Long‐term effects of recommended management practices on soil carbon changes and sequestration in north‐eastern Italy

Management practices can have significant implications for both soil quality and carbon (C) sequestration potential in agricultural soils. Data from two long-term trials (one at field scale and the other at lysimeter scale), underway in north-eastern Italy, were used to evaluate the dynamics of soil organic carbon (SOC) and estimate the impact of recommended management practices (RMPs) on soil carbon sequestration. Potential SOC sequestration was calculated as the differences between the change in SOC of treatments differing only for the specified RMP for a period of at least 25 years. The trials compared the following situations: (a) improved crop rotations versus monoculture; (b) grass versus improved crop rotations; (c) residue incorporation versus residue removal; (d) high versus low rates of inorganic fertilizers; (e) integrated nutrient management/organic manures versus inorganic fertilizers. At the lysimeter scale, some of these treatments were evaluated in different soils. A general decrease in SOC (1.1 t C ha -1 year -1 ) was observed after the introduction of intensive soil tillage, evidencing both the worsening of soil quality and the contribution towards global CO 2 emissions. Initial SOC content was maintained only in permanent grassland, complex rotations and/or with the use of large quantities of livestock manure. SOC sequestration reached a maximum rate of 0.4 t C ha -1 year -1 comparing permanent grassland with an improved crop rotation. Crop residue incorporation and rates of inorganic fertilizer had less effect on SOC sequestration (0.10 and 0.038 t C ha -1 year -1 , respectively). The lysimeter experiment highlighted also the interaction between RMPs and soil type. Peaty soil tended to be a source of C independent of the amount and quality of C input, whereas a proper choice of tillage practices and organic manures enhanced SOC sequestration in a sandy soil. The most promising RMPs in the Veneto region are, therefore, conversion to grassland and use of organic manures. Although some of these RMPs are already supported by the Veneto Region Rural Development Plan, their more intensive and widespread implementation requires additional incentives to become economically feasible.

[1]  L. M. Vleeshouwers,et al.  Carbon emission and sequestration by agricultural land use: a model study for Europe , 2002 .

[2]  A. Walkley,et al.  AN EXAMINATION OF THE DEGTJAREFF METHOD FOR DETERMINING SOIL ORGANIC MATTER, AND A PROPOSED MODIFICATION OF THE CHROMIC ACID TITRATION METHOD , 1934 .

[3]  Pete Smith,et al.  Carbon sequestration in the agricultural soils of Europe , 2004 .

[4]  Ronald F. Follett,et al.  Soil management concepts and carbon sequestration in cropland soils , 2001 .

[5]  Pete Smith,et al.  Europe's Terrestrial Biosphere Absorbs 7 to 12% of European Anthropogenic CO2 Emissions , 2003, Science.

[6]  David S. Powlson,et al.  Potential for carbon sequestration in European soils: preliminary estimates for five scenarios using results from long‐term experiments , 1997 .

[7]  Walter J. Rawls,et al.  Pedotransfer functions: bridging the gap between available basic soil data and missing soil hydraulic characteristics , 2001 .

[8]  K. Smith,et al.  SOILS AND THE GREENHOUSE EFFECT , 1997 .

[9]  Pete Smith.  Carbon sequestration in croplands: The potential in Europe and the global context , 2004 .

[10]  R. Lal.  Soil carbon sequestration to mitigate climate change , 2004 .

[11]  D. Pennock,et al.  Cultivation-Induced Effects on Belowground Biomass and Organic Carbon , 2002 .

[12]  Rattan Lal,et al.  Agricultural soils as a sink to mitigate CO2 emissions , 1997 .

[13]  T. Shepherd,et al.  Effects of clay minerals and land use on organic matter pools , 1997 .

[14]  G. Buyanovsky,et al.  Post-harvest residue input to cropland , 1986, Plant and Soil.

[15]  F. Skjøth,et al.  Tillage caused dispersion of phosphorus and soil in four 16-year old field experiments , 2000 .

[16]  D. W. Reeves.  The role of soil organic matter in maintaining soil quality in continuous cropping systems , 1997 .

[17]  Jürgen K. Friedel,et al.  Review of mechanisms and quantification of priming effects. , 2000 .

[18]  Stefano Bona,et al.  Fibrous root turnover and growth in sugar beet (Beta vulgaris var. saccharifera) as affected by nitrogen shortage , 2003 .

[19]  Ram C. Dalal,et al.  Relationships of soil respiration to microbial biomass, substrate availability and clay content , 2003 .

[20]  A. Berti,et al.  Soil organic matter properties after 40 years of different use of organic and mineral fertilisers , 2004 .