Improvement of saline-sodic grassland soil properties by rotational grazing in Argentina.

VECCHIO MC; GOLLUSCIO,RA; RODRIGUEZ, A; TABOADA MA

Rangeland Ecology and Management (ex JRM)

SOC RANGE MANAGEMENT

Lugar: Boulder, Colorado; Año: 2018

1550-7424

We investigated the effectiveness of rotational and permanent grazing exclosure periods for improving topsoilquality in three commercial farms devoted to cattle breeding in sodic grassland (halophytic steppe) soils of theFlooding Pampa of Argentina. We compared two plots under continuous grazing (C1-C2) with two plots undermore than 8 yr of rotational grazing management (R1-R2) and two adjacent plots under permanent grazingexclosure for more than 8 (E1) and 4 (E2) yr. Periodic and permanent grazing exclosure periods caused significant (P b 0.05) and progressive increases in topsoil organic carbon content and organic carbon stock (0−20cm; from 24 to 61 Mg ha−1) as follows: (C1 = C2) b (R1 = R2 = E2) b E1 plots. Topsoil physical properties(bulk density, structural instability, and bearing capacity) and salinity were higher (P b 0.05) in C1 and C2 thanin the other plots, while infiltration rate was higher in the oldest exclosure (E1) than in the other plots. TopsoilpH decreased from C1-C2 plots (9.5−9.9) to R1-R2 plots (7.3−8.2) to E1-E2 plots (6.5−7.5), while SAR washighest in C1-C2 and lowest in E1 plots. We propose a conceptual model leading to soil recovery in this halophyticsteppe community, triggered by organic carbon accumulation induced by grazing management. Short-time grazing exclusion periods (i.e., rotational grazing) are a plausible and low-cost management option to be recommended to the farmers in this highly restrictive environment.