Rice

From AgriWiki
Jump to: navigation, search
Oryza sativa

Contents

General information

Rice (Oryza sativa) production systems in Africa can be classified into rainfed upland, rainfed lowland (swamp), irrigated lowland and flood-prone (deep water) systems, based on the water availability for growth and the topography where rice is grown. Challenges of rice production in Senegal and Mali

Due to prevailing challenges such as low soil fertility and low soil moisture, it has been difficult to achieve the full potential of the existing rice production systems in Africa. Challenges include:

  • Limited access to good quality seeds;
  • Decreasing soil fertility;
  • Land shortage;
  • Soil erosion;
  • Water;
  • Weeds;
  • Pest and disease, including birds;
  • High post-harvest losses;
  • Low returns from rice production.

Selection of suitable varieties

  • Decide whether to grow upland or lowland rice, determined by the type of land available (upland or lowland with available water).
  • Consider locally adapted traditional or improved varieties which have been tested under local conditions by other farmers or research stations. It should be clear if the variety’s growing period, weed tolerance, moisture and nutrient requirements are adaptable to local climatic stresses. It is also important to consider varieties that are in high demand on the market and varieties that are preferred by locals because of local cuisine preferences.
  • Select varieties whose seeds can be selected, multiplied and re-used for the next crop. If brand new seeds are brought from another area, they should be tried and tested under local conditions before scaling up. When possible, select at least four varieties to create the genetic diversity necessary to satisfy different needs.

Seed selection

  • Select healthy and superior plants (true-to-type) of that variety for seed to make sure that only the best seeds which are well adapted under local conditions are used.
  • Before the final harvest, select that part of the farm where the plants are uniform, healthy, and disease-free with productive panicles.
  • At full maturity, harvest the panicles and allow them to dry under a cool environment until the moisture content of the grain reaches about 14 to 15%. Thresh manually as the seeds could be contaminated with other varieties.
  • From the harvested seeds, recycle 30 to 40kg to plant one hectare. The dry season harvest is a better source of good seeds because it has reached full maturity and, therefore, the lifespan of seeds is longer than seeds harvested during the wet season.
  • Store the seeds in a cool, dry place in an airtight container like a pot or hang in the house to deter rodents and other pests.
  • Sometimes, pest repelling materials may be added to keep away storage pests. For example, by mixing dried and crushed neem, castor leaves or any locally available herbal repellents.

Water management

Water supply is needed for optimum rice production in both upland and lowland systems. Water management depends on rice variety, rainfall patterns, soil properties, management practices and availability of water sources.

The water requirement in rainfed upland systems is met by making the most use of the available rainwater. Therefore, rice planting should be based on the cropping calendar, so that the stages of growth that need water most (from panicle initiation to heading) receive maximum rainfall. This will be complemented with reduced tillage practices, 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 2cm during most of the growing season, except during the ripening stage. However, it is possible only if access to water is assured 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 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.

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 as well as 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 (1-2cm) on the surface of the soil. The field should not be supplied with extra water during the 25 days before harvest.
  • Transplanting young seedlings, usually 8-12 days old, with just two small leaves. It must be done carefully and quickly to cause minimum trauma to the roots, putting only one seedling per hole instead of 3 to avoid root competition. Use wide spacing to encourage greater root and canopy growth in a square grid pattern, 25*25cm 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 as it allows more air into the soil for the roots to utilize. Doing one or two additional weedings (3 or 4 total weedings) before the plants have completed their growth or begin flowering, will provide even more oxygen to the soil. A very simple hand powered mechanical weeder, called a rotating hoe, has been developed to enable farmers to eliminate weeds easily, quickly and early. It reduces the hard labor 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, 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). 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.

Minimizing post-harvest losses

Proper post-harvest handling of organic rice aims at maximizing grain quality and minimizing losses and any contamination risks from extraneous materials and agents. In case of certified organic rice production, maximum separation of organic, in-conversion and conventional rice throughout the handling process is also important.

