Ph valu of soil

Soil pH is a measure of the acidity and alkalinity in soils.
The optimal pH range for most plants is between 5.5 and 7.0.

1. pH value of soil Course Title: Chemical Technology II Name: Shaikh Ashraful Alam Applied Chemistry & Chemical Engineering

2. Soil PH: What it Means Soil pH is a measure of the acidity and alkalinity in soils. The optimal pH range for most plants is between 5.5 and 7.0. Range of PH The pH scale goes from 0 to 14 with pH 7 as the neutral point . From pH 7 to 0 the soil is increasingly more acidic and from pH 7 to 14 the soil is increasingly more alkaline or basic. Any soil above pH 10 and below pH 3 may be said sterile.

3. Sources of acidity Rainfall Fertilizer use Plant root activity Acid rain Mine spoil Sources of alkalinity Alkaline soils have a high saturation of base cations (K+, Ca2+, Mg2+ and Na +). Alkaline soils are characterized by the presence of carbonates . Soil in areas with limestone near the surface are alkaline from the calcium carbonate in limestone constantly mixing with the soil.

4. Measuring Soil pH The most accurate method of determining soil pH is by a pH meter Using certain indicators or dyes . pH Affects Nutrients, Minerals and Growth The effect of soil pH is great on the solubility of minerals or nutrients. Phosphorus is never readily soluble in the soil but is most available in soil with a pH range centered around 6.5. Extremely and strongly acid soils (pH 4.0-5.0) can have high concentrations of soluble aluminum, iron and manganese which may be toxic to the growth of some plants . A pH range of approximately 6 to 7 promotes the most ready availability of plant nutrients.

5. Changes in Soil pH Increasing pH of acidic soil: Lime is usually added to acid soils to increase soil pH . The addition of lime not only replaces hydrogen ions and raises soil pH. Eliminating most major problems associated with acid soils but it also provides two nutrients, calcium and magnesium to the soil. Lime also makes phosphorus that is added to the soil more available for plant growth . Decreasing pH of alkaline soil: The pH of an alkaline soil can be reduced by adding acidifying agents or organic materials. Acidifying fertilizers, such as those containing ammonium, can help to reduce the pH of a soil. Add elemental sulfur (90 or 99% sulfur material) annually at a rate of 6 to 10 pounds per 1000 square feet of area.