Greenhouse Cultivation in a Hot Arid Area

A facility for controlled environment agriculture is under investigation at Kothara (Kutch), a hot and extremely arid region. It consists of a greenhouse of 120 m2 floor area coupled in closed-loop mode to an earth-tube-heat-exchanger (ETHE) buried directly below. The ETHE provides conditioned air at 20 air changes per hour when needed. A 7.5 hp blower moves the air. Greenhouse is furnished with two continuous roll-up side vents, close-able continuous ridge vents and a retractable top cover made of shade net. Greenhouse has a fertigation system and an array of overhead foggers to supplement humidity and cooling. The ETHE was able to heat the house easily from 9oC to 22-23oC in half hour in the cold winter nights. Static ventilation from side and ridge vents along with shading was effective for day time control till early March. Subsequently ETHE was operated. It limits the greenhouse temperature gain keeping the inside near 36oC while shaded on top and when crop is inside. ETHE holds promise as an effective environmental control device in hot arid areas. A higher air change rate appears desirable to lower the temperature further. Two rounds of cropping has been done, the third is in progress. The results of growing tomato were presented else where. In this paper we present the results of growing capsicum.