Screening forage and browse legumes germplasm to nutrient stress: II. Tolerance of Lablab purpureus L. to acidity and low phosphorus in two acid soils

Although lablab (Lablab purpureus L.) is grown in many parts of Africa relatively little investigation has been done on its adaptation to acid soils, which are generally low in available In the present study, lablab was evaluated for tolerance to acidity and low available P on two Ethiopian soils. The two soils were a Nitosol (Soddo soil) and clay loam with 77 percent Al saturation (Chencha Soil). The PH of the Soddo soil unlimed was 4.8 and 5.6 when limed and with 0 and 37.5 mg/P/kg soil applied at each lime rate. The treatments on the Chencha soil were PH 4.1 and 5.9 with combinations 0 and 25 mg/P/kg added. There were highly significant differences between the mean shoot and root dry matter yields and the shoot/root ratios of the lablab accessions on the two soils as well as plant height on the Chencha soil. The mean shoot and root dry matter yields were increased by liming alone by 14 and 23 percent, while P application increased growth by 8 and 12 percent, respectively. Lime and P together suppressed mean root yields. On the Chencha soil, lime increased shoot and root yields by 87 and 35 percent, and by 58 and 14 percent with P added, respectively, while P alone increased growth by 28 and 17 percent with little effect on the limed soil. Labla could be screened for differential performance using mean dry matter yields on both soils but screening for varying levels of acidity and P was reliable only with root yield on the Soddo soil and plant height on the Chencha soil

Variability in the growth and mineral nutrition of African clovers

A study conducted to develop a classification for Ethiopian clovers based on the performance and phosphorus requirement which has potential for selecting accessions from the rest of the ILCA germplasm suitable for different levels of soil The effects of different P levels on the growth and N and P nutrition of 20 accessions from eleven Ethiopian clover (Trifolium) species were investigated in a glasshouse. The treatments were 0, 12.5, 25, 37.5 and 50 mg P/kg

Screening forage and browse legumes germplasm to nutrient stresses: IGrowth rates of Sesbania as affected by aluminium and low phosphorus in soils and nutrient solutions

Sesbania have multifarious utilization, and in many instances growth rate is one of the most important criteria for the selection of suitable Sesbania. This paper reports results of a study on the growth rates of Sesbania on two acid soils both low in available P, but one with toxic levels of Al. Growth rate was assessed by measuring plant height at 21, 29, 35, 45, 52, and 60 days on a clay loam (chencha soil). Growth was also evaluated in nutrient solutions containing 0, 3, and 6 PPm Al in combination with 155 and 6200 PPm On the Soddo soil, the Sesbania varied in their growth rates, but responded similarly to liming the soil from PH 4.8 to 5.6 throughout the growing period. The accessions showed similar response to P during early growth, but varied sharply during late growth 35 to 60 days without Lime was progressively move effective with P applied. The growth patterns fell into four categories based on responses to P applied to the Soddo soil. On the Chencha soil which had 77 percent Al saturation, the Sesbania differentially responded to liming the soil from PH 4.1 to 5.9 and to applied P at each growth interval. Accessions which had the best plant height on the Chencha soil were generally tolerant to Al. Variability in the growth rates of accessions from different countries suggested potential for screening Sesbania for differential tolerance to soil acidity and low P in relation to source of origin

Screening forage and browse legumes germplasm to nutrient stress: I. Tolerance of Medicago sativa L. to aluminium and low phosphorus in soils and nutrient solutions

