What makes soil acidic?
Soil pH is a measure of acidity or basicness. It measures the amount of hydrogen ions (H+) in solution compared to hydroxide ion (OH-) ions. The pH scale ranges from 0 being neutral and 7 being highly acidic. A soil’s pH can vary depending on its origin, but it generally stays within a range between 4 and 6. When the pH drops too low, it becomes less soluble in water and may become toxic.
The pH of soil varies widely from one location to another due to factors such as weather conditions, organic matter content, fertilization level and other environmental influences. Some soils are naturally very acidic while others have a higher proportion of minerals which tend to lower the soil’s acidity. Soil types differ greatly in their ability to retain nutrients and water; some are better at retaining these elements than others.
When soil pH falls below 5.5, it becomes less soluble in water and will eventually become toxic. Acidic soils are often found near sources of pollution or where there is high levels of heavy metals like lead or arsenic. These substances leach into groundwater when they enter the soil through runoff from landfills, factories or other areas contaminated by human activity.
How do I fix alkaline soil?
Sources & references used in this article:
Soil acid and alkaline phosphatase activity as pH adjustment indicators by WA Dick, L Cheng, P Wang – Soil Biology and Biochemistry, 2000 – Elsevier
Soil and plant factors relating to the poor growth of Lupinus species on fine-textured, alkaline soils-a review by JE Russell – 2002 – Daya Books
Diagnosis and improvement of saline and alkali soils by PF White – Australian Journal of Agricultural Research, 1990 – CSIRO
Biomass and biofertilizer production by Sesbania cannabina in alkaline soil by LE Allison, LA Richards – 1954 – books.google.com
Long-term nitrogen fertilization decreased the abundance of inorganic phosphate solubilizing bacteria in an alkaline soil by DLN Rao, HS Gill – Bioresource technology, 1995 – Elsevier