Wet/dry paddy cycles using Azolla

Supachai Pitiwut founded Thailand’s Weekend Farmer Network and its Facebook page. The Network has developed an Integrated System of Rice Intensification (SRI), using alternate ‘Wet and Dry Cultivation’ of rice.

Supachai Pitiwut founder of Thailand’s Weekend Farmer Network

Supachai Pitiwut founder of Thailand’s Weekend Farmer Network

The following outline is summarized from a scientific paper presented at the 2013 ‘International Network for Water and Ecosystem in Paddy Fields (INWEPF)’: ‘Wet/dry paddy cycles to optimize rice production for total quality of life: regarding rice as a water-resistant plant’ by Doi &  Supachai.

All images on this page were kindly supplied by Supachai Pitiwut.

The Weekend Holiday Farmers is a network of rice farmers whose objective is the sustainable management of the members’ paddy fields in order to generate a good quality of life for the farmers and the rural communities.

The network’s core technique is the use of wet/dry cycles in rice cultivation, providing a variety of technical strengths, which minimizes difficulties experienced by rice farmers. Following scientific trials, the technology is now used with technical variations by farmers and villagers in north and central Thailand. The technology has resulted in yields of up to 0.875 kg per square metre, an increase of 57%, plus reduced use of chemical fertilizers and pesticides,

wet dry systemThe technology has other benefits. It improves the health of farmers and villagers, increases their financial security, increases their free time, provides new opportunities, and hence overall quality of life. Many farmers previously experienced financial difficulties, health issues, long-time consumption, and other problems. Villagers in rural areas also suffered from polluted environments, weakened economy, and ruined communities. As a result, the farmers and villagers were often subjected to health and financial challenges.

The wet/dry cycle technique

The key practice is allowing the paddy soil to dry, especially during the tillering and rice maturity stages. Its effectiveness was first demonstrated by a farmer in the central region of Thailand in 1970, when his irrigation system stopped due to a technical problem at a pump station, resulting in a shortage of irrigation water. The technique was subsequently named as ‘wet/dry cycles’ by a local farmers’ network, ‘The Weekend Holiday Farmers’, and tested at ten sites in the north and central regions of Thailand in May 2013 (Figure 1).

Figure 1. Sites at which interviews about the wet/dry system were conducted.

Figure 1. Sites at which the wet/dry system was tested.

The technique uses two periods of drying the paddy field during the tillering stage, whereas many conventional water regimes have a single drying period during the elongation / booting period (Figure 2). The sinking water table can be visually observed in a 25 cm-depth well prepared from plastic pipe, and the water table sinks down to 15 cm depth from the soil surface when drying the soil (Figure 3). Rice seedlings are planted when their age is 15 to 20 days, at a distance of 30 cm between hills, with 5 to 10 seedlings per hill.

Figure 2. Schematic diagram of water regimes showing (a) the Weekend Holiday Farmers’ Network. and (b) a conventional water regime for rice production.

Figure 2. Schematic diagram of water regimes showing (a) the Weekend Holiday Farmers’ Network. and (b) a conventional water regime for rice production.

Figure 3. Changes in ground water level in a paddy field in which the technique, wet/dry cycles to strengthen rice, is applied to enhance aeration of the soil and elongation of rice root.

Figure 3. Changes in ground water level in a paddy field in which the technique, wet/dry cycles to strengthen rice, is applied to enhance aeration of the soil and elongation of rice root.

Organic matter and chemical fertilizers are periodically applied at the same time, depending on the plants’ needs. Pesticides, insecticides, and herbicides are occasionally applied depending on circumstances, but their use is minimized. Azolla is added to fix gaseous nitrogen before the seedlings are transplanted.

Introducing ducks is another option, mainly for weeding and removing snails, as well as the production of duck eggs to markets. Manual weeders are periodically used to exclude weeds between the rows of rice plants. After harvesting, rice straw is incorporated into the soil before the next rice season. To cope with snails, tea seed powder is sometimes applied in the paddy preparation. These practices are flexible and reflect farmers’ needs and their circumstances.

Figure 4. Three images of Azolla growing between rice plants. The red coloration is due to the presence of anthocyanins in the vacuoles of the leaf epidermal cells which act as a sun filter for the plant and its cyanobacterial symbiont Anabaena.

Figure 4. Three images of Azolla growing between rice plants. The red coloration is due to the presence of anthocyanins in the vacuoles of the leaf epidermal cells which act as a sun filter for the plant and its cyanobacterial symbiont Anabaena.

The addition of Azolla (Figure 4) fixes from ten to more than 100 kg of nitrogen per hectare. Its ability to fix gaseous nitrogen significantly contributes to rice productivity because less than 100 kg of nitrogen per hectare is often adequate to achieve a good yield of 6 kg per hectare.

The cycle of Azolla, thriving, dying, and decomposing on the surface of paddy soil also provides other advantages for rice production. For example, on the aerobic soil surfaces, the loss of nitrogen through denitrification is suppressed, of significant benefit because denitrification releases up to 65 kg of gaseous nitrogen per hectare to the air under the tropical climate during each season. Aerobic conditions also minimize the greenhouse effect by suppressing emissions of the greenhouse gases methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O).

Multiple benefits of the system

The system has multiple benefits:

  • Increased net profit result due to increased rice yield and reduced costs.
  • It provides multiple additional factors, including significant reduction in the use of herbicides, pesticides, insecticides and chemical fertilizers.
  • It results in a marked decrease in labor intensity, which are often the deciding factor for the adoption of a technology introduced.

Labor cost and time consumption for rice production were significantly reduced because of the following factors;

  • Farmers do not need to go to the paddies as often because no complicated and precise control of water level is required
  • Labor saving due to the use of the transplanter and other machinery
  • Decrease in the frequency of necessary actions, such as insecticide application
  • Walking and working on the dry soil surface are easy and comfortable

Contribution to farmers’ quality of life

The extra time generated by less labor-intensive technology provides additional opportunities for the farmers. For example, some farmers  manufacture products such as bottled fungal Mycelia which are purchased by other farmers. Many farmers also said that they gained extended personal, physical, and financial freedom after using the wet/dry system.

Health-promotion and environmental protection result from decreased use of toxic chemicals and the frequency of exposure to harmful chemicals. These multiple benefits can be extended from personal to community level at locations where a single farmer  adopts the technology and neighbors follow this example.

Conclusions

The wet/dry system technology was found to be ideal at a variety of rice farming sites in north and central Thailand where it achieved up to 57% increases in yield. This reflects the new paradigm that differs from the conventional one, i. e., maximization of yield per unit.

Farmers’ comments on the technology and soil analyses confirm that the system is successfully in terms of the sustainability of the soil, the overall environment, the health of farmers and villagers, plus their financial security, freedom, and hence their total quality of life.

The Weekend Farmer Network and its Facebook page includes numerous videos of the system.

Supachai Pitiwut will also be pleased to provide additional information by email about ‘Wet and Dry Cultivation of rice’.

 

 

 

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