Grain yield was weighed to estimate the input of organic carbon
(OC) after harvest of the early rice in 2011. Rice straw and root
biomass were estimated from the ratios of grain yield to rice straw
biomass (1.40) and grain yield to root biomass (2.49) that was
measured in the samefield, but not in the same season. The 50–
100 mm rice stubble accounted for 12.5% of the total rice straw. The
carbon content of rice straw and root was 420 and 380 g kg
1
,
respectively. The early grain yield and the amount of OC input
before the late rice in 2011 are presented inFig.1. The amount of OC
input was C2 > C1 > C0 irrespectively of tillage depth and was
ST > DT for both C1 and C2