Dr. M. Kousalya Devi, Dr. Kappala Deepthi2 and and Dr.S.Durga3
1Ph.D. Scholar, Division of Animal Genetics and Breeding, National Dairy
Research Institute, Karnal -132001
2Assistant professor, Dept. of Veterinary Microbiology, FVAS, RGSC-BHU
3Ph.D. Scholar, Dept. of Livestock Production Management, Veterinary College and Research Institute, TANUVAS, Namakkal– 637 001
Introduction:
Area under rice cultivation in India is approximately 44 million hectares. Roughly 130 million tonnes of straw are produced annually. However, after harvest this vast bulk of material is poorly utilized. Straw burning is commonly practiced in regions where sufficient time is not left between crop rotations for ploughed-in straw to decompose. This practice not only results in complete waste of organic matter, but also causes air pollution. Open burning of the stubble releases large amount of toxic gases like methane, carbon monoxide, volatile organic compound, and carcinogenic polycyclic aromatic hydrocarbons which are also the potential causes of climate change. To combat the adverse effect of stubble burning and to utilize the organic matter in the straw, efficient ways for utilizing straws, mainly as livestock feed and as compost material are being recommended. This article tries to focus on some of the farmer friendly methods for paddy utilization.
Rice straw as animal feed
Rice straw is poor quality roughage in terms of crude protein, minerals and digestibility.
Nutrient of rice straw
| Nutrient | Amount in percentage |
| Digestibility by ruminants | 45 – 50 |
| Crude protein | 3 – 5 |
| Phosphorus | 0.02 – 0.16 |
| Calcium | 0.25 – 0.55 |
| Silica | 12 – 16 |
| Lignin | 6 – 7 |
| Oxalates | 1 –2 |
However, ensiling and chemical treatment of the straw are excellent feasible methods to increase the digestibility of the rice straw and its nutrient content to some extent.
Silage making with rice straw:
The nutritive value of rice straw can be improvised by ensiling. Silage making is a type of fodder preservation which involves the storage of wilted green fodder in an anaerobic condition, typically in silo, to prevent spoilage by aerobic microorganism. In anaerobic condition, lactic acid bacteria utilize water soluble carbohydrate to produce lactic acid which decreases pH of the silage. The decrease in pH inhibits the growth of other undesirable microorganisms like Clostridia and Enterobacteria. Poor fodder package cause leakage of oxygen and culminate in the bad quality silage production. The growth of the lactic acid bacteria is hampered when there is high moisture content in the fodder. Therefore, it is recommended to dry the forage to a moisture content of about 60-70% before ensiling. Good quality silage is indicated by high concentration of lactic acid, acetic acid and decrease in butyric acid, ethanol and ammonia concentration.
In rice straw silage making, the fermentation process can be enhanced by silage additives that promote nutrient and energy recovery, rapid fermentation and increase animal performance. Application of lactic acid bacteria like Chikuso-1 and NLRI401 as fermentation stimulant improve the quality of silage by increasing lactic acid, acetic acid and crude protein in the rice straw silage. In addition to fermentation stimulant, inoculation of enzyme additives likes hemicellulases, cellulases, xylanases, pectinases, and amylases improves the fiber digestibility of rice straw silage. These enzymes help in releasing free sugar from fodder to be used by fermentative microbes. In addition, enzymes degrade the cell wall and decrease the total fibre content which improves digestibility. Rice straw contains high level of lignin which is very much resistant to enzymatic hydrolysis and thus requires pre-treatment with alkali digestion, acid hydrolysis, steaming, and radiation. This pre-treatment with alkaline solution improves feed intake and digestibility. Addition of stimulant sugars like molasses helps in fast acidification that inhibits the growth of Clostridia. Because of high viscosity, molasses are recommended to mix with equal quantity of water for easy application. In order to prevent the growth of undesirable microorganism, molasses are always inoculated with bacterial or enzyme additives. Apart from stimulants, addition of acid like formic acid, propionic acid and acetic acid helps in rapid drop in pH and decreases fermentation losses of carbohydrate and protein. Addition of urea increases protein content and digestibility. Urea removes lignin and silica and thus exposes the tissue of straw for bacterial colonization. Therefore, the use of inoculants with good management practices can improve the nutritive and digestive value of rice straw silage.
Urea treatment of rice straw:
Treating rice straw with urea enhances the crude protein content of the straw.
• A solution of urea is prepared by mixing 4 to 6 kg of urea in 50 to 80 liters of water for 100 kg
• A polythene sheet should be spread
• One fourth of the rice straw is placed on the polythene sheet and sprinkled with urea solution
• Mix the straw well after sprinkling
• Repeat sprinkling and mixing by placing next one-fourth of quantity straw
• Wrap the polythene sheet airtight for 21 days
• Slowly include the urea treated straw in cattle diet
• The treated straw should be fed after keeping the straw in open air for ten minutes
Precaution:
Do not feed the urea treated straw to calves less than 6 months and to pregnant cattle
Alkali treatment of rice straw:
A solution of caustic soda (NaOH) can be prepared by mixing 4 to 6 kg of NaOH in 200 litres of water to wet 100 kg of straw. The optimum concentration of NaOH solution should be around 5 %. This treated straw can then be fed to about 50 % of the diet.
Further if feasible, alkali spray-treated straw can be ensiled satisfactorily for up to one year without microbial fermentation.Because of the high pH the straw remains stable. The concentrated alkali treated straw can also be pelleted and stored.
Composting of rice straw:
Composting of rice straw is one of the eco-friendly ways of utilizing rice straw. It is a bio-oxidative process which involves the conversion of organic waste to a stabilized final product free of plant toxins and pathogens. It can be made on the farm at very low cost and used as organic fertilizer. Although organic fertilizers, including rice compost, are often low in major nutrients such as nitrogen (N) and phosphorus (P), they can be highly beneficial because they contain micronutrients, enzymes and micro-organisms that are often not found in inorganic fertilizers.
How to make paddy straw composting?
- Rice straw is used as the main material for composting togther with animal manure or green leaves.
- Composting heaps should be formed as layers combined with rice straw and animal manures / green leaves to maintain the Carbon:Nitrogen ratio (2:1) in the compost.
- Compost heap should be kept moist, but not too wet or not too dry
- Mix and turn the heap at 7 days interval for better aeration
- Final compost maturity is deterimened by its pH, moisture, colour, odour, texture and fungal growth which is given in the below table
Physical parameters to assess compost maturity
| Physical parameters | 0 day | 15 day | 28 day |
| Colour | Yellow | Light brown | Dark brown |
| Texture | Fragile, smooth textured | Non fragile, rough textured | Non fragile, crumpled, crust textured |
| Odour | No odour | Putrid | Pleasant earthy |
| Fungal growth | No growth | White fungal mycelium visible | No visible growth |
The rice compost contains about 2 per cent nitrogen, 1.5 per cent phosphorous and potassium. Rice straw composting is easy to perform and organic way of waste recycling that provides a quality output which can be used as soil conditioner to improve crop yield.
Some of the farmer friendly solutions to manage the paddy straw are given here. However, providing economically viable marketing channel to sell silage, pelleted straws, organic rice straw compost etc. at competitive prices would be an eco-friendly and profitable solution for the farmers to manage the agro-waste.
