Cropping in semi-arid north-west India in greenhouse with ground coupling shading and natural ventilation for environmental control

Abstract

Research is ongoing to develop greenhouse technologies which economically control water and energy in order to improve farming in water-scarce, hot, semi-arid regions of north-west India. A greenhouse under investigation was coupled to earth-tube– heat–exchangers (ETHE) and also had provisions for shading, natural ventilation and mist nozzles. Tomatoes were grown in the greenhouse. In the cooler months, a regime of natural ventilation and top shading kept the greenhouse temperature close to ambient temperature. Mist was not used. Evaporation and later transpiration may have aided cooling. This cooling effort became less effective in warmer periods as the cooling load increased and dense foliage appeared to hinder ventilation. Forced ventilation via ETHE and top shading was then implemented. Inside temperature occasionally rose 2-3 °C above the ambient temperature. Cropping could be done through the spring and early summer. Heating was affectively achieved with ETHE in cold nights of December and January keeping the inside temperatures well above 12°C. Yields were 68 t/ha - nearly twice the open field production, while the water used (266 mm) was nearly half of the open-fields usage. This appears to be a promising new way to improve livelihoods from farming.