Due to the special environment of greenhouse cultivation, greenhouse soil and exposed soil still have some differences. Through the measurement of soil moisture meter, it is found that the soil water content in greenhouse soil is not the same as that in open soil, and the change rule of greenhouse soil moisture is mainly The following features are exhibited.
The fluorinated mica crystals have very good
high temperature resistance, corrosion resistance and light transmission
properties, and can work for a long time at a high temperature of 1100°C.
No reaction occurs
with strong acids and alkalis; complete light transmittance (pure and
transparent). The natural mica plates traditionally used in the observation
window of high-pressure boiler water level gauge are all brown, and the light
transmittance is not good, and the temperature resistance is in the range of
200-700°C, especially the corrosion resistance is poor. The boiler steam drum
water in thermal power plants contains alkali. After reacting with natural mica
and alkali, it is washed with hot air and hot water, and it is prone to
fluffing, scaling, and being broken. In the short term (about 1-2 months), the
water level is not clearly understood. After being broken, it can easily cause
leakage. The fluorite mica does not react with the acid-base solution, and does
not react with water in the hydration reaction, so that it does not form a
layer, does not scale, and does not break. In the long-term (2 to 3 years)
scouring of high-temperature and high-pressure water (including acid and
alkali), the original clarity and transparency can still be maintained. In
China, it has been widely applied to the observation window of steam boiler
water level gauge in high-pressure boilers of thermal power plants. It has also
been selected by Japanese BBK company and NDK (Colin) company for the
observation window of high pressure boiler drum level gauge.
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1. In general, the greenhouse soil moisture mainly depends on the storage of natural precipitation in the soil during the relaxation period and post-buckling membrane artificial irrigation. The soil water consumption is mainly ground evaporation and crop evapotranspiration. In the early stage of each crop, evaporation is the main factor, and in the later period, the transpiration is greater than evaporation. The measurement of the soil moisture meter found that the sunlight greenhouse produces less water than the exposed land.
2. In the case of less air release during the winter, the contact of water vapor with cold film will condense into water mist on the inner surface and accumulate into water droplets. Water mist and water droplets will continue to evaporate into the air or drip off the ground, creating a small water cycle. Because water droplets tend to fall into a relatively fixed place, resulting in uneven soil water seals, this condition is most pronounced when water is rarely or not watered in winter.
3. The soil covered by the capillary mainly transports the deep soil moisture to the soil surface. In the case of high air humidity, the surface soil absorbs moisture from the air and receives moisture from the deep soil. Therefore, it becomes muddy and gives people the impression that there is no shortage of water. Therefore, in order to ensure the water demand of greenhouse crops, The soil moisture meter should also be used for accurate determination.
The above is the change rule of greenhouse soil moisture analyzed by the soil moisture measuring instrument. In the modern intelligent greenhouse production, in order to understand the soil moisture content in real time, most of them use the soil moisture sensor to measure, which is for crop water demand. The timely replenishment and precision irrigation are of positive practical significance. In the open field production, with the aid of a soil moisture measuring instrument, similar results can be achieved.