Alfalfa or lucerne (Medicago sativa L.) is an important forage legume grown extensively in the world. There have been relatively few investigations on the adaptation of alfalfa to soils found in suitable eco-zones in Africa. In the present investigations, twenty accessions were evaluated for tolerance to soil acidity, low phosphorus (P) and tolerance to aluminium (Al), and their response to P in nutrient solutions to identify indicator rresponse to P in nutrient solutions to identify indicator cultivars for acid soil mineral stresses. The soils were a Nitosol (Soddo soil) and a clay loam with 77 percent al saturation (Chencha soil). The treatments were PH 4.8 (unlimed) and PH 5.6 (limed) with 0 and 37.5 mg/P/kg added at each PH of the Soddo soil. The treatments on the Chencha soil were PH 4.1 and 5.9 with 0 and 25 mg P/kg unlimed soil and 0, 25 and 37.5 mg P/g limed soil. Additions to the nutrient solution were 0, 3 and 6 PPm Al (0, 111, and 222 um) in combinations with 155 and 6200 PPm P (5 and 200 um) as KH2P04. The alfalfa accessions differed in mean growth except for similar values of mean shoot yield on the Chencha soil. Phosphorus increased the mean shoot and root yields on the Soddo soil by 5.7 and 6.3 times, respectively, compared to 1.7 and 2.1 times due to liming. However on the highly Al saturated Chencha soil, the mean was increased five times by liming but 1.7 and 2.1 times by P application. The accessions also showed large differential Al tolerance and rresponse to P in nutrient solutions. A potential usefulness of the data may be in the selection of ILCA forage germplasm for adaptation to similar soils of the relatively cool climatic regions of the eastern African highlands

Response of castor cultivar "Hale" to rate and method of nitrogen fertilizer application in different environments of Zimbabwe

The effects of different rates and methods of N fertilizer application were assessed at five sites over two seasons (1987/88 and 1988/89). Fertilizer rates of 0, 30, 60, 90 and 120 kg N ha-1 were applied in a single dose at planting or in two splits, half applied at planting and the other half as topdressing at primary floral initiation. The sites at Makoholi, Mlezu and Matopos were on sandy soils in low rainfall areas while those at Kadoma and Panmure were in sandy clay loam soils in higher rainfall areas. There were significant interactions between N rate and season on seed yield in the sandy soils except at Makoholi. The effect of N rate on these parameters contrasted at each site between the two seasons, indicating that the amount of N fertilizer needed for castor (Ricinus communis L.) on the sandy soils depended on the amount of rainfall. Application of N in a single dose did not significantly increase seed yield when available soil N was medium to high (>24 ppm) except at Kadoma where application of 30 kg N ha-1 increased yield when soil N status was rated as medium. Yield responses to N applied at planting in 1987/88 at Matopos and Panmure and in 1988/89 at Makoholi and Mlezu indicated that 60 kg N ha-1 was the optimum application rate for castor. When compared to a single dose, splitting N application enhanced its effectiveness in increasing yield in 1987/88 at Mlezu and Matopos, and at Kadoma in two seasons. These results suggest that split N applications are beneficial to castor when seasonal rainfall is greater than 700mm.Les effets de differentes proportions et methodes d'application d'engrais azote ont ete evalues dans cinq stations au cours des saisons 1987/88 et 1988/89. Les proportions du fertilisant de 0, 30, 60, 90 et 120 kg de N ha-1 ont ete utilisees. Elles ont ete appliquees soit a dose unique aux plantes et l'autre a dose dedoublee dont une partie aux plantes et l'autre a l'initiation de l'epanouissement floral primaire. Les stations de Makoholi, Mlezu et Matopos etaient situees sur des sols sablonneux dans des regions a faibles precipations. Celles de Kadoma et de Panmure etaient, par contre, situees sur des sols sablo-angileux dans des regions a fortes precipitations. Les interactions entre la teneur en N et la sason sur la production des graines se sont sevelees hautement significatives dans des stations a sols sableux sauf a Makoholi. L'effet de la teneur en N sur ces parametres variait a chaque site en fonction de la saison. Cela monre que la quantite d'engrais azote souhaitable pour la poivriere (Ricinus communis) sur des sols sablonneux est fonction de la quantite de pluies. L'application de N a dose unique n'a pas augmente de facon significative la production des graines lorsque l'azote disponible du sol etait de moyenne a eleve (>24 ppm) sauf a Kadoma. Dans ce dennier cas, l'application de 30 kg de N ha-1 augmentait la production quand le statut de l'azote du sol etait considere comme moyenne. Les reponses de la production a l'azote applique aux plantes en 1987/88 a Matopos et Pammure et en 1988/89 a Makoholi et Mlezu a montre que 60 kg de N ha-1 etait la proportion optimale pour la poivriere. Contrairement a la dose unique, le dedoublement de l'application de l'azote a accru son efficacite. La production a donc augmente a Mlezu et Matopos en 1987/88 et a Kadoma au cours des deux saisons. Ces resultats montrent bien que les applications de l'azote a dose dedoublee sont benefiques a la poivriere loisque les precipations saisonnieres sont superieures a 700mm

