59 research outputs found
Relationship between soil physical properties and crop yields in different cropping systems in southern Cameroon
Crop yields in sub-Saharan Africa (SSA) has been more or less stagnant since 1961. This can be connected to the traditional slash-and-burn agricultural based system. A growing population has forced most farmers to cultivate the same fields repeatedly. The resulting rapidly declining crop yields led eventually to an accelerated conversion of forest land into agricultural
land to cope with food demand. However, the integration of leguminous species, the use of fertilizer and tillage have been proven to increase yield especially in intensive cropping systems.
Although, depending on its frequency and kind, tillage can destroy soil aggregates resulting in degradation of soil organic matter. Else, it is known that improved crop varieties can be higher-yielding and more yield responsive to increased fertilizer application than traditional crop varieties.
Information is scarce on the effects of soil physical properties on plantain, maize and tomato yield formation and on their changes during their cropping phase. This study aimed at understanding the relationships between soil physical parameters and crop yields in different cropping systems in southern Cameroon with the goal to identify improved management strategies. This led to the setup of 4 experiments:
In a first experiment, the effects of soil physical properties on plantain yield were determined in a factorial trial in three southern Cameroonian villages comparing four cropping systems comprising two planted legumes (1) Flemingia macrophylla, (2) Pueraria phaseoloides, as well as (3) a crop, i.e. hot pepper, and (4) natural regrowth, all planted with plantain, established after conversion of old forest versus young bush fallow. Between 2002 and 2006, clay and silt content, MWD, GMD and the proportion of macroaggregates increased, whereas relative sand content, bulk density, the proportions of mesoaggregates and microaggregates decreased (not absolute decreased for sand content) in all villages, fallows and cropping systems. Changes of aggregate MWD and GMD were larger in the F. macrophylla and natural regrowth systems than in Pueraria systems. Plantain fresh bunch yield was 107 unaffected by village, fallow, and cropping systems. Plantain cultivation did not lead to a degradation of the determined soil physical properties.
In a follow up second trial at Mfou, it was evaluated, if maize cropped immediately after plantain was affected by the previous plantain systems and if tillage or N fertilizer would affect maize growth and grain yield and soil physical properties. In 2006, all plantain plots were cleared and split into 4 subplots, to assess the response of maize to tillage versus notill,
and of 60 kg ha-1 of N as urea compared to no N in a 2 x 2 factorial design. Freshly cleared eight years old bush fallow served as control. Maize grain yield was highest in the previously not cropped bush control and lowest in the previous Flemingia system. Grain yield in the previous Pueraria and natural regrowth systems were not different from the control. Maize grain yield was highest, when tillage was combined with fertilizer application, being significantly higher than in individual tillage or fertilizer application treatments. Soil physical properties were affected by tillage but did not remain different until the end of the maize growing phase.
In a third experiment the response of different tomato cultivars to different cultivation practices in an on-farm factorial trial was tested at Essong Mintsang in the central region of Cameroon on a Rhodic Kandiudult. Treatments were: current farmer practice of manual tillage yet not destumped, with either reduced input (no tillage, not destumped) or increased input (no tillage yet destumped, manual tillage and destumped, mechanical tillage and destumped). Yields of three tomato varieties were determined to assess, if changes in intensity of land preparation can improve soil physical properties and thus yields. At harvest, across land preparations the cv. Rossol produced higher yields (8.12 Mg ha-1) than cv. Roma (6.05 Mg ha-1) and cv. Rio Grande (4.46 Mg ha-1). Tomato total and marketable yields were significantly higher on the destumped tractor till, destumped manual till and stumps-retained manual till treatments than in the stumps retained no-till treatment. Total fresh yields of cvs. Roma and Rossol increased, when the soil was tilled, while cv. Rio Grande had no response to land preparation. Soil aggregates were least stable in the destumped, tractor till treatment, with significantly lower MWD (p=0.02) and higher mesoaggregate proportions (p=0.05) than in the other treatments. Across tomato cultivars and treatments, the marketable fruit yield could be predicted by clay, macroaggregates and bulk density. Early flowering and fruit production combined with nematode resistance were probably the main contributing factors to the high yields of cv. Rossol.
