Temporal change in soil macropores measured using tension infiltrometer under different land uses and slope positions in subtropical China

Abstract

Purpose Soil macropores play a principal role in water infiltration but they are highly variable. The objectives of this study were (1) to investigate the temporal change in macropores of an Ultisol as affected by land use and slope position and (2) to analyze contribution of macropores to water infiltration. Materials and methods Water infiltration was measured at upper and lower slopes in citrus orchard and watermelon field once every 2 months for 1 year using tension infiltrometers at a successive pressure head from −12, −6, −3, to 0 hPa. Results and discussion Hydraulic conductivity (K) was significantly affected by land use and slope position except at 0 hPa pressure head, showing a significant temporal variation. Effective macroporosity, derived from the increment of hydraulic conductivity between −3 and 0 hPa, showed a significant temporal variation. Such temporal variation was land use (P<0.05) and slope position (P<0.001) dependent. Despite of low proportion in total soil volume (averaged 3.5 cm 3 m −3 ), the macropores contributed 47 % of water flux on average. The macroporosity was more stable and higher in the citrus orchard (2.43 cm 3 m −3 , coefficient of variance (CV)=75 %) than in the watermelon field (1.72 cm 3 m −3 , CV=117 %) and contributed more to infiltration in the citrus orchard (60 %, CV=16 %) than in the watermelon field (33 %, CV=43 %) as well, because tillage was operated only in the watermelon field.Conclusions No-tillage increased water conducting macropores but did not increase hydraulic conductivity irrespective of slope position.

Estimates of Tillage and Rainfall Effects on Unsaturated Hydraulic Conductivity in a Small Central European Agricultural Catchment

“…In 2013 and 2014, the K h0 was increasing as topsoil was consolidating after tillage, which is in agreement with other studies [57,58]. This trend suggests that the loose soil after tillage has a high proportion of larger inter-aggregate voids that decrease water flux during unsaturated conditions [20].…”

Contribution of soil macropores to water infiltration across different land use types in a desert–oasis ecoregion

“…The number of each pore size class (e.g., > 0.5, 0.25–0.5 mm), N (m −2 ) was determined as follows (Watson & Luxmoore, 1986; Wilson & Luxmoore, 1988): Where: μ is the viscosity coefficient of water (N m −2 s −1 ), ρ is the water density (kg cm −3 ), and r is the lower limit of equivalent pores radius (cm). Effective pores indicate that the pores conduct water actively (Zhang et al, 2016). Effective porosity (cm 3 m −3 ) of each pore size class (e.g., > 0.5, 0.25–0.5 mm), θ e , was given by (Watson & Luxmoore, 1986; Wilson & Luxmoore, 1988): …”

“…Conventional tillage has been found to destroy the connectivity of soil macropores and further alter hydraulic conductivity and porosity (Buczko et al, 2006). The vegetation cover types affect the effective porosity and control the ratio of water that flows through macropores and mesopores (Bodhinayake & Si, 2004; Holden, 2009; Zhang, Lin, Wang, & Peng, 2016). Soil pore structure and macropores are highly correlated with soil hydraulic properties in different habitat types.…”

Runoff and erosion as affected by tillage system and polyacrylamide in two sandy loam soils differing in silt and clay contents in semi-arid regions

“…In some cases, even lower than that under tillage treatment, as in deeply tilled soils, intensive tilled soil pores are formed primarily by the tillage tool. Similarly, Zhang et al (2016) concluded that No-tillage although increased water conducting macropores but did not increase hydraulic conductivity. However, our results are contradictory with soil macroporosity under no-tillage is usually higher (Bodhinayake and Si, 2004;Coquet et al, 2005;Moret and Arrúe, 2007) under tilled soil.…”