Fig. 3. Recovery of ¹³C (top) and ¹⁵N (bottom)-crop residue as a percentage of that applied in November 1998 from soil sampled in April 1999 and September 1999. Soil recoveries were from soil sampled to the 0- to 15-cm depth when straw was incorporated (I) or burned (B) and the fields were winter flooded (WF) or nonwinter flooded (NF) (N = 4).