Effects of rice straw incorporation and tillage depth on soil puddlability and mechanical properties during rice growth period

Impacts of long-term chemical and organic fertilization on soil puddlability in subtropical China

“…5). Similar results were observed in previous studies (Li and Zhang, 2007;Yao et al, 2014). As the sinkage resistance was measured at water saturation, the negative correlation between sinkage resistance and SOC content suggested Fig.…”

“…A previous study noted that the sinkage resistance less than 100 kPa did not impose restriction on rice transplantation, but influenced the rice or post-rice crop yields in some soil types through the effects of soil hydraulic properties during and post the rice growth periods (Kirchhof et al, 2000). A recent study reported that the roots grew longer in the soils with higher sinkage resistance though the sinkage resistance was below 70 kPa (Yao et al, 2014). The sinkage resistance in this study ranged from 300 to 480 kPa in the no fertilization and chemical fertilization treatments, which might cause a high resistance to rice plant transplantation.…”

“…The soil bulk density after drying depends on the maximum drying intensity (Peng et al, 2007;Yoshida and Hallett, 2008) and clay content (Boivin et al, 2004;Eickhorst and Tippkotter, 2009). Recent studies demonstrated that the soils with lower SOC had larger shrinkage capacity and then became more compacted after intensive drying (Peng and Horn, 2005;Deng et al, 2013;Yao et al, 2014). This can also explain the lower soil bulk density of the plow layer in the treatments with higher SOC content than those with chemical fertilization and no fertilization.…”

“…In other words, both experiments here indicated that paddy fields need a minimum of 2.0-2.5 Mg-C ha À1 yr À1 through application of organic amendments to maintain the SOC level (23 g kg À1 ) to prevent a poor puddlability as such in the treatments without organic amendment. Yao et al (2014) reported that incorporation of the total amount of rice straw into soil caused a decrease in sinkage resistance to <70 kP compared with the soil without organic C input where the sinkage resistance ranged from 100 to150 kPa, depending on tillage depth.…”

“…Long-term application of organic manure or crop residues has been shown to improve soil puddlability as indicated by the formation of water-stable aggregates with macropores (Sharma and Bhushan, 2003;Deng et al, 2013) and the decrease in sinkage resistance (Yao et al, 2014). In contrast, the paddy soils under chemical fertilization have large shrinkage capacity, resulting in high bulk density or compacted structure due to loss of structural macropores upon drying (Deng et al, 2013).…”