108 In a fourth experiment, the residual effects of the previous land preparation methods on maize growth and yield as well as impacts on soil physical properties were assessed. Land preparation methods had been applied to the preceding tomato crop. At harvest, maize fresh cob yield was significantly (P<0.05) lowest in the stump retained no till treatment. The equivalent
maize dry grain yields varied from 2.35 Mg ha-1 in the stump retained no-till treatment to 4.16 and 4.33 Mg ha-1 in the manual till stump retained and destumped treatments, respectively.
Soil aggregates were the least stable in the destumped tractor till treatment, with significantly lower (P=0.10) GMD than in the destumped manual till treatment. Maize fresh cob yield showed a strong correlation (R2~0.50, P=0.037) with soil aggregation and cone resistance to soil penetration.
In summary, the transition from shifting to permanent cultivation with acceptable yields is possible if an appropriate combination of crops (cultivar), use of leguminous species, tillage and fertilizers is implemented. Soil physical properties can control crop yield and hence can be manipulated to maximise yield. Tillage can contribute to yield increase if there
is an adequate SOM content and a suitable crop cultivar is chosen. Yet, tillage is labour intensive and degrades soil physical properties. Therefore, it is crucial to identify a minimum tillage frequency for low labour demand and minimal soil degradation, but with improved yields in conjunction with optimised fertilization and the development of improved crop cultivars
adapted to a wide range of soil conditions.Die Ernteerträge in Subsahara-Afrika (SSA) stagnieren größtenteils seit 1961, teilweise bedingt durch das traditionelle Brandrodungs-System. Eine wachsende Bevölkerung hat die meisten Landwirte dazu gezwungen, die gleichen Felder wiederholt zu bebauen. Der daraus resultierende rasche Rückgang der Bodenfruchtbarkeit und der Ernteerträge führte letztendlich zu einer beschleunigten Umwandlung von Waldflächen zu Ackerland um die Nachfrage nach Lebensmitteln zu befriedigen. Allerdings wurde bereits nachgewiesen, dass die Integration von Hülsenfrüchten in die bestehenden Fruchtfolgen, die vermehrte Verwendung von mineralischen Düngemitteln und eine verbesserte Bodenbearbeitung eine wichtige Rolle bei der Erhöhung des Ertrags spielen, besonders bei intensiven Anbausystemen. Dennoch kann die Bodenbearbeitung je nach Häufigkeit und Art und Weise Bodenaggregate zerstören, was zu einem Abbau organischer Substanz im Boden führt. Auch ist bekannt, dass verbesserte Sorten höhere Erträge generieren können, sowie auf einen erhöhten Einsatz von Düngemitteln
besser reagieren als traditionelle Sorten. Zurzeit gibt es nur wenige Studien über die Auswirkungen der physikalischen Eigenschaften vom Böden auf die Erträge von Kochbananen, Mais oder Tomaten, sowie über deren Veränderungen während des Anbaus. Diese Studie zielte daher darauf ab, das Verhältnis zwischen physikalischen Parametern vom Böden und Ernteerträgen in verschiedenen Anbausystemen im südlichen Kamerun zu erfassen, um verbesserte Management-Strategien identifizieren zu können. In diesem Zusammenhang wurden
vier Experimente durchgeführt:
In einem ersten Experiment wurden in drei Dörfern in Südkamerun die Auswirkungen der physikalischen Eigenschaften des Bodens auf den Ertrag von Kochbananen bestimmt. Diese Studie verglich vier Kochbananen Anbausysteme, zwei mit Leguminosen (1) Flemingia macrophylla, (2) Pueraria phaseoloides , (3) zusammen mit scharfem Pfeffer (Capsicum sp.), und (4) natürlicher Wiederaufwuchs; alle Systeme gepflanzt direkt nach der Umwandlung des Regenwaldes oder nach jungem brachliegendem Buschland dominiert von Chromolaena odorata. Zwischen 2002 und 2006 hat in allen Dörfern, Brachen- und Anbausystemen der Gehalt an Ton und Schluff MWD, GMD und der Anteil von Makroaggregaten zugenommen, während der relative Sandgehalt, die Bodendichte, und die Proportionen von Meso- und Mikroaggregaten verringert wurden (nicht absolute verringert für Sandgehalt). Die Veränderungen der Aggregate MWD und GMD in den Systemen mit F. macrophylla und natürlichem Wiederaufwuchs waren größer als in den Pueraria Systemen. Der Ertrag von Kochbananen war vom jeweiligen Dorf, Brachen- oder Anbausystem unbeeinflusst. Der Anbau von Kochbananen hat zu keiner Verschlechterung der physikalischen Eigenschaften des Bodens geführt.
