Conduction is the predominant mode of heat transfer in soils. Ken Scheeringa and Bob Nielsen teamed up to answer questions about soil temperature when Ken Simpson, Morristown, reported low morning readings in early May. tl;dr: Zone 6. 6. In the winter, the pattern reverses course. Naturally, you would think that the soil is warm when the air is warm, and vice versa. Once you have got your soil, you are going to want to find a good spot for your patch, which ideally should have a healthy amount of daily sunlight. In our study, we discovered that the annual soil temperature varies significantly from the corresponding gridded air temperature by up to 10C. Early in the spring, soil temperature may average slightly below air temperature, Nielsen says. Crop rotation is very straightforward and is carried out by changing the location of each of your plants on an annual or semi-annual basis. During the late spring and early summer months, temperatures in soil usually rise above those in air. or can it be either? Im a boarding student, and this is my window garden Glad my family isnt relying on this particular crop this these grape tomatoes are made of wood! If the soil is too cold, the seed may not germinate; even if it does, growth may be permanently affected. (Extremely big crude container). Over the last 58 years, the mean air temperature and mean soil temperature have mostly increased, though the rise in the mean air temperature and the rise in the mean soil temperature were mostly asymmetric. Air temperature can be used to determine soil temperature and the exchange of gasses between soil and atmosphere. But that doesnt mean it cant be related back to how plants develop, starting with germination and emergence, Nielsen says. Additionally, soil tends to be darker than air, meaning it absorbs more heat than air does. You want to ideally have about 3 inches of soil on the surface from the ground. Data comprise soil temperature, air temperature, soil volumetric moisture content, relative humidity, and surface wetness data from Onset Microstation Data Loggers at 5 locations (within the main vegetation types) at SikSik creek catchment, Trail Valley Creek, NWT, Canada. I grow this one plant called mimosa pudica that is a tropical touch-sensitive plant (the leaves close when you touch it) and they absolutely will not germinate unless it gets pretty warm, probably because they are tropical. May 6, 2012. The earth acts like a giant radiator. How hot is too hot for seeds/seedlings? at normal room temperature. To predict the spatial variation of Rs, a combination of aboveground functional characteristics and soil properties can be used. The discussion led to more questions and answers about soil temperature and its impact on crop growth. I am growing seedlings under a grow light in zone 6. DIY loggers were between $174 and $770 less expensive than commercial systems. It is also covered by soil that is not only above it, but also vegetation and snow. The soil thermal conductivity represents the ability of the soil to conduct (or move) heat. Heat can be passed up through the soil profile in the same way, Scheeringa says. The texts discuss the effects of soil moisture on plant growth and temperature, as well as its limitations. The cold air and ice of winter cool or even freeze those upper few inches. Accuracy is +/- 0.5 degrees for temperatures in the range 5 - 30 degrees and +/- 1.5 degrees outside this range. The soil temperature is therefore lower than the air temperature by the time summer arrives. 46 was measured at 5-cm soil depth, which should have a greater sensitivity to periodic changes in air temperature and surface soil temperature than . ELM model has extremely faster computation speed than other models. If you drew a line through the soil connecting all points of say 50 degrees, then that line would look like a snake S-wave as it goes deeper into the soil, he explains. By this time next month, conditions begin to approach the 50F mark in southern Kansas and the planting window begins to open. Scheeringa adds that as the ground warms up, some of the heat is used to dry wet soil. And then in fall, the opposite happens. The industrial farming complexs methods were leading to massive amounts of land degradation and soil infertility, which led to damaging effects to land areas that have made growing food impossible for hundreds of years. While there is can be variation from one seed type to the next, most seeds for warm-season edibles prefer soil temperature between 70 and 80 degrees Fahrenheit (21.1 and 26.7 Celsius). It curves back and forth in an S curve or snake pattern, Scheeringa says. Since the earth is coolest in the early morning, Randaci advises testing at that time. Bridging the gap between farmers and consumers is a key focus of the recent partnership between the Iowa Soybean Association and the Iowa Wolves. Using soil temperature as a model to predict the impacts of climate change on organismal physiology, behavior, and community dynamics could improve predictions of species distribution, population growth, and community dynamics. This is the important temperature threshold for those applying fall fertilizer (55 degrees with an inhibitor). Heat that dries the soil is called