Water and nutrient management in botanical gardens and horticulture

Securing good plant growth conditions in botanical gardens and achieving high and stable yields in horticulture requires sustainable water and nutrient management. Even short-term deficits can lead to growth stress. On the other hand, excessive water can lead to growth depressions as a result of lack of air, as well as losses of water and nutrients due to leaching. Sustainable, resource-saving water, and nutrient management requires knowledge of i) physical and chemical soil or substrate properties to quantify the water and nutrient demand, ii) effective irrigation and drainage systems, and iii) in situ methods to test the effectiveness of these measures. The basic hydraulic properties are the water retention curve and the unsaturated hydraulic conductivity function. The HYPROP (HYdraulic PROPerty system) allows the simultaneous measurement of both functions and the dry bulk density. In addition, the measurement of hysteresis and shrinkage is possible. All necessary information for sustainable water management can be derived from these hydraulic functions. Special in situ measurements of water content and tension allow the quantification of the water balance. With additional soil water sampling, it is possible to quantify the nutrient balance and leaching. These methodologies have been used successfully on agricultural/horticultural and experimental sites over the last 20 years.