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Technonology Guide for Rice Straw Composting with Urea


Introduction

Rice is the main crop during the wet season in rainfed areas such as the Ilocos. Hence, rice straw is very abundant as a farm by- product.  Garlic and onion growers use it as mulch, others feed it to their livestock, but many farmers simply burn it after harvest.

With roughly 62,000 ha planted to rice in Ilocos Norte, 74,000 to 124,000 tons of rice straw are produced annually. Instead of burning this farm by-product, it can be used as the main material for composting.

Converting rice straw to compost supports the recent ordinance of the province that prohibits burning of rice straw. Instead of buying commercially available organic fertilizers, farmers can use their own compost and save on fertilizer expenses.

The government recommends the use of a fungus activator (Trichoderma) for rapid composting. And lately, a private company has been promoting the use of effective microorganism (EM) in composting. However, these activators are not readily available.

To help solve the problem, the JICA-PhilRice Technical Cooperation Project (TCP3) introduces a very simple and sustainable way of composting. The technology uses available farm wastes such as rice straw and animal manure, and innovates on the use of urea as activator. Urea is readily available because it is used by most farmers in farming, and it can be easily bought from local farm suppliers. 

Essential Requirements for Making Compost

Compost making requires billions of microbes (fungi, bacteria, etc.) to help break down the organic residues. For these living organisms to function effectively, they need air, water, and food.

  1. Aeration (oxygen)

    Composting microbes are aerobic, and they work well when air is provided. Rice straw is an excellent composting material because it allows a lot of air to circulate within the pile. The sole use of wet leaves is not recommended because they mat down very easily into slimy layers and do not allow air within the compost pile. However, a mixture of green and dry materials can be used as compost materials. Turning the pile also allows air into the composting materials. A poorly aerated compost pile decomposes slowly and produces a foul odor.

  2.  Moisture (water)

    The compost pile should be saturated with water for the microbes to multiply and disperse rapidly throughout the pile. A dry pile is not a conducive microbial habitat, and composting is slowed signi?cantly. On the other hand, a very wet pile becomes matted that it restricts air from circulating within. Again, the composting process slows down, and the pile creates a foul
    odor.

  3. Carbon and Nitrogen Ratio (C//N ratio)
The C/N ratio of the organic matter used in composting should be below 40 with at least 1% Nitrogen content for easy decomposition.  Adjust the C/N ratio by adding nitrogen.

The following table shows the Carbon and Nitrogen content of different farm wastes and their C/N ratio.

Carbon and Nitrogen contents of selected farm by- products and wastes

Rice straw Requires supplementary nitrogen to speed up decomposition. Add 1.0 kg urea or 2.0 kg ammonium sulfate for every 100 kg of rice straw.

 

Organic Matter

 

Total Carbon

(%)

 

Total Nitrogen

(%)

 

C/N Ratio

Rice straw

40

0.50

80

Wheat straw                      45                        0.38                    117

Cattle manure                   35                        2.20                      16

Swine manure                   41                        3.60                      11

Poultry manure                  35                        4.00                        9


Steps in Rice Straw Composting

  1. Set on the ground a square wooden frame with 1.5 m sides and 0.2 m height.


    setting up the wooden frame

  2. Pile rice straw evenly up to the top of the frame. If a shredder is available, use shredded rice straw to hasten decomposition.

    Grasses, broadleaf weeds like Chromolaena odorata or Hagonoy, and leguminous plants like peanut and beans can be added to the rice straw.

  3. Compact the 1rst layer of the pile, putting pressure along the corners of the frame. One layer is approximately 50 kg rice straw.


    compacting the pile


  4. Add 0.5 kg urea or 1.0 kg ammonium sulfate on top of each layer.

  5. Water the pile. The amount applied is already sufficient if water drips between the fingers when the composting material is squeezed with the hand.


    watering the compost pile


  6. If animal manure is available, spread it on top of the pile. Since manure is rich in nitrogen, the amount of supplementary nitrogen applied can be reduced depending on the amount and source of manure applied (refer to the table on C and N content of animal manure).

  7. Carefully remove the frame from the compacted layer. Place the frame on top of the pile.

  8. Repeat steps 2-7 until the pile is about 1.5 m high.

    making the succeeding layers of the pile

  9. Cover the pile with a tarpaulin sheet to prevent evaporation of moisture from the heat of the sun and leaching of nutrients from rainfall.

    If tarpaulin sheet is not available, use polyethylene sacks (opened and sewed together), or any plastic sheet that can protect the pile from the sun and rain. If sacks are used, apply water if the surface of the pile becomes dry.


    covering the pile with tarpaulin sheet


  10. The temperature in the pile should rise up to within 60 C to 70 C in 3–4 days after piling. This means that the microbes are actively decomposing the pile. If the temperature in the pile does not rise up to this level, the three essential requirements of compost making were not met


    taking the temperature of the pile

  11. Turn over the pile 3–4 weeks after piling. Pile again the composting materials. Add 0.2 kg urea then apply water on top of each layer. Make sure that the drier materials are piled at the middle of the new pile.


    turning over the pile

  12. The compost matures after 2 to 2.5 months. Good compost does not smell bad, is soft, and has deep brown or black color.


    collecting the mature compost


  13. If not to be used immediately, pack the compost in plastic sacks and store it in a shady and dry place.


packing the compost

 

Uses of Compost

1) Improves the physical property of the soil

Sandy soils have poor water- and nutrient-holding capacity. When compost is applied, it acts as a sponge and retains water and nutrients. Hence, the sandy soil can now maintain healthier plants.

Compost enhances the porosity of clay soils. Hence, drainage is improved.

2) Provides nutrients such as N, P, K and micro-elements

Compost is one of the raw materials used in formulating the sowing medium of seedling trays for vegetables like ampalaya, tomato, eggplant, pepper, etc. It provides the nutrients needed by the seedlings while they are in the tray.

Compost is applied as basal fertilizer for cucurbits like ampalaya, patola, squash and upo. The compost acts as a slow-release fertilizer.


3) Inoculates the soil with beneficial microorganisms like bacteria and fungi

The microorganisms extract nutrients from the soil and pass them to the plants.



4) Serves as mulch

As mulch, it helps conserve water by protecting the soil from the sun. When it eventually disintegrates, the compost is incorporated in the soil and becomes an additional source of nutrients in the soil.

5) Acts as a buffer for extreme soil pH resulting from excessive chemical fertilizer application

6) Soil with organic matter is a preferred habitat of spiders and other beneficial insects



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