Fig. 3. Concentration of inorganic N in leachate during periodic leaching events (bars) and percentage N mineralized from transgenic tobacco and isogenic control plant residues (lines) for (a) residues mixed with soil and (b) residues on soil surface. Asterisks represent significant differences (P 0.05) in inorganic N concentration in leachate between transgenic and isogenic control residues. Bars represent the least significant difference (P 0.05) in cumulative residue N mineralized between transgenic tobacco and isogenic control plant residues. PI, protease inhibitor.