Rice (Oryza sativa) is produced in Nigeria as food and cash crop and there is about 5% annual increase in the production. Over 10 million people are involved in rice production and processing. Local rice production increased from 4,080,940 MT in 2010 to 6,734,100 MT in 2014 (NAERLS,2014), but as a result of the increasing population and consumption the quantity being produced is not adequate to meet the growing demand. Increasing consumption of rice in sub Saharan region results in increase in the importation with Nigeria accounting for about 20% of the rice imports. Ban was imposed on rice importation in the country in 1985 and was lifted in 1995 when the local production couldn't meet the demand. Despite increasing prices of imported rice people have continued to demand for it because local rice production is not adequate. Rain fed lowland rice and rain fed upland rice production are the main production systems, others are irrigation system, deep water rice, and mangrove production systems. Rain fed low land rice accounts for about 50% of total rice production in the country.
Soil requirement
Rice grows well in fertile sandy loams and clays with organic matters and good water holding capacity. Rice requires soil with PH range between 5.5 and 7.0 and heavy soils with higher water holding capacity. Yields are usually associated with the heavy clay content, organic matter, water retention capacity, good drainage but not excessive drainage. Rice production must be rotated with leguminous crops such as cowpea, soybeans and groundnut.
Land preparation
Land preparation depends on soil type and cropping system. The land can be ploughed once and then harrowed or harrowed twice to provide good tilt and uniform distribution of water. Ridging is not necessary when harrowing is available. Clearing of the bush, packing of thrashes and removal stumps must have been done before first rain late February or early March. Plough the land with the first rain if the soil is moist enough.
Varieties
There are numerous varieties and selection is based on the environment and market. These are early maturing, medium maturing and late maturing varieties. There are also varieties for different ecosystem such upland ecology, irrigated lowland and mangrove ecology.
Seed treatment
Fungicides and herbicides are used to treat and protect the seeds against soil and seed borne diseases and insects and to ensure good germination. Seed priming should be done to hasten germination and emergence of rice plant. It is done by soaking the seeds in cold water for 12 hours or overnight and then dry for about 2 hours before planting. This is done to get higher percentage of germination, good establishment and vigorous growth that can suppress weeds.
Planting
Rice can be sowing in the field by drilling, broadcasting and dibble sowing. If germination percentage is greater than 80% use the following seed rates: Dibble sowing 50 - 60kg/ha, Drilling 80kg/ha and broadcasting 80 - 100kg/ha. But If the germination percentage is less than 80% increase the seed rates accordingly. Plant rice at dept of 2-4cm. Dibble 5-6 seeds at 25cm between rows and 20cm between plants and later thin to 3 - 4 seedlings two to three weeks after planting. If drilling method his used, drill rows 15 - 20cm apart.
Nursery practice
If nursery is to be used to raise rice seedlings, soak the seeds for 24 hours, incubate them by covering with polythene bags for about 48 hour for the seeds to sprout and then plant in the nursery beds
When to plant rice?
In the forest area, plant middle of March to April after 2 or 3 rains in the forest area
In the savannah area, plant middle of May to middle of June depending on the rainfall
Transplanting
Transplant from the nursery after 21 days and plant 2-3 seedlings per hole at spacing of 20cm between rows and 15 - 20cm between plants. Replace seedlings that die after germination with the remaining seedlings in the nursery bed.
Determining plant population
Plant population is calculated as total area of land divided by the spacing. For example, 25cm by 20cm spacing will give (10000/0.05) X number of plants per stand.
Nutrient requirements
Combination of organic and inorganic plant nutrients is required for optimum production and to sustained rice production for a long time on the same piece of land. Test the soil for nutrient deficiency in order to know the type and quantity of fertilizer that will be applied. Use organic manure, crop residues, green manures, bio fertilizers and soil amendments. Follow proper time and method of nutrient application, and manage water properly. The following doses can be applied under upland (Sahel, Northern Guinea and Southern Guinea Savannah) , forest and swampy rice ecosystems.
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Methods of fertilizer application
Fertilizer can be applied by drilling or broadcasting on moist soil conditions or incorporated into the soil at 10 cm from the base of the plants.
Water requirement
Rice needs adequate supply of water for optimum yields. Annual rainfall of 1200 - 1600mm, evenly distributed during the growing season and seed formation is required. Irrigate the crop at tillering, panicle initiation, flowering, milking and dough stage whenever water is not available. Rice field should be drained few days before harvesting to promote uniform ripening and allow timely harvest.
Weeding
Timely weeding within 2 - 3 weeks and 5 - 6 weeks after planting is recommended. Chemical weeding can done with the use of appropriate herbicides.
* Preemergence herbicide are applied to the soil to kill weed seeds.
- Oxidiazone
* Post-emergence herbicides are applied to control weed in the rice field. Examples are:
- Propanil + bentazone
- Propanil + Florourodifen
- Propanil + thiobencarb
- Propanil + 2, 4-D Amine. Remove resistant weeds especially grass-like weeds by hand. Follow the recommended rates and use appropriate herbicides.
Striga infestation
Striga is a serious problem in rice field. It germinates only where rice is planted and commonly found where rice has been grown continuously and where soil nutrients are not well maintained. The symptoms include stunted growth, wilting, yellowing and scorching of leaves, low yields and death in severe cases. The weed produces numerous tiny seeds and can easily be spread from place to place. Striga can be controlled by the use of healthy and striga-free seeds, proper fertilisation with combination of organic and inorganic fertilizers, timely weeding and crop rotation.
Control of pests and diseases
Pest management- The best approach is to practice integrated pest management (IPM) which is a combination of available pest control to keep pest population below economic threshold levels.
Cultural and mechanical method
This includes the use of resistant/tolerant varieties, adjustment of planting date, inter cropping, crop rotation, crop sanitation, efficient water management, use of traps/poison baits, removal and destruction of diseased plants. Rice pests are stem borer, rice army worm, termites, rice bugs, rice gall midge, birds and rodents. Use bird scaring devices to control birds.
Disease management
Integrated Disease management (IDS) should be practised to keep plant disease and infection below the economic threshold level. Various methods that can be used are: use healthy and clean seed; plant resistant varieties; destroy alternative hosts plants; select suitable land; practise crop rotation; follow appropriate plant population; timely weeding, proper inspection of the crops and removal of diseased plants.
Disease causal organism are:
* Rice blast, fungus disease caused by Pyrcularia grisea, Magnaporthe grisea
* Brown leaf sport, fungus decrease caused by Helminthosporium oryza
* Bacteria leaf blight caused by Xanthomonas campestris
* Bacteria leaf streak caused by Xanthomonas oryza
Harvesting
Rice is ready for harvesting when the grains are hard and the plant turning yellow/brown (about 40 days after flowering). Harvest when 80- 90% of the plants have turned brown to avoid shattering, cut the stems with a sickle, tie the panicles in bundles and dry before threshing and storage. Store the paddy in a cool, dry and rodent-proof place. Use actellic dust and phostoxin to control storage pests.
Yields
Yields between 1,200 and 3000kg/ha for swampy/lowland rice and 1000 - 1500kg for upland rice can be obtained with farmers' practices. Improved varieties yield 5000 - 6000/ha for swampy/lowland rice and 2500 - 3000 for upland rice.
Read rice processing
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