Fig. 1 Contents of organic carbon and nitrogen in reddish paddy soil under long-term winter planting green manure. A, content of organic carbon. B, content of nitrogen. C, C/N ratio. R-R-WF, rice-ricefallow; R-R-RP, rice-rice-rape; R-R-MV, rice-rice-Chinese milk vetch; R-R-RG, rice-rice-ryegrass. The same as below.
The total N contents in >5-mm water-stable aggregates in the R-R-WF were the same as in the R-R-RG plot; slightly lower in 1-2-mm aggregates in R-R-RG than in R-R-WF; and slightly lower in 0.5-1-mm aggregates in R-R-MV than in R-R-WF. Total N contents in
the other sizes of aggregates were higher in winter green manure than winter fallow plots. Total N contents in the other sizes of water-stable aggregates were the highest in the R-R-RP plot, except for 1-2-mm aggregates for which the R-R-MV plot was the highest. Thus, the winter green manure increased the total N content in each size of water-stable aggregates, with the largest increase in the R-R-RP plot.