Report No 4 - 11 September 1996
INCREASING RAINS IN MID AND LATE AUGUST HAVE IMPROVED CROP PROSPECTS IN MOST COUNTRIES
Following below-normal rains in July in several parts of the Sahel, precipitation improved significantly in August over the main producing areas, thus reconstituting soil water reserves, providing relief to stressed crops and improving crop prospects in most countries. However, in the areas affected by earlier dry conditions, yield potential will be reduced and late plantings or replantings will need rains late in the season to cover their entire growing cycle. From west to east, crop conditions are satisfactory in Senegal and The Gambia following widespread above-normal rains in late August. Abundant rainfall also favoured desalination and transplanting of swamp rice in Guinea Bissau. In Mauritania, increased rains benefited crops in late August. In Mali, reduced rains in mid-August may have stressed crops in the centre-north. In Burkina Faso, crop condition improved significantly following reduced rains in June. In Niger, good rains in mid-and late August favoured crop and pasture growth but rainfall remained below normal in the centre. In Chad, well above normal rains covered the south and the centre in late August. In Cape Verde, crop condition vary from island to island reflecting irregular pattern of rains.
The last Meteosat satellite image up to the morning of 10 September (i.e. almost the entire first dekad) shows a southwards movement of the cloud coverage. Following generally good rains in late August, rains are expected to decrease significantly in most countries, notably in Mauritania, northern and central Senegal, northern Mali, northern Burkina Faso, central and eastern Niger and northern Chad. Precipitation remained relatively abundant in The Gambia, southern Senegal, Guinea Bissau, western and southern Mali, most parts of Burkina Faso and southern Chad.
Grasshoppers are reported in several countries but damage to crops remains limited. During August, significant Desert Locust infestations continued to develop in the summer breeding areas of the Sahel, albeit on a smaller scale than last year in the same period, possibly due to less rain. The infestations were dispersed over a wide area in southern Mauritania but to date they seem to have remained limited in size and numbers. Control operations were limited to about 800 hectares during August. In northern Mali and northern Niger, breeding was in progress but infestations remained limited.
BURKINA FASO
CAPE-VERDE
CHAD
GAMBIA
GUINEA-BISSAU
MALI
MAURITANIA
NIGER
SENEGAL
BENIN
CAMEROON
COTE DIVOIRE
GHANA
GUINEA
LIBERIA
NIGERIA
SIERRA LEONE
TOGO
In these reports, reference will be made to four different eco-climatic zones based on the average annual precipitation and agricultural features, i.e. Sahelian zone, Sudano-Sahelian zone, Sudanian zone and Guinean zone. They are shown in the map and described below:
Sahelian zone: Where average annual precipitation ranges between 250 and 500 mm. This zone is at the limit of perennial vegetation. In parts where precipitation is less than 350 mm, only pastures and occasional short-cycle drought-resistant cereal crops are grown; all cropping in this zone is subject to high risk.
Sudano-Sahelian zone: Where average annual precipitation ranges from 500 to 900 mm. In those parts of this zone where precipitation is less than 700 mm, mostly crops with a short growing cycle of 90 days are generally cultivated predominantly sorghum and millet.
Sudanian zone: Where average annual precipitation ranges from 900 to 1 100 mm. In this zone, most cereal crops have a growing cycle of 120 days or more. Most cereals, notably maize, root and cash crops are grown in this zone.
Guinean zone: Where average annual precipitation exceeds 1 100 mm. Guinea-Bissau and a small area of southern Burkina Faso belong to this zone, more suited to root crop cultivation.
Reference will also be made to the Intertropical Convergence Zone (ITCZ), also known by its trace on the earth's surface, called the Intertropical Front. The ITCZ is a quasi-permanent zone between two air masses separating the northern and southern hemisphere trade winds. The ITCZ moves north and south of the equator and usually reaches its most northerly position in July. Its position defines the northern limits of possible precipitation in the Sahel; rain-bearing clouds are generally situated 150-200 km south of the Intertropical Front.