In einer zweiten Folge-Studie in Mfou wurde untersucht, ob Mais, wenn er unmittelbar nach Kochbananen angebaut wurde, durch die vorherigen Anbausysteme beeinflusst wurde, und ob die Bodenbearbeitung oder die Verwendung von N-Düngern eine Auswirkung auf das Maiswachstum, den Kornertrag und die physikalischen Eigenschaften des Bodens haben. Im Jahr 2006 wurden alle Kochbananenpflanzen entfernt und die Felder in vier Parzellen unterteilt, um die Reaktion von Mais auf die konventionelle Bodenbearbeitung im Vergleich zu keiner Bodenbearbeitung zu bewerten, sowie die Reaktion auf 0 oder 60 kg N ha-1 Gabe in einem 2 x 2 Faktorendesign zu vergleichen. Eine geräumte Buschbrache von 8 Jahren diente als Kontrolle. Der Maiskornertrag war am höchsten in der zuvor nicht bestellten Buschbrachenkontrolle und am niedrigsten im vorherigen Flemingia-System. Der Kornertrag im vorherigen Pueraria und im natürlichen Wiederaufwuchs-System unterschied sich nicht von demjenigen der Kontrollparzelle. Der Maiskornertrag war am höchsten, wenn die Bodenbearbeitung mit Düngemitteln kombiniert war, und somit deutlich höher als bei den unabhängigen Behandlungen mit ausschließlicher Bodenbearbeitung oder Behandlung mit Düngemitteln. Die physikalischen Eigenschaften des Bodens wurden von der Bodenbearbeitung beeinflusst,haben sich aber erst zum Ende der Maiswachstumsphase verändert.
In einem dritten Experiment wurde auf der Basis einer On-Farm-Faktorenstudie in Essong Mintsang in der zentralen Region von Kamerun auf einem Rhodic Kandiudult die Reaktion verschiedener Tomatensorten auf verschiedene Anbauverfahren getestet. Die Verfahren waren wie folgt: aktuelle Bauernpraxis mit manueller Bodenbearbeitung ohne dem Entfernen von Baumstümpfen, entweder mit reduziertem Einsatz (keine Bodenbearbeitung mit Baumstümpfen)oder mit erhöhtem Einsatz (keine Bodenbearbeitung aber mit Entfernung der Baumstümpfe, manuelle oder maschinelle Bodenbearbeitung ohne Baumstöcke). Die Erträge der drei Tomatensorten wurden ermittelt, um zu bewerten, ob Veränderungen in der Intensität 111 der Landbearbeitung die physikalischen Eigenschaften des Bodens verbessern und damit auch den Ertrag. Bei der Ernte produzierte der Kultivar Rossol in Verbindung mit Landbearbeitung höhere Erträge (8.12 Mg ha-1) als Kultivar Roma (6.05 Mg ha-1) und Kultivar Rio Grande (4.46 Mg ha-1). Der gesamte marktfähige Tomatenertrag war deutlich höher bei der Traktoren-
Bodenbearbeitung und der manuellen Bodenbearbeitung mit jeweiligem Entfernen der Baumstümpfen und bei der manuellen Bodenbearbeitung unter Beibehaltung der Baumstümpfe, als bei den Verfahren ohne Bodenbearbeitung, die Stümpfe beibehielten. Die Gesamt-Erträge von cvs. Roma und Rossol wurden erhöht, im Zusammenhang mit der Bodenbearbeitung, während cv. Rio Grande auf die Landvorbereitung nicht reagierte. Die Bodenaggregate waren weniger stabil in dem Verfahren Traktoren-Bodenbearbeitung ohne Baumstümpfe, mit einem deutlich niedrigeren MWD (p=0.02) und höheren Mesoaggregaten-Proportionen (p=0.05) als in den anderen Verfahren. Über die verschiedenen Tomatensorten und Bearbeitungsverfahren konnte der marktfähige Früchteertrag durch den Gehal an Ton, Makroaggregaten und Bodendichte vorhergesagt werden. Die frühe Blüte und Frucht-Produktion, die mit der Widerstandsfähigkeit gegenüber Nematoden verbunden waren, waren wohl die wichtigsten Faktoren für den hohen Ertrag von cv. Rossol.
