Soil water capacity, pore-size distribution and CO2 e-flux in different soils after long-term no-till management

Abstract

On Planosol, the soil CO2 e-flux peak ranges were lower, i.e. approximately 0.170–0.200 m3 m-3. Long-term residue returning onto soil surface on Planosol acted as a physical obstruction inside mesopores in 5–10 cm and within macropores in 5–10 and 15–20 cm layers and, finally, causing clogging them. Increase of soil surface volumetric water content in Planosol caused a decrease in soil CO2 e-flux. Little is known about the effects of modern soil management practices, especially no-tillage, on soil physical state, soil pore size distribution and soil water capacity after a long-time of successive application on different soil types. The investigations were performed in 2014 at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry in Central Lithuania’s lowland on a sandy loam-textured Endocalcari-Epihypogleyic Cambisol (CMg-p-w-can) and at the Experimental Station of Aleksandras Stulginskis University on a silt loamtextured Endohypogleyic-Eutric Planosol (PLe-gln-w). The goals of this paper were a) to compare soil water capacity, soil pore-size distribution and CO2 e-flux in Cambisol and Planosol, b) to evaluate the effect of long-term no-tillage application in combination with and without residue management on hydro-physical properties of soils with different genesis and c) to assess the suitability of such management practice for practical use. Regarding different soils genesis, the lower bulk density and higher total porosity were registered within 0–20 cm depth in Planosol than in Cambisol, while Cambisol was better aerated than Planosol due to a greater space of macropores. A risk of waterlogging condition may occur in Planosol due to a greater share of meso- and microporosity within 5–35 cm soil depth, compared to Cambisol. No-tillage application with crop residue returning was more suitable on Cambisol than on Planosol. This soil management system increased volumetric water content in the soil and CO2 e-flux. No-tillage with residue removal on Cambisol conditioned soil CO2 e-flux increase when volumetric soil water content ranged from 0.159 to 0.196 m3 m-3. When soil water content increased up to 0.220–0.250 m3 m-3, the e-flux peak was reached at which the further CO2 e-flux sloped down.