6th Grade - Social Studies

LESSON PROBLEM: Economics: How can rice straw be disposed of in an economical and safe way?


STUDY GUIDE

Rice straw is a byproduct of rice cultivation. After rice is harvested, the stems of the rice plant, the rice straw, is left in the field. Before planting begins the next year, something must be done to eliminate this straw in the field. Rice straw is dry and tough and it decomposes very slowly in a dry field.

Traditionally there have been two ways to handle the disposal of the straw. It can be burned or it can be incorporated back into the soil. Burning old straw is fast and cheap. It is also an effective way of getting rid of any plant disease organisms that have attached themselves to the old straw. Unfortunately, the smoke from this practice pollutes the air. This has become a particular nuisance as residential populations increase and expand into rural areas. This is particularly true in California where rice burning now has been virtually phased out by state regulations. Incorporating the straw into the field's soil is a slow, laborious process. A major disadvantage to this practice is that any diseases and parasites which have taken hold of the straw will become afixed to the soil and may damage next year's rice crop. With neither of these two methods being ideal, it has been a challenge for the agricultural sector to find a way to make rice straw a useful commodity rather than a waste product.

The 25,000 acres of rice field in Yolo County, California yield four tons of rice straw. Because of the ban on burning, many farmers have turned to an improved form of soil incorporation. To help farmers in solving this dilemma, the Yolo County Resource Conservation District offers a roller that rents for $3/acre to rice farmers. This roller flattens and mashes the straw in the field which is left in very shallow water. This standing water further helps the straw decompose. The idea and construction of the rollers was sponsored by the waterfowl conservationist group, Ducks Unlimited. The rice straw thus treated becomes an ideal habitat for ducks, geese and other waterfowl. The birds also are instrumental in further breaking down the straw.

New uses have also been found for rice straw. One of the most feasible has been to use rice straw as a component of animal feed. On a smaller scale, rice straw has been gathered and mixed with manure for composting. It has also been harvested and used as animal bedding. Even more recently, rice straw has found a new use as a building material. It has been used to bind clay in the making of bricks. It has also been used as a component in constructing drains and pipelines. Rice straw can be a great building material because it is made up of strong fibers that do not easily decay. It has even been demonstrated that a whole house can be constructed from rice straw bales.




ACTIVITIES

What are the two traditional methods of dealing with rice straw? What are the advantages of each method? The disadvantages?




EXTENDED LEARNING

Name some of the new uses of rice straw you read about. Can YOU think of any other uses for rice straw?




VOCABULARY
  • straw
  • laborious
  • bale
  • component
  • nuisance
  • commodity


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