Sharing cultivation and growing experience: experience with water for planting and growing

Sinceorchidsrequire a nutrient concentration that is only 1/4 to 1/6 of that needed by most fast-growing plants, it is very necessary to understand the composition of the water used for watering orchids. Although fresh, unpolluted rainwater is best, it may be hard to obtain. The examination of water sources can be divided into two parts: 1. Total salt content 2. Analysis of the content of various salts Salt content: A relatively accurate and practical method for measuring the salt content in water is to measure the electrical conductivity (EC) of the water. Pure water conducts almost no electricity, but most salts dissolved in water do conduct electricity, and the conductivity or electrical conductivity of water is directly related to the concentration of salts in the water. The unit for measuring conductivity can be MHOM (the reciprocal of the resistance unit ohm) or expressed as siemens (S). Fororchidwatering, the conductivity you measure is very small, amounting to a few millionths of a siemens, called microS, represented by the symbol μS; 50 means 50μS, and 100 means 100μS. The instrument used to measure conductivity is called a conductivity meter. Instruments usually used to measure the conductivity of liquids fall into two categories: one type gives readings in MHOM (μS); the other type gives readings in total dissolved salts (TDS). TDS is calibrated with a coefficient and reflects content in parts per million (PPM). However, TDS obscures the fact that different salts have different conductivities (for example, urea dissolved in water conducts almost no electricity). In horticulture, the conductivity unit siemens is mostly used, but urban water source analysis reports mostly use TDS to express analysis results. The two readings can be converted easily; roughly, 1000μS is equivalent to 666TDS. The choice of conductivity meter can be based on the type of plant you cultivate. Fororchids, a reading range of 1-1999μS with temperature compensation is relatively ideal, because conductivity is affected by temperature. Since orchids require a lower nutrient concentration, it is very important to use water with low salt content. The table below gives water quality assessment for use withorchids: Water conductivity Assessment ====================== Below 50μS Very good 50-100μS Good 100-200μS Acceptable Above 200μS Poor Analysis of the content of various salts: The content of various salts in water is just as important to us as the total salt content. In developed countries, some orchid or other plant associations provide their members with analysis results of the content of various salts in local water sources. The unit of the data provided is PPM, that is, the number of milligrams of a certain salt contained per liter of water. Water in many regions is relatively hard, meaning it has a relatively high salt content, and most of it contains relatively high levels of calcium and magnesium carbonates. For example, most areas of northern China with little rain. Excessive calcium and magnesium will poison orchids. It is not hard to understand that using water with low salt content enables us to better control the balanced nutrition oforchids. By the way, a reminder to our orchid friends in the north: adding organic acids (oxalic acid, citric acid, etc.) to the water to neutralize the alkalinity of hard water carries a certain risk! It is true that these organic acids can indeed reduce the conductivity of water at the same time, but conductivity cannot reflect the content of all salts, such as the urea mentioned earlier. Adding other salts to water that is already too high in salt seems inappropriate, and I hope everyone will act prudently. Because of my limited knowledge and shallow learning, if there are inappropriate points in the article, I ask the broad community of orchid friends to criticize and correct them. (Mutu)