## Rainwater Collection and Storage

Many regions have a high water surplus for the irrigation of plants during rainy seasons and a deficit of water in dry seasons. When growing plants in greenhouses, the rainwater running off the roofs of greenhouses can be collected and used for irrigation. If salty water is available, this can be mixed with rain water […]

## Water Use Efficiency

Water use efficiency is defined as ratio of yield to irrigation water requirement (De Pascale and Maggio 2005) WUE = yield/irrigation water requirement (kg crop/m3 irrigation water) The irrigation water requirement IWR is CWR + eventual soil leaching require­ment. The WUE in greenhouses normally is much higher than in open field production because of • […]

## Example 2: Bangkok (Thailand)

Calculation of ET0 and CWR in April and May for Bangkok, Thailand. ET0 (April) = 3.67 (mm/day) ET0 (May) = 3.11 (mm/day) The crop water requirement for a tomato crop is CWR = ET0 x kC x 1.05 x 0.9 (mm/day) The crop coefficient for a high tomato crop in greenhouses can be higher than […]

## Example 1: Almeria (Spain)

The reference evaporation for an unheated greenhouse at Almeria (Spain) in May has been calculated by the adapted Penman-Monteith equation (see calculation sheet in Annex 3): ET0 = 3.16 (mm/day) without considering the soil heat flux. Fernandez et al. (2009) presented an equation for the calculation of the ET0 in unheated greenhouses: ET0 = (0.288 […]

## This Penman-Monteith Method Can Also Be Applied for Greenhouse Conditions, if the Parameters Are Adapted to Greenhouse Climate Conditions

The climate data for outside conditions can be taken from adequate references, for example Muller 1996 or climate data tools of FAO aquastat (www. fao. org/nr/water/ aquastat/gis/index3.stm). Given data and parameters are: Mean max temperature, mean min temperature, mean relative humidity, number of sunshine hours, global radiation, mean wind velocity. The equivalents for the radiation […]

## Crop Water Requirement and Water Use Efficiency

13.1 Crop Water Requirement Irrigation water is a scarce factor in many regions. Therefore, crop water require­ment has to be calculated, and irrigation systems have to be designed carefully. Knowledge of the evapotranspiration inside the greenhouse is important for suc­cessful plant growth, calculation of irrigation water consumption, and possible and economical rainwater collection and storage […]

## Solar Heating

Solar energy covers a part of the heating energy that is needed during the daytime. To use solar energy for heating during the night, two problems have to be solved (von Zabeltitz 1987, 1988a): • The conversion of global radiation into thermal energy, • The storage of the thermal energy for heating purposes during night […]

## Geothermal Energy for Greenhouse Heating

The use of geothermal energy for greenhouse heating is a very good solution, if the geothermal water is available not too deep in the subsoil, if the water temperature is suitable, and if the water is not too corrosive. This is the case for example in Tunisia and in Turkey. Fig. 12.14 Corrugated PP tubes […]