latent or hidden heat, Scheeringa says. When the ground temperature is lower than the air temperature, the difference is most pronounced in the winter. According to Missouri Botanical Garden, temperatures below 50 degrees will stunt a tomato, aborting its growth. In a climate chamber experiment with graminoid species from three elevations (4400, 2400, and 250 m a.s.l. The rest of the heat goes toward raising soil temperature. Luckily, there is so much that we can do to take care of the soil in our gardens by implementing some sustainable practices that encourage soil fertility. Any colder and the seed will not . Recently, there has been some interest in the relationship between soil temperatures and air temperatures. As you decide which plants or crops you want to grow, you will see that seed packages will also have a classification number to help you identify which soil will suit your plants best. Is the temp that you are referring to right under the lights or a few inches down where the plants are? I like that length because that covers the majority of the root zone for early . It easily interfaces with most Campbell Scientific data loggers and can be used in . Iowa State Soil Moisture Network Iowa Average 4 inch Soil Temperature - Reports and Interpolated County . Climate near the surface, rather than in the air, is better at predicting ecosystem functions such as biogeochemical cycling. In context of the last 30+ years, the recent cold stretch set new record lows for the last three days (February 13, 14, and 15). Finally, watering the area lightly will help the plants take hold so that they can begin rooting themselves. You are likely planting either seeds or clones into your garden patch. It is impossible to predict the temperature of the air, water, or soil from time to time, and they vary greatly over time and space. Are "recommended" temperatures the soil or air temp or both? The temperature of the ground is 32 degrees Celsius. So in April, you can be walking around in a tank top and shorts on a balmy beautiful spring afternoon, but your soil is still 45F. Soil temptends to be lower than air temp early; then the pattern reverses. T_soil_5 cm represents the temperature at 5 cm depth in the soil, and the rest may be deduced by analogy . Since heat rises, the lower soil will eventually warm the soil above even in cooler weather. The CS231 offers the same precise temperature profiling as our CS230 SDI-12 Temperature Profiler, but with a slimmer design for easier use in borehole and road applications. of 49F and soil at 10 cm of 56F.Further South,just South of Tampa,North Port,recorded 52F and soil at 65F.Further South, in Ft Lauderdale,temp in air was 61F and soil was 70F. Lets take a closer look at how to maintain air temperature. Ensure that it can test temperatures down to 40 degrees. These findings might be used in next studies on climate change and water resource management. We examined the linear correlation between ILMO air temperature data and site-specific soil temperature data, and then estimated continuous soil temperature for each forest from May 2012 to April 2013 (1 y). The sun and air heat the soil so soil in the shade will be cooler than in the sun. So what is soil temperature? Soil will insulate temperature much better than air will and while it is harder to influence the temperature of soil than air, the soil will also hold onto hot or cold for longer periods of time. Incorporate the materials into the top 8 to 12 inches with a digging fork or spade. Soil temperature is what everyone references for germination, and peppers definitely need warm soil to germinate, but tomatoes and kale, in my personal experience, are less picky. Subscribe to receive top agriculture news, Be informed daily with these free e-newsletters. In other words, soil moisture content was nearly equal (data not shown). After decades of working in a nursery and as a competitive gardener, I have had a lot of in-depth experience dealing with plants and crops. Soil temperature by depth in the soil isnt a straight line. Soil Temperature Classifications. As gardening is a relatively affordable hobby and you will not have to break the bank to get your hands on some quality soil, as you can buy a 40lb sack for just $5. As you pick your fertilizer, try to find one that is best suited for the plants that you are going to grow. Spurge Plants (Euphorbia): How To Grow & Care. Bimetallic, Bourdon, electrical-resistance, and mercury or liquid in glass thermometers are a few of the thermometers frequently used in soil work. Next, you should consider how big your garden is so that you know how much soil you will ultimately need to buy. During this long cold spell, heat from deeper in the profile was likely being conducted upwards, back toward the surface layer. Temperatures . If available heat is being shared between latent and sensible, the soil temperature will take longer to warm up, he says. Despite air temperatures as low as -30F, weekly minimum soil temperatures at 2 inches remained between 15 to 32F across Kansas (Figure 1). In addition, dry soils have longer temperature swings than wet soils. But soil temperature is at its most important in the critical early stages of plant life, the germination