EFFECTS OF TILLAGE SYSTEMS ON ENERGY AND CARBON BALANCE IN NORTH-EASTERN ITALY

An energy analysis of three cropping systems with different intensitie s of soil tillage (conventional tillage, CT; ridge tillage, RT; no til lage, NT) was done in a loamy-silt soil (fulvi-calcaric Cambisol) at L egnaro, NE Italy (45 degrees 21'N, 11 degrees 58'E, 8 m above sea-leve l (a.s.l.), average rainfall 822 mm, average temperature 11.7 degrees C). This and measurements of the evolution of the organic matter conte nt in the soil also allowed the consequences to be evaluated in terms of CO2 emissions. The weighted average energy input per hectare was di rectly proportional to tillage intensity (CT > RT > NT). Compared with CT, total energy savings per hectare were 10% with RT and 32% with NT , Average energy costs per unit production were fairly similar (betwee n 4.5 and 5 MJ kg(-1)), with differences of 11%. The energy outputs pe r unit area were highest in CT for all crops, and lowest in NT. The RT outputs were on average more similar to CT (-12%). The output/input r atio tended to increase when soil tillage operations were reduced, and was 4.09, 4.18 and 4.57 for CT, RT and NT, respectively. As a consequ ence of fewer mechanical operations and a greater working capacity of the machines, there was lower fuel consumption and a consistently high er organic matter content in the soil with the conservation tillage me thods. These two effects result in less CO2 emission into the atmosphe re (at 0 degrees C and pressure of 101.3-103 kPa) with respect to CT, of 1190 m(3) ha(-1) year(-1) in RT and 1553 m(3) ha(-1) year(-1) in NT . However, the effect owing to carbon sequestration as organic matter will decline to zero over a period of years.