Water scarcity is ever increasing the need and desire to utilize non-conventional sources of
water for irrigation. Water for irrigation today includes brackish groundwater, recycled
wastewater and desalinated water. Each type of water has a unique chemical composition,
requiring independent consideration regarding management of crop nutrition. Water
quality/composition has influence and repercussions on interactions with fertilizers, soil
chemistry and nutrition, and of course, on plants.
In order to adapt the fertilization regime to irrigation water quality the contents of inorganic
macro and micro essential nutrients have to be taken into account. The most conventional
sources of irrigation water are groundwater, lakes and rivers. In many regions, this type of
water contains calcium, magnesium, sulphur and boron. However, in other regions such
water sources can be poor in these nutrients. In brackish groundwater one may find also
potassium and chloride whereas in recycled wastewater, nitrogen, phosphorus and
micronutrients are found. Contrastingly, desalinated water contains only calcium and boron.
High concentrations of essential elements and other ions affect the uptake of nutrients by
plants. For example, brackish water and recycled wastewater contain high concentrations of
sodium, which might inhibit potassium and calcium uptake and high concentrations of
chloride and sulphate which might inhibit nitrate uptake by plants. In addition, Irrigation
with water containing high mineral concentrations requires a leaching fraction which,
consequently, increases amount of applied fertilizer and may create environmental hazards.
The soluble organic matter found in recycled wastewater can contribute nitrogen and
phosphorus but the mineralization rates of these nutrients are complex and it is difficult to
assess their contribution to plant nutrition.
The talk will address these issues and bring examples and case studies from horticultural
crops including fruit trees, fresh herbs and vegetables.