2.1. Experiment 1
A field experiment was conducted at the experimental site of
the Academy of Agricultural Sciences of Yanjiang District (32◦13N,
120◦63W). The farming system is a winter wheat (Triticum aestivum
L.) – summer rice (Oryza sativa L.) rotation. Mid-subtropical
monsoon climate dominates this agricultural region, with an average
annual temperature of 14.4 ◦C, average annual sunshine of
2078 h and mean annual precipitation of 1057mm. The soil is a
typical sandy loamy containing 20.5 g/kg organic matter, 1.62 g/kg