Data from: Legacy effects of diversity in space and time driven by winter cover crop biomass and nitrogen concentration

Plant diversity can increase nitrogen cycling and decrease soil-borne
pests, which are feedback mechanisms influencing subsequent plant growth.
The relative strength of these mechanisms is unclear, as is the influence
of preceding plant quantity and quality. Here, we studied how plant
diversity in space and time influences subsequent crop growth. During 2
years, we rotated two main crops (Avena sativa, Cichorium endivia) with
four winter cover crop (WCC) species in monocultures and mixtures. We
hypothesized that, relative to monocultures, WCC mixtures promote WCC
biomass (quantity) and nitrogen concentration (quality), soil mineral
nitrogen, soil organic matter, and reduce plant-feeding nematode
abundance. Additionally, we predicted that preceding crops modified WCC
legacies. By structural equation modelling (SEM), we tested the relative
importance of WCC shoot biomass and nitrogen concentration on succeeding
crop productivity directly and indirectly via nitrogen cycling and
root-feeding nematode abundance. WCC shoot biomass, soil properties and
succeeding Avena productivity were affected by first-season cropping,
whereas subsequent Cichorium only responded to the WCC treatments. WCC
mixtures’ productivity and nitrogen concentration showed over- and
under-yielding, depending on mixture composition. Soil nitrogen and
nematode abundance did not display WCC mixture effects. Soil organic
matter was lower than expected after Raphanus sativus + Vicia sativa
mixture. Subsequent Avena productivity depended upon mixture composition,
whereas final Cichorium productivity was unresponsive to WCC mixtures. SEM
indicated that WCC legacy effects on subsequent Avena (R2 = 0.52) and
Cichorium (R2 = 0.59) productivity were driven by WCC biomass and nitrogen
concentration, although not by the quantified soil properties. Synthesis
and applications. Through understanding plant–soil