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Rice Hull Biorecycling in Rocha, Uruguay
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| Overview | Rice hulls can be used in compost and vermicompost to obtain a high quality organic fertilizer in a short time. |
| Scale | Field, household, farm, rural school, local region. |
| Location | North Region of Rocha Municipality, Biosphere Reserve East's Wetlands, Uruguay (34.2°S, 54.1°W). |
| Elevation | 0 to 150 meters |
| Climate | Humid Subtropical with hot summer (Ca). |
| Agricultural Region | Commercial Livestock and Crop Farming (J). |
| Population Density | 1 - 10 persons / square kilometer. |
| Principle Crops | Rice (Oryza sativa) |
| Domestic Animals | Beef and Dairy Cattle, Sheep, Pigs, Chickens |
| Soils | Mollisols, Udolls (M4), soils of the steppe. Thick, black organic rich surface horizons and high base supply. |
| Natural Vegetation | Grass and other herbaceous plants Broadleaf deciduous trees, growing singly or in groups or patches (GDp). |
| Ecoregion | Prairie Province (H9). |
| Basic Principles addressed | Use Renewable Resources, Minimize Toxics, Maximize Long-Term Benefits |
| Page Author and Date | Ana Cecilia Castillos, from studies by PROBIDES, 1999. |
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Rice is the principal crop in the North Region of Rocha Municipality, and is produced in 55% of the Biosphere Reserve. After processing, the rice industry produces about 143,000 metric tons of rice hulls per year in the region. This crop residue is not utilized, and in most cases is burned. During 1994 and 1995, PROBIDES (Biodiversity of Conservancy and Development Sustainable Program at East's Wetlands of Uruguay) conducted several experiments to obtain organic fertilizers by rice hull composting and vermicomposting, and to evaluate the effect of adding different sources of nitrogen and inoculum. The duration of this process was about 4 months. Using standard composting methods, rice hull degradation was not total, whereas in the vermicompost, rice hulls lost their structure. |
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Worms can play a key role in rice hull decomposition, as rice hulls can be difficult to compost, with their high C:N ratio (~70), their high cellulose and lignin content, and their waxy surface cover that impedes microbial attack, due to its low capacity to absorb water. Using composts made by mixing rice hulls with manure contributes micronutrients and improves soil structure (more water and air retention). This is a good example of crop residue utilization and its transformation into a resource. Rice hulls, with their high lignin and cellulose content are a source of the precursors of humus, the organic matter component with the most stability and nutrient availability. At this time, people are adopting rice hull composting practices to obtain organic fertilizers, which are sold in this region for application in gardens, homegardens, parks, etc. This organic fertilizer is sold in bags made from recycled paper. |
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Use Renewable Resources Rice hulls are a renewable fertilizer resource. Using rice hulls for fertilizer recycles nutrients and eliminates wastes. Composting rice hulls with manures recycles micronutrients. Minimize Toxics When rice hulls are burned, toxic substances are released to the atmosphere. Composting this residue eliminates a source of air pollution. Maximize Long-Term Benefits Using rice hulls and rice hull/manure composts and vermicomposts improves soil fertility, soil organic matter, soil physical properties, and soil structure over the long-term. Rice hull compost is especially useful in boosting the humus content of soil organic matter, providing a long-term source of nutrients that will gradually become available. |
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