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NUTRIENT SAMPLES PREPARATION GUIDE
8. NUTRIENT SAMPLES PREPARATION GUIDE
8.1. INTRODUCTION TO PLANT NUTRIENTS
The three elements that are mostly needed by the plants are nitrogen (N), phosphorus (P) and
potassium (K). They are called the macronutrients while other elements, needed by plants in smaller
amounts, are called microelements. In hydroponics, plants need a balanced nutritive solution,
composed of macro and microelements.
Shortage or excess of even only one nutritive element may cause an imbalance in plant physiology
and in the absorption of the other nutrients. Nutrients shortages may result in irregular plant growth,
low resistance to diseases, scarce production both in quantity and quality, while nutrients excess may
cause waste of fertilizer, pollution of the groundwater and the possible accumulation of dangerous
substances in the crops produced.
Nitrogen
Nitrogen (N) is mostly absorbed by plants as nitrates (NO
3
-
) and, in smaller amount, in the form of
ammonium (NH
4
+
). In hydroponics, an adequate ratio between the two forms is generally used in
nutritive solutions.
PRESENT IN proteins, enzymes, chlorophyll, hormones, vitamins, DNA and RNA
ACTION
• is fundamental for plants in phase of growth
• promotes lengthening of trunks and sprouts
• increases the production of foliage
• helps to absorb other nutrients (in particular phosphorus)
• assists a bigger production for both size and number of fruits
SHORTAGE EFFECTS
• slower growth
• smaller leaves
• yellowing of leaves
• smaller fruits
• premature ripening
EXCESS EFFECT
• reduction in resistance to diseases and atmospheric agents
• increase of water demand (caused by an excessive production of leaves)
• bad quality of fruits
• delayed ripening
• reduction in potassium absorption
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