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

Abstract

Research is ongoing to develop greenhouse technology with controls economical on water and energy, to improve farming in water-scarce, hot, semi-arid region of north-west India. A greenhouse under investigation, is coupled to earth-tube�heat� exchanger (ETHE) and has provisions for shading, natural ventilation and mist nozzles. In a recent round tomatoes were grown. A regime of natural ventilation and top shading kept the greenhouse temperature close to the ambient in cooler months, although a difference of up to 3 �C was anticipated. Evaporation and later transpiration may have aided cooling. Mist was not used. This became less effective in warmer period as 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. But cropping could be done through 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. Yield was 68 t / ha nearly twice the open fields, water used 266 mm nearly half of the open-fields. This appears to