Tillage and manure effect on soil physical and chemical properties and on carbon and nitrogen mineralization potentials
The objective of this work was to study the effects of tillage and liquid manure applications on some physical and chemical properties and also on the carbon and nitrogen mineralization potential from a meadow soil. Our results indicated that tillage and manure applications had no effect on the concentration of Cu, Mn, total N and organic C in the 0 - 15 cm layer of soil after 15 years of treatment. However soil P, Ca, Mg and Zn contents increased significantly with manure applications. Soil organic matter and total N significantly decreased in the 15 – 30 cm depth. No significant change could be detected in soil structural stability in both layers. Moreover, tillage affected significantly soil soluble C and the C/N ratio. Application of 100 t ha-1 manure significantly increased soil soluble C. The results of this study suggest that tillage increased significantly the soil N mineralization rate. The potentially mineralizable nitrogen (N0) was higher in tilled than in no-tilled soil and was at its maximum in the 0 – 15 cm layer of the soil. Furthermore, a significant positive interaction was observed between tillage and manure application on N mineralized after 1.4 wk (Ne). No significant change was detected in both C mineralization rate (Cm) and potentially mineralizable C (C0). The total amounts of mineralizable carbon (Cm) and nitrogen (Nm) significantly decreased in 15 – 30 cm depth and were very closely correlated with the total amounts of C or N and mineralization rate constants (K).
Key words: Carbon and nitrogen mineralization potentials, k constants, physical and chemical properties.