Maize cropping degrades soil hydraulic properties relative to grazed pasture in two contrasting soils

Abstract

Soil hydraulic properties (SHPs), including available water content and near-saturated hydraulic conductivity (Kns), affect hydrological and biochemical processes. The SHPs information is crucial to agricultural water management. The objective of this study using paired sites was to investigate the effects of land use on SHPs in two contrasting soil orders. Soil water retention curves and Kns at three soil depths (0–10, 10–20 and 20–30 cm) were measured under two land uses (pasture, consisting of a rye grass [Lolium perenne L.] and white clover [Trifolium repens L.] mix, and maize [Zea mays L.] cropping > 10 years) in Waikato, New Zealand. For each land use, two soil orders with contrasting soil structural vulnerability were selected: less vulnerable Allophanic soil and more vulnerable Gley soil. Compared with pasture, maize cropping reduced macroporosity, readily available water capacity and Kns of 0–30 cm, and the effect was greater in the deep layer (20–30 cm). This indicated that maize cropping practices result in greater structural degradation to soils compared with pasture, which include the potential for greater subsoil compaction. There was no land use by soil order interaction effect on SHPs, suggesting that the relative SHP degradation under maize cropping compared with pasture grazing was not associated with soil structural vulnerability. Our study emphasised that long-term continuous cropping with maize on the more vulnerable soil (i.e. Gley soil) resulted in the poorest soil physical health.