Soil Water Capacity, Pore-size Distribution and CO2 E-fflux in Cambisol and Planosol after Long-term No-till Management

Abstract

Long-term residues 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 soil C02 e- fflux decrease. Little is known about effects of modern soil management practices, especially no-till, on soil physical state, soil pore size distribution and soil water capacity after long-time of successive application on different soil types. The investigations were performed in 2014 on the basis of long-term (since 1999) field experiments on sandy loam textured soil at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry (Cambisol), and on silt loam at the Experimental Station of the Aleksandras Stulginskis University {Planosol). The goals of this investigations were a) to compare soil water capacity, soil pore-size distribution and CO2 e-fflux in Cambisol and Planosol, b) to evaluate the effect of long-term no-tillage application in combination with and without residues 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-fflux. No-tillage with residue removal on Cambisol conditioned soil CO2 e-fflux 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-fflux peak was reached at which the further C02 e-fflux sloped down. On Planosol, the soil C02 e-fflux peak ranges were lower, i.e. approximately 0.170-0.200 m3 m"3.