PH has direct and indirect impact on crops. The direct impact is that the pH value in the root environment is too high or too low, which will damage the root system of the crop, each crop has the most suitable pH value range. Indirect effects are manifested in affecting the availability of nutrients, which may reduce or even ineffective. Due to the accumulation of a large number of salt in the saline-alkali soil, the "water potential" of the soil solution is greatly reduced, and it is difficult for the roots of plants to absorb water. Plants will die if they don't get enough water. In saline-alkali soils, there is often too much of a certain salt (such as sodium chloride), which will damage plants, which is called "single salt poisoning".
A serious problem with acidic soils is low nutrient availability and the variety of nutrients involved. For example, acid soils are generally deficient in nitrogen, phosphorus and potassium; many soils are deficient in calcium and magnesium; some soils are deficient in molybdenum. The lack of these nutrients is mainly determined by the characteristics of acidic soil composition and climatic characteristics. Iron and aluminum in acidic soil are highly active, and form insoluble iron phosphorus and aluminum phosphorus with phosphorus, and even less effective closed phosphorus, so that most soil phosphorus and fertilizer phosphorus are converted into fixed phosphorus , resulting in severe phosphorus deficiency in most acidic soils.