Resumen de Acumulación y lavado de sales en columnas de suelo regadas con agua salina procedente de un pozo petrolero

Roberto Villafañe, Natacha DeLeón, Fernando Camacho, Ricardo Ramírez, Luis Sánchez

• español

  Con el propósito de estudiar los procesos de acumulación y lavado de sales en un suelo regado con agua salina (CE = 6,7 dS m-1 y pH = 7,44), procedente de un pozo petrolero ubicado en San Silvestre, estado Barinas, Venezuela; se realizó un experimento de invernadero utilizando 32 lisímetros sembrados de pasto Brachiaria dictyoneura, se condujo durante 32 semanas, aplicando riego sin lavado durante las primeras 16 semanas y lavado con agua desmineralizada las 16 semanas restantes. Durante el período de riego se implementaron los siguientes tratamientos: t0) riego con agua desmineralizada desde el inicio; t1) riego con agua desmineralizada los primeros diez días y luego riego con agua salina; t2) riego con agua salina desde el inicio y t3) riego con agua salina desde el inicio, diluida a un tercio de su concentración original. El pasto fue cortado cada 8 semanas, determinando en cada corte la producción de materia seca, y en los 3 últimos, los contenidos de sodio y cloruro. Los tratamientos con agua de producción provocaron un aumento violento de la salinidad en el suelo. El lavado posterior con agua desmineralizada condujo a un descenso de la salinidad en dichos tratamientos, mas no la remoción total. No se detectaron efectos adversos en las propiedades físicas por la utilización del agua de producción en sus distintos tratamientos ni por el posterior lavado. La producción de materia seca del pasto se afectó cuando se utilizó el agua de producción sin diluir. Además, se observó que el agua salina afectó la germinación, emergencia y establecimiento del pasto.

• English

  A greenhouse experiment was designed to study the processes of accumulation and leaching of salts in soil columns irrigated with saline water coming from an oil well located in San Silvestre, Barinas State, Venezuela (EC = 6,7 dS m-1 and pH = 7,44). The experiment was managed with 32 lysimeters planted with Brachiaria dictyoneura grass, applying irrigation with saline water without leaching for the initial 16 weeks and leaching with desmineralized water for the remaining 16 weeks. During the irrigation period, 4 treatments were implemented: t0) Irrigation with desmineralized water, t1) Irrigation with desmineralized water the firsts 10 days and then irrigation with saline water, t2) Irrigation with saline water from the beginning and t3) Irrigation with saline water from the beginning, diluted to a third of its original concentration. At the end of the irrigation period, 16 lysimeters (4 per treatment) were dismounted and their soil columns divided in 4 strata, collecting unaltered and altered samples in each one; in the unaltered samples hydraulic conductivity, bulk density and porosity were determined and in the altered samples, salinity, sodicity and dispersion. At the end of the leaching period the 16 remaining lysimeters were dismounted, following the same procedure of collection and analysis of samples. Grass was cut every 8 weeks, determining dry matter at each cut, and sodium and choride contents during the last 3 cuts. Nitrogen was applied as urea after planting and after the first and third cuts. The saline treatments brought about an increase of salinity in the soil due to scarce first and third cuts. The saline treatments brought about an increase of salinity in the soil due to scarce leaching or no leaching during the irrigation period. Subsequent leaching with desmineralized water led an important descent of the salinity in soil columns although not a total removal. However, the use of water of production in its different treatments and the posterior leaching with desminalized water did not cause adverse effects on the soil's physical properties. The yield of grass dry matter was affected when saline water was used without diluting. Moreover, an effect of saline water on germination, emergency and establishment of the plants was observed.