Long-term effects of different land use and soil management on various organic carbon fractions in an Inceptisol of subtropical India

Abstract

Land use changes, especially the conversion of native forest vegetation to cropland and plantations in tropical regions, can potentially alter soil C dynamics. A study was conducted to assess the effects of various land uses and soil managements (agro-forestry plantation, vegetable field, tube-well irrigated rice–wheat, sewage-irrigated rice–wheat, and uncultivated soils) on soil pH, bulk density, soil organic C (SOC), particulate organic C (POC), microbial biomass C (MBC), C mineralisation (Cmin), microbial quotient, and microbial metabolic quotient (qCO2) in 0−0.05, 0.05−0.10, and 0.10−0.20 m soil depths. At 0−0.05 m, the bulk density was lowest (1.29 Mg/m3) in agro-forestry soil, whereas the uncultivated soil (jointly with vegetable field soil) showed highest bulk density (1.48 Mg/m3). Sewage-irrigated rice–wheat soil showed lowest pH particularly in the 0−0.05 and 0.10−0.20 m soil layer. Irrespective of soil depths, agro-forestry plantation showed greater SOC followed by sewage-irrigated rice–wheat soil. Nevertheless, agro-forestry soil also showed highest stock of SOC (33.7 Mg/ha), POC (3.58 Mg/ha), and MBC (0.81 Mg/ha) in the 0−0.20 m soil layer. Sewage-irrigated rice–wheat jointly with agro-forestry soil showed greatest Cmin in the 0−0.20 m soil layer, although the former supported lower SOC stock. The decrease in SOC (SOC0−0.05 m/SOC0.10−0.20 m) and Cmin (Cmin 0−0.05 m/Cmin 0.10−0.20 m) along soil depth was significantly higher in the agro-forestry system than in most of the other land use and soil management systems. Microbial quotient was highest in sewage-irrigated rice–wheat soil, particularly in the 0−0.05 m soil depth, whereas qCO2 was greater in uncultivated soil. In general, microbial quotients decreased, whereas qCO2 increased down the soil profile.

Effects of nitrogen fertilizer and manure application on storage of carbon and nitrogen under continuous maize cropping in Arenosols and Luvisols of Zimbabwe

“…Variations in C and N stocks can be caused by different C inputs from biomass leftovers (Purakayastha et al . 2007), although return of crop residues to fields is threatened by competing uses as some farmers collect and store the crop residues for livestock feed over the dry season. If left in the field, existing policies allow free-range livestock grazing over the dry period (Rufino et al .…”

“…Bremer et al (1994) and Eghball & Ginting (2003) found the application of manure and compost to have significant C sequestration effects while chemical fertilizers had no effect. Variations in C and N stocks can be caused by different C inputs from biomass leftovers (Purakayastha et al 2007), although return of crop residues to fields is threatened by competing uses as some farmers collect and store the crop residues for livestock feed over the dry season. If left in the field, existing policies allow free-range livestock grazing over the dry period (Rufino et al 2011), threatening the persistence of residues in the fields.…”

Temporal dynamics of iron-rich, tropical soil organic carbon pools after land-use change from forest to sugarcane

“…Soil organic C dynamics can be influenced by climate and land-use changes (Schlesinger 1990;Paul et al 1997;IPCC 2001;Purakayastha et al 2007) and soil management practices (Matson et al 1997;Blumfield et al 2006;Xu and Chen 2006;Xu et al 2008a, b). There is much concern that land-use change may have significant feedbacks on the global C cycle (Batjes and Sombroek 1997;Post and Kwon 2000).…”

The impact of land use change on soil organic carbon and labile organic carbon stocks in the Longzhong re-gion of Loess Plateau

“…Active soil organic carbon is easily and directly used by organisms. It is active and most sensitive to physical and chemical disturbances (Purakayastha et al, 2007). These SOC fractions are also important for nutrient cycle.…”