Organizacion superficial de los tepetates cultivados, Texcoco (Mexico)

1997

Colloque

Lauffer M., Leroux Yann, Prat Christian, Janeau Jean-Louis

Zebrowski Claude (ed.), Quantin Paul (ed.), Trujillo G. (ed.), Villamar M.D. (collab.), Suelos volcanicos endurecidos

Quito (ECU) ; Quito (ECU) ; Quito (ECU) ; Quito : UE ; ORSTOM ; PUCE ; UCE, 1997, p. 443-456

Suelos Volcanicos Endurecidos, 3., Quito (ECU), 1996/12/9-14

In Mexico, there is very few informations about the soil surface crusting in relation to the rain. When creating a new soil from a indurated volcanic tuff, it is important to study the behaviour and dynamics of the new structure under the action of rain and cultivation practices. We followed 6 terraces during 3 years on different kinds of soil and tepetate, as well as different kinds of soil tillage and crops. We used the rugosimeter and a crop covermeter of 2 m2 with a precision of 10 cm2 for each mesure. We measured the humidity and thecrusting of the soil after every runoff-producing event and the vegetation covering once a week. At the same time, we followed the state of the row and their ruptures along every terrace. This study confirms and details the 4 different kinds of crusting of this new soil. They are following this dynamic: 1) a structure crust with predominance of plasma is formed; 2) then come the erosion crust; 3) then the runoff crust and nearly in the same time; 4) the deposit crust. To pass from the phase 1 to 2, the cumulated energy of the rain must be higher than 560 MJ/h. In the case of the beginning of destruction of the row, this energy is nearly the same: 530 for the tepetate and 580 MJ/ha for the soil (phoeozem). Laboratory tests and the following of agregates bigger than 5 cm show that in the case of terraces with manure, the strucutre of the soil is more stable. But in the fields, there is not such a clear difference with the other treatments. The protection of the soil by vegetation is clearly better with the other treatments. It does not only protect the aggregates but also the row. In effect, corn produces a stem flow which destrys the row at the foot of the plant, while the association of corn and string bean limitsthis influence by the captation of the rain by the string bean. In the case of barley, the erosion is laminar and diffuse but, at the base of the terrace, it is possible to notice a clear runoff concentration. In the case of corn, water is concentrated inside the row and under certain conditions occurs a movement from one row to the other one due to their rupture. Erosion is more visible but really less intense than with barley because there is runoff only during strong and exceptional rains, while with barley runoff occurs during quite all rains over 3 mm. Cleaning of the fields during the rainy season could have catastrophic results. Under this climate, we recommend rows with little rain catchment and with an association of corn and string bean to limit destruction of the furrows and soil erosion. (Résumé d'auteur).

Erosion et conservation des sols [068EROSOL]

CROUTE ; DEGRADATION DU SOL ; EROSION ; MAIS ; PRECIPITATION ; AGREGAT ; SYSTEME DE CULTURE ; TEPETATE ; ORGE ; HARICOT, FEVE ; CULTURE EN TERRASSE

MEXIQUE

Fonds IRD [F A010012910] ; Montpellier (Centre IRD)

fdi:010012926