PERSISTENCE OF THE EFFECT OF SUBSOILING ON A SOIL UNDER CROP ROTATION-GRAZING IN THE DRY LAND OF THE ARAUCANIA REGION, CHILE

Abstract

 Compaction is a recurring problem in soils of the dryland zone of the Araucanía Region, affecting yields considerably. The objective of this study was to determine the persistence over time of the effect of subsoiling, as a tool to reduce soil compaction, on a soil under crop rotation-grazing. A field experiment was established for 5 consecutive seasons (t). Soil compaction was measured at a depth of 0-45 cm, using the Cone Index as an indicator and considering ?2000 kPa as compacted soil. The diagnosis was conducted in 2015 (t₀), while the experimental trials started in 2016 (t₁) when oats were sown on a site with two different treatments: ‘Subsoiling’ and ‘No subsoiling’. The obtained results showed that subsoiling increased yield by 14.9% compared to the no subsoiling treatment. Subsequently, the experimental site was used for grazing without animal load control from 2017 to 2020  (t₁-t₅). During this period, the persistence of the effect of subsoiling on the experimental site  was evaluated by measuring soil compaction of a depth of 0-45 cm and contrasting the values to those obtained in 2015 (t₀). In the last season (t₅), the 0-10 cm profile showed surface compaction, which was attributed to grazing. It can be concluded that compaction levels (kPa) return to the original levels (t₀) from the second season after subsoiling (t₂), which ends the residual effect derived from the use of  this tool.