Differential impacts of soil salinity and water logging on Eucalyptus growth and carbon sequestration under mulched vs. unmulched soils in south-western Punjab, India

Aims To study the impact of salinity and water logging on Eucalyptus growth, carbon (C) sequestration in tree biomass and organic C pool under mulched and unmulched ridges. Methods We studied the performance of five Eucalyptus clones viz. C-413, C-2135, C-7, PE-8 and PE-11 on mulched and unmulched ridges, their impact on C sequestration in tree biomass and soil organic C pool, and soil properties. Results Electrical conductivity (E.C.) of soil under mulched ridges (3.54 +/- 0.3 dS m(-1)) was decreased by similar to 3.9-times, compared with the unmulched ridges (13.9 +/- 0.3 dS m(-1)) due to Eucalyptus plantation. Tree survival rate on mulched ridges was similar to 78.1%, while on unmulched ridges was similar to 63.4%; C-7 clone had the lowest (similar to 55.0%), while the PE-8 had significantly (p < 0.05) higher (similar to 89.5%) survival rate. Mulching increased the tree girth (similar to 8.7%), height (similar to 13.8%), timber wood (similar to 18.4%), branches (similar to 21.8%), twigs + leaves (similar to 22.6%) and root biomass (similar to 34.6%) after one year of plantation, compared with their plantation on unmulched ridges. Regardless of the plantation method, C-2135 clone had the lowest, while the PE-11 had the highest timber dry biomass, branches, twigs + leaves and root biomass. After 4-years of plantation, trees planted on mulched ridges had significantly higher C sequestration in timber dry biomass by 147.8 +/- 18.4 Mg C ha(-1) than those on unmulched ridges. Conclusions Eucalyptus plantation offers a low cost strategy for C sequestration in waterlogged saline soils. Plastic mulching has overwhelming significance in enhancing tree survival rate and decreasing soil salinity with co-benefits of increased biomass productivity of Eucalyptus.