Using Distillery Spent Wash For One Time Controlled Land/Presown Land Application

Using Distillery Spent Wash For One Time Controlled Land/Presown Land Application

By Dr. Yashpal Singh

For other topics related to the Distillery Sector and a review based on more than 350 publications  covering Indian Distillery Industry, Manufacturing Process, Composition of Effluents, Environmental Impacts, Treatment Technologies, Utilization of Spent Wash In Agriculture, Impact On Soil, Crops And Yield, Pre-Sown Land Application, Ferti-Irrigation, Bio Composting, Soil Reclamation, International Practices in The Utilization of Spent Wash in Agriculture, Major Provisions of The Environment, Forest and Pollution Control Laws in India, Environmental Performance Rating, Major Policy Interventions and The Views Of The Honorable NGT On Sustainable Technology Adoption see Singh Yashpal 2020, Distillery Spent Wash and Its Utilization in Agriculture. Publisher РThe Wealthy Waste School India. ISBN No. 978-93-5396-249-4. Pages 1 to 360 (Available at Amazon and Kindle Books)

The Central Pollution Control Board is of the opinion that bio-methanated spent wash with a BOD of less than 7000 mg/L could be used for pre sown irrigation. Studies carried out by Agricultural Scientists have revealed that most of the food crops show good response to pre sow distillery effluent irrigation and the addition of effluents increases the soil fertility. Around 200 cubic meters per ha is required 25 to 30 days before sowing. The application is governed by the N requirement of the crop and soil type and is usually done 30 days in advance of sowing and onset of rains. Some estimates indicate that application of distillery effluents @ 50 m3/ha will supply 75 kg N, 40 Kg. P and 50 Kg K which represents almost half the N and P and 100 percent of the K requirement. It will also supply 105 kg Ca, 100 Kg Mg, 200 kg S, 0.5 kg Zn, 3.25 Kg Fe, 0.2 Kg Cu and 0.25 Kg Mn. A significant increase in yield indicators of various crops (20 to 60%) subject to pre sown irrigation has been reported without associated environmental hazards. The addition of spent wash also increase the soil fertility. Ammoniacal nitrogen build up has been found to be the maximum in soils when one time soil application @120 m3/ha and N and P supplement has been practiced. Post harvest soils have been seen to demonstrate an increase in the available micro nutrients like Fe, Zn, Cu and Mn. Pre-sown application of less than 300 m3/ha has not been observed to adversely affect soils. Leachates from a long time application of spent wash to agricultural fields have been observed to cause an increase in the Nitrate levels but the concentrations were not beyond the levels harmful to human health. There are different observations on leachability of spent wash constituent to ground water. It is generally felt that with a cautious application, the problem could be sufficiently managed without any damage to ground water quality.

Presowing generally involves filling post harvest fields with distillery effluents and allowing it to dry for 15-20 days after which the fields are tilled and sown. Subsequent irrigation is given with fresh water. A centimeter of post methanated effluents applied on one hectare of land could annually yield about 600 kg of Potassium, 360 kg of calcium, 100 kg of Sulphates, 28 kg of nitrogen and 2 kg of phosphates.

Application could be carried out twice in a year. Application rates of over 400 m3/ha have been variously tried. Pre sown application is also practiced in Australia, Brazil, Cuba and Philippines where up to 240 m3/ha spent wash has been applied in addition to chemical fertilizers and improved cane and sugar yields obtained. Paddy, maize, sugarcane, sweet sorghum, barley, low land grasses, turmeric, pulses, pineapple, tuber/root medicinal plants have all responded well to pre sown irrigation.

Utilisation of distillery effluents in agricultural fields creates organic fertilization, reduces the pH, increases the availability of nutrients, the capability to retain water and also improves the physical structure of the soil. Post harvest fields are usually filled with distillery effluents and after the surface is almost dried, the fields are tilled and the crops are sown. Some estimates point out that one cm of post methanated effluent if applied on one hectare land annually will yield 600 kg of Potassium, 360 kg of Calcium, 100 kg of Sulphates, 28 kg of Nitrogen and 2 kg of Phosphates. The ammonification, nitrification and enzyme activities of the soil have been observed to increase augmenting thereby the N availability in soil. When applied to soil, the color of effluent is amenable to microbial and photo degradation. For preseason sugar crop the recommended dose of NPK by State University in Maharashtra is 340:170:170 based on nutrient contents in BMSW. Post methanated effluent has a lower C:N ratio which facilitates it to degrade more swiftly in soil as compared to untreated spent wash. It has been said that effluent application would reduce the nutrient requirement through fertilizers. What also needs to be studied is the impact of high salt loads on sustained crop yields due to long term application of effluents. Suitable cropping patterns, agronomic practices, irrigation plans and water management practices have to be drawn up.

The CPCB in 2005 had proposed a protocol for one time controlled land application of treated post methanated spent wash as liquid manure. It specified that the BOD should be less than 7000 mg/L and pH over 7. It also specifies a system of sampling, monitoring and evaluation, storage during months of non utilization (30 days), transportation guidelines, ensuring land availability and consents and a crop wise likely volume of utilization. The Central Pollution Control Board has also felt that one time controlled land application is difficult to practice and that new stand alone distilleries may not be allowed to use this scheme for zero effluent discharge. It however does not restrict existing attached distilleries going in for expansion from adopting the practice of pre sown irrigation. The CPCB also recognizes pre sown effluent irrigation to be an emerging technology.

Post methanated effluent has a lower C:N ratio which facilitates it to degrade more swiftly in soil as compared to untreated spent wash. It has been said that effluent application would reduce the nutrient requirement through fertilizers. What also needs to be studied is the impact of high salt loads on sustained crop yields due to long term application of effluents. Suitable cropping patterns, agronomic practices, irrigation plans and water management practices have to be drawn up.

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