Because it provides information about the levels of the three primary macronutrients that plants need in order to grow: nitrogen (N), phosphorus (P), and potassium (K). By understanding the NPK content of their soil, farmers and gardeners can make informed decisions about which fertilizers to use and how much to apply, which can ultimately lead to increased crop yields and improved crop quality. One of the main benefits of NPK testing is that it can help farmers and gardeners to identify nutrient deficiencies in their soil. For example, if a soil test indicates that a soil is low in phosphorus, a farmer or gardener can target their fertilizer applications to add more phosphorous to the soil, which can help to improve crop yields. Similarly, if a soil test indicates that a soil is high in potassium, a farmer or gardener can adjust their fertilizer applications accordingly to avoid applying too much potassium, which can lead to nutrient imbalances and reduced crop yields.
NPK testing can also help farmers and gardeners to optimize their use of fertilizer. By knowing the exact NPK content of their soil, they can avoid applying unnecessary or excessive amounts of fertilizer, which can save money and reduce the risk of nutrient runoff and environmental pollution. Additionally, NPK testing can help farmers and gardeners to select the most appropriate fertilizer for their crops. Different crops have different nutrient requirements, and NPK testing can provide information about which fertilizers are best suited to a particular soil and crop. This can help farmers and gardeners to select fertilizers that are more likely to provide the nutrients that their crops need, leading to higher yields and improved crop quality.