[The living wall terrace technology for prosustainable farming of tilled hillslopes in the subhumidid tropics of Mexico] | La terraza de muro vivo, tecnologia para la explotacion prosostenible de laderas roturadas del tropico subhumedo de Mexico

anglais. A long term field experiment is conducted in a plow-tilled 14-5 % hillslope typic tropofluvent since the summer of 1988 in order to test the hipothesis that inexpensive living wall terraces (LWT) may be developed from the interaction between the following elements; downslope plowing, rainfall, hillslope, a hedgerow of a native, seed reproduces legume tree, and a filter of sediments, namely, a ridge of crop residue parallel and adjacent upslope to the hedgerow. Five LWT treatments are compared involving 0.75m and 1 m vertical distances between hedgerows, two plowing intensities and two legume tree species: Glilicidia sepium and Leucaena leucocephala, plus a check that is plow-tilled unprotected against erosion. Rainfed maize is double cropped under constant agronomic plans across treatments for the summer and the winter growing seasons. Hedgerows are slashed 30 cm above the terrace level twice a year. Average terrace slopes became 6.1% by the sixth year. The first erosion cycle (EC- l june through october 1988) did not interact with the terrace elements since hedgerows were being developed. Two thirds of total terrace slope decrement took place in EC-2 (1989). On the average, LWT had amaximum sediment accumulation of 27 cm as measured in the lower terrace section, 50.6 cm living walls, and a 92.1% farmable space. The process of terrace development was assodated to a 4 % loss of clay in the original topsoil and 11% loss in its cation exchange capacity, Survival rates were 93% for G. sepium and 58% for L. leucocephala. LWT treatment that had 1 m vertical distance, shallow plowing and G. sepium hedegrows outyielded the check by 0.5 Mg ha-sup1 (P0.05) only in the winter: "dry" growing season

espagnol; castillan. Desde el ciclo Primavera-Verano 1988 se conduce un experimento de largo plazo en una ladera roturada con 14.5% de pendientes de un Typic Tropofluvents, para cotejar la hipotesis de que es factible desarrollar terrazas de Muro Vivo (TMV) estables a bajo costo, a traves de la interaccion de los siguientes elementos: la roturacion vertiendo hacia abajo, la lluvia, la pendiente, los setos y un filtro de sedimentos elaborado a partir de los residuos de cosecha. Se comparan cinco tratamientos de TMV que involucran 0.75m y 1m de distancia vertical entre setos, dos intensidades de roturacion y dos especies arboreas: Gliticidia sepium y Leucaena leucocephala, mas un testigo en el que se rotura sin proteger contra la erosion. Los setos son rozados a 30cm de altura dos veces al ano. Se practica el cultivo doble de maiz de temporal bajo un plan agronomico constante entre tratamientos y cambiante entre ciclos de cultivo. En el sexto ano, los tratamientos de TMV habian causado la reduccion de la pendiente original hasta 6.1 %, como pendiente promedio de las terrazas. El ciclo erosivo 1 (CE-1 junio-octubre de 1988) no interacciono con los tratamientos. Las dos terceras partes del decremento total de pendiente ocurrio durante CE-2 (1989). En promedio, lasTMV retuvieron 27cm de sedimentos, medidos en el extremo inferior de las terrazas, con muros vivosque promediaron 50.6cm, un espacio cultivable de 92.1%. En el proceso de formacion de las TMV se perdio el 4% del contenido original de arcilla y el 11% de la capacidad de intercambio de cationes de la capa arable donante. Las tasas de sobrevivencia de G. sepium y de L. leucocephala fueron 93 y 58%, respectivamente. El tratamiento con 1m de caida, roturado ligeramente y con setos de G. sepium. rindio 0.5 Mg ha-sup1 (P0.05) mas que el testigo en el ciclo Otono-Invierno (ciclo seco) y no hubo diferencia en el ciclo Primavera Verano (lluvias abundantes)