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Soil pH - Importance of soil ph in agriculture Nutrient Management

Posted On : July 09, 2021

Generally, soil pH is perhaps fine if you see that plants are growing well and healthy. But as a gardener, testing soil pH is suggested to obviously measure the acidity or alkalinity of the soil. it's especially imperative if plants aren't growing optimally or if they're having some nutrient troubles, looking sickly, or languishing.

Read our guide below on the way to test soil pH yourself so you'll be more prepared for cultivating your plants optimally. what's Soil pH? As you'll remember from class , pH may be a measurement wont to specify how…

What Is Soil pH?

pH may be a measurement wont to specify how acidic or basic something is. In gardening, we would like to make sure our fertilizer is that the right balance thereon scales for what we are growing. you'll measure soil pH on a scale of 1 to 14. The neutral mark is 7 and pH value below 7 is taken into account acidic, while a worth above 7 indicates alkalinity. Alkaline soils are sometimes mentioned as sweet and acidic soils sour. Most soils have pH values are in between 3.5 and 10. In more rainfall areas the natural pH of soils is 5 to 7, while in drier areas the value is 6.5 to 9.


Soil pH affects the quantity of nutrients and chemicals that are soluble in soil water, and thus the number of nutrients available to plants. Some nutrients are high under acid conditions while others are high under alkaline conditions.

Most of the mineral nutrients are already available to plants when soil pH is near neutral.

The development of strongly acidic soils (less than 5.5 pH) may result in poor plant growth as a result of one or more of the subsequent factors:

  • aluminium toxicity
  • manganese toxicity
  • calcium deficiency
  • magnesium deficiency

low levels of essential plant nutrients like phosphorus and molybdenum.

Alkaline soils may have problems with deficiencies of nutrients like zinc, copper, boron, and manganese. Soils with a particularly alkaline pH (greater than 9) are likely to possess high levels of sodium.

The correct balance is where the soil pH is between 5.5 and 7.5, so every effort should be taken to see soil pH levels regularly. Early identification of soil pH problems is vital because it is often both costly and difficult to correct long-term nutrient deficiencies.

Changing soil pH

And few fertilisers change soil pH and increase or decrease the number of nutrients in the plants.

Fertilisers like crushed sulfur and a few ammonium-based nitrogen fertilisers lower pH and make the soil more acidic. helpful for soils and makes problems caused by high pH.

How To Test Soil pH?

Some gardeners throw limestone in their lawn annually out of habit to extend the soil’s pH but aren't quite sure whether or not the soil is basically acidic. Trial and error may be a dangerous move. Test your soil’s pH first before farming or cultivation.


You can purchase various sorts of pH testing kits online or at a garden tool shop nearest you. Once you identify your pH, you'll start gradually adjusting it.

Soil acidification

Soil acidification is brought about by so many processes such as high rainfall, crop growth, the use of fertilizers, acid rain, and oxidative weathering.

1. High rainfall

Soils usually become acidic under heavy rainfall. this is often because rainwater is slightly acidic (about 5.7) thanks to a reaction with CO2 within the atmosphere that forms acid . As this rainwater passes through soil pores, it leaches basic cations from the soil as bicarbonates, which increases the share of AI3+ and H+ relative to other cations within the soil. Root respiration and decomposition of organic matter by microorganisms also release CO2 that increases the acid (H2CO3) concentration resulting in leaching.

2. Crop growth

Soil nutrients are haunted by crop roots within the sort of ions NO3−, NH4+, Ca2+, and H2PO4−. Crop roots are take up high cations than anions. And crops should maintain a common charge in their roots for normal physiological processes to require place. H+ ions are released by root crops to catch up on the additional positive charges leading to acid soils.

3. Use of fertilizers

Some fertilizers like ammonium NH4+fertilizers undergo a nitrification process to make nitrate (NO3−), and through this process, H+ ions are released resulting in acid soils.

4. Acid rain

And Oxides of sulfur and nitrogen are released into the atmosphere which burning fossil fuels. Released oxides mixed with rainwater in the atmosphere to produce tetraoxosulphate acid and trioxonitrate acid.

5. Oxidative weathering

Sulphides and other compounds containing Fe2+ produced acidity during the oxidation process.

Soil alkalinity

If soil alkalinity increases with weathering of silicate, aluminosilicate, and carbonate compounds that contain Na+, Ca+, Mg2+, and K+. The listed minerals are usually added to the soil by the deposition of eroded sediments by water or wind. Soil alkalinity also can be increased by the addition of water containing dissolved bicarbonates, especially when irrigating with high-bicarbonate water. Insufficient water flowing to leach soluble salts can cause accumulation of alkalinity during the soil. this is often common in arid areas or poor internal soil water drainage situations, where the water that comes in is either transpired by crops or evaporates instead of flowing through the soil.

Both acid and alkaline soils have an influence on crop growth and development. agricultural crops grown in acid soils may experience some stresses like AI, H, and Mn toxicity also as Ca and Mg nutrient deficiencies. Aluminum toxicity, which is that the most generally spread problem of acid soils, occurs when aluminum is present in ionic Al3+ form. Aluminum ion Al3+ is that the most soluble of all sorts of aluminum at soil pH but 5.0 (acidic condition). Aluminum isn't a plant nutrient but an ionic sort of Al3+ that enters crop roots passively through the method of osmosis. Aluminum inhibits root growth and development by interfering with the uptake and transport of essential nutrients, cellular division , cell membrane formation, and enzyme activity. However, strong alkaline soils (sodic soils) are characterized by slow infiltration, reduced hydraulic conductivity, and poor soil water retention capacity that make crops to experience water stress.

Agricultural crops are varied in terms of suitability for soil pH range. Some crops are often impatient with a specific soil pH due to a specific mechanism. as an example , soil pH 5.5 isn't suitable for soybean plants when molybdenum is low within the soil, but an equivalent pH 5.5 becomes optimum for soybean when molybdenum is sufficient within the soil. Most agricultural crops grow well around soil pH 7.0 (neutral). This shows that it's vital to bring both acidic and alkaline soils to neutral soil pH value for optimum performance of crops.

What to Apply: Limestone or Sulfur?

Adding limestone to the soil raises the soil pH. But aside from reducing soil acidity, limestone also raises the calcium level within the soil. Dolomitic limestone is understood for its ability to also increase the magnesium level within the soil. Many gardeners use ground limestone because it’s economical but others prefer pelletized limestone since it's less dusty.

You may start applying limestone as long because the ground isn't frozen. If possible, integrate the limestone into the highest six to eight inches of soil. If you want to use over 10 pounds of ground limestone for every 100 square feet, limit the appliance to the soil surface. Do a split application.

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