Soil-plant water relations in the Altiplano of Peru

Date

1985-12

Journal Title

Journal ISSN

Volume Title

Publisher

Texas Tech University

Abstract

The growth patterns of key range species and forage production on two major range sites, and the influence of soil water on plant water status and growth were measured. The research was conducted at La Raya Research Station, Department of Cusco (highlands of southern Peru) during June 1984 to May 1985- Site II (light sandy loam soil) had higher mean forage production (2,417 kg/ha) than Site I (heavy sandy loam soil (1,436 kg/ha). Site I was dominated by Festuca dolichophylla and Muhlenbergia fastigiata. Vegetative composition included grasses, 87%, sedges and reeds, 7%, and forbs, 5%. Site II was dominated by F^. rigida and Stipa obtusa. The vegetation was composed of grasses, 93%, forbs, 6%, and sedges, 1%.

Festuca dolichophylla and Festuca rigida started regrowing in September; although Festuca rigida grew at a faster rate than Festuca dolichophylla and produced a greater amount of dry matter, it started decreasing earlier (May-June) than Festuca dolichophylla (July).

Soil water content increased as the wet season progressed. The soil water content was higher on Site I (heavy sandy loam) 26% than at Site II (light sandy loam) 20% from September to April. The greatest water content occurred in November (36% and 34%, Site I and Site II, respectively). The water content was lowest (10% and 8%, Site I and Site II, respectively) in September.

Soil water potential averaged across month and time of day (dry season and early wet season) was higher on Site II (light sandy loam), -47 bars, than at Site I (heavy sandy loam), -54 bars. During the dry season, the potentials were -70 and -69 bars, on Site I and Site II, respectively. Plant water potentials also increased as the wet season progressed. Festuca dolichophylla had lower plant water potentials than Festuca rigida throughout the day.

Festuca dolichophylla attained higher conductance rates than Festuca rigida during November; conductances at mid-day were 0.3727 and 0.2900 cm.sec respectively.

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