., Bojacá, C.R. and Schrevens, E. (2018). Modeling the suitability of the traditional plastic greenhouse for tomato production across Colombian regions. Acta Hortic. 1205, 857-864