Determination and regulation of soil acidity and alkalinity

What is the effect of soil pH on crops? What are the determination methods of soil acidity and alkalinity? How to adjust soil acidity and alkalinity? Please also ask netizens to help introduce that the acidity or alkalinity of the soil will reduce the availability of soil nutrients in varying degrees, it is difficult to form a good soil structure, and seriously inhibit the activities of soil microorganisms, thus affecting the growth and development of various crops. therefore, soil acidity and alkalinity plays a key role in planting industry, so the planting network collates the effect of soil acidity and alkalinity on crops and its determination and regulation methods. The following is listed in detail for netizens' reference. The effect of soil pH on crops: first, the effect on soil nutrients: when the soil pH value is more than 7.5 or lower than 6, phosphoric acid and calcium or iron and aluminum form a late state, which reduces the availability. Calcium, magnesium and potassium are easy to be replaced and easily leached in acidic soil. The solubility of calcium and magnesium in strongly alkaline soil is low, and the availability is decreased. The availability of trace elements such as boron, manganese and copper in alkaline soil is greatly reduced, while the precipitation of molybdenum with free iron and aluminum in strongly acidic soil can reduce the availability. Second, the effect on soil microorganisms: the most suitable pH value for soil microorganisms is the neutral range between 6.5 and 7.5. Excessive acid or alkali will seriously inhibit the activity of soil microorganisms, thus affecting the transformation and supply of nitrogen and other nutrients. Microorganisms can improve the utilization rate of nutrients, promote the absorption capacity of crops to nutrients, loosen and improve soil, secrete growth hormone, secrete antibiotics, promote crop growth and development, and improve disease resistance. (3) soil is easy to produce harmful substances: excessive acid in soil is easy to produce free Al3+ and organic acid, which is directly harmful to crops. When the soluble salt in alkaline soil reaches a certain amount, it will directly affect the germination and normal growth of crops. The alkalized soil with more sodium carbonate is more toxic to crops. Fourth, it has an effect on the growth of crop roots: most plants are in pH > 9.0 or