Causes and management of soil acidification

Acid soils can be naturally occurring, however, a number of agricultural practices have expanded the areas of such soils. Main causal factors include crop offtake of basic ions and use of fertilizers those leave acidic residues. Leaching of nitrate also results soil acidity. Nitrate is infinitely soluble in water and leaches below the root zone at a rate faster that the crop uptake, leaving the soil acidic.

The management strategies are generally aimed at curbing the acidifying activities and ameliorating soil acidity. Some of the most common management strategies are listed below.

*Application of lime to enhance nutrient availability, use of burrowing activity earthworms to ameliorate subsoil acidity and mechanical mixing of lime where subsoil acidity very high

*Nitrogen management include sourcing through urea, improving nitrogen use efficiency by matching the crop demands

*Adoption of agri-horti-silvicultural system

*Avoidance of long fallow

*Retention/incorporation of plant residues (stubbles) with high C:N ratio into the soil to increase microbial activity so that microbes use soil nitrogen to break down residues, thus preventing nitrate from being leached and standard agronomic practices

*Use of acid-tolerant plants such as pineapple, banana, potato, mango etc. Having said so, cultivars do differ in their tolerance to low pH and toxic level of aluminum and manganese and perennials, in general, is having higher tolerance to annuals.

*Maintenance of submergence or artificial high water table is the key to rice culture in acid sulphate soil