Soil amendments
By altering the soil’s pH, increasing nutrient availability, enhancing the soil’s physical properties, and mitigating the effects of harmful substances, soil amendments have a positive impact on plant growth.
There are three types of soil amendments.
- substances used to modify acidic soil. Like Lime
- substances used to improve alkali soils. such as phosphogypsum and gypsum.
- soil conditioners or aggregating chemicals to stabilise soil aggregates and create granular structures For instance, poly-electrolytes such as silicates, polyvinylites, polyacrylates, cellulose gums, and lignin derivatives.
Gypsum
- Gypsum is a common supplement for reclaiming alkali soils and is simply dehydrated calcium sulphate (CaSO4.2H2O).
- Gypsum is pure when it is 18.6% S and 23.2% Ca.
- 13–15% S and 16–19% Ca are present in commercial agricultural grades (70–80%).
- Gypsum contains sulphur in a plant-accessible sulphate form, and its solubility is equivalent to SSP’s.
- The majority of gypsum mines are in Rajasthan.
Phosphogypsum
- It is a by-product of the manufacturing of phosphoric acid.
- As dehydrate (CaSO4.2H2O), hemihydrate (CaSO4.1/2 H2O), anlydrate (CaSO4), or as a mixture of dehydrate and hemihydrate, CaSO4 is present in phosphogypsum.
- Gypsum that has an 80–90% purity level is called phosphogypsum. Iron, manganese, zinc, copper, and may also be present in trace amounts.
- As a source of S, this fertiliser is crucial in alkali soils.
Lime and Liming Materials
- The only substance to which the name “lime” may legitimately be applied is calcium oxide (CaO).
- It is also known as fast lime, scorched lime, and unslaked lime.
When compared to pure CaCO3, it is most effective with a high neutralising value or calcium carbonate equivalent (CCE) of 179%. - It is exceedingly challenging to fully incorporate this substance into the soil. Slaked lime, also known as hydrate lime [Ca(OH)2], is a white powder made of calcium hydroxide. Calcium carbonate (CaCO3), calcite or calcium-magnesium carbonate [CaMg(CO3) 2] or dolomite are the other major liming materials.
- Open pit mining is used to extract limestone. Because of the contaminants present, the majority of agricultural limestones have CCE values between 90 and 98 percent.
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