Fig 1.
Case study site (a) approximate location of trial site, (b) monthly average rainfall of the season in comparison with the long-term average, (c) soil surface at the trial site (Photos taken by Hanlu Zhang in 2021). Cracking soil surface is a characteristic of the vertosols of the study site.
Table 1.
Components of the farm system at the trial site.
Weather records are for the growing season (Jan-Nov 2021).
Table 2.
Soil attribute tests performed in this study and the purpose of conducting those tests.
Fig 2.
Use of neutron moisture meter probe in the field.
Table 3.
AMF species groups and species in each group.
Fig 3.
(a) Soil total organic carbon (TOC) and particulate organic carbon (POC) and permanganate oxidizable carbon (POXC) at 10 cm depth at the time of termination of summer cover crop; (b) TOC and POC measured at harvest time of winter wheat; (c) volumetric soil water (VSW) content at 15cm, 25cm and 35cm and (d) whole profile soil water at wheat sowing time; AMF Group A (e) and Group B (f) measured at the time of termination of summer cover crop; (g) wheat above-ground dry biomass measured at grain filling and early maturity phenology stages and yield at harvest; (h) grain quality. SC: Summer control; ET: Early termination; MT: Mid termination; LT: Late termination.
Table 4.
One-way ANOVA tests showing the significant level of the observed variables means under cover crop treatment in comparison to summer fallow (control).
Comparisons without a significant level were considered statistically insignificantly different i.e., P-value>0.05. Grey shadowed values: a significance P<0.05 was observed.
Fig 4.
Soil water storage of top layers (0-15cm, 15-30cm and 30-45cm) and whole profile (0–150 cm) during summer cover crop.
At the planting time, in the absence of rainfall for 18 days before planting, Early termination had stored higher water in surface soil (0-30cm) while performed same as fallow for all other layers and averaged for the whole profile.
Fig 5.
Soil water in topsoil layers (0–15cm, 15–30cm and 30–45cm) and whole profile (0–150cm) during the winter season.
Table 5.
Water use (WU) by summer cover crop and water use efficiency (WUE) in wheat plots following cover crops.
Table 6.
Relative change in soil carbon, soil water, wheat biomass, yield and grain quality affected by summer cover crop compared to the control (fallow).
Fig 6.
The two-dimensional principal subspace for the observed data.
SW: Soil water; BD: Bulk density.
Fig 7.
The relationship between total organic carbon and particulate organic carbon (POC) and permanganate oxidizable carbon (POXC).
Top left: TOC and POC in summer and winter control plots; Bottom Left: TOC and POXC measured in summer control plots; Top right: TOC and POC in summer and winter cover crop plots; Bottom right: POXC and TOC in summer cover crop plots. The grey shadow area represents a 95% confidence interval.
Fig 8.
Relationship between soil water at top layers and whole profile at planting time and wheat yield and biomass accumulation at grain filling and early maturity stages.
The grey shadow area represents a 95% confidence interval.