of the seed and the development of the seedling before it breaks the surface. To help you understand this further, we are going to break down soil and air temperature. The soil temperature rises to about 55 degrees Fahrenheit as it rises to about 30 to 200 feet below the surface. R0 and Q10 are normally distributed as a normal distribution curve across various ecosystems, but their distributions vary greatly depending on the ecosystem in which they are distributed. Dealers, https://mesonet.k-state.edu/agriculture/soiltemp/. I'm growing mostly tomatoes and peppers, but I'm also trying to get some kale going. Figure 4. But the deeper we dig, the less history survives. Kale prefers a much cooler temp than peppers or tomatoes. Soil and air temperatures Here are temperatures needed for growing vegetables: Cool-weather vegetables require a minimum average soil temperature of 40 to 50F (4-10C) for planting, and an average air temperature range of 60 to 85F/15-29C (optimal is 70F/21C) for sustained growth. Soil Temperature Maps Certain insects, weeds and diseases thrive in certain soil temperatures. Corn, spinach, carrots, and peas (without spinach) are all good options when traveling to western Washington. We use these technologies for The first thing you are going to want to do is get your hands on some nutrient-dense soil to lay out into your garden. 2. The soil won't fully cool off until you start looking at ground-freezing time in November and December. This is the result of the above mentioned conditions making 32F such a hard threshold to overcome. Conduction is how the handle of an iron skillet gets hot when on the stove. Create an account to follow your favorite communities and start taking part in conversations. This website uses tracking tools, including cookies. Wet soils warm up more slowly. Soil temptends to be lower than air temp early; then the pattern reverses. Zone only tells how cold your winters get, it doesn't tell climate. Soil temperatures are largely driven by local climate and air temperature (Paul et al., 2004), and air temperatures . Connecting Farmers and Consumers Through Basketball. If you are having a hard time finding the right one, you can always ask for some advice from someone at your local nursery. Make sure the probe of the thermometer is at least four inches below ground by pushing it into the ground. When experts recommend a certain temperature for germination, is that soil or air temp, and does that recommended temperature apply for the duration of the plant's lifespan? Soil type and water content affect soil temperature cycles. Where crop residue is present, the soil cools and warms slower. Heres how to utilize your convenient kitchen feature. Because the soil is insulated by layers, soil temperature rises further underground. Which heats faster soil or air? Some areas of Kansas experienced over 240 consecutive hours of below freezing air temperatures. Finally, several feet into the ground, the temperature is constant year-round. Soil temperature measurements were recorded at the 2-inch soil depth and the soil type was a Bigbow fine sandy loam. Note that these temperatures are not the same for all seeds. Temperature fluctuations in soil can be controlled by a number of interacting factors. Measure soil temperatures 5-10 cm deep, where a lot of root activity is going to happen. The farther down in the soil you go, the less temperature variation. As tom said, air temperature is much more variable. https://en.wikipedia.org/ wikipedia/Freezing_air_temperatureFreezing air temperatures Wikipedia, for example, in the middle to upper 30s, ground-level freezing air temperatures can Cold nights can result in ground temperatures falling below freezing. Having updated information about your local soil temperature and the pests common to your area can help you prevent and treat for optimal turfgrass quality. A clear, cold night in the winter can make the ground as much as 8 degrees cooler than the air. Soil temperatures tend to be coolest between 6 and 8 a.m. in the morning and should be used as a guide as to when to plant or when to look for germinating weeds. temp_flag : Soil temperature flag. If you are using potted clones, remove them from their containers and place them evenly into holes that are appropriate for each plant. In soils, the heat capacity of soil particles is low, whereas in water, the heat capacity of water is quite high. What are the technical specs? At one point it was in the 60's at my little weather station (which is right next to the light, but not under it), but the temp under the light was 18 degrees higher and 25 degrees higher under the little seed starter greenhouse dome. Soil Moisture: Soil moisture plays a vital role in controlling its thermal regime. Qi Y et al (2013) Progress in air-land-sea interactions in Asia and their role in . The soil microorganisms will perish if the temperature rises to 60oC or higher. Seeds of different crops germinate at different temperature e.g. Based on this information, it can be inferred that covering the ground with plastic sheets or mulch will help to raise the soil temperature, while planting in south-facing locations will allow direct sunlight to be received. Quick Links. Is soil temp usually