Screening forage and browse legumes germplasm to nutrient stresses: III. Tolerance of Sesbania to aluminium and low phosphorus in soils and nutrient solution

Sesbania, particularly S. sesban species, grow naturally in many parts of Africa where they form natural browse. Productivity of Sesbania as animal feed is widely limited by soil acidity and low In this study, eighteen ILCA accessions of S. sesban and two of S. goetzei, all but two from Africa, were evaluated for tolerance to acidity and low P on two Ethiopian soils as well as their tolerance to Al and response to P in nutrient solutions. The treatments were O and 4000 mg CaCO3/kg (PH 4.8 and 5.6) in combination with O and 37.5 mg P/kg on a Soddo Nitosol. On the chencha clay loam with 77 percent Al saturation, the PH values were 4.1 (unlimed) and 5.9 (limed) in combination with 0 and 25 mg P/kg on the unlimed soil plus 37.5 mg/P/kg on the limed soil. Treatments applied to the nutrient solutions were 0, 3, and 6 ppm Al in combination with 155 and 6200 PPm P as KH2p04. On the Soddo soil, Sesbania responded primarily to P which increased average shoot growth by 171 to 822 percent with low response (6.5 percent) to lime which did not significantly differ among the accessions. On the chencha soil, the Sesbania were highly responsive to lime and P which increased shoot growth by 129 to 425 percent, and 100 to 492 percent respectively. The Sesbania varied in their tolerance to Al which gave shoot yield reductions of 18 to 69 percent with 3 PPm and 33 to 84 percent with 6 PPm Al at low Increasing P level to 6200 PPm greatly alleviated the deleterious effects of Al to such an extent that only one accession had growth reduction greater than 50 percent at 3 PPm Al. The accessions from Uganda showed similar high performance in soils and nutrient solutions, but there was more divergence in the performance of the accessions from each of the other countries, Kenya, Ethiopia, and Tanzania

Phosphorus response and mineral composition of Ethiopian highland Trifolium (clover) species

Pot trials and laboratory phosphorus (P) sorption studies were conducted to evaluate the response of seven Ethiopian clover species (T. decorum, T. steudneri, T. quartinianum, T. rueppellianum, T. schimperi, T. tembense, and T. subterraneum) to applied P and further to determine the critical external P requirements of these legumes. Application of P fertilizer increased the dry matter yield, N, and P contents of all species, and P and N use efficiency in T. steudneri. Maximum dry matter yields were attained between 20 and 40 kg p/ha. At zero P application, T. decorum gave the highest dry matter yield, indication that this species can thrive better than the others on soils of low available The external P requirements of the species ranged from 0.003 to 0.025 mg/L on a low P - fixing soil, and 0.0004 to 0.0019 mg P/L on a high P-fixing soil. These results suggest that the fertilizer requirements of crop species may not be based on a single P sorption curve if the soils have widely different P sorption characteristics

Evaluation of phosphorus uptake and use efficiency and nitrogen fixation potential by African clovers

Phosphorus deficiency is the major soil fertility problem limiting forage production in many parts of Africa. The objective of this study was to screen African Trifolium species for dry matter production, nutrient use efficiency and nitrogen fixation potential at different rates of applied Twenty accessions of native Ethiopian clovers were grown in a greenhouse on Vertisol at P rates of 0, 12.5, 25, 37.5 and 60 mg P kg-1 soil. The experiment was conducted in Addis Ababa, Ethiopia. In the absence of P fertilizer, there was total inhibition of nodulation in all the accessions, which virtually eliminated the potential for the clovers to fix nitorgen. Nodulation, shoot and root dry matter (DM) increased with added Shoot DM yields at 50 mg P kg-1 soil were 15-to 70-fold higher than those without applied Corresponding responses in root DM were 10- to 48-fold. Trifolium decorum accessions ILRI9682 and ILRI6264 had the highest shoot and root DM, N and P uptake, and N efficiency ratio, but the highest P efficiency ratios were found in Trifolium steunderi accession ILRI9720

