Soil Info – the Dirt on Dirt!

Our precious earth is what we inherit from our parents and bequeath to our children. It gives us life and hope, sustains our body, mind and spirit, and helps us grow in every way 🙂 Get to know your earth better in this quick overview….


Soil pH is an indicator of soil acidity, neutrality and alkalinity based on the negative log of the activity of the hydrogen ion in an aqueous solution. Neutrality is indicated at pH value 7. Soil with a pH less than 7 is acidic. Soil with a pH over 7 is alkaline. Pure water has a pH of 7 and is neutral. Rain water has a pH of 6 and is slightly acidic. Veggie plants and herbs grow across a range from pH 5 to pH 9 (strongly acidic to strongly alkaline).

pH LevelFrom our perspective as urban farmers, the most important insight to note is that most fruiting and leafing veggies need acidic soil, and most rooting veggies need neutral to alkaline soils. There are exceptions, so do see the Plantopedia for individual details. You can also use soil amendments to work with nature and change pH levels. For info on this, please see here


Soil can be classified into 3 main types based on texture:

  1. CLAY: High in moisture retentiveness, low in aeration and porosity
  2. SILTY: Medium in moisture retentiveness, low in aeration and high in porosity
  3. SANDY: Low in moisture retentiveness, high in aeration and porosity

Loamy soil combines the benefits of each type, and is the ideal soil for most veggie plants and herbs. It is light and granulated, retains moisture when watered, and releases it when squeezed in a handful. Take a look at this graphic that does a great job of depicting types and sub-types:

Sand Silt Clay Triangle


We can also classify soil in India according to place of origin:

ALLUVIAL: Silty to Clay

Alluvial SoilRich in humus and organic matter; found on river banks

 BLACK: Clay to Loamy

Black SoilRich in lime, iron, magnesium, potash; found in Central India (former volcanic plateau land)

 RED: Loamy to Clay Loam/Sandy Clay Loam

Red SoilRich in iron, found in Central India (former metamorphic rock)

LATERITE: Sandy to Silt Loam

Laterite SoilHeavily leached soil; found in hills of Kerala, Tamil Nadu, Assam & Central India

MOUNTAIN:  Clay to Silty to Loamy

Mountain Soil HimalayasHigh in forest-based organic matter; found in Himalayan regions


Desert SoilHigh in salt and low in organic matter; found in deserts of Rajasthan


(NB: Pics not my own. Sourced from publicly accessible websites.)

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