Water retention and field soil water states in a vertisol under long-term direct drill and conventional tillage

Authors: VANDERLINDEN, KARL - Research And Training Institute For Agricultural And Fisheries Of Andalusia, Ifapa; Pachepsky, Yakov; PEDRERA-PADILLA, AURA - Research And Training Institute For Agricultural And Fisheries Of Andalusia, Ifapa; MARTINEZ, GONZALO - University Of Cordoba; ESPEJO-PEREZ, ANTONIO - University Of Cordoba; PEREA, FRANCISCO - Research And Training Institute For Agricultural And Fisheries Of Andalusia, Ifapa; GIRALDEZ, JUAN - University Of Cordoba

Submitted to: European Journal of Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2021
Publication Date: 4/1/2021
Citation: Vanderlinden, K., Pachepsky, Y.A., Pedrera-Padilla, A., Martinez, G., Espejo-Perez, A.J., Perea, F., Giraldez, J.V. 2021. Water retention and field soil water states in a vertisol under long-term direct drill and conventional tillage. European Journal of Soil Science. https://doi.org/10.1111/ejss.12967.
DOI: https://doi.org/10.1111/ejss.12967

Interpretive Summary: The Vertisol soils have high clay contents and yet are capable to provide water to plants and soil microorganisms for long periods of droughts in many regions. Our objectivewas to test the hypothesis that there is no difference between the Vertisol’s water retention ability of this soil managed via conventional tillage or via direct drilling. We monitored field soil water contents and obtained a very detailed soil pore size distributions for Vertisol under wheat-sunflower-pea crop rotation. The soil at the direct drilling plots had a smaller number of large pores and a larger number of small pores compared with the conventional tillage plots, and field water contents were significantly larger than at the plots with the conventional tillage. These findings can be used by consultants and farmers in Vertisol soil cover areas who may consider the direct drilling as the soil management practice that creates soil water regimes that are more favorable forplants as compared with the conventional tillage. 

Technical 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 (0-0.05m) samples collected at the CT and DD plots from a long-term experiment. Water retention was significantly higher in DD (p<0.05) for |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 a combined effect of tillage and compaction, increasing and decreasing the amount of the largest pores in CT and DD, respectively, in favor of a larger abundance of smaller equivalent pore-sizes in DD. Significant differences in water retention and abundance of equivalent pore-sizes in the dry domain appear to be associated with the higher organic matter content in DD. These results were corroborated by field-measured soil water content data, showing a persistently higher soil water content than the spatial average in DD. 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.