RR and SR under all SMs ranged from 60% to 75% and 80% to 90%
(Fig. 5). The largest RR and SR were found under BMWC and BM, respectively.
These results indicated that whole jujube branches mulch played
the best role on decreasing runoff, and such mulch was also efficient in
sediment reduction when combined with white clover cover. No significant
differences in RR and SR were detected among SMs. In each treatment,
SR was always greater than RR, which indicates that SMs were
more efficient in decreasing soil loss than reducing runoff. A scatter
diagram of SYtotal versus RVtotal under all treatments is shown in Fig. 6.
Apparently, SYtotal increased with increasing RVtotal, although the type
of increase varied with different treatments. According to the increased
rate of sediment yield with increasing runoff volume, the data are better
divided into two groups: (i) the no cover cultivation — NC, (ii) the four
SMs. The equations describing these relationships are given in Fig. 6.
Line ① is steeper than line ②, which indicates that with the same increase
in runoff volume, more sediment was generated under group
(i) than under group (ii).