Distribución y brotación de plántulas de malezas en tres sistemas de labranza y tres profundidades del suelo
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Vargas Gutiérrez, Marlen
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Universidad de Costa Rica
Abstract
En el año 1987, en el Centro Agronómico Tropical de Investigación y Enseñanza (CATIE), se estudió la distribución y emergencia de plántulas de malezas en tres sistemas de labranza de suelo: convencional, reducido y cero, y en tres profundidades del suelo: 0-5, 5-10 y 10-20 cm. El ensayo se realizó en una casa de mallas con muestras de suelo tomadas de un terreno que se ha sembrado durante seis años con maíz y se ha sometido a los mismos sistemas de labranza del suelo. Se tomaron muestras de suelo de 500 g y se colocaron en potes plásticos de 14 cm de ancho por 5 cm de alto. Cada 15 días se realizaron recuentos y reconocimiento de plántulas de malezas. Se usó un diseño de Bloques Completos al Azar con cuatro repeticiones en un arreglo de parcelas divididas, donde las parcelas grandes fueron los sistemas de labranza y las parcelas pequeñas las profundidades de muestreo del suelo. Los sistemas de labranza convencional y cero labranza a una profundidad de 0-5 cm presentaron el mayor número de plántulas brotadas, mientras que el sistema reducido presentó el menor número de plántulas. Con las muestras de suelo de 10-20 cm el sistema de labranza convencional presentó el mayor número de malezas, mientras que en los sistemas reducido y cero labranza hubo una disminución en el número de plántulas emergidas. En el sistema de labranza convencional predominaron las malezas anuales Eleusine indica, Digitaria sp. y Drimaria sp., mientras que en los sistemas reducido y cero labranza dominó la maleza perenne Cyperus sp. Se concluyó que la labranza convencional recicla las semillas de malezas a capas inferiores del suelo, mientras que los sistemas de labranza reducida o cero las mantienen en las capas superficiales.
The distribution and emergence of weed seedlings under three tilling systems: conventional, reduced and notilling and three soil depths: 0-5, 5-10 and 10-20 cm was studied in 1987 at the Centro Agronómico Tropical de Investigación y Ensenanza (CATIE) in Turrialba, Costa Rica. The trial was conducted in a screened house with soil samples taken from a plot which had be en planted with corn during the last six years and that had been subjected to the same tilling system. Soil samples of 500 g were taken and put in plastic pots of 14 cm wide by 5 cm high. Identilication and weed counts were recorded every two weeks. A Randomized Complete Block Design in a Split-Plot arrangement with four replications was used, where the large plots were the tilling systems and the small plots the sampling soil depths. The conventional and no-tilling systems at the depth of 5 cm showed the largest number of emerged seedlings while the reduced system showed a smaller number of Seedlings. The soil samples taken at 10-20 cm showed the largest number of seedlings under the conventional tilling method, while with the reduced and no-tilling systems there was a diminishing number of emerged seedlings. Eleusine indica, Digitaria sp. and Drimaria sp. were the prevailing annual weeds in the conventional tilling system, while in the reduced and no-tilling systems the perennial weed Ciperus sp. was dominant. It was concluded that the conventional tilling method recycles the weed seeds to the lower soil layers, while in the reduced and no-tilling systems the seeds remain in the superficial layers.
The distribution and emergence of weed seedlings under three tilling systems: conventional, reduced and notilling and three soil depths: 0-5, 5-10 and 10-20 cm was studied in 1987 at the Centro Agronómico Tropical de Investigación y Ensenanza (CATIE) in Turrialba, Costa Rica. The trial was conducted in a screened house with soil samples taken from a plot which had be en planted with corn during the last six years and that had been subjected to the same tilling system. Soil samples of 500 g were taken and put in plastic pots of 14 cm wide by 5 cm high. Identilication and weed counts were recorded every two weeks. A Randomized Complete Block Design in a Split-Plot arrangement with four replications was used, where the large plots were the tilling systems and the small plots the sampling soil depths. The conventional and no-tilling systems at the depth of 5 cm showed the largest number of emerged seedlings while the reduced system showed a smaller number of Seedlings. The soil samples taken at 10-20 cm showed the largest number of seedlings under the conventional tilling method, while with the reduced and no-tilling systems there was a diminishing number of emerged seedlings. Eleusine indica, Digitaria sp. and Drimaria sp. were the prevailing annual weeds in the conventional tilling system, while in the reduced and no-tilling systems the perennial weed Ciperus sp. was dominant. It was concluded that the conventional tilling method recycles the weed seeds to the lower soil layers, while in the reduced and no-tilling systems the seeds remain in the superficial layers.