The post-harvest handling process starts with proper and timely harvesting, threshing, drying, milling, storage and secure packaging:

  • Harvesting. Rice is ready for harvest when the grains are full-sized, hard and the panicles have bent down. The number of days from flowering to harvest is fixed for the varieties. This should be used to ensure timely harvest and reduce grain shattering. At this stage, most of the panicles have turned golden brown in color. To prolong the shelf life, rice should be harvested only when it reaches full maturity. The date is chosen taking into consideration the stage of maturity, the shattering characteristics of the variety and the weather conditions (preferably during dry weather). Avoid mixing weed seeds with the harvested rice grains, so any weeds with fully matured seeds can be removed prior to harvesting. Harvesting by cutting the stem of the rice close to the ground with serrated sickles is much faster than harvesting using knives. The harvested paddy should be put on tarpaulins or similar materials to reduce contamination with foreign materials such as stones.
  • Drying. Rice is harvested when it has high moisture content and, therefore, needs immediate drying. Delays in drying or uneven drying will result in qualitative and quantitative losses by discoloration of grains and molding, and will increase the risk of insect damage. The paddy should be spread evenly on the tarpaulin; if it is too thick it will develop heat and cause discoloration. Drying under a cool, dry environment is preferred to fast drying of the grains under a hot sunny environment, which may affect the quality of the grain and break during milling.
  • Threshing and Milling. Threshing methods range from simply beating the rice sheaves on a stone or piece of wood to the fully mechanized combine harvesting. The rice husk and the bran are separated by milling to obtain the edible seed. If the rice was not dried well before threshing then it should be dried again to about 14% before milling. In the simple method, mostly used at the household or village level, rice is milled in a one-step process. However, proper milling facilities are required to achieve a higher percentage of whole grains for better quality and higher price. To fetch good prices, the milled rice must be made of whole grains and free of husks, weed seeds, stones and other foreign materials. Under certified organic production, the rice mill should be cleaned properly prior to milling organic rice. For example, five sacks of organic rice can be milled first to clean the mill and will be classified as conventional. Only the succeeding milled rice will be recognized as organic.
  • Storage. Rice quality can be affected by temperature and air moisture. Different processed rice (wholegrain or white) require different storage conditions. For example, wholegrain rice can be stored for two years under airtight storage and moderate temperatures 10-35°C while white rice can be stored up to three years under the same conditions.

Marketing and organic certification

Organic certification of rice production is only reasonable if done as a market requirement, as there should be a market that demands it. As the organic markets continue to grow in Africa’s domestic and export markets, more rice producers will need to verify and approve their farming systems as organic. Thus, certification is expected to become increasingly important. Interested farmers should be willing to adopt the general organic production requirements: eradicating the use of synthetic pesticides and fertilizers as well as treated and genetically modified seeds, and employing other sustainable production methods. Farmers should be willing to learn and apply new knowledge to find organic solutions to any existing challenges to rice production.

Other considerations include:

  • Farmers should have a sizable amount of land to produce rice beyond the household requirement (commercial volumes) to be able to cover the extra costs of certification. The land should also be owned by producers or they should have assured a long-term lease on the land.
  • The producers should have access to at least one processing facility (especially for milling and packing), where they can negotiate for preferential treatment of their harvests to minimize contamination. Eventually, as volumes increase, they can acquire their own processing facilities.
  • A group of farmers of the same village with adjacent fields can form a producer organization of organic producers to minimize the risks of contamination from neighboring fields. For organic rice, it is also important to avoid any contamination with conventionally grown rice and other substances during processing. All post-harvest equipment used for handling conventional rice should be adequately cleaned before being used for organic rice. It is also very important to use clean sacks that have not been used for synthetic fertilizers or any chemicals, or sufficiently wash them before using them for harvested produce.

Sources and References

Bibliography

Senegal (2010). Research information from infosysplus.org: Organisations and projects in Senegal.

FiBL, Research Institute of Organic Agriculture, Switzerland (2011). African Organic Agriculture Training Manual. Soil Fertility Management. [Accessed 19 March 2012]

FiBL, Research Institute of Organic Agriculture, Switzerland (2011). African Organic Agriculture Training Manual. Conversion to Organic Farming. [Accessed 19 March 2012]

FiBL, Research Institute of Organic Agriculture, Switzerland (2011). African Organic Agriculture Training Manual. Crop Management. [Accessed 21 March 2012]


FiBL (2011): African Organic Agriculture Training Manual. Version 1.0 June 2011. Edited by Gilles Weidmann and Lukas Kilcher. Research Institute of Organic Agriculture FiBL, Frick. [Accessed 12 July 2012]

FiBL, Research Institute of Organic Agriculture, Switzerland (2011). African Organic Agriculture Training Manual. Soil Fertility Management. [Accessed 19 March 2012]

External Links

Personal tools
Namespaces

Variants
Actions
Navigation
Tools