A água do solo e o sombreamento dos cafezais na américa central

Abstract

<abstract language="eng">The coffee plant does not thrive well under shade in most of the coffee areas of the State of São Paulo, Brazil. It has been shown that water competition from the shade trees during the dry season is the factor responsible for the failure in growing coffee under shade in São Paulo. In all cases where the coffee plants were not thriving well under shade, the soil moisture after two to three months of drought was at the wilting point at the depths most utilised by the root systems of shade trees and coffee plants. In open plantations this was never observed. All commercial coffee plantations of Central America are shaded. Most of them are located in areas with a dry season as long as in São Paulo and some times even longer. A comparative study of the climatological factors, methods of cultivation and most common species of shade trees was made. No one of these factors explained the different behavior of the coffee plant under shade in Central America and in São Paulo. The available soil water was measured in many coffee plantations in Costa Rica and El Salvador after four months without apreeiable rainfall. In all cases it was' found that, the actual moisture percentage was considerably higher than the wilting point. The amount of available water held by soils in São Paulo and Central America does not seem to be significantly different, although this was not carefully determined. It is suggested that a comparative study of the moisture-tension curves of soils of São Paulo and Central America might explain the different behavior of the coffee plant with shade under these two different conditions. It is possible that, as a consequence of a much steeper moisture-tension curve, the plants in São Paulo soils transpire freely until the soil moisture reaches the wilting point. This would result in a rapid soil water consumption. If the Central American soils have a smoother moisture-tension curve, the Avater absorption and transpiration rate by plants may be slower and as a consequence the available water may last longer in the soil. The ratio of the moisture equivalent to the wilting point was found to be around 1.29 for the soils studied in the Meseta Central of Costa Rica, around 1.44 for those in El Salvador and 1.94 for the ashy soils in the vicinity of San Salvador volcano

Shade management in coffee and cacao plantations

“…If high agrochemical applications are feasible, for example when crop prices are high and environmental issues are not considered, maximum attainable yields per hectare are often higher without shade (Willey, 1975). In seasonally dry zones, root competition for water may limit the use of shade trees for coffee (Franco, 1951 ). Pest and disease problems may increase (Fonseca, 1939;Dakwa, 1980;Smith, 1981;Wrigley, 1988;I CAFE, 1989b) or decrease (Tapley, 1961;Ahenkorah et al, 1974;Nataraj and Subamanian, 1975;Smith, 1981;Eskes, 1982;Campbell, 1984) with increased shade.…”

“…The influence of shade trees on water availability for the understory crop in seasonally dry zones is as important a research topic now as when Franco (1951) identified it as the main justification for eliminating shade trees from coffee plantations in many areas of Brazil. Competition for water can occur, even in tropical rain forest areas, during short dry periods (Kozlowski, 1982).…”

Advantages, disadvantages and desirable characteristics of shade trees for coffee, cacao and tea

“…(1) Shade tree root competition for moisture during the dry season and oxygen during the wet season [3,34,36,47,57,90].…”

Studies on Productivity of Coffee: Ii - Effect of Soil Moisture on Photosynthesis and Transpiration of Coffea Arabica

“…Several studies on the influence of rainfall frequency and irrigation on growth and production of coffee have been made, also measurements of plant transpiration have been reported at different natural conditions (DEAN 1939;NUT-MAN 1941;FRANCO 1951FRANCO , 1952FRANCO & INFORZATO 1950-1951. Generally speaking coffee plants seem to be rather resistant to drought although the growth may be depressed to a large extent (GUISCAFRE-ARRILAGA 1957;RINGOET 1952;SYLVAIN 1959).…”