Carbon and nitrogen mineralization in row and interrow areas of chisel and ridge tillage systems

Abstract

Understanding linkages between C and N cycles will improve our ability to estimate soil N supplying power. This study investigated temporal patterns in C and N mineralization at two sampling locations within ridge tillage and chisel plow systems. The study was conducted on a Brandt silty clay loam (fine-silty over sandy or sandy skeletal, mixed Pachic Udic Haploboroll) near Aurora, SD. Maize ( Zea mays L.) was planted at the site in 1992 and 1993. In the chisel plow treatment, net C mineralization rates in samples from the row and interrow areas were similar. However, in the ridge tillage treatment, net C mineralization rates in samples from row areas were higher than those from valley areas for seven and similar for five, of the 13 sampling dates. In 1992 and 1993, net N mineralization was influenced sampling date but not sampling location. Net N and C mineralization peaks did not occur at the same time. Mineralization peaks occurred during early spring for N and during late spring to mid summer for C. Temporal changes in mineralized C: N ratios indicate that organic substrate quality changed during the year. This study shows that C and N mineralization linkages are complex and vary in both space and time, and suggest that problems associated with relating chemical N mineralization indices to field responses may result from difficulties associated with estimating the effect of tillage or climatic parameters on microbial activity.