Desempenho do inhame (taro) em plantio direto e no consórcio com crotalária, sob manejo orgânico.

Estudaram-se os efeitos do plantio direto em cobertura morta de aveia-preta e do consórcio com Crotalaria juncea, em sistema orgânico de produção de inhame, em ensaio na EE de Nova Friburgo(Pesagro-Rio), região serrana do estado do Rio de Janeiro. Utilizouse o delineamento de blocos ao acaso com quatro repetições, em esquema fatorial 2 x 2, onde os tratamentos corresponderam ao: modo de plantio (direto ou convencional) e modo de cultivo (monocultivo ou consórcio com crotalária). O cultivo consorciado com a leguminosa promoveu maior altura nas plantas do inhame, assim como reduziu a queima de folhas pelos raios solares. A população infestante de ervas espontâneas foi mais efetivamente controlada com a combinação entre consórcio e plantio direto. Nenhum dos tratamentos influenciou a produtividade do inhame, que foi considerada satisfatória, indicando o potencial do manejo orgânico adotado

Balanço do nitrogênio e fósforo em solo com cultivo orgânico de hortaliças após a incorporação de biomassa de guandu.

Os objetivos deste trabalho foram avaliar os efeitos de faixas de guandu (Cajanus cajan) e da incorporação da biomassa proveniente de sua poda na fertilidade do solo e na produtividade de três hortaliças sob cultivo orgânico. O delineamento usado foi de blocos casualizados completos em esquema de parcelas subsubdivididas com três repetições. As produtividades de beterraba, cenoura e feijão-de-vagem não foram afetadas pelos tratamentos. Nas parcelas onde não houve incorporação da biomassa de guandu, o balanço de nitrogênio no sistema foi negativo, ao passo que com a incorporação, esse balanço foi positivo. Embora tenha ocorrido balanço positivo para o fósforo nas parcelas sem a incorporação de biomassa de guandu, houve um aumento significativo na absorção desse elemento pelas hortaliças quando o material foi incorporado. O sistema de cultivo em aléias de guandu pode representar uma prática vantajosa para os produtores orgânicos, por contribuir na manutenção da fertilidade do solo

Reduction of P fertilizer requirement using lime and Mucuna on high P-sorption soils of NW Cameroon.

Soil acidity and high phosphorus (P) fixation are real problems in the Highlands of Central and Eastern Africa. Phosphatic fertilizers are imported and costly for the average farmer. We used lime and Mucuna green manure to reduce fertilizer P requirement of traditional food crops in NW Camcroon. Lime and phosphorus significantly improved stand count, root and stem weights as well as yields of maize (Zea mays L.), bean (Phaseolus spp.), and Irish potato (Solanum tuberosum L.) in three consecutive cropping seasons. Liming was most effective at low P rates and its effect on yield diminished with increasing P fertilization. Likewise, high P was unnecessary when lime was applied. Mucuna green manuring behaved similarly to liming and reduced maize P requirement by between 45 and 83%. Additionally, liming raised soil calcium (Ca), pH, effective cation exchange capacity (ECEC), and lowered exchangeable acidity (Al+H) as well as Al saturation. Consequently, maize and bean yields correlated positively (P<0.01) with pH, ECEC and exchangeable Ca but related inversely (P<0.01) with total acidity and Al saturation. Liming at 2 t ha-1 was observed to be uneconomical at the current prices of lime and P fertilizer. Thus, our results suggest that farmers could use either a much lower rate of lime or Mucuna green manuring with less than 85 kg ha-1 P fertilizer to sustain production on acid infertile soils in NW Cameroon. Résumé L'acidite du sol et la haute fixation du Phosphote (P) sont des veritables problemes des regions montagneuses de l'Afrique Centrale et de l'Est. Les engrais phosphoriques sont importes et sont tres couteux aux fermiers de la classe mayenne. Nous avous utilise des chaux et fumiers verts "Mucuna" pour reduire les exigences des engrais P des cultures traditionnelles au NW Cameroun. Les chaux et les engrais du phosphore ont cousiderablement ameliores la qualite des racines, les poids des tiges ainsi que les rendements du mais (Zea mays L.), l'haricot (Phaseolus spp.), et la pomme de terre (Solanum tuberosum) dans trois saisons des cultures consecutives. L'utilisation du chaux etait la plus effective a un faible niveau de taux et son effet sur le rendement a diminue avec l'augmentation d'engrais. De meme, la haute densite du phospore (P) n'etait pas necessaire apres l'utilisation des chaux. Les fumiers verts "Mucuna" ont remplace les chaux et reduit les besoins d'utilisation des phosphates pour le mays de 45 a 83%. En plus, l'utilisation des chaux a augmente la capacite effective d'echange sol calcium (Ca), pH, (ECEC) et a diminue la possibilite d'echange de l'acidite (Al + H) aussi bien que la saturation Al. Par cousequent, les rendements du mais et de l'haricot ont des correlations positives (P<0.01) avec pH, ECEC et echangeable Ca mais a l'inverse (P<0.01) avec l'acidite totale et la saturation Al. Les chauf a 2t ha-1 etait constate etant moins economique par rapport aux prix actuels des chaux et des engrais P. Ainsi, d'apres nos resultats nous aimerions suggerer aux fermiers d'utiliser soit un taux moins eleve des chaux ou des engrais verts "Mucuna" avec moins de 85 kgs ha-1 d'engrais P en vue de maintenir la production sur les sols infertiles d'acides au NW Cameroun

