Effect Of Tillage On Carbon And Nitrogen Sequestration In Soils

Abstract

Loss of soil organic matter (SOM) has been associated with increased tillage intensity. To investigate the effect of tillage on soil organic carbon (O.C) and total nitrogen (T.N) sequestration and hydraulic conductivity (H.C) two sites were selected for this study, the first site (Elselete North) was conventionally cultivated (sub- soiler, smoothing by disk harrow, leveling and ridging) and was compared with grassland (G.L) (control). The second site (Elgrouf Shambat) was traditionally cultivated (plough drawn by animal) and similarly compared with grassland (G.L) (control). Soil samples were taken from profiles at an interval of 7.5 cm to a depth of 30 cm. Across all soil depths, content O.C reported in traditional tillage (T.T) were significantly (P X04; 0.017 – 0.004) higher than that of conventional tillage (C.T), while tillage showed no significant differences in T.N content. In the 0 – 7.5cm soil depth, tillage had no effect on T.N and H.C, while O.C determined in T.T (14.82 gkg-1) was significantly (P X04; 0.017) higher than that of C.T (9.26 gkg-1). In the 7.5-15 cm depth, H.C in T.T (0.250cm/min) was significantly (P X04;0.05) higher than that of C.T (0.038 cm/min). In this depth (7.5-15cm), O.C in T.T (14.56 gkg-1) was significantly (P X04; 0.05) higher than that of C.T (8.58 gkg-1). In the third depth (15-22.5cm), O.C in T.T (15.08 gkg-1) was significantly (P X04; 0.01) higher than that of C.T (7.28 gkg-1), and in the same depth T.N in G.L (0.37 gkg-1) was significantly (P X04; 0.05) higher than that of C.T (0.19 gkg-1). In the lower soil depth (22.5-30cm), O.C in T.T (14.82 gkg-1) was significantly (P X04; 0.004) higher than that of C.T (7.89 gkg-1), and in the same depth O.C in G.L (16.9 gkg-1) was significantly (P X04; 0.05) higher than that of T.T (14.82 gkg-1), similarly, T.N in the T.T (0.42 gkg-1) was significantly (P X04; 0.05) higher than that of G.L (0.23 gkg-1). H.C in the G.L (0.068cm/min) was significantly (P X04; 0.05) higher than that of C.T (0.016cm/min). Modeling O.C of C.T and T.T showed that it was best fitted to the exponential model ( R2 = 40%), while T.N was best fitted to the logarithmic model (R2 = 89%) followed by the liner model (R2 = 84%).