Abstract

IGLESIAS, Julio O.; GALANTINI, Juan A.; VALLEJOS, Adrian  and  IMHOFF, Silvia. Optimal water interval in an argiudol in sw Buenos Aires province under two tillage systems. Cienc. suelo [online]. 2021, vol.39, n.2, pp.52-66. ISSN 1850-2067.

Management practices can alter soil structure, influencing water availability, oxygen diffusion, and mechanical resistance with consequences on productivity. Least limiting water range (IHO) is a useful tool, since it integrates these effects. It is suggested that the IHO allows showing tillage systems differences in the availability of water. The experience was carried out in the SW of Buenos Aires province (SOB) with two tillage systems, no- (SD) and conventional-tillage (LC). Soil samples were taken every 5 cm up to a depth of 20 cm and water retention, penetration resistance (PR) and bulk density (DA) were determined to calculate the IHO. Highest values of RP and DA were found in SD. The IHO ranged between 0.024 to 0.095 cm3 cm-3 in SD and 0.007 to 0.110 cm3 cm-3 in LC. The value of DA where θRP replaced θPMP as the lower limit of the IHO was 1.26 g cm-3 for LC and 1.29 g cm-3 for SD, with 20% of the samples above this value in LC and 42% in SD. LC presented higher IHO up to Da 1.28 g cm-3, from this value it decreased more rapidly than SD who presented higher IHO values at higher densities. The projection of the critical limits showed that the critical DA would be reached at a higher value in SD than in LC (1.49 and 1.40 g cm-3, respectively), showing better physical condition under no tillage soil. To evaluate the sensitivity of the IHO, 3 cutoff values of θRP were used. The slope of the IHO was always lower in SD, indicating that the amplitude of the IHO decreases more slowly with the increase in DA compared to LC. The results of this study suggest the IHO as an indicator to evaluate the water availability in SOB soils under different tillage.

Keywords : available water; penetration resistance, bulk density, soil qualit.

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