Pearl millet-based intercropping systems in the semiarid areas of Senegal

Pearl Millet ( Pennisetum glaucum (L.) R. Br.) is one of the principal cereal crops grown in the semiarid agroecosystem of Senegal. It usually is cultivated as a monocrop but yields are low because of inappropriate management and erratic rainfall. The objective of this study was to investigate the potential of agronomic practices, cultural methods and application of organic manures in maintaining crop productivity in pearl millet-based intercropping systems. On-farm research was conducted from 1989 to 1995 to evaluate performance of different millet varieties intercropped with grain and forage cowpea ( Vigna unguiculata (L.)Walp.) in two ecozones in the peanut zone of Senegal. The treatments imposed on the experimental units comprised of appropriate cultural techniques and application of compost and rock phosphate. The ecozones were the Central North Region (CNR) and the Central South Region (CSR). Mean rainfall in CNR ranges from 300 to 500 mm y-1 and in the CSR it ranges from 500 to 750 mm y-1. High-yielding millet varieties selected were IBV 8004 and Souna3 for the CNR and CSR. Sole-crop yields were higher than intercrop yields for both species but the millet-grain cowpea intercrop association was more productive than sole crops with a Land Equivalent Ratio of more than one. Millet variety IBV 8004 in sole crop as in intercrop association was more stable than was Souna 3. The yield of selected millet varieties increased more than 40% by compost application as compared to the control with no nutrients applied. There was an additional 10% increase in yield when compost was supplemented with rock phosphate.Le millet ( Pennisetum glaucum (L.) R. Br.) est l&apos;un des principaux céréals plantés dans la région agro-écologique semi-aride du Sénégal. Il est souvent cultivé en monocrop mais le rendement est généralement faible à cause de la gestion inappropriée et des pluies érratiques. L&apos;objectif de cette étude était d&apos;évaluer le potentiel des pratiques agronomiques, méthodes de cultures et l&apos;application des matières organiques pour maintenir la productivité dans le système d&apos;interculture basé sur pennisetum glaucum. Des recherches sur champs étaient conduites entre 1989 et 1995 pour évaluer la performance des différentes variétés du millet en combinaison avec le niébé ( Vigna unguiculata (L) Walp.) dans deux zones écologiques de la cacahuète au Sénégal. Les traitements imposés sur l&apos;unité expérimentale comprenaient des techniques de cultures appropriées et l&apos;application des compostes et du phosphate des roches. Les zones écologiques étaient la région centrale du nord (RCN) et centrale du sud (RCS). La moyenne pluviométrique dans le RCN rangée entre 300 et 500 mm y-1 et dans le RCS elle range entre 500 et 700 mm y-1. Les varétés du millet à forte rendement sélectionnées étaient IBV 8004 et Souna 3 pour le RCN et RCS. Le rendement associé à la monoculture était élévé pour les deux espèces mais le millet-niébé combiné était plus productive que la monoculture avec un taux de terre équivalent de plus que un. La variété IBV 8004 en monoculture comme en combinaison était plus stable que le Souna 3. Le rendement des variétés de millet sélectionnées augmenta de 40% avec l&apos;application du composte comparées au contrôle sans intrants. Il y avait une augmentation de 10% en rendement quand le composte était ajouté au phosphate des roches

Fertility characterization of soils at six research sites in NW Cameroon

Fertility capability of surface (0–20 cm) soils was evaluated at six sites in the North-West Cameroon highlands. Two main soil groups, designated as Classes A and B, were identified based on elevation. The Class A soils from low elevations (600–1178 m) had higher Ca, Mg, K, pH, sorbed less P and were lower in organic carbon and sesquioxides than the highland (> 1200 m) soils. Soil acidity (Al saturation > 30%) and high P sorption appeared to be the most limiting factors to crop production especially on the Class B soils where the Standard P Requirement exceeded 500 mg kg−1. Phosphorus sorption data were best described by the Freundlich equation. Amorphous aluminium was the most important determinant of solution P concentration (r = 0.85,p < 0.001) followed by soil organic carbon, (r = 0.80,p < 0.001) at high P rates. Nitrogen deficiency symptoms of maize were pronounced on the Class B soils. Consequently, crop growth and yield were lower on Class B than on Class A soils despite the high organic carbon in B. We hypothesize that the supply of high quality organic material (high in N and low in lignin and polyphenols) at site B through agroforestry and related cropping systems, would improve the fertility of the soil and crop yield