Climate vulnerability of sorghum and millet

Sorglium and millet are !lie most imoortnnl cereals lor resourcu.l)nor larnlersof West Alrica. Tliey are Ille o~ilyst aple crops that can whlistnnll tlie ravages of weatlier in that area. Tenl~~uraanl d snatral variat~oris1 11 rainfall and tlie persistence and patterns df railifall sl;ortages, especrally since 1969, have conlribured lo low producl~vitvo ver the last 2 decades. Increased yields can only be acliieved tlirougli effective rnanaye~risnot f available resources, both pliysical and biolog~calO. ngoing research iri West Africa offers hope, but s~gnilicant clianges In present farming n~etliodsw ill be needed lo reduce tlie cli~iiatic~ [rlnerab~lo~lt yso rghu~ri arid millet

Integrating Soil and Crop Models for Agroclimatological Analysis

In spite of the rapid advances made In the past 2 decades. world food production will barely manage to keep up with population and demand from now until the year 2000. The exceptionally stable climatic period witnessed by the world over the past 40 years is highly unlikely to continue (Cusack. 1983). Climatic Instability will Increase the vulnerability of the already marginal areas currently under cultivation In the semiarid regions of Asia and Africa. Integration of information from soils. crops. and the environment is crucial to evolve carefully managed systems of cultivation that make the most emcient use of natural resources

Canopy-air temperature differentials, water use and yield of chickpea in a semi-arid environment

Stress degree days (SDD) and canopy-air temperature differential summation procedures were used to quantify the response of crops of chickpea (Cicer arietinum L.) to soil water availability and atmospheric demand over a four year period on a deep and medium-deep Vertisol in India using different irrigation treatments and planting dates. Canopy temperatures measured between 13.00–14.00 h provided a good index of the daily mean canopy temperature. Differences in the diurnal variation in the canopy-air temperature differentials between irrigated and non-irrigated chickpea reflected clearly the differential response of the crop to soil water availability. Total water use of chickpea decreased with increasing SDD. Data pooled over three growing seasons showed a close relationship between SDD and yield of chickpea. Calculated water stress index (WSI) which includes the vapor pressure deficit term showed a similar relationship with yield to that with SDD

Climate change and implications for agriculture in niger

Five-year moving averages of annual rainfall for 21 locations in Niger showed a decline in the annual rainfall after 1960. Correlation coefficients of the moving averages of monthly rainfall with annual rainfall showed significant correlations between the decline in the annual rainfall with decreased rainfall in August. Analysis of daily rainfall data for rainy season parameters of interest to agriculture suggested that from 1965 there was a significant decrease in the amount of rainfall and in the number of rainy days in the months of July and August, resulting in a decreased volume of rainfall for each rainstorm. In comparison to the period 1945–64, major shifts have occurred in the average dates of onset and ending of rains during 1965–88. The length of the growing season was reduced by 5–20 days across different locations in Niger. The standard deviation for the onset and ending of the rains as well as the length of the growing season has increased, implying that cropping has become more risky. Water balance calculations also demonstrated that the probability of rainfall exceeding potential evapotranspiration decreased during the growing season. The implications of these changes for agriculture in Niger are discussed using field data

Growth and Yield of Millet and Cowpea in Relay and Intercrop Systems in the Sahelian Zone in Years when the Onset of the Rainy Season is Early

Field trials conducted previously in Niger have shown that in years when the onset of the rains is 15–20 days earlier than average, the long growing season can be exploited by growing a relay crop of millet (Pennisetum glaucum) and cowpea (Vigna unguiculata). In the trials reported here, the advantages of relay cropping were compared with intercropping with improved management and intercropping under traditional management during the 1989, 1990 and 1991 rainy seasons at the ICRISAT Sahelian Center, Sadore, Niger. The length of the growing season varied from 139 to 150 days over the three seasons. The relay crop produced more dry matter and leaf area and yielded more than the intercrops in all three years, confirming that in years when the onset of the rains is early, relay cropping with millet and cowpea is a better option than growing the same two species as an intercrop. Relay cropping avoids the competitive effects inherent in intercropping systems, while offering the additional advantages of rotating cereals with legumes

Exploiting rainy season potential from the onset of rains in the Sahelian zone of West Africa

Field studies were conducted at the ICRISAT Sahelian Center, Niamey, Niger, during 1986 and 1987 to test the methodology described earlier by Sivakumar (1988) that the potential of the rainy season in the Sahelian zone of West Africa can be determined from the date of onset of rains. We tested an early onset of rains treatment (imposed with supplemental irrigations) with the natural onset of rains. In 1986, natural onset was early while in 1987 it was considerably late. In both the seasons, dry matter production of millet (Pennisetum glaucum (L.) R. Br.) in the early onset of rains treatment reached 7 t ha−1 while late onset of rains resulted in only 3 t ha−1. Data on soil water profiles showed that at the time of the millet harvest in the early rains treatment, profile soil water is adequate to establish a second crop of cowpea (Vigna unguiculata (L.) Walp.) for hay. This enables efficient exploitation of soil moisture. In addition, the combined water use of the two crops in the early rains treatment was much higher. Results of this study suggest that by tailoring management tactics to weather conditions, in years with early onset of rains it is possible to establish a second crop of cowpea for hay in the Sahelian zone where the farmers traditionally grow only millet. The implications of the suggested methodology for other climatic zones in West Africa and its limitations are discusse

Agroclimatic Aspects of Rainfed Agriculture in the Sudano-Sahelian Zone

Characteristics of the rainfall in the Sudano-Sahelian Zone (SSZ) such as temporal and spatial variability, persistency, and geographical patterns of variability are described. A brief review of rainfall intensities, infiltration, and runoff is presented. Cumulative frequency distribution of maximum and minimum air temperatures at the time of sowing and harvesting of crops in the SSZ show that maximum temperatures at the time of sowing could exceed 40 deg C. Such high temperatures, together with wind erosion, can cause crop establishment problems. Maps of potential evapotranspiration and growing-season length are presented. The application of agroclimatic information for cropping strategies in the SSZ is described. A significant relationship is established between the onset of rains and the length of growing season for several locations based on which a new concept of "Weather-responsive crop management tactics" is proposed. The application of rainfall and drought probabilities and water balance is discussed