Due to a series of reasons such as my observation not being meticulous enough and detecting equipment defects (too few probes inserted into the ground, no probes inserted at depths of 5cm, 10cm, 15cm, 25cm, 40cm and below 50cm deep, and some geothermal meters are not accurate or even fail), I once concluded and publicly said: the ground temperature of the greenhouse is low during the day and high at night; The highest point of the shallow ground temperature (30cm deep) of the greenhouse occurred in the lowest time period before the sun rose, and the lowest point occurred in the highest temperature period in the shed at noon. The heat radiated by the sun during the day in winter cannot reach the position below 20cm deep on the floor of the greenhouse; The deeper the depth, the higher the ground temperature. Until one afternoon, I occasionally found in the solar heating and cooling test shed that when the ground temperature 20cm deep during the day was higher than the ground temperature at 30cm deep, I immediately carried out a continuous test of the ground temperature at 5cm, 10cm, 15cm, and 25cm deep for many days (without these depth geothermometers, I inserted a 30cm deep geothermometer into different depths for testing, and purchased a 50cm geothermometer). After testing, I learned how ridiculous my previous conclusions are, and I apologize to all netizens for my ignorance!
The test found that for greenhouses that did not take floor heating, on days when the sun was good, the shallow ground temperature (0~20cm) was high during the day and low at night. The deep ground temperature (50 cm and below) is in a descending position until the inflection point appears, and the deeper the depth, the higher the ground temperature. Ground heating greenhouse, when the light is good during the day in winter, the shallow ground temperature in the afternoon is likely to be higher than the deep ground temperature for a short time, and the closer to the ground, the higher the ground temperature. The deep ground temperature at night will definitely be higher than the shallow ground temperature, and the closer to the ground, the lower the ground temperature (this also applies to unheated greenhouses). The floor heating greenhouse, the buried depth of the floor heating pipe, is the highest place of floor temperature.
Tomato colorant
Whether the heat of solar radiation can reach the ground depth of 20cm depends on the intensity of solar radiation, more bluntly, depending on the higher temperature in the shed (about 28 °C, which is also the upper limit of the optimal growth temperature for most plants) sustainable time and the shallow ground temperature in the shed! Because greenhouses are affected by the optimal temperature required to grow crops and the humidity in the shed. Ordinary greenhouse during the day is difficult to control the temperature at about 28 ° C and control the humidity below 60%, in order to drain moisture, the only way is to open the air outlet, after opening the air outlet, the temperature in the shed will drop rapidly, unless the installation of intelligent air outlet machine, can better adjust the temperature and humidity in the shed, the general growers, whether it is the base or individuals, can not do the greenhouse temperature and humidity more accurate control, either sacrifice temperature to remove humidity, or sacrifice humidity to insulate. In fact, greenhouse growers would rather sacrifice temperature to remove humidity, because high temperature and high humidity and low temperature and high humidity are taboos in greenhouse planting!
Greenhouse solar floor heating and cooling, heating part of the test is basically successful
The purpose of studying solar floor heating and cooling in greenhouses: aiming to provide enough heat for fruits and vegetables in greenhouses with low initial installation cost and low use cost (high yield of vegetables in winter and early sleep breaking of fruits and trees need to increase the temperature of the shed and the temperature of night and rainy and snowy weather) and the amount of cold (fruit and tree hibernation and high yield of vegetables in summer need to reduce the ground temperature and shed temperature), strive to create an environment suitable for the growth of fruits and vegetables, advance or delay the market time of vegetables, increase the yield of fruits and vegetables per unit area, improve the income of growers, and reduce the use of pesticides. Make fruits and vegetables greener, taste better and more nutritious.
Busan 88 can not only be eaten as a fruit, but also stir-fried with it, the taste is also barred, more juicy and delicious than the tomatoes in childhood, but it is too laborious to cut
Up to now, the test shed is the only greenhouse in the 88 planting shed in Busan that has not sprayed antifreeze and has not suffered frost damage after winter, and the other sheds have been sprayed with antifreeze on the foliar surface after the weather turns cold, but all have frost damage to varying degrees.
In terms of yield, the current output of the test shed is the highest in the same batch of planting sheds, and the finished fruit rate and fine fruit rate are higher, which is due to the high ground temperature and high night temperature of the test shed. The test shed 0~50cm daily ground temperature is 3~5 °C higher than other sheds, the night temperature is 2~3 °C higher than other sheds, the difference between the minimum temperature of the night experimental shed and the lowest temperature of other sheds reaches 7 °C (it is predicted that the temperature in the shed may be lower than 12 °C in the morning, I will turn on the night mode, sacrifice the ground temperature for the temperature), there are 3 consecutive days, the lowest temperature of the test shed is 12 °C, while the lowest temperature of other sheds is only 5~6 °C.
