Water retention and field soil water states in a vertisol under Long‐Term direct drill and conventional tillage

Abstract

Understanding differences in the agro‐hydrologic performance of Vertisols under conventional tillage (CT) and direct drill (DD) requires a thorough knowledge of the soil hydraulic properties. We measured water retention on 54 undisturbed topsoil (0–0.05 m) samples collected at the CT and DD plots from a long‐term experiment. Water retention was significantly larger in DD (p < .05) for absolute pressure heads (|h|) ranging from 63 to 3.2 × 103 cm, and at 1.8 × 104 and 3.3 × 104 cm. A comparison of the equivalent pore‐size distributions showed combined effects of tillage in the CT topsoil and compaction as a result of machinery traffic and natural consolidation in the DD topsoil, increasing and decreasing the amount of the largest pores in CT and DD, respectively, in favour of a larger abundance of smaller equivalent pore‐sizes in DD than in CT. Significant differences in water retention and abundance of equivalent pore sizes near the dry end of the soil water retention curve (|h| ≈ 4 × 104 cm) appear to be associated with the larger organic matter content in DD. These results were corroborated by field‐measured soil water content data (0–0.10 and 0.25–0.35 m), showing a persistently larger soil water content in DD than the spatial average of both tillage systems. Differences in the observed trimodal soil water content probability density functions between CT and DD were related to equivalent pore‐sizes for which significantly different water retentions were measured. This work elucidates direct and indirect effects of soil management on water retention and the equivalent pore‐size distribution, with important consequences for the soil´s agro‐hydrologic performance. Highlights Water retention, pore‐size distribution and field soil water states of a vertisol under conventional tillage and direct drill are compared Direct drill yields larger water retention for 63 < |h| < 3.2 × 103 cm, and at |h| = 1.8 × 104 and 3.3 × 104 cm. Larger water retention near |h| ≈ 4 × 104 cm in direct drill is associated with larger organic matter content Field soil water states are controlled by specific SWRC and pore‐size distribution ranges in both management systems

Soil hydraulic properties and pore dynamics under different tillage and irrigated crop sequences

“…Total porosity was equal to saturated soil water content or water content at 0 cm H 2 0 soil matric potential, and IT showed 7 % higher θ s than NT (Table 2) which was directly related to greater total soil porosity observed under IT caused by tillage operation (Talukder et al, 2022b). Tillage often increases soil porosity by loosening the soil surface (Kargas et al, 2016;Patra et al, 2019;Vanderlinden et al, 2021). Again, IT had greater soil water content at Ψ from − 1 to − 3 cm H 2 O, whilst at Ψ from − 50 to − 1000 cm H 2 O, NT showed constantly greater soil water content than IT (Fig.…”

“…They found that soil W-row had twice ponded infiltration rate than Brow. Further, temporal changes of soil hydraulic properties caused by management practices were documented by several authors (Kargas et al, 2016;Hu et al, 2018;Kreiselmeier et al, 2019;Vanderlinden et al, 2021) but very few studies considered dynamics of soil hydraulic properties together with pore system characteristics (Kabir et al, 2020;Villarreal et al, 2020). For example, Villarreal et al (2020) observed that under maize-legume crop rotation, intensive tillage demonstrated higher hydraulic conductivity and water conducting macroporosity than no-tillage due to biological activity during the crop vegetative phase in a loam soil.…”

Editorial for the special issue on “Advances in soil scaling: Theories, techniques and applications”

“…Therefore, the transfer of information between scales may amount to relating processes and patterns. One example of such a relation is given by Vanderlinden et al (2020), who observed patterns of field water states under long‐term direct drill and conventional tillage and related them to water retention parameterization at the finer (ped/aggregate) scale. In their research on a Haplic Vertisol soil under wheat‐sunflower‐pea rotation, the authors demonstrated that the preferred field water states and the recurrent differences between soil water regimes at the direct drill and conventional tillage sites could be explained by water retention features at the ped/aggregate scale.…”