Saturday, 15 July 2006

Sawah System and Power Tiller, Necessities for Sustainable Rice Production in Sub-Saharan Africa - the Case of Nigeria.

Oluwarotimi O. Fashola, International Institute of Tropical Agriculture, IITA, PMB 5320, Ibadan, Oyo State, Ibadan, Nigeria, Joshua Aliyu, Watershed Initiative in Nigeria (WIN 2001), GRA, PMB 1, Bida, Niger State, Bida, Nigeria, and Toshiyuki Wakatsuki, Faculty of Agriculture, Kinki University, 2-3-22 Tomio, Nara, 631-8505, Japan.


The importance of rice in Nigeria is no longer in doubt, the question is rather how we can meet the growing demand, reduce imports, and be self-sufficient. Consumption per capita jumped from 2.9 kg (1970/74) to 24.1 kg (1995/99). Production increased by 6 times within the period to 3.27 million tons but imports by 1998 stood at 1 million tons accounting for one-third of the total imports of rice for West Africa. There are 57 high yielding varieties for various ecologies officially released and more than 10 NERICA varieties in the pipeline for upland areas. In spite of the availability of these high yielding varieties, available data show that on average, the unit yield per hectare across rice ecology has increased only marginally from 1.3tons/ha to 1.6tons/ha in 20 years. This can be attributed mainly to the fact that the rainfed upland ecology has been a focus of production and unit yield did not increase from an average 1 ton/ha in 20 years, because of declining fertility and poor soil. The upland soils have less than 0.3g/kg Total Nitrogen with an Organic Carbon content less than 0.4%, the micronutrients are very limiting especially Fe (20ppm), Mn (5ppm), and Zn (less than 0.5ppm), Clay content is generally less than 10%. Also rainfall is erratic both in frequency and quantity and most farmers use little or no fertilizer because of high cost and/or non-availability. The upland is plagued with continuous pressure for urbanization and this has greatly reduced the fallow period to less than 2 years. By implication the upland soils are no longer a sustainable production terrain and as such cannot deliver the green revolution for self-sufficiency.

This leaves us with the lowlands. By 1999, the area harvested from rice stood at 2.2 million hectares of which 65% was from lowland. Rainfed lowland takes 53% of the share of the total rice production and 47% of rice area. The grain yield per hectare increased from 1.4 to 2.0 tons/ha in the last 20 years. More rice farmers have access to rainfed lowland than irrigated lowland and it is the only ecology with a tradition of two cropping seasons. The rainfed lowland has better micronutrient levels than the upland, the levels of Total Nitrogen, Organic Carbon and available Phosphorus are also higher, and the Clay content is greater than or equal to 20%. The rainfed lowland elite varieties with good management could yield up to 6 tons per ha. These potentials are never achieved on farmers' fields because of poor water control system and bad soil management. Traditionally the rice farmers have little or no bunding and the level of fertilization is low. This can be attributed to the fact that African rice farmers were originally upland cultivators. Therefore, the culture of bunding rice fields as seen in Asia rice field was not part of their farming practices. Consequently, the rainfed lowland topsoils are being eroded of its nutrients and most are mining the soil of its nutrients.

To arrest this situation and to demonstrate that the green revolution can indeed take place, a project was started on farmers' fields in 2001. This project, referred to as the Sawah system succeeded in increasing farmers' grain yield from less than 1.5tons/ha to 4tons/ha average. The Sawah package is described as the use of appropriate mechanization, Power Tiller (2-wheel hand-driven machine) for land leveling and puddling after the field has been divided appropriately into manageable plots of between 400m2 to 800m2 depending on the slope, and bunded with inlet and outlet canals for water intake and outlet. The package includes the use of fertilizer, straight row planting at a spacing of 25 cm 25cm, using the released high yielding varieties. In 4 years, the project has been able to scale-out to 25 ha on farmers fields from the original 0.1ha. Sawah i.e. a man-made rice environment has demonstrated its ability to provide better fertilizer use efficiency and weed control as a result of better water and soil management. This is why a renewed call for a concerted effort needs to be made for a better water and soil management practices referred to in this paper as Sawah System for increased and sustainable rice production.


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