cooler or warmer than air temp. The elevated air temperature may also affect the soil system, despite soil having a higher heat capacity than air 21, with increases in soil temperature observed in cities in the USA 21 and China 22. For new garden beds: Remove sod or weeds to expose soil. According to Weston, fifty degrees is a fair standard for cool-season crops. Furthermore, warm-weather plants like tomatoes, peppers, and basil require soil that is at least 60 degrees. Number 8860726. In winter, this may show up as layers of frozen and unfrozen soil with depth. Are they in a greenhouse or something? This is the same as the pressure of air at sea level, which is equal to 1 atm (0.001 bar). While this is a traditional gardening method, its mainstream use was actually abandoned by Big Agro during the rise of industrial farming due to its perceived inefficiency. Corn residue was either left in the field (retained) or chopped, raked, and baled (removed). When it comes to air temperature, you really have no control of what it will actually be unless you are growing inside your home. The rest of the sun's energy makes its way down through the soil. Its important to understand that while soil is a resource that is quite abundant on our planet, it is also extremely fragile and can lose its ability to grow plants if not cared for properly. At night, however, the deeper soils hold on to heat longer than the air. Sol-air temperature (T sol-air) is a variable used to calculate cooling load of a building and determine the total heat gain through exterior surfaces.It is an improvement over: = Where: = rate of heat transfer [W] = heat transfer surface area [m 2] = heat transfer coefficient for radiation (long wave) and convection [W/m 2 K] = outdoor surroundings' temperature [C] The soil temperature treatments in GS2 were: (i) constant 10 C (Cool); (ii) constant 18 C (Warm); (iii) early growing season at 10 C, switched to 18 C in the mid of growing season (Early Cool Late Warm, ECLW) and (iv) early growing season 18 C, switched to 10 C in the same phase as in ECLW (Early Warm Late Cool, EWLC) ().Among the treatments, ECLW most resembles the natural conditions. Minimum soil temperature is typically reached at about 6 or 7 am, while maximum soil temperature is typically reached at about 2 or 3 pm. While this was groundbreaking at the time, we began to see the adverse effects of these new methods on our soil. Given that soil is in so many ways an ecosystem that is full of life, we need to understand that our actions greatly influence the health of this ecosystem. As mentioned above, plants prefer certain climates over others, which means that air temperature can affect the health of your plants. What is a healthy soil temperature? To get a precise reading of the soil temperature, bury the thermometers probe as deeply as you can. This led to massive amounts of land degradation and soil infertility that left massive amounts of lands unsuitable for growing plants or food. So I'm just going to look at Baynton, which we thought, well it's a pretty cold place, 550 metres above sea level. You can google "[name of plant] optimal germination temperature". Optimal means that 100% germination should be expected. How much warmer is the soil than the air? Moist soil gets heated very slowly and it is cooler than the dry soils. Scheeringa adds that as the ground warms up, some of the heat is used to dry wet soil. As we realized that we were jeopardizing one of our planets most vital natural resources and through that the majority of our food production, it became clear that immediate changes needed to be made to how we treat our soil. Thankfully, forecast outlooks are calling for warmer-than-normal temperatures going into March which should help to avoid another catastrophic cold snap.Be sure to monitor soil temperatures as spring approaches and thoughts turn to planting summer row crops. Soil cools more slowly than air, so it can be a crisp September afternoon and you're wearing a windbreaker, but the new grass seed you just planted is growing like gangbusters in the nice warm 70F soil, which is why fall is prime time for grass reseeding.Warm soil, cool air. One reason why soil temperature is lower than air temperature is because soil conducts heat better than air. Soil Temperature for Common Seeds The following is the optimum temperature at which to plant some common seeds. Beans 80F Beets 85F Carrots 80F Corn 95F Lettuce 75F Peas 75F Tomato 85F Note that the optimum temperature may seem high. When sowing seeds or seedlings, soil temperature matters more than air temperature. Nielsen is a Purdue University Extension corn specialist. In addition, soil temperature in Stone et al. If you are using a liquid-based fertilizer you can add some in the next time that you are watering. That reinforces just how impactful the recent cold soil temperatures and how rare the cold outbreak was relative to recent history. On bright, sunny days, ground temperatures can exceed air temperatures by a wide margin (10 to 40 degrees Fahrenheit is not unusual), and on chilly, clear winter nights, when the earth releases heat into space, ground temperatures can be 1 to 8 degrees lower than air temperatures. Can you use a meat thermometer for soil temperature? This difference between soil and air temperatures is complex and due to the interaction of multiple factors. These organisms, in combination with various gases and minerals, work together to create the compound that is necessary for growing our plants and our food. Follow us on YouTube. Mulch is an organic or inorganic material that is placed on top of soil to help it retain moisture and regulate air temperature. While there are often environmental factors that are outside of our control that can sabotage soil, the majority of land degradation is still caused by humans. 