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Structural characterization of a compacted alfisol under different tillage systems

Abstract:

Conservation tillage is a management system used to mitigate and rehabilitate the dryland areas of southern-central Chile in severely compacted soils. The objective of this study was to evaluate the soil physical properties in the root zone under an oat-wheat crop rotation after three years of the establishment of three tillage systems: conventional tillage (CT), zero tillage (ZT) and zero tillage with subsoiling (ZTS). Soil bulk density, porosity, water retention curve, stability of macro-and microaggregates, airflow at field capacity, rest coefficient, and number of roots were evaluated. The results showed that the soil had low water holding capacity in the profile due to the low water retention at the permanent wilting point (matric water potential lower than-1.500 kPa), associated with a high bulk density and clay content. The conservation tillage systems (ZT and ZTS), were similar in the parameters of fast drainage pores (FDP), aggregate stability index, airflow, and rest coefficient compared with CT. However, the volume of pores with diameters between 10-50 μm was higher in ZTS in a 24% and 13%, compared with ZT and CT, respectively. In addition, the root development increased significantly in ZTS. In conclusion, the physical condition of the compacted soil was improved by the zero tillage system with subsoiling, which promoted a better root system in the first horizons in highly compacted soils.