The soil temperature sensor helps control the many physical, biological and chemical processes that take place in the development of plants, therefore its measurement makes the phenological process precise.
Soil temperature sensor
The sensor measures the soil temperature in real time, up to a depth of 60cm, and reflects the state of the crop's root activity.
It is wireless and allows a reading frequency of two minutes up to one hour per reading.
Normally we measure the outside temperature and forget the importance of controlling the temperature of the environment of the root system. The health of the roots directly influences the development of the plant.
The soil temperature sensor helps us predict plant growth periods and the amount of evaporation that occurs. It also improves the application of fertilizers and treatments.
The information helps in making decisions to favor the entire development and fruiting process of the plant. If we combine the information with the moisture sensors and conductivity, cflowmeter and pluviometer, we will have control of the crop in all its phenological stages.
Importance of control with floor temperature sensor
We have to distinguish the influence of soil temperature on plant growth and on subsoil microorganisms.
Influence on the plant:
- La germinación de la semilla, desarrollo de las raíces, desarrollo de los tubérculos, de gran importancia tanto para sembrados directos como para semilleros. La medición de la temperatura con el sensor nos puede indicar el momento idóneo de la siembra.
- The phenological development of the plant, shoots, flowering and fruiting.
- La absorción del agua por el sistema radicular que depende parcialmente de la temperatura del suelo que fomenta la actividad metabólica.
- La absorción de nutrientes por las raíces. Las bajas temperaturas dificultan la absorción de nitratos.
- Also in the transpiration and the deterioration of the fruit.
Influence on the subsoil:
- Low temperatures influence nitrification, favoring the oxidation of ammonia to convert it into nitrates and nitrites with the help of soil bacteria.
- La descomposición de la materia orgánica. Esto influye en la absorción del dióxido de carbono del suelo a la planta.
- La intensidad del efecto de los pesticidas.
Heat propagation in the ground
Thermal properties depend on two parameters: the capacity of the soil to store heat and the amount of heat transferred per unit of time.
The temperature of the irrigation water can modify the temperature of the soil and alter the growth of the plant.
Soil temperature directly influences plant development. It is modified by seasonal or nocturnal changes and the variation decreases with depth. The spread depends on the composition of the soil and the water it contains.
The higher the temperature, the greater the evaporation and the need for irrigation increases. According to (Ibañez, 2008) «it is considered that the part of the ground located 50 cm or more is only affected by seasonal temperature fluctuations, but not by changes throughout the day. For this reason, the depth of 50 cm is taken as a reference to establish the temperature regime of the soil.
Factors that modify soil temperature.
The interns are:
- The texture: the sandy ones get hotter due to the amount of air that circulates. The least clayey and silty.
- The structure of the terrain: corresponds to the physical configuration of the soil. Soil structures are defined as a 3D arrangement of the primary particles, that is, how the particles are located and connected to each other.
- The structure of the land that varies from sandy to silty or clayey. The ideals the Franks.
- The color like the silt ones that heat up less.
- Water content that displaces heat from the surface to deeper areas.
- The amount of organic matter.
The external ones:
- Ambient temperature provided by solar radiation. During the day it heats up and the heat moves down. At night it decreases. The changes have effects on the root system according to Fischer.
- The latitude of the terrain. The orientation towards the sun and the perpendicularity of the rays influence heating.
- The altitude. UV rays are stronger in high areas than in valleys.
- The existence of vegetation cover. If the heat is very intense or, on the contrary, very cold, the covers protect the ground from the entry and exit of radiation. The temperature fluctuation is less in soils with cover.
- Soil tillage. The compact floor does not allow air to circulate and neither does heat. For this reason, in times of frost, tillage is not recommended. At planting time in many crops, furrows are formed in the ground to favor the increase in temperature when the plant germinates. In addition, in the spring rainy season, they protect the plant from flooding.
Effect of temperature on the root system
Any control of the subsoil temperature is favorable to the plant and to the yield of the crop.
The phenological state of the plant depends on many factors and a very important one is the temperature around the root system, influencing germination, the appearance of shoots and the fall of the leaf due to the influence of temperature on chemical reactions.
Roots have temperature dependent functions:
- Synthesize hormones and organic substances.
- Absorb water and inorganic substances. Temperature directly influences this absorption.
- Metabolize carbohydrates and store them with direct influence on the longitudinal growth of the plant.
- Use carbohydrates in respiration. transpiration increases with the temperature of the root system.
- Nutrient intake increases with temperature. Those most affected by low temperatures are the phosphates, influencing the coloration of the plant.
- The health of the roots influences the absorption of calcium, the intracellular transport is better carried out by young roots, for this reason it is important to maintain good root activity, the optimized temperature of the soil favors the constant development of the root. The lack of calcium fundamentally affects the growing plant and the development of the fruit.
At very low temperatures there is less decomposition of organic matter. Root uptake is also decreased by cooling and resistance to water movement through the plant's symplast or intracellular framework that allows water flow increases.
The health of the root system is one of the most important factors to take into account to obtain a quality crop.
Ways to protect the soil.
The best way to protect the soil is with mulches. They can be organic matter such as straw or crushed pruning debris. They can also be plasticized covers of lower or higher density, depending on the climate and crops. The most common is polyethylene
Mulches also prevent evaporation and the soil holds moisture better. Correctly managing the covers, we influence the temperature of the soil.
We also modify the temperature with drains in the case of excess humidity.
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