Maize Response to Method and Rate of Manure Application

Field experiments to determine the effect of solid beef manure application method and rate on maize grain yield and maize dry matter yield were carried out in Chinyika Resettlement Area (CRA) in Zimbabwe in the 1996/97 and 1997/98 seasons. Four rates of manure (5, 10, 20, 30 t ha-1) were applied using two methods: broadcasting and banding laid out as a 4 x 2 factorial in a randomised complete block design with three replicates. Other treatments used were the extension recommendation, farmer practice, control and no basal fertiliser application. Maize plants were sampled at 5, 10 and 15 weeks after crop emergence (wace) for dry matter yield at one site. There were no significant effects of manure application method and rate on maize dry matter yield at 5 wace in both seasons. At 10 wace in the 1996/97 season banding resulted in significantly higher maize dry matter yield than broadcasting (P < 0.05). There was also a significant (P < 0.01) increase in dry matter yield with manure application rate. At 15 wace there were no significant effects of manure application method on maize dry matter yield in both seasons. Maize grain yield increased significantly (P < 0.001) with an increase in manure application rate at both sites in both seasons, and band application of manure resulted in higher maize grain yield than broadcasting at all manure application rates in both seasons. Band application of 30 t ha-1 manure resulted in the highest net benefit. Economic analysis indicated that 10 t ha-1 banded was the economical manure application rate in both seasons. The current general recommendation by extension agents is effective for dry - land maize production.Des essais en champs ont \ue9t\ue9 conduits durant les saisons de 1996/97 et 1997/98 dans la zone de repeuplement au Zimbabwe pour d\ue9terminer des effets du taux et de la m\ue9thode d\u2019application de la fumure solide du boeuf sur le rendement en grains et le rendement en mati\ue8re s\ue8che du mais. Quatre taux de fumure (5, 10, 20, 30 t ha-1) ont \ue9t\ue9 appliqu\ue9s utilisant deux m\ue9thodes: semis \ue0 la vol\ue9e et r\ue9partition en bandes comme factoriel 4 x 2 dans un bloc compl\ue9tement rendomiz\ue9 avec trois r\ue9p\ue9titions. Autres traitements comprenaient la recommendation de la vulgarisation, la pratique du fumier, le contr\uf4le et la non application d\u2019engrais de base. Les plantes de ma\uefs \ue9taient \ue9chantiollonn\ue9es \ue0 5, 10 et 15 semaines apr\ue8s emergence (SAE) pour le rendement en mati\ue8re s\ue8che \ue0 un seul site. Il n\u2019yavaient pas d\u2019effets significatifs du taux et de la m\ue9thode d\u2019application de la fumure sur le rendement en mati\ue8re s\ue8che du ma\uefs \ue0 5 SAE dans les deux saisons. A 10 SAE dans la saison de 1996/97, la r\ue9partition en bandes a donn\ue9 un rendement en mati\ue8re s\ue8che siginificativement plus \ue9l\ue9v\ue9 plus que le semis \ue0 la vol\ue9e (P<0.05). Il yavait aussi une augmentation significative (P <0.01) du rendement en mati\ue8re s\ue8che avec le taux d\u2019application de la fumure. A 15 SAE, il n\u2019y avaient pas d\u2019effets significatifs de la m\ue9thode d\u2019application de la fumure sur le rendement eu mati\ue8re s\ue8che du ma\uefs dans les deux saisons. L\u2019application en bandes de la fumure a aboutit \ue0 un rendement en grain plus \ue9lev\ue9 plus que le semi \ue0 la vol\ue9e pour tous les niveaux d\u2019application de la fumure dans les deux saisons. L\u2019application en bandes de 30 t ha-1 de fumure s\u2019est sold\ue9e par un b\ue9nifice net dans les deux saisons. L\u2019analyse \ue9conomique a r\ue9v\ue9l\ue9 que le taux d\u2019application de 10 t ha-1 de la fumure en bandes \ue9tait le plus \ue9conomique pendant les deux saisons