Since the start of heating on November 4, 2022, the lowest temperature of the test shed appeared at 6:10 am on December 10, 7.6 °C, when the outside temperature was -1 °C (the lowest temperature at night on the 9th was -7 °C, due to the failure of the greenhouse roller shutter machine, the quilt was not put down on the night of the 9th, and because the pool was repaired on the 9th, the water in the pool was pumped out, and it was not repaired that day, and it could not be filled with water, so when the quilt of the roller shutter machine failed in the afternoon, it could not be started at night), the second low temperature was 9 °C, and it appeared 3 times, At 7:00 on December 11 (although the pool was repaired and filled with water on the 10th, the sun was not good that day, there was no heat exchange of the system, and the circuit in the field failed to power out that night, because I misjudged and thought that the temperature in the shed at night would not be too low, and the circuit was not repaired, so this low temperature appeared), 7:00~9:00 on January 15 (on the evening of the 14th, the night mode was turned on, but there was no money on the card in the middle of the power outage, and it was not started again until 9:00 in the morning. On January 12 and 13, due to the needs of the shed work, the shed was lit at 7:30 in the morning, the light rain on January 12, and the quilt was put at 17:30 in the afternoon. On January 13, it was cloudy, the north wind was 6~7, it snowed on January 14, the quilt was 7:00 liters in the morning, and when the quilt was put in the afternoon, it could not rise the next day because of fear of being frozen, leaving a slit nearly a foot high from the ground, and the north wind at night was 6~7. On the evening of January 15, when the quilt was put down, there was still a seam nearly a foot off the ground, the greenhouse quilt was not waterproof, nor was it covered with the second film, the second membrane we had tried to cover several times with the old shed film that was replaced, it may be that the technology is not in place, or it may be too windy, covered for a few days, it was damaged by the wind, and it was abandoned, no way. Although the weather forecast on January 15 shows that it is sunny, it is actually cloudy weather, the maximum temperature in the shed during the day does not exceed 20 °C) and 7:30 am on the 16th (the outside temperature dropped to -9 °C at 00:00 on the 16th, I started the night mode at 00:30, the temperature in the shed was 9 °C at the time of start-up, and the 7-hour night mode consumed 17.85KWH, and only maintained that the temperature in the shed did not drop, because of the rainy and snowy weather for many days, the impact of operation and the defects of the greenhouse envelope itself, As a result, the heat in the shed was rapidly lost, and by the time the system was started, the 50cm ground temperature had dropped to 16.1 °C, and the heat that could be extracted was already very limited), and the outside temperature was -9 °C.
Greenhouse solar floor heating and cooling, buried pipe construction site
In other sheds, due to low night temperatures and low ground temperatures, the fruits are not red for a long time (yellow after ripening) and the fruits are large. Busan 88 first-class fruit weighs more than 8 grams, the current purchase price is 7.5 ~ 8 yuan / jin, the secondary fruit weighs more than 13 grams, the current purchase price is 3.5 ~ 4 yuan / jin, the third grade fruit weighs more than 17 grams, the current purchase price is 1.6 ~ 2 yuan / jin, the experimental shed in addition to the first ear of fruit, can generally reach the primary fruit standard, and our other shed fruits generally weigh more than 15 grams, no way, in order to improve the amount and quality of the fruit, we have begun to spray a spray of red and cyclamatein in other sheds, that is, use drugs to induce redness and sweetening, because play greenhouses, Play is the time difference and quality (not only must it be delicious, it must also be good-looking, if it is not good-looking, no matter how delicious it is, it is not for nothing, because such a fruit it cannot be sold for a price, as for whether it is organic or green, it is not a matter for growers and farmers to consider).
Experiments have proved that the installation of solar floor heating and cooling system in the greenhouse is the heating and cooling method with low investment (20,000 yuan / mu), the lowest energy consumption (average daily electricity consumption of 15KWH), and the most likely to achieve profitability (increasing production does not necessarily increase efficiency, when encountering the epidemic, no matter how much output is in vain, the motor still has to use electricity). Through experiments, I think there are the following points to pay attention to: First, the system should preferably be highly intelligent, at least it must be automated, otherwise it will be too troublesome. Second, in areas with many continuous rainy and snowy days and when planting temperature-sensitive crops, the system must be equipped with auxiliary cold and heat sources (in the coldest month, the heat stored underground can only ensure the growth of crops in 3 consecutive rainy and snowy weather crops, if only to ensure that no frost damage occurs, then the days of sustainable supply will grow too much). Taking tomatoes as an example, the nighttime suitable temperature for tomato growth is 12 °C ~ 15 °C, below 8 °C, growth stops, below 5 °C, frost damage occurs. After the night mode is turned on, the floor heating pipe laid in the shed is equivalent to the horizontally arranged ground source heat pump pipe network, which will continuously absorb the heat in the soil, and then dissipate heat through the greenhouse radiator to increase the air temperature in the shed, and when the outside temperature is -10 °C, the water temperature of 16 °C can ensure that the temperature in the shed is not less than 10 °C). Third, in cold winter areas, quilts must be waterproof. Fourth, in the heating mode, the greenhouse without an auxiliary heat source is installed, and the starting temperature of the night mode of the coldest month should be set as low as possible, which is slightly higher than the temperature at which the crop stops growing, and try to make the ground temperature in the shed drop slower to cope with more rainy and snowy weather.