Soil pH

Soil pH is a measure of the activity of M , and commonly falls between 3 & 10, with 7 being neutral. Acid soils gain a pH below 7 as well as alkaline soils name a pH above 7. Ultra-acidic soils pH < 3.5 in addition to very strongly alkaline soils pH > 9 are rare.

Soil pH is considered a master variable in soils as it affects many chemical processes. It specifically affects plant nutrient availability by controlling the chemical forms of the different nutrients and influencing the chemical reactions they undergo. The optimum pH range for near plants is between 5.5 and 7.5; however, numerous plants have adapted to thrive at pH values outside this range.

Plant pH preferences

In general terms, different plant generation are adapted to soils of different pH ranges. For many species, the suitable soil pH range is fairly alive known. Online databases of plant characteristics, such(a) USDA PLANTS and Plants for a Future can be used to look up the suitable soil pH range of a wide range of plants. Documents like Ellenberg's indicator values for British plants can also be consulted.

However, a plant may be intolerant of a particular pH in some soils as a or situation. of a specific mechanism, and that mechanism may not apply in other soils. For example, a soil low in molybdenum may not be suitable for soybean plants at pH 5.5, but soils with sufficient molybdenum let optimal growth at that pH. Similarly, some calcifuges plants intolerant of high-pH soils can tolerate calcareous soils whether sufficient phosphorus is supplied. Another confounding component is that different varieties of the same shape often have different suitable soil pH ranges. Plant breeders can use this to breed varieties that can tolerate conditions that are otherwise considered unsuitable for that species – examples are projects to breed aluminium-tolerant and manganese-tolerant varieties of cereal crops for food production in strongly acidic soils.

The table below allows suitable soil pH ranges for some widely cultivated plants as found in the USDA PLANTS Database. Some species like Pinus radiata and Opuntia ficus-indica tolerate only a narrow range in soil pH, whereas others such as Vetiveria zizanioides tolerate a very wide pH range.