In einem vierten Experiment wurden die Nachwirkungen der früheren Landvorbereitungsmethoden auf das Maiswachstum, seinen Ertrag sowie deren Auswirkungen auf die physikalischen Eigenschaften des Bodens ausgewertet. Die Landvorbereitungsmethoden waren die gleichen wie bei dem vorherigen Tomatenanbauversuch. Bei der Ernte war der Konertrag von Mais im Verfahren ohne Bodenbearbeitung, die Baumstümpfe beibehielt, deutlich am niedrigsten (P<0.05). Die Erträge der äquivalenten trockenen Maiskörner variierten zwischen
2.35 und 4.16 Mg ha-1 im Verfahren ohne Bodenbearbeitung mit Baumstümpfen, beziehungsweise 4.33 Mg ha-1 im Verfahren mit manueller Bodenbearbeitung, die Baumstümpfe beibehielt, und mit manueller Bodenbearbeitung mit Entfernung von Baumstümpfen. Die Bodenaggregate waren am wenigsten stabil im Verfahren mit Traktoren-Bodenbearbeitung ohne Baumstümpfe, mit einem deutlich niedrigeren GMD (P=0.10) als in der manuellen Bodenbearbeitung mit Entfernung von Baumstümpfen. Der Ertrag von Mais zeigte eine starke Korrelation (R2~0.50 und P=0.037) zwischen der Bodenaggregation und dem Bodenpenetrationswiderstand
In vitro and in vivo antiestrogenic effects of dichloromethane-methanol extract of Crateva adansonii DC
Abstract: Despite significant developments occurring in the treatment of cancer, it still remains the second deadly disease, responsible for 8.2 million deaths every year. Various natural substances have been studied for active molecules of tumor suppression in the past and the tropical flora, by its diversity, continues to provide new antitumor drugs. Crateva adansonii dichloromethane-methanol (DCM/MeOH) extract was previously reported to prevent breast tumors in Wistar rats. However, it exhibited weak cytotoxic effect in human MCF-7 cells. The present study, therefore, deals with the investigation of its estrogenic and antiestrogenic effects. In vitro estrogenicity and antiestrogenicity of C. adansonii DCM/MeOH extract were performed by E-screen assay. In vivo, the investigation was carried out using the 3 days uterotrophic assay in ovariectomized rats, a classical tool for the prediction of estrogenicity of chemicals. As a result, C. adansonii extract did not induce MCF-7 cells proliferation, which is an estrogenic hallmark. However, C. adansonii extract induced a significant (P <0.05) decrease in a concentration-dependent manner of the MCF-7 proliferation when co-administered with E2B. In vivo, no estrogen-like effect was observed following a 3-day treatment with C. adansonii extract in estrogen target organs. However, the co-administration of C. adansonii extract with E2V lead to decreased uterine wet weight (P <0.05), total protein levels in uteri (P <0.01) as well as uterine and vaginal epithelial heights (P <0.05) as compared to animals treated with E2V only. These results suggest that C. adansonii has antiestrogenic effects but not estrogenic effects, which might account for its previously observed antimammary tumour effects in rats
Partial anomalous pulmonary venous connection with intact atrial septum in a child with ventricular septal defect: a case report
Partial anomalous pulmonary vein connection (PAPVC) is a rare congenital abnormal cardiac defect involving the pulmonary veins draining into the right atrium (RA) directly or indirectly by venous connection. Ninety percent of PAPVCs are accompanied by atrial septal defect (ASD). To our knowledge, there is no previous report of PAPVC with ventricular septal defect (VSD) without ASD in Korea, and in this paper, we report the first such case. A 2-day-old girl was admitted into the Chonnam National University Hospital for evaluation of a cardiac murmur. An echocardiogram revealed perimembranous VSD without ASD. She underwent patch closure of the VSD at 5 months of age. Although the VSD was completely closed, she had persistent cardiomegaly with right ventricular volume overload, as revealed by echocardiography. Three years later, cardiac catheterization and chest computed tomography revealed a PAPVC, with the right upper pulmonary vein draining into the right SVC. Therefore, correction of the PAPVC was surgically performed at 3 years of age. We conclude that it is important to suspect PAPVC in patients with right ventricular volume overload, but without ASD
