In response to the extensive development of upland rice on the hillsides of the Malagasy highlands, alternative cropping systems based on conservation agriculture have been recommended to halt loss of soil
fertility. To assess the yield performances of these cropping systems, an experiment was set up in 2003
at Andranomanelatra (1640 m asl) in the Malagasy highlands. Grain yield, yield components, biomass
accumulation and nitrogen uptake of upland rice were analyzed in the 2004–2005, 2006–2006, and
2006–2007 seasons, and root length density was measured in the 2007–2008 season. The rice crop was
planted every second year following two different crops: maize intercropped with soybean (M + S, with
both conventional tillage and no tillage) and maize intercropped with Brachiaria ruziziensis (M + B only
with no tillage). For each cropping system, two levels of fertilization were used: no fertilizer or application of organic inputs and mineral fertilizer. The season, cropping system, and fertilization treatment had
significant effects on rice grain yields. Higher yields were associated with a greater number of plants per
m2
, which decreased significantly over the three seasons, probably due to the highly variable beginning of
the rains, and in the final season, with attacks by soil insects. The rice yield with conventional tillage was
the highest and differed significantly from rice yield when maize was intercropped with Brachiaria under
the no-till system, but not when the maize was intercropped with soybean with no tillage. In all three
seasons, grain yields were closely linked to crop N at harvest. Differences in N uptake between treatments
appeared very early in the crop cycle. Under conventional tillage, root length density at 68 days after sowing was higher between 0 and 30 cm depth than with no tillage. In these cold highlands conditions, plant
establishment appeared to be more difficult with no tillage and resulted in reduced plant development
and plant N uptake, particularly when rice was planted after maize intercropped with Brachiaria
In response to the extensive development of upland rice on the hillsides of the Malagasy highlands, alternative cropping systems based on conservation agriculture have been recommended to halt loss of soil
fertility. To assess the yield performances of these cropping systems, an experiment was set up in 2003
at Andranomanelatra (1640 m asl) in the Malagasy highlands. Grain yield, yield components, biomass
accumulation and nitrogen uptake of upland rice were analyzed in the 2004–2005, 2006–2006, and
2006–2007 seasons, and root length density was measured in the 2007–2008 season. The rice crop was
planted every second year following two different crops: maize intercropped with soybean (M + S, with
both conventional tillage and no tillage) and maize intercropped with Brachiaria ruziziensis (M + B only
with no tillage). For each cropping system, two levels of fertilization were used: no fertilizer or application of organic inputs and mineral fertilizer. The season, cropping system, and fertilization treatment had
significant effects on rice grain yields. Higher yields were associated with a greater number of plants per
m2
, which decreased significantly over the three seasons, probably due to the highly variable beginning of
the rains, and in the final season, with attacks by soil insects. The rice yield with conventional tillage was
the highest and differed significantly from rice yield when maize was intercropped with Brachiaria under
the no-till system, but not when the maize was intercropped with soybean with no tillage. In all three
seasons, grain yields were closely linked to crop N at harvest. Differences in N uptake between treatments
appeared very early in the crop cycle. Under conventional tillage, root length density at 68 days after sowing was higher between 0 and 30 cm depth than with no tillage. In these cold highlands conditions, plant
establishment appeared to be more difficult with no tillage and resulted in reduced plant development
and plant N uptake, particularly when rice was planted after maize intercropped with Brachiaria
การแปล กรุณารอสักครู่..
![](//thimg.ilovetranslation.com/pic/loading_3.gif?v=b9814dd30c1d7c59_8619)