Proper water management

Enough supply of water is needed for optimum rice production in both upland and lowland systems. Proper management of water depends on the rice variety, rainfall patterns, soil properties, management practises and availability of other sources of water.

The water requirement in rainfed upland systems is met by making the most use of the available water from the rains. Therefore, planting of rice should be based on the cropping calendar, so that the stages of growth that need water most (i.e. from panicle initiation to heading) receive maximum rainfall. This will be complemented with reduced tillage practises, mulching and proper water harvesting channels on sloping lands. It is important to establish the time to sow in each season based on the long-term (15 years) daily rainfall pattern or actual trials on optimum sowing date.

Ideally, the water level in irrigated flooded rice needs to be maintained at about 2 cm during most of the growing season, except during the ripening stage. This is, however, possible only if the producer is assured of access to water whenever it is needed. In many situations this is not the case as the availability depends on rainfall patterns and irrigation is not accessible to many farmers. Where resources permit, farmers should tap and conserve the available water more appropriately, for example, by creating bunds and channels to trap moving water from uphill into man-made ponds or dams. Such collected water can later be redistributed into the fields in seasons of low water availability.

Discussion: Water management in rice fields

Assess the situation by asking the participants the following questions;

How do you ensure enough water availability for both upland and lowland rice production?
Are there any farmers who irrigate their rice farms? If yes, where do they get the irrigation water from?

The System of Rice Intensification (SRI)

SRI is a methodology for increasing the productivity of irrigated rice by changing the management of plants, soil, water and nutrients. SRI, which originated in Madagascar, leads to healthier soil and plants supported by greater root growth and the nurturing of soil microbial abundance and diversity. In its simplest form, SRI involves:

Soil only needs to be kept moist during the period of growth when the plant is putting out tillers and leaves, before it begins to flower and to produce grains. During this reproductive stage, the rice plants should be given a thin layer of water (1-2 cm) on the surface of the soil. The field should not be supplied with extra water during the 25 days before harvest.
Transplanting seedlings when still very young, usually just 8-12 days old, with just two small leaves, done carefully and quickly to have minimum trauma to the roots, putting only one seedling per hole instead of 3 to avoid root competition, and using wide spacing to encourage greater root and canopy growth in a square grid pattern, 25 x 25 cm or wider in good quality soil.
The first weeding should be within about 10 days after transplanting, and at least one more weeding should follow within two weeks. This will dig up weeds at the same time that it allows more air into the soil for the roots to utilize. Doing one or two additional weedings (3 or 4 weedings in all), before the plants have completed their growth or begin flowering, will provide still more oxygen to the soil. A very simple mechanical weeder, called a rotating hoe, pushed by hand has been developed to enable farmers to eliminate weeds easily, quickly and early. It reduces the hard labour of pulling up individual weeds by hand once they emerge.
Adding compost or manure whenever possible to add nutrients to the field.

The benefits of SRI, which have been demonstrated in over 40 countries include: increased yield (50 to 100 % or more), a reduction in required seed (up to 90 %) and water savings (50 % or more). Many SRI users also report a reduction in pests, diseases, grain shattering, unfilled grains and lodging. Additional environmental benefits stem from the reduction of agricultural chemicals, water use and methane emissions that contribute to global warming. See SRI website: ciifad.cornell.edu/sri/  for more information on country experiences with SRI.

Recommendations for farmers for better water management in irrigated systems:

For efficient water saving in irrigated rice systems, allow water into the field 3 to 4 days after transplanting, then irrigate and drain the field alternately from the seedling stage up to flowering time. Plan to irrigate, especially during the flowering or heading period, which requires adequate water for good yields. Allow the soil surface to dry before irrigating but keep the soil in a saturated state. But avoid leaving standing water of more than 2 cm except in rice-fish systems and construct borders on the rice plots to facilitate proper collection and drainage of excess water. Make sure the water is free of contaminants from conventional fields and is of good quality to avoid soil related problems, like salinity.

Ensure that no inflow of water from any conventional fields exists. But if the field is already contaminated, construct drainage canals to divert the water away, thus minimizing contaminants from entering the plots. Meanwhile encourage all immediate neighbouring farmers to adopt organic farming practises and reduce use of pesticides or fertilizers.

Brainstorming session: The SRI approach

Explain the SRI approach to the participants and afterwards, ask the participants whether the approach is applicable under their local conditions and what could be some of its challenges.

Working group/field visit – Pest and disease identification

Visit different rice fields and, together with the participants, identify any observable signs of pest or disease problems. Ask the participants whether they are familiar with those signs of pests and diseases and whether they have monitored to see when the pests and diseases attack.