Francesco Alluvione

Nitrogen, tillage, and crop rotation effects on carbon dioxide and methane fluxes from irrigated cropping systems.

Long-term effects of tillage intensity, N fertilization, and crop rotation on carbon dioxide (CO(2)) and methane (CH(4)) flux from semiarid irrigated soils are poorly understood. We evaluated effects of: (i) tillage intensity [no-till (NT) and conventional moldboard plow tillage (CT)] in a continuous corn rotation; (ii) N fertilization levels [0-246 kg N ha(-1) for corn (Zea mays L.); 0 and 56 kg N ha(-1) for dry bean (Phaseolus vulgaris L.); 0 and 112 kg N ha(-1) for barley (Hordeum distichon L.)]; and (iii) crop rotation under NT soil management [corn-barley (NT-CB); continuous corn (NT-CC); corn-dry bean (NT-CDb)] on CO(2) and CH(4) flux from a clay loam soil. Carbon dioxide and CH(4) fluxes were monitored one to three times per week using vented nonsteady state closed chambers. No-till reduced (14%) growing season (154 d) cumulative CO(2) emissions relative to CT (NT: 2.08 Mg CO(2)-C ha(-1); CT: 2.41 Mg CO(2)-C ha(-1)), while N fertilization had no effect. Significantly lower (18%) growing season CO(2) fluxes were found in NT-CDb than NT-CC and NT-CB (11.4, 13.2 and 13.9 kg CO(2)-C ha(-1)d(-1) respectively). Growing season CH(4) emissions were higher in NT (20.2 g CH(4) ha(-1)) than in CT (1.2 g CH(4) ha(-1)). Nitrogen fertilization and cropping rotation did not affect CH(4) flux. Implementation of NT for 7 yr with no N fertilization was not adequate for restoring the CH(4) oxidation capacity of this clay loam soil relative to CT plowed and fertilized soil.

The Stable Isotopes Approach to Study C and N Sequestration Processes in a Plant–Soil System

This chapter reviews the main methods for tracing N and C stable isotopes in natural and agricultural systems following organic and mineral amendments to soil. Moreover, we present the results obtained from two field experiments conducted, within the MESCOSAGR project, to evaluate either the fate and flow rate of N added as 15N-compost in a maize–soil system or the contribution of sorghum roots to soil organic carbon. Compost contribution to plant nutrition was about 20% of applied N in the first experimentation year, while this value decreased in the following 2 years. The mineralization rate in the first year was anyhow variable depending on compost maturity and composition, while compost amendments mostly affected the inclusion of 15N in soil macro-aggregates. The compost-derived nitrogen sequestered in soil, due to repeated amendments, was estimated to account for 34.2, 38.2 and 42.5% of total N-compost for the first, second and third years, respectively. On the other hand, it was found that soil carbon derived from sorghum residues reached about 28% after 3 years, though this percentage decreased with depth, and more rapidly below 30 cm.

Field Plots and Crop Yields Under Innovative Methods of Carbon Sequestration in Soil

This chapter reviews the issues related to the responses of crops and soil fertility to management strategies aimed to conserve soil carbon, especially for Mediterranean-Temperate conditions. It reports the main results from field experiments conducted in three different Italian sites in order to compare traditional and innovative soil treatments for carbon sequestration. Field agronomic treatments included traditional and minimum tillage, green manuring, two rates of mature compost application, and spreading of water-soluble Fe–porphyrin. Their effects were tested in different sites representing distinct pedo-climatic conditions.