Voisin’s Rational Grazing, as agroecologial sustainable route for acid-sandy soils of low natural fertility
Primary productivity, Urochloa, asphaltic emulsions, labile phosphorous, phosphoric rock
An agroecological Voisin’s Rational Grazing production system was established in 2013 in Barinas, Venezuela, with the aim of studying a sustainable agroecological route in acid-sandy soils. A pasture of 27 ha with Urochloa brizantha and Urochloa ruziziensis was divided in 64 paddocks. Four treatments were established: application of a single dose of 1.5 Mg ha-1 asphaltic emulsion; single dose of 440 kg ha-1 of phosphoric rock; asphaltic emulsion with phosphoric rock, with the same previous dose, and control, only with Voisin’s Rational Grazing. Four replicates of each treatment were established in 16 randomly chosen paddocks in which periodic soil and vegetation samplings were carried out. The highest yields of dried matter in t ha-1 yr-1 of pasture corresponded to asphaltic emulsion (34-62) and asphaltic emulsion with phosphoric rock (54-48) in comparison to the control (22-31) and phosphoric rock (24-25) treatments, for years 2015 and 2016, respectively. This brought about better quality pastures, from the first year of the management the pasture yields tripled and an increase of the animal load from 1.2 to 3.7 LU ha-1 between 2015 and 2016, and to 4.3 LU ha-1 in 2017 was achieved. Applying a single dose of asphaltic emulsion aided to accelerate the regular increases with time. The labile fractions of P showed that Voisin’s Rational Grazing induced a high phosphoric fertility which displaced phosphorous as the main limiting factor in primary productivity of these soils of low natural fertility, that are widely distributed in savannah ecosystems and the Neotropic.
Alonso David Ojeda-Falcón, Olgioly Domínguez-Quintero
Universidad Central Marta Abreu" de Las Villas"