Table 2. Estimated average of yearly carbon (C) inputsa,b,c to each crop phase (g C m-2) and analysisd,e,f,g.
| Crop phase | System | Aboveground biomass C | Root biomass C | Est. root exudates | Manure | Total C inputs | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Average of all crop years | 2 | 293.1 (93.1) | a | 13.15 (3.37) | a | 12.56 (4.14) | A | 319.2 (97.2) | a | ||
| 3 | 304.9 (97.9) | a | 11.18 (2.59) | a | 9.96 (3.25) | A | 46.1 (68.0) | a | 372.6 (166.6) | a | |
| 4 | 175.8 (178.6) | a | 12.56 (6.80) | a | 11.89 (4.47) | A | 34.6 (61.8) | b | 235.6 (231.2) | b | |
| Corn | 2 | 374.6 (38.8) | a* | 14.7 (3.53) | a | 14.72 (3.71) | A | 404.5 (40.3) | b | ||
| 3 | 428 (50.2) | a* | 12.43 (3.01) | a | 13.24 (3.09) | A | 138.2 (0.0) | 592.8 (48.9) | a | ||
| 4 | 413.5 (51.8) | a | 12.78 (4.74) | a | 12.00 (6.68) | A | 138.2 (0.0) | 577.6 (57.6) | a | ||
| Mean | 405.4 (49.0) | A | 13.30 (3.61) | AB | 13.32 (4.46) | A | 92.2 (68.1) | 525.0 (99.9) | A | ||
| Soy | 2 | 211.5 (32.9) | b | 11.59 (2.67) | a | 10.39 (3.69) | A | 233.9 (33.8) | b* | ||
| 3 | 258.4 (28.4) | a | 10.30 (3.43) | a | 8.85 (2.11) | A | 277.8 (31.8) | ab* | |||
| 4 | 260.4 (22.2) | a | 12.94 (2.56) | a | 10.18 (4.14) | A | 283.8 (22.0) | a | |||
| Mean | 243.4 (34.4) | B | 11.61 (2.83) | AB | 9.81 (3.18) | A | 265.2 (35.2) | B | |||
| Oat/legume | 3 | 228.5 (24.6) | a | 10.80 (0.74) | a | 7.80 (1.60) | A | 247.2 (23.5) | a | ||
| 4 | 0.0 (0.0) | b | 6.31 (3.49) | a | 12.78 (2.81) | A | 19.5 (3.4) | b | |||
| Mean | 114.3 (123.7) | C | 8.56 (3.11) | B | 10.29 (3.40) | A | 133.4 (123.0) | C | |||
| Alfalfa | 4 | 29.4 (4.5) | 18.20 (9.18) | 12.61 (4.95) | A | 61.6 (7.2) | |||||
| Mean | 29.4 (4.5) | D | 18.20 (9.18) | A | 12.61 (4.95) | A | 97.5 (7.2) | C | |||
a C from stover measured in fall 2009
b C measured in roots collected in fall 2009.
c Sum of aboveground and root biomass C from the previous crop, manure C incorporated to the crop, if any, and root exudate C calculated after [45] as 0.65*summer root C
d Standard deviations are in parenthesis.
e Different lowercase letters represent differences between systems in a specified crop that were significant at p<0.05
f Asterisks * represent differences between systems in a specified crop that were significant at p<0.10.
g Different uppercase letters represent differences that were significant at p<0.05 between values for each crop averaged over all rotations and both depths.