Identification of cover crops for the semi-arid savanna zone of West Africa

Leguminous cover crops may be an appropriate component of sustainable food-production systems in the semi-arid savannas of West and Central Africa- A set of erect and spreading legumes was observed for adaptation D to a semi-arid climate (700-900 mm annual rain-fall), without fertilizer application, on three soil types in northern Cameroon. Mucuna pruriens generally reached l00% ground cover 60-90 d after planting, whereas Canavalia ensiformis rarely reached 100% ground cover, Two C. ensiformis accessions, one erect and one spreading, differed in their ability to cover the soil surface. Maximum foliage drymatter (DM) exceeded that of the locally adapted spreading cowpea in most cases. Foliage DM of M. pruriens, C. ensiformis, Clotalaria ochroleuca, and Cajanus cajan generally exceeded 4 t ha-' at all but the most degraded site. At the degraded site, the erect C. ensiformis accession produced 5-7 t DM htt. Canavalia ensiformis grow longer into the dry season and maintained higher moisture content, suggesting some drought resistance Because of strong winds during the dry season and trampling during seed collection, foliage DM less than about 4 t ha I did not persist through the dry season. Uncontrolled cattle grazing was another threat to persistence of mulch though the dry season

Identification of cover crops for the semi-arid savanna zone of West Africa

In IDL-1387

Identification of cover crops for the semiarid savanna zone of West Africa

Leguminous cover crops may be an appropriate component of sustainable food-production systems in the semi-arids avannas of West and Central Africa- A set of erect and spreading legumes was observed for adaptation D to a semi-arid climate (700-900 mm annual rainfall), without fertilizer application, on three soil t ?es in northern Cameroon- Mucuna pwiens genetically reached l00o/o ground cover 60-90 d after planting, where is Canaralid ensi form is rarely reached1 0070g round cover, Two C. enst form is accession so, ne erect and one spreading differed in their ability to covert the soil surface. Maximum foliage dry matter (DM) exceeded that of the locally adapted spread it rg cowpea in most cases. Foliage DM of M. pruriens, C. ensiformis, Clotalaria ochroleuca, and Cajanus cajan genetally exceeded 4 that all but the most degraded site. At the degraded site, the erect Censi-onnrs accession produced 5 -7 t DM htt. Canavaliae nsifotms grcw longer into the dry season and maintained high ermoisture content, suggesting some drought resistatnce because of strong winds during the dry season and trampling during seed collection, foliage DM less than about 4 t ha I did not persist through the dry season. Uncontrolled cattle grazing was another threat to persistence of mulch though the dry season

Effect of herbicide and handweeding on current and subsequent season Striga hermonthica density on sorghum

Striga hermonthica is an important cause of yield loss in sorghum in the semi‐arid zone of Africa. Two trials were conducted in northern Cameroon to evaluate the effect of herbicides for two cropping seasons on densities of emerged Striga in treatment years and on densities of Striga seed and plants in subsequent years. Herbicide application using 2,4‐D, triclopyr, paraquat, and bromoxynil and urea solution (20%) was compared with hand‐weeding of Striga and an unweeded control. Reduction of emerged Striga density was greatest with 2,4‐D and triclopyr. Sorghum grain yield was greatest in the urea solution treatment. Subsequent (third‐year) Striga seed densities were not significantly different, although they were substantially lower in the 2,4‐D‐treated plots. Emerged Striga densities in subsequent years were generally not significantly affected by previous herbicide treatments. One major source of variation in Striga density in the first year following the Striga suppression treatments was plot position along the slope, reinforcing the hypothesis that soil moisture plays a major role in Striga germination

ESTABLISHMENT OF OPTIMUM PLANT DENSITIES FOR DRY SEASON SORGHUM GROWN ON VERTISOLS IN THE SEMI-ARID ZONE OF CAMEROON

Dry season transplanted sorghum is grown on Vertisols in the Lake Chad Basin at approximately 10,000 plants ha-1. Increasing plant density was hypothesised to be one way of increasing yields in this cropping system. To test this hypothesis, a trial was conducted in four environments near Maroua in northern Cameroon (one year at Yoldeo and three years at Salak) examining densities ranging from 10,000 to 50,000 plants ha-1. Grain yields were not significantly increased by increasing planting density in any of the environments because of reduced panicle size. For example, as planting density was doubled from 10,000 to 20,000 ha-1, the mean density of panicles harvested was increased by 85% but mean grain weight per panicle was decreased by 45%. Thus, in all environments, mean grain yields increased by 100 kg ha-1 (9%) at the transplant density of 20,000 ha-1 and 150 kg ha-1 at 26,667 plants ha-1. A comparison of results from three years at Salak suggests that the fraction of plants bearing panicles is influenced by the annual rainfall and, especially, the amount of rain during August and September. However, even after a season of adequate rainfall, panicle grain weight decreased with increasing panicle density, suggesting that there is little scope for increasing dry season sorghum transplant density without supplemental irrigation. Considering increases in labour input for nursery establishment, transplanting and harvest, the increased revenue from increasing planting density does not compensate for increased costs. The economic optimum is around 10,000 ha-1, which is similar to the current farmers' practice

