Control cultural de las malezas en yuca

Some cultural control measures of weeds in cassava are discussed: quality of the material, planting system and density, density x plant type interaction and use of mulching. In order to study the interaction plant type x planting density, var. M Mex 59 (vigorous) and M Col 22 (nonvigorous) were planted in plots of 7500 and 15,000 plants/ha; and 3 levels of weed control were established: complete, intermediate and no control. The vigorous var. was less than sensitive to a deficiency in control than the nonvigorous var.; the increase in fresh root yield reached up to 60 percent at high densities. Different materials for mulching were evaluated at Carimagua and CIAT (Colombia), obtaining effective weed control with corn husks, hay from Hyparrhenia rufa and Stylosanthes guyanensis, and sugar cane leaves. Moreover, 2 cover crops (Desmodiutn heterophyllum and Phaseolus vulgaris) were evaluated, as well as cane bagasse, chemical control and continuous manual weeding systems. Highest yields in cassava were obtained with weeding 22, 40, 60 and 115 days after planting, but it was the most expensive because of the labor. The 2 cover crops are valid choices for their effectiveness, but their high cost justifies their use only when seed is produced locally and with family labor. Intercropping systems and different weed control practices were studied whereby the stabilizing effect of the cassava yield was verified and the utilization of legumes with short growing cycles was shown to reduce weed growth. It is concluded that there are many possibilities of combining cultural weed control with other measures to permit the farmer to choose between capital or labor input. (CIAT)Se describen algunas medidas de control cultural de malezas en yuca: calidad del material; sistema y densidad de siembra; interaccion tipo de planta x densidad y uso de coberturas. Para estudiar la interaccion tipo de planta x densidad de siembra, se sembraron las var. M Mex 59 (Vigorosa) y M Col 22 (no vigorosa) en parcelas de 7500 y 15.000 plantas/ha y se establecieron 3 niveles de control de malezas: completo, intermedio y sin control. La var. vigorosa fue menos sensible a una deficiencia en el control que la var. no vigorosa; el incremento del rendimiento de raices frescas alcanzo hasta un 60 por ciento empleando la densidad de siembra alta. En Carimagua y CIAT (Colombia) se evaluaron diferentes materiales como cobertura, y se obtuvo buen control de malezas, con paja de maiz, heno de pasto puntero (Hyparrhenia rufa) y de Stylosanthes guyanensis, y hojas de cana de azucar. Se evaluaron ademas 2 coberturas verdes (Desmodium heterophyllum y Phaseolus vulgaris) junto con bagazo de cana y sistemas de control quimico y manual continuo. El mas alto rendimiento de la yuca se obtuvo con desyerbas a los 22, 40, 60 y 115 dias de la siembra, pero fue el de mayor costo de mano de obra. Los 2 sistemas de coberturas verdes aparecen como opciones validas por su efectividad, pero su alto costo solo justifica su empleo cuando la semilla se produce localmente y la mano de obra es familiar. Se estudiaron sistemas de cultivo intercalado y diferentes practicas de manejo de malezas, con los cuales se confirmo el efecto estabilizador del rendimiento de la yuca, y se demostro que la utilizacion de leguminosas de ciclo vegetativo corto reduce el crecimiento de las malezas. Se concluye que existen muchas posibilidades de combinar el control cultural de malezas con otras medidas para permitir al agricultor escoger entre insumos de capital o mano de obra. (CIAT

Soil tillage and windbreak efects on millet and cowpea: I. Wind speed, evaporation, and wind erosion

Deforestation, overgrazing, and declining soil regeneration periods have resulted in increased wind erosion problems in dry areas of th; West African Sahel, but little is known about the bio-physical factors involved. This research was conducted to determine the effects of ridging and four different windbreak spacings on wind erosion, potential evaporation, and soil water reserves. A field trial was conducted from 1985 to 1987 on 12 ha of a Psammentic Paleustalf in Southern Niger. Millet, Pennisetum glaucum (L.), and cowpea, Vigmi unguiculata (L.) Walp., were seeded in strips on flat and ridged soil. Windbreaks of savannah vegetation were spaced at 6, 20, 40, and 91) m. The effects of ridging on wind speed, evaporation, and wind erosion were small and mostly non-significant. However, average wind speed at 0.3 m above ground in the center of cowpea and millet strips was significantly reduced from 2.8 to 2.1 m s"1 as windbreak distances narrowed from 90 to 6 m

Soil tillage and windbreak effects on millet and cowpea: II. Dry matter and grain yield

In the West Africa Sahel, sand storms occuring early in the growing season may severely damage emerging crops. This study was conducted to determine the influence of ridges and windbreaks on growth, water use and grain yield of millet, pennisetum glaucum (L.), and cowpea, Vigna unguiculata (L.) Walp

Follow-up evaluation of two harvesting machines

Meeting: Workshop on Cassava Harvesting and Processing Technology, 24-28 Apr. 1978, Cali, COIn IDL-598