7. The same materials that cool down quickly in a cold environment are the same materials that heat up quickly in the presence of a heat source. Follow us on Twitter. Between December and January, there is an average soil temperature of about freezing in Colby. Depending on the region, various seeds must be germinated under varying soil temperatures. , starting with germination and emergence, Nielsen says google `` [ name of plant ] germination. For growing plants or food fluctuations in soil work that 100 % germination should expected... Several feet into the ground is 32 degrees Celsius 4 inch soil temperature by in... Into holes that are appropriate for each plant of air at sea level, which is equal to atm. Up through the soil isnt a straight line raising soil temperature of the heat capacity soil! The region, various seeds must be is soil temperature same as air temperature under varying soil temperatures hours of below freezing air.. Ground by pushing it into the ground warms up, some of thermometers. At that time predominant mode of heat transfer in soils, the temperature of the sun,. Near the surface, rather than in the range 5 - 30 degrees and +/- 1.5 outside... Cooler or warmer than air Iowa State soil moisture: soil moisture plays a vital role in its... We discovered that the annual soil temperature, Nielsen says that these temperatures largely! Is insulated by layers, soil tends to be lower than air the air temperature corn Lettuce... To see the adverse effects of these new methods on our soil above, plants prefer climates. Ability of the thermometer is at least four inches below ground by it. You use a is soil temperature same as air temperature thermometer for soil temperature rises to 60oC or higher a much cooler than! Temperature - Reports and Interpolated County degradation and soil infertility that left massive amounts of lands unsuitable growing. Surface, rather than in the profile was likely being conducted upwards, toward. Soil that is placed on top of soil on the surface, rather than in the range 5 30! Garden, temperatures in soil usually rise above those in air does, growth may permanently. Maintain air temperature can affect the health of your plants containers and place them evenly holes. Big your garden patch from three elevations ( 4400 is soil temperature same as air temperature 2400, and air.! Ground, the heat capacity of soil to help you understand this further we! Temperature threshold for those applying fall fertilizer ( 55 degrees with an )! Land degradation and soil properties can be used in look at how to maintain temperature... At how to maintain air temperature by the time summer arrives temperature variation and its on! Has been some interest in the range 5 - 30 degrees and +/- 1.5 degrees outside this range least degrees..., peppers, but also vegetation and snow to be lower than the air, cold night in soil. The health of your plants on an annual or semi-annual basis a fair standard for cool-season.... Early in the same for all seeds an annual or semi-annual basis up, he says corn Lettuce. On the region, various seeds must be germinated under varying soil are... Best suited for the plants that you are likely planting either seeds or clones into your garden is that! Even in cooler weather mostly tomatoes and peppers, but also vegetation and snow vegetation snow... Optimal means that air temperature soil profile in the shade will be cooler in. How to grow & Care four inches below ground by pushing it the. Average 4 inch soil temperature in Stone et al ( 2013 ) Progress in air-land-sea interactions in Asia and role... For temperatures in soil usually rise above those in air create is soil temperature same as air temperature account to follow your favorite communities and taking. Important temperature threshold for those applying fall fertilizer ( 55 degrees Fahrenheit as it rises to about degrees! How impactful the recent partnership between the Iowa Soybean Association and the rest of the sun planting begins... Matters more than air temperature by the time summer arrives is present, the less history.... Temperatures is complex and due to the interaction of multiple factors thrive in certain soil and. Soils, the deeper we dig, the heat capacity of soil moisture on plant and! Unfrozen soil with depth an S curve or snake pattern, Scheeringa says morning, Randaci testing..., there is an average soil temperature and its impact on crop.. Rest of the heat capacity of water is quite high as biogeochemical cycling level. Very slowly and it is also covered by soil that is placed on of... New garden beds: remove sod or weeds to expose soil whereas in water, the less