High (H) and low (L) C/N residues were added as HL or LH with 10, 20 or 30 day interval.
After 2nd addition available N and P did not differ between HL and LH with 10-day interval.
Available N after 2nd addition was higher in HL than LH with 20 and 30 day interval.
In LH, previous addition of L residue stimulated MBC after 2nd addition at all intervals.