Maize (Zea mays L.) yield and soil physical properties as affected by the previous plantain cropping systems, tillage and nitrogen application
We evaluated if cropping maize immediately after plantain is affected by the previous plantain systems and if tillage or N fertilizer would affect maize growth and grain yield and soil physical properties. The on-farm experiment was conducted at Mfou in the central Cameroon on a clayey, kaolinitic, Typic Kandiudult. The previous plantain cropping systems that had been established between 2002 and 2006 had 4 systems: two planted legumes (1) Flemingia macrophylla, (2) Pueraria phaseoloides, (3) an intercrop with hot pepper and (4) natural regrowth. In 2006, all plantain plots were cleared and split into 4, to assess the response of maize to tillage versus no – till and of 60 kg ha−1 of N as urea versus nil in a 2 × 2 factorial design. Bush fallow of 8 years of age not cropped during the plantain phase served as control. Maize grain yield was highest in the previously not cropped bush control and lowest in the previous Flemingia system. Grain yield in the previous Pueraria and natural regrowth systems were not different from control. Maize grain yield was highest when tillage was combined with fertilizer application, significantly higher from individual tillage or fertilizer application. Tilled only and fertilized only produced higher yields than no-till and no fertilizer. Soil physical properties were affected by tillage but did not remain different until the end of the maize growing phase. N fertilizer application had no effect on soil physical properties. Differences in maize grain yield could not be explained by soil physical properties and correlations with maize yield parameters were generally weak
Influence of different plantain cropping systems on physical properties of soil and plantain bunch yield
Published online: 20 June 2011Information on the effects of soil physical properties on plantain yield is rare. A factorial trial was conducted in three southern Cameroonian villages comparing four cropping systems comprising: two planted legumes, (1) Flemingia macrophylla and (2) Pueraria phaseoloides; a crop, (3) hot pepper; and (4) natural regrowth, all planted to plantain established in old forest versus young bush fallow. Initially, bush fallow had significantly higher sand content, mean weight diameter (MWD) and proportion of macroaggregates, but lower clay content and lower proportions of mesoaggregates and microaggregates than forest soil. Between 2002 and 2006, clay and silt content, MWD, geometric mean diameter and the proportion of macroaggregates increased, whereas sand content, bulk density, and the proportions of mesoaggregates and microaggregates decreased in all villages, fallows and cropping systems. Changes in aggregate stability parameters were greater in forest than in bush fallow at Ngoumou and Mfou, and greater in the F. macrophylla and natural regrowth systems than in the pepper and Pueraria systems. In Ngoumou and Nkometou, available water capacity increased. Plantain fresh-bunch yield was unaffected by village, fallow and cropping systems, and was not correlated with soil physical properties or their changes
Peritoneovenous shunt in malignant ascites. The Bordet Institute experience from 1975-1998
