Response of cowpea and soybean to P and K on terre de barre soils in southern Benin

Good growth of Grain Legumes helps food security and protection of the environment but this may require nutrient inputs. A participatory technology development activity explored from 1998 to 2000 the responses of cowpea (Vigna unguiculata) and soybean (Glycine max (L.) Merr.) to inorganic soil amendments (P and K) on terre de barre soils with different levels of degradation in southern Bénin. Adingnigon, on the Abomey plateau, represents a level of severe degradation, while Hayakpa, on the Allada plateau, is still relatively non-degraded. Treatments included: (i) an unamended control, (ii) P fertilizer only, applied in 1998 or 1999, and (iii) P plus K applied in 1999. At Hayakpa, yields without fertilizer were generally moderate to high; responses to P were statistically significant and K application had a significant effect on soybean yield in 2000. At Adingnigon, P application had a large relative effect (30–200%) but a small absolute effect (less than 100 kg/ha) on cowpea and soybean yield. Subsequent K application increased grain yields further (approximately 100 kg/ha) but still not up to the cowpea yield potential. When 13 Mg/ha of organic amendment (chicken manure or cotton seed) were applied to severely degraded plots at Adingnigon with prior grain yields below 200 kg/ha, cowpea yields of more than 500 kg/ha were achieved, approaching their biological potential for the zone. It is clear from this study that (i) P and K inputs are needed for Grain Legumes even on relatively non-degraded terre de barre soils and (ii) inorganic fertilizer alone will not revive highly degraded soils on the terre de barre plateaus of southern Bénin

Potential of herbaceous legume cover crop fallow systems in the savanna zone

A set of herbaceous legumes was screened in the northern Guinea savanna zone of Nigeria in 1993-1994 to assess the ecological adaptability of the species and to observe characteristics that would influence their suitability in farming or cropping systems. Their fertilizer replacement value was estimated and the effects of P application to legumes in rotation with maize were examined. The following species were selected: cowpea, Mucuna pruriens var. cochinchinensis, Lablab purpureus, and Crotalaria ochroleuca. It was found that the legume rotation effect is small because the dry season is long and much of the residue disappears due to fire, wind, termites, or grazing. The N-fertilizer requirement can be reduced by applying P to legumes, but N fertilizer will still be needed for maize grain yields of 2.5 t/ha or more. KEYWORDS: TROPAGZea maysVigna unguiculataMucuna pruriensLablab purpureusCrotalaria ochroleucarotational croppinglegumesCrotalariaLablabMucunaVignafertilizersNIGIA

Multiple purpose tree use by farmers using indigenous knowledge in subhumid and semiarid northern Nigeria

Published online: 04 April 2012The northern Guinea savanna is generally known to be suitable for the production of annual crops of short-to-medium duration but is threatened with soil degradation because of inadequate organic inputs. Trees can be one important source of organic supplement to crop fields. Farmers' preferences for trees are related to a myriad of needs which vary in different environments. A survey was undertaken in Bauchi and Kaduna States of northern Nigeria to determine the extent of farmer knowledge in identifying niches for agroforestry trees. A total of 190 farmers were interviewed in Bauchi State and 154 farmers in Kaduna State. In Bauchi State, the preferred location for most trees was first bush fields (21 species or 64%), then compound fields (12 species or 36%), and village fields (6 species or 18%). There was more than one preferred location for some tree species. The 33 species in Bauchi State have important uses ranging from human food (42% of species), animal feed (12%), medicinal and windbreak/shading (both 9%), and live fencing and tools (both 6%). In Kaduna State important uses for a high proportion of the 12 species were medicinal and human food (both 50%), fuelwood (42%), and tools (33%) while the preferred location was in bush fields. In Kaduna State use of trees for soil improvement appeared stronger than in Bauchi State, especially with Parkia biglobosa. Descriptive and principal component analysis (PCA) further showed that in Bauchi State, compound fields are preferred for trees producing human food and shelter, while bush fields are used for trees producing animal feed and tools. In Kaduna State, trees producing food are preferred on all field types while field borders, woodlots and isolated trees were favored over hedgerows. This indigenous knowledge and preferences are essential when designing agroforestry systems in the sub-humid/semi-arid regions of northern Nigeria

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 nutrients limiting cassava yield maintenance on a sedimentary soil in southern Benin, West Africa

Market opportunities will drive intensification of cassava production and fertilizer will play a role in this. A trial was initiated on 15 farmers ' fields (replications) in one village territory in Benin on a relatively fertile sedimentary soil site to identify nutrients limiting cassava yield using nutrient omission plots over three cropping years. There was no response to fertilizer in the first year when fresh root yields in the unamended control averaged 19.1 t ha−1. In the second year, the control yield was 16 t ha−1 and there were significant reductions from withholding P (3.5 t ha−1) and K (2 t ha−1) from a complete fertilizer regime. Nutrient balance after 1 and 2 years (cumulative) showed substantial P and K deficits in unamended plots. In the third year, the control yield was 12.9 t ha−1 and effects of withholding K (5.3 t ha−1), P (5.0 t ha−1) and N (3.0 t ha−1) were statistically significant. Soil K was a significant source of variation in yield in the third year. In the third year of annual nutrient additions soil P and K in the top 0.3 m were increased by 37 and 40%, respectively. Based on the cumulative nutrient balance calculation, the annual application needed to compensate nutrient depletion was 13 kg N, 10 kg P, and 60 kg K ha−1. Partial budget analysis based on these amounts of fertilizer suggested that investment was clearly justified in the third year of continuous cropping at current low cassava prices

Effect of use of savanna tree leaves as mulch materials on germination and growth of selected annual crop seedlings

Leaves of indigenous and exotic tree species adapted to the climatic conditions of the northern Guinea savanna of West Africa were evaluated for use as a mulch material and screened for their effect on germination and early growth of two varieties each of soybean (Glycine max), cowpea (Vigna unguiculata), maize (Zea ways), sorghum (Sorghum bicolor) and millet (Pennisetum glaucum). Seed germination, and radicle and shoot fresh weight were examined after 7 days of incubation in petri dishes with aqueous extracts of dried ground tree leaves. Aboveground dry matter content and weed numbers were observed in a pot study in which dried ground tree leaves were mixed with the top 3cm layer of soil. The most consistent negative effects across both trials and all crops were observed in the Erythrophleum suaveolense and Combretum molle treatments. Vitellaria paradoxum, Prosopis africana and Entada africana induced adverse effects in the petri dish test but not in potted soil. Tamarindus indica also induced negative effects on germination and radicle growth in petri dishes but stimulated early crop growth in the pot study. Based on these studies E. suaveolense, C. molle, and Daniellia oliveri should not be used as mulch materials in the development of agroforestry systems utilizing MPTs (Multi Purpose Trees). On the other hand, the beneficial effect of the use of T. indica, Ficus polita and Piliostigma reticulatum should be confirmed. Since the in vitro screening method applied is rapid but some discrepancies in the results were observed, it should be complemented by pot screening