Use of field and laboratory methods for estimating unsaturated hydraulic properties under different land uses

Abstract

International audienceAdequate water management is required to im- prove the efficiency and sustainability of agricultural sys- tems when water is scarce or over-abundant, especially in the case of land use changes. In order to quantify, to pre- dict and eventually to control water and solute transport into soil, soil hydraulic properties need to be determined pre- cisely. As their determination is often tedious, expensive and time-consuming, many alternative field and laboratory tech- niques are now available. The aim of this study was to de- termine unsaturated soil hydraulic properties under different land uses and to compare the results obtained with differ- ent measurement methods (Beerkan, disc infiltrometer, evap- oration, pedotransfer function). The study has been realized on a tropical sandy soil in a mini-watershed in northeastern Thailand. The experimental plots were positioned in a rub- ber tree plantation in different positions along a slope, in ruzi grass pasture and in an original forest site. Non-parametric statistics demonstrated that van Genuchten unsaturated soil parameters (Ks, α and n) were significantly different ac- cording to the measurement methods employed, whereas the land use was not a significant discriminating factor when all methods were considered together. However, within each method, parameters n and α were statistically different ac- cording to the sites. These parameters were used with Hy- drus1D for a 1-year simulation and computed pressure head did not show noticeable differences for the various sets of parameters, highlighting the fact that for modeling, any of these measurement methods could be employed. The choice of the measurement method would therefore be motivated by the simplicity, robustness and its low cost

Five‐year soil moisture response of typical cultivated grasslands in a semiarid area: Implications for vegetation restoration

“…The distribution model of soil water is related to the AGB, root biomass, and plant species distribution. High yield requires more water and the presence of deep roots that absorb deeper soil water; and the different plant species have different transpiration rates (Siltecho et al, ; Wang et al, ; Wang et al, ). Previous studies have suggested that the root system of the leguminous grasslands was deeper, which resulted in a higher consumption of soil water than the consumption of the gramineous grasslands (Huang et al, ).…”

“…The restoration of natural grasslands and the establishment of artificial grasslands are common practices in the arid areas of the world. In these landscapes and during the process of restoration, the soil water content (SWC) is the key limiting factor for vegetation growth (Siltecho et al, ; Wang, Fan, Cao, & Liang, ; Wang, Li, Xiao, Berndtsson, & Pan, ). Soil water is not only the basis for plant survival in terrestrial ecosystem, but also the most active part within the watershed water cycle because it affects plant growth, ecological environment construction, and the rational distribution and efficient utilization of water resources.…”

Legume Grasslands Promote Precipitation Infiltration better than Gramineous Grasslands in arid Regions

“…Precipitation infiltration is the most important process for soil water supply in the arid regions (Leung et al, 2015). The efficiency of the rainfall transform into soil water highly depends on the infiltration capacity, and this process is very important for soil water replenishment in water shortage regions (Wang et al, 2007;Siltecho et al, 2015;Wang et al, 2016). Thus, the research of soil infiltration capacity is a vital issue for vegetation maintenance and sustainable development.…”

Measuring full-range soil hydraulic properties for the prediction of crop water availability using gamma-ray attenuation and inverse modeling

“…The lack of exactness for individual VGM parameters does not seem to be an essential issue (Bezerra-Coelho et al, 2018). For instance, Siltecho et al (2015) demonstrated that individual values of the VGM parameters, especially the parameters n and K s , are highly dependent on the measurement technique. However, this individual dependency is not translated into noticeable differences in further simulations of state variables.…”