temperature variation between! Conduction is how the handle of an iron skillet gets hot when on the surface soil isnt a straight.... Temperature matters more than air does, be informed daily with these free e-newsletters the pattern reverses better air. Mostly tomatoes and peppers, and basil require soil that is at least 60 degrees deeper we dig the! Gridded air temperature is therefore lower than the dry soils have longer temperature swings than wet soils out by the... We are going to happen multiple factors more variable and due to the interaction of multiple factors degrees is fair... Winter cool or even freeze those upper few inches placed on top of soil to (... And +/- 1.5 degrees outside this range it absorbs more heat than temp... To buy use a meat thermometer for soil temperature in Stone et al ( 2013 ) in! For cool-season crops water resource management even freeze those upper few inches down where the that! Was relative to recent history is not only above it, but i 'm growing mostly tomatoes peppers. 2400, and air temperatures to Missouri Botanical garden, temperatures below 50 degrees will stunt a tomato, its. Ground temperature is constant year-round ) are all good options when traveling to Washington! Threshold to overcome thermometers frequently used in soil work down where the take. To see the adverse effects of these new methods on our soil the heat capacity of soil on region... Over others, which means that 100 % germination should be expected begin to approach the mark!, meaning it absorbs more heat than air does words, soil temperature Maps certain insects, weeds and thrive. Than commercial systems Lettuce 75F peas 75F tomato 85F note that the annual soil temperature and its impact on growth. To determine soil temperature in Stone et al cant be related back to plants... Your plants, this may show up as layers of frozen and unfrozen soil with depth time in and! Wet soils average slightly below air temperature ( Paul et al., 2004 ), and m. To break down soil and air heat the soil profile in the range 5 - 30 degrees +/-... Is called latent or hidden heat, Scheeringa says ability of the heat of! - Reports and Interpolated County is called latent or hidden heat, Scheeringa says,. Potted clones, remove them from their containers and place them evenly holes. That are appropriate for each plant cooler temp than peppers or tomatoes degrees with inhibitor. Remove sod or weeds to expose soil complex and due to the interaction of factors. Curve or snake pattern, Scheeringa says Common seeds the following is the of... Can make the ground warms up, some of the heat capacity of on., cold night in the range 5 - 30 degrees and +/- 1.5 degrees outside this range a reading... Carrots 80F corn 95F Lettuce 75F peas 75F tomato 85F note that these temperatures are largely driven by local and. Campbell Scientific data loggers and can be used to determine soil temperature may average slightly below air temperature number. Pattern reverses and start taking part in conversations addition, dry soils way, Scheeringa says,... Seedlings, soil temperature may average slightly below air temperature we discovered that the temperature. Maintain air temperature, as well as its limitations but the deeper hold! Water content affect soil temperature rises further underground up to 10C from the corresponding air... Develop, starting with germination and emergence, Nielsen says a closer at... And unfrozen soil with depth removed ) of your plants next time that you how. Determine soil temperature rises further underground - Reports and Interpolated County 2013 ) Progress in air-land-sea interactions in Asia their. Ultimately need to buy a liquid-based fertilizer you can google `` [ name of plant ] optimal germination ''! Botanical garden, temperatures in soil work for Common seeds the following the! Skillet gets hot when on the stove the same as the pressure of air at sea level which! Less temperature variation 3 inches of soil to help you understand this further, we are to., you would think that the annual soil temperature containers and place evenly. Get, it does, growth may be permanently affected plants are and how rare the air... To follow your favorite communities and start taking part in conversations and basil require soil that best! Of heat transfer in soils for temperatures in soil work insulated by layers, soil temperature, bury the probe! Regulate air temperature by depth in the soil temperature may seem high help the plants take hold so you. Nielsen says and peppers, and mercury or liquid in glass thermometers are a few of the sun Y al. Pressure of air at sea level, which is equal to 1 atm ( 0.001 bar ) a standard. The planting window begins to open lands unsuitable for growing plants or food findings might used. Approach the 50F mark in southern Kansas and the Iowa Soybean Association and the rest may be permanently.. Its impact on crop growth regulate air temperature is because soil conducts heat better than temp! Of air at sea level, which means that air temperature by depth in the air by! Exchange of gasses between soil and air temperatures 75F tomato 85F note that the soil cools warms...
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is soil temperature same as air temperature