Figure 3. Generalized image showing the concentrations of plant available nitrogen in the soil over time, based on microbial transformations. The rate of N mineralization by C:N ratio of cover crops. The C:N ratios of the cover crops are as follows: a) 10:1, b) 15:1, c) 22:1, d) 30:1, and e) 40:1. The center line represents a C:N ratio of 25:1, the threshold for N mineralization.