Establishment of optimum plant densities for dry season sorghum grown on Vertisols in the semiarid zones of Cameroon

Dry season transplanted sorghum is grown on Vertisols in the Lake Chad Basin at approximately 10,000 plants ha-1. Increasing plant density was hypothesised to be one way of increasing yields in this cropping system. To test this hypothesis, a trial was conducted in four environments near Maroua in northern Cameroon (one year at Yoldeo and three years at Salak) examining densities ranging from 10,000 to 50,000 plants ha-1. Grain yields were not significantly increased by increasing planting density in any of the environments because of reduced panicle size. For example, as planting density was doubled from 10,000 to 20,000 ha-1, the mean density of panicles harvested was increased by 85% but mean grain weight per panicle was decreased by 45%. Thus, in all environments, mean grain yields increased by 100 kg ha-1 (9%) at the transplant density of 20,000 ha-1 and 150 kg ha-1 at 26,667 plants ha-1. A comparison of results from three years at Salak suggests that the fraction of plants bearing panicles is influenced by the annual rainfall and, especially, the amount of rain during August and September. However, even after a season of adequate rainfall, panicle grain weight decreased with increasing panicle density, suggesting that there is little scope for increasing dry season sorghum transplant density without supplemental irrigation. Considering increases in labour input for nursery establishment, transplanting and harvest, the increased revenue from increasing planting density does not compensate for increased costs. The economic optimum is around 10,000 ha-1, which is similar to the current farmers' practice.La densité de plantation pour des sorghos repiqués en saison sèche sur les Vertisols dans le basin du lac Tchad environne 10000 plantes ha-1. L'augmentation de la densité semble être un moyen d'augmenter son rendement dans ce systeme agricole. Pour tester cette hypothèse, un essai comportant cinq densité variant entre 10000 et 50000 plantes ha-1 a été conduit pendant trois ans à Salak et un an à Yoldeo dans le nord du Cameroun près de Maroura. Le rendement en grains n'a pas significativement augmenté avec la densité des plantes à cause de la réduction de dimensions de la panicule. Par exemple, en doublant la densité de 10000 plantes ha-1, la densité moyenne de penicules récoltées a augmenté de 85%, mais le poids moyen de grains par penicule a dimunué de 45%. Pour différents environnements, le rendement en grains a été augmenté de 100 kg dans le traitement de 20000 plantes ha-1 et 150 kg dans le traitement de 26666 plantes ha-1. Les résultats suggèrent que à Salak la fraction de plantes avec penicules est influencée par la pluviométrie des mois d'Août et Septembre. Toutefois, malgré un regime pluviométrique adéquate, le poids de grains des penicules a diminué avec l'augmentation de la densité de penicules faisant transparaitre moins d'espoir d'augmenter la densité de repiquage du sorgho sans irrigation, pendant la saison sèche. Considérant le coût du travail pour l'installation des pépinières, le repiquage et la récolte, le revenue généré ne couvre pas les dépenses engagées. L'optimum économique est autour des 10000 plantes ha-1 actuellement utilisé par les agriculteurs

Response of dry season sorghum to supplemental irrigation and fertilizer N and P on Vertisols in northern Cameroon

A series of trials was conducted to quantify response of dry season transplanted sorghum to water and fertilizer application in order to test the hypothesis that soil moisture limits production more than nutrient supply. The trials were conducted at two field sites representative of a large land area in the Lake Chad Basin of Africa. Water was clearly the limiting factor as grain yield response to two irrigations (10 cm total) was a statistically significant 58% over 3 years. One irrigation during vegetative growth resulted in sorghum grain yield increases of 24–29%. Response to P fertilizer was negligible. Response to N fertilizer was 32% over three environments but was not statistically significant at P < 0.05. Future research should focus on improvements in soil moisture availability, either through increased soil moisture storage or through reduced evaporative losses