Background/Aims: This is the review of our experience in the treatment of malignant ascites using Le Veen and Denver peritoneovenous shunt. Methodology: From 1975-1998, 24 peritoneovenous shunts were inserted in 22 patients with malignant ascites. Results: All patients benefited from the procedure. The principal cause of failure was shunt occlusion (n=5). Conclusions: This study permits us to conclude that a preoperative appropriated selection of patients, should decrease failure rate. Patients should be sent to surgery as soon as the diagnosis of recalcitrant ascites is confirmed, to obtain a longer and more comfortable quality of life with terminal cancer.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Hematome intramural extensif de l'aorte thoracique
A[TRACE;del] 53-year-old hypertensive patient presenting with acute chest pain was found to have an intramural haematoma (IMH) of both ascending and descending aorta associated with a 6 cm ascending fusiform aortic aneurysm. Six weeks of antihypertensive treatment allowed complete resolution of the intramural haematoma of the descending aorta. Limited surgical repair of the ascending aorta by Gore-Tex graft prosthesis interposition was then performed. The patient was in good health with a one-year follow-up. (C) 2000 Editions scientifiques et medicales Elsevier SAS.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Tillage and varietal impacts on tomato (Solanum lycopersicum L.) production on an ultisol in central Cameroon
Across Africa the production of high value horticultural crops is being recognized as a possible route out of rural poverty. To determine at which level of intensification tomato yields were maximized and which tomato cultivar responds best to intensification, an on-farm, factorial trial was conducted at Essong Mintsang in the central region of Cameroon on a rhodic Kandiudult. Current farmer practice of manual tillage yet not destumped was compared with either reduced input (no tillage, not destumped) or increased input (no tillage yet destumped, manual tillage and destumped, mechanical tillage and destumped). Yields and yield components of three tomato varieties were determined to assess if changes in intensity of land preparation can improve soil physical properties and thus yields. At 6 weeks after planting, cultivar Rossol had more flowers (521,126 ha?1, p = 0.09) than cv. Rio Grande (403,930 ha?1), with cv. Roma (504,718 ha?1) not being significantly different from either variety. At harvest, across land preparations the cv. Rossol produced higher yields (8.12 Mg ha?1, p = 0.005) than cv. Roma (6.05 Mg ha?1) and cv. Rio Grande (4.46 Mg ha?1); the latter being significantly different (p = 0.03) from both others. Tomato total and marketable yields were significantly higher in the destumped tractor till, destumped manual till and stumps-retained manual till treatments than in the stumps retained no-till treatment. Yields in destumped no-till treatment were not significantly different from any of the treatments. Total fresh yields of cvs Roma and Rossol increased when the soil was tilled, while cv. Rio Grande had no response to land preparation. Tomato pest and disease damages were not affected by land preparation. Weeding took less time (p = 0.05) in destumped manual till (153 h ha?1) and tractor till (157 h ha?1) than in not destumped manual till plots (243 h ha?1). Soil aggregates were least stable in the destumped, tractor till treatment, with significantly lower MWD (p = 0.02), and higher mesoaggregate proportions (p = 0.05) than in the other treatments. Across tomato cultivars and treatments, the marketable fruit yield could be predicted by clay, macroaggregates and bulk density in the 0–10 cm layer: marketable yield = 0.12 clay ? 0.14 macroaggregate + 12.20 (with r2 = 0.50, n = 15, p = 0.016) and for the 10–20 cm soil layer: marketable yield = 0.17 clay + 5.15 bulk density ? 10.25 (with r2 = 0.58, n = 15, p = 0.005). Early flowering and fruit production combined with nematode resistance were probably the main contributing factors to the high yields of cv. Rossol
- …