Technonology Guide for Rice Straw Composting with Urea

Introduction

In rainfed areas like the Ilocos, rice is the primary crop grown during the wet season, resulting in a surplus of rice straw. While some garlic and onion growers use the rice straw as mulch, others feed it to their livestock, and many farmers burn it as waste.

With an estimated 62,000 hectares of rice cultivation in Ilocos Norte, up to 124,000 tons of rice straw is generated annually. However, instead of being burned, this farm by-product can be transformed into compost, which aligns with the recent provincial ordinance that prohibits rice straw burning. By composting their rice straw, farmers can produce their own organic fertilizer and save on purchasing commercial fertilizers.

Traditionally, Trichoderma fungus activators have been recommended by the government to speed up the composting process, and EM activators have been promoted by private companies. However, these activators are not always readily available.

To address this issue, the JICA-PhilRice Technical Cooperation Project (TCP3) has developed a simple and sustainable composting method that utilizes rice straw, animal manure, and urea as an activator. Urea is easily accessible since it is commonly used by farmers and can be purchased from local farm suppliers.

Essential Requirements for Making Compost

To create compost, it is crucial to provide the billions of microorganisms (such as fungi, bacteria, and more) with the necessary conditions to break down organic matter. These living organisms require three essential components to function effectively: air, water, and food.

1. Aeration (oxygen)
   
   Aeration, or the presence of oxygen, is vital for the efficient functioning of aerobic composting microbes. Materials that allow air to circulate well within the pile, such as rice straw, are excellent for composting. On the other hand, wet leaves tend to mat down and create slimy layers that restrict airflow, making them unsuitable for composting alone. A mixture of both dry and green materials can be used to create a well-balanced compost pile. Turning the pile regularly is also important to allow oxygen to penetrate the composting materials. Poorly aerated compost piles decompose slowly and may emit unpleasant odors.
   
   
2.  Moisture (water)
   
   Optimal moisture is crucial for successful composting. To promote rapid multiplication and dispersion of microbes throughout the compost pile, it should be adequately saturated with water. However, a dry pile can hinder microbial growth and significantly slow down the composting process. Conversely, an overly wet pile can become matted, restricting airflow and leading to slow decomposition and foul odors. Striking the right balance of moisture is essential for creating a healthy and efficient compost pile.
   
   
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