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Water: what matters when growing orchids?

       Talvez um dos maiores mitos que corre de boca em boca entre os orquidófilos seja that overwatering kills an orchid. Who has never heard of it? 

      _cc781905-5cde-3194-bb3b-136bad5cf58 actually kills an orchid but the lack of air around its roots when these  receive too much water.   One of the needs of orchid roots is to absorb oxygen and when the medium is flooded, the little air around the roots is displaced, causing the root to suffocate. After this death, space is opened for all sorts of opportunistic pathogens to invade the plant, taking care of finalizing the death of the orchid.

      _cc781905-5cde-3194-bb3b-136bad5cf58 There are also many questions regarding the better aquadophile to be used in the irrigation of our orchids and there are also many baseless answers that we can find!  

This is because water has quantifiable characteristics, which need to be taken into account according to the characteristics of its substrate and fertilization so that they can form an ideal combination for cultivation.   The following are characteristics to be observed: pH, alkalinity, hardness and electrical conductivity. 

         Existe uma grande confusão no entendimento  between pH and alkalinity. To begin with it is necessary to say that alkalinity is very different from alkaline solution. The definition of pH is related to the balance of H+ and OH- ions in a solution and has already been better detailed in a separate chapter.(to review, click here!)

         A alcalinidade é uma medida que refers to the amount of acid needed to lower the pH of a given solution, also called buffering capacity. Alkalinity is usually measured with a test kit in which diluted acid is added until a change of color occurs at a specific pH.   Alkalinity is not related to a specific ion, but rather to the concentration of various ions that affect the buffering capacity. 5cde-3194-bb3b-136bad5cf58d_bicarbonates such as calcium, magnesium and sodium  and, to a lesser extent, carbonates such as calcium or sodium. Various other ions  including hydroxides, phosphates, ammonium, silicates, sulfides, borates and arsenate can also contribute to alkalinity, but their concentration is usually so low that they can be ignored. The unit of measure that can be used to measure alkalinity can be parts per million (ppm), mg/liter or milliequivalents (meq.)

          Effect of alkalinity on the substrate

         A alcalinidade tem muito mais efeito on the substrate than the pH. The use of water with high alkalinity in substrate irrigation will increase the pH to values above those acceptable for plant health and growth. 

          Para ser ter uma ideía of the power of water alkalinity to increase pH  in a substrate, adding 50ppm alkalinity (which is very little) will have the same effect as using water with pH 11 (which is a pH extremely high).  Using water with a pH of 8 has the same effect on the substrate as using water with an alkalinity concentration of 0.05ppm. 

         O pH da água ainda é important for management, but has little impact on the substrate. O pH of water affects the solubility of fertilizers and the effectiveness of insecticides and fungicides.

             Water hardness...

      _cc781905-5cde-3194-bb3b-136bad5cf58d is related to the property of dissolved minerals mainly salts of s of Calcium (Ca2+) and Magnesium (Mg2+).  Water hardness is usually measured based on the amount of Parts per Million (ppm) Calcium Carbonate (CaCO3), also represented as mg/l de_cc781905-5cde -3194-bb3b-136bad5cf58d_CaCO3. The higher the amount of "ppm", the more "hard" the water will be considered.   To differentiate, while alkalinity is the measure of all bases present in water, hardness is actually the amount of insoluble calcium and magnesium salts in water. 

         Electric conductivity...

      _cc781905-5cde-3194-bb3b-136bad5cf58d the more saltiness in the water this water has the ability to conduct. So, in practice, it is a measure of the amount of salt we have in the water. It is used to determine the potential risk of salt accumulation when water is applied to a substrate. With fertilizer solutions, the electrical conductivity  can be directly correlated with the concentration of individual nutrients (typically nitrogen) of a variety of fertilizer salts, or with the total concentration of nutrients provided by a soluble fertilizer in water.

        A condutividade életrica tem relação com a_cc781905-5cde-3194-bb3b- 136bad5cf58d_concentration of nutrients made available to plants. In general, irrigation water is not a significant source of the primary macronutrients of nitrogen (N), phosphorus (P) or potassium (K). However, irrigation water can contain high levels of the nutrients calcium (Ca), magnesium (Mg) and sulfur (S). And, like alkalinity, the concentration of nutrients contained in irrigation water can vary dramatically between locations.

        Laboratory water analysis is the starting point!

      _cc781905-5cde-3194-bb3b-136bad5cf58d laboratory analysis must be carried out as a starting point your fertilization program will work.  One of the few sources de reliability, that is, that doesn't need correction, is rainwater (if you don't live in a region with a lot of atmospheric pollution).           _cc781905-5cde-3194 -bb3b-136bad5cf58d_   It should also be considered that the characteristics of your water easily change over time, requiring that these analyzes be carried out at least once a year._cc781905-5cde-3194-bb3b -136bad5cf58d_


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