Dolochun is a white powder, also known as dolo-oxy lime or dolomite powder. Among the many problems in crop production, one of the most serious is strong soil acidity, which keeps rising because chemical fertiliser is used continuously and without planning. The way out is to apply dolochun to the land at the recommended rate.

The strength of soil acidity is measured by its pH, which can go up to 14. Soil with a pH below 7 is acidic and above 7 is alkaline. The further the pH falls below 7, the more acidic the soil becomes, and soil at pH 5.5 or lower counts as strongly acidic. Dolochun applied at the recommended rate can correct strongly acidic soil: it contains calcium and magnesium, which help reduce acidity.

Research has found strongly acidic soil in greater Rangpur, greater Dinajpur, greater Sylhet, greater Chattogram, the Barind area of Rajshahi and the Madhupur area of Tangail.

On highly acidic soil the recommended rate is 4 kg per decimal, 400 kg per acre or 1,000 kg per hectare. The dose must not be raised or lowered in any way. Once dolochun has been applied to a plot, it does not need to be applied again for three years.

Before applying, divide the total recommended quantity into two equal halves. While the soil is moist enough to work, spread one half along a north-south line and the other half east-west, crosswise. Immediately after spreading, plough crosswise and harrow to mix it well into the soil. This is very important.

Crops can be sown or seedlings planted after the necessary ploughing and harrowing at least 12-14 days later. Sowing seed straight after applying dolochun can lower the germination rate or hold back the growth of the roots and stems of the seedlings.

If the land is dry or has little moisture, apply the required amount crosswise on the empty field, plough, level it with a harrow and give a light irrigation. Crops can then be sown or planted, after the necessary ploughing and harrowing, at least seven days later.

Dolochun can generally be applied at any time of year, but the best time is on fallow land after the Aman rice harvest or in the Rabi season. Because it corrects soil acidity, improves soil health and makes the land fit for cropping, it can be used on acidic soil for higher yields and better quality in all crops, including wheat, maize, potato, mustard, jute, pulses, oilseeds, spices and vegetables.

• It is easy to apply, cheap and readily available in the market.
• Yields of wheat, maize, potato, mustard, pulses, spices and vegetables rise by 10-50%.
• One application lasts for the next three years.
• Once dolochun is applied, magnesium fertiliser is not needed.
• Crop quality improves: potatoes get less scab, vegetables have brighter colour and jute suffers less black band disease.
• Crops grow evenly across the field.

• Do not apply more than the recommended dose.
• Mix it into the soil by ploughing and harrowing immediately after applying.
• Do not apply it while a crop is standing in the field.
• Do not spread it in strong wind.
• Do not apply it to standing water or muddy fields.
• Make sure it is used at the correct recommended rate and by the correct method to correct soil acidity.
• For crops other than rice, apply dolomite once every three years.
• Apply dolomite at least 15 days before planting seedlings or sowing seed.
• If the right amount of dolomite is used, no separate magnesium sulphate fertiliser is needed for the next three years.
• For Rabi crops (wheat, potato, maize, mustard, onion, vegetables and so on), mix 12-16 kg of organic manure (cow dung, compost and the like) per decimal into the soil at the final stage of land preparation.

Source: Jagonews24. First published in Bengali on The Agro News.