The various water districts usually furnish this information on request. Knowledge of particular plant materials is necessary to set optimum pH levels. Irrigation practices can be critical if the water contains high total salts. Frequent light irrigations may cause salt accumulations in the roots and lead to serious plant injury. To avoid salt damage, water applications should be less frequent, but longer in duration to wash excess salts below normal root depth.
Plants obtain the primary and secondary nutrients and some micronutrients solely from the soil.
While we can generalize and say soils often contain most elements required by higher plant life, there are many possible variations. Some soils, particularly sands, can be deficient in several elements, either because they have been depleted by plants or because they have been leached out by rain and irrigation. Macro-nutrient Functions Nitrogen is part of every living cell and usually increases plant growth more than any other element. Inside the plant, nitrogen is part of amino acids, which in turn make up proteins. It is also part of the chlorophyll molecule, thus it is important in photosynthesis.