**2.2 Water availability and quality**

Water source and supply for greenhouse crop irrigation and other necessities are often overlooked. Enough quantities of good-quality water are highly important for the vegetable crops grown in a modern greenhouse, as vegetables are very sensitive to water deficiency. Before starting with any type of vegetable crop production, either in open field or in a greenhouse, it is crucial to send samples of a potential water supply to an irrigation water testing laboratory for analysis—quality test, along with both chemical and biological ones. A water testing laboratory should be a recognized and accredited one (ISO 17025). Water chemical testing is very important for modern greenhouse crop irrigation, due to an application of modern technologies and modern irrigation systems and vegetable crop feeding. Particularly significant factor is the concentration of nitrates and certain microelements, which in high doses may be toxic to plants (e.g. iron (Fe) compounds). In such cases, there are particular technological ways of decreasing the unfavorable concentrations of certain elements and compounds. For greenhouse irrigation and other necessities, the main sources of water are groundwater from wells, surface water (rivers and ponds), rain, and municipal water. Irrigation water microbiological analysis is important for two reasons:


#### **2.3 Greenhouse site physical requirements**

The topography of the site affects where a growing structure is built. (Topography refers to the shape of the land, e.g., hilly, steep, rocky, flat.) The surface of the ground should be level. A 0 to 5 percent slope is recommended. Placing a growing structure on a flat surface is efficient because it facilitates easy adjustments to various mechanical controls in the greenhouse, which is economical. On steep terrains, it is recommended to build several separate greenhouses with axes parallel to contour lines [8]. Provisions must be made for the evacuation of rainfall water, and greenhouses should not be situated in hollow lands prone to landslides.
