Analysis of the Advantages and Disadvantages of Growing Media Such as Humus Soil and Moss

Apart from having very good air permeability, growing media such as humus soil, sphagnum moss, sawdust and weathered stone differ greatly in composition and are completely different in their physical and chemical properties. Yetorchidsdo not need only good air permeability to grow;orchids, like other plants, require their growing medium to satisfythe orchid'sneeds in four aspects: water, fertilizer, air and heat. What kind ofcultivationmedium is relatively suitable for orchid growth? We might as well seek some inspiration from the soil environment of wild orchidsFlower's! As long as we observe carefully, we will find that the soil in which wild orchids grow generally consists of three layers: the upper layer is the fallen-leaf humus layer. It is mostly made up of fallen leaves and withered stems of plants, in an undecayed and semi-decayed state, with a fairly large amount of mycelium attached and parasitic, lightweight and porous, with very strong air permeability, and somewhat acidic, and it can provide a large amount of organic matter. The bottom layer is various mountain soils. Some are clayey and some are loose, some are acidic and some are alkaline or neutral, with comprehensive nutrients; it has relatively good "ground moisture" and "ground warmth" and can supply water to the upper and middle layers, keeping them in a "moist" state, and can also regulate the temperature of the upper and middle layers. The middle layer is formed by a mixture of materials from the upper and lower layers and is also the transitional layer between them, where various substances undergo further decomposition and synthesis. Because this layer of soil contains relatively more organic matter, it is generally called humus soil. The middle layer is the main distribution zone of wild orchid roots, and the orchid roots grow flat and spread radially around. If the bottom layer is loose, slightly acidic soil, a small number of orchid roots also grow downward. The middle layer has very good air permeability, suitable humidity, sufficient organic matter and a certain amount of mineral nutrients, and a small temperature fluctuation range, which is very conducive to the growth of orchid roots and the reproduction of root fungi, thereby providing abundant nutrients for orchid growth. From the soil environment in which wild orchids grow, it can be seen that orchidcultivationgrowing media should meet the following requirements: ① Very strong air permeability. ③ A certain water-retention and water-drainage capacity, with the growing medium kept in a "moist" state. ③ Sufficient organic matter and a certain amount of mineral nutrients. ④ Favorable for heat dissipation in summer and favorable for heat retention in winter. Now let us see whether the four growing media of humus soil, sphagnum moss, sawdust and weathered stone can meet the above requirements. ① Humus soil. It contains sufficient organic matter and a certain amount of mineral nutrients, and its air permeability, water retention and water drainage capacity are all relatively good, and its heat dissipation and heat retention performance is also acceptable; but when used in pots, after a period of watering and leaching, the soil aggregate structure deteriorates, air permeability declines, and the soil becomes waterlogged, so it is not very suitable for growing orchids. ② Sphagnum moss. It has strong air permeability and strong water permeability, but because it is a living plant, it is not easy to rot and decompose, and it cannot provide orchids with organic matter and mineral nutrients; its heat dissipation performance is relatively good, and its heat retention performance is relatively poor. ③ Sawdust. It has strong air permeability and good water retention and water drainage capacity, and after decomposition it can provide sufficient organic matter and a small amount of mineral nutrients, and its heat dissipation and heat retention performance is relatively good. But in the process of decomposition, the fungi in sawdust need a large amount of nitrogen, and their demand is in a certain proportion to the carbon they take up (the so-called carbon-to-nitrogen ratio), which will cause a serious shortage of nitrogen supply to orchids, making orchid seedlings thin and small, withwild-collected orchidsshowing obvious shrinkage. ④ Weathered stone. It has strong air permeability and strong water permeability, and after decomposition it can provide abundant mineral nutrients; its heat dissipation performance is relatively good, its heat retention performance is slightly poor, and it contains no or only a small amount of organic matter, so it cannot provide a sufficient source of organic matter for orchid growth. From this it can be seen that each type of orchid growing medium has its own strengths and weaknesses, and none can fully meet the needs of orchid growth when used alone. To obtain a relatively ideal orchid growing medium, the only way is to make up for each other's shortcomings and mix them for reuse. The author uses a mixed growing medium of 60% weathered stone, 20% humus soil and 20% sawdust to grow orchids. This growing medium has strong air permeability, good water retention and water drainage capacity, keeps the growing medium often in a "moist" state, has sufficient organic matter and a certain amount of mineral nutrients, has relatively good heat dissipation and heat retention performance, and resists watering and leaching. In the early stage, the decomposition of sawdust will compete with orchids for nitrogen, but the nitrogen in the soil can basically meet the needs of orchid growth, and in the later stage the decomposed sawdust in turn supplies nitrogen to the orchids. In addition, sphagnum moss can be used as a soilless orchid growing material; it is clean and hygienic and does not require a particular pot, and as long as a full nutrient solution of a certain concentration is applied regularly, orchids can grow normally. (Hubei - Liu Jingqiu)