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Boron deficiency in crops occurs mainly in soils with low organic matter content in humid areas and in acidic sandy soils. The main reason is related to the chemical reactions between the most common forms of boron in soil, namely H3BO3 or B(OH)3, and various soil components. Borate ions are highly active ； Its mobility is said to be second only to nitrate ions in soil. The various factors in the soil that can affect the effectiveness of boron for plants are often different. The main soil factors affecting boron availability are as follows: Soil texture. In areas with high rainfall or in irrigated areas with well-drained sandy soils, boron deficiency is most likely to occur, as these soils have a high potential for leaching. These soils may require more frequent boron application. However, if the subsoil beneath the sandy surface layer is fine (with a high clay content), boron application does not need to be done so frequently. In clayey soils, the total boron content is usually high, but its availability to plants in the soil can be low, as boron binds more strongly to the surface of clay particles. Soil pH and lime application: Generally, as the soil pH increases, especially when it is above 6.5, the availability of boron to plants decreases. However, the availability of boron in highly acidic soils (with a soil pH of less than 5.0) also tends to decrease, as boron gets adsorbed onto the surfaces of iron and aluminum oxides in soil minerals. Some crops that require higher levels of boron, such as alfalfa, also need a soil pH level above 6.5 to achieve optimal growth. In this case, it may be necessary to apply lime. However, applying too much lime to acidic soils, especially when the pH rises above 7.0 after lime application, can lead to a temporary boron deficiency. Soil organic matter: The available boron in the soil exists mostly in the form of organic matter. When boron fertilizer is applied and boron levels are high, organic matter can complex with boron, causing it to be removed from the soil solution. Soil organic matter must be decomposed before bound boron can be released; therefore, cold and humid weather or hot and dry weather, by reducing the degree of decomposition of organic matter, will decrease the available boron in the soil. As the soil organic matter decomposes, boron is supplied again. When the boron concentration in the solution decreases due to being taken up by the crops or washed away, re-supplying boron can help maintain appropriate boron levels. Soils with low organic matter content have a lower capacity to supply boron; therefore, the frequency of boron application needs to be increased at lower application rates. Soil microbial activity: Microorganisms can degrade soil organic matter, thereby releasing plant-available boron from organic complexes. Favorable conditions for enhancing microbial activity are warm, moist, and well-aerated soil. The soil conditions that affect optimal microbial activity are drought conditions, cold and humid soils, and poor soil cultivation (poor aeration). Soil tillage: Generally, after the soil surface is plowed, the availability of boron to plant roots increases. Tilling mixes the soil, improving its aeration and drainage properties. These conditions are the optimal ones for the decomposition of organic matter, and the decomposition of organic matter releases available boron. As the crop production system shifts to minimal or no-till management, organic matter accumulates on or near the topsoil, allowing it to degrade rapidly. Therefore, the effectiveness of boron will depend even more on the moisture conditions in the topsoil, making fertilizer management even more important. Drought conditions: During droughts, the topsoil dries out, and especially when boron fertilizer is applied over a long period, plant roots are unable to absorb nutrients from the uppermost layers of soil where most of the available boron is found. Dry weather, by restricting water flow, also limits the effectiveness of boron, preventing it from delivering the available boron in the solution to the plant roots. Some subsoils may contain available boron, which may originate from the topsoil, especially through leaching following long-term application of boron fertilizers. During droughts, plant roots may penetrate deeper into the subsoil, thereby obtaining sufficient available boron for continued growth and development. In summary, boron deficiency mainly occurs in soils with low organic matter content and acidic sandy soils, especially in wet areas prone to leaching. An understanding of soil boron responses can help predict where boron deficiency is most likely to occur. The test results for available boron in the soil can inform people about the current status of boron in the soil of a particular plot. If the level of available boron is low or very low, especially when cultivating crops such as alfalfa that have high demands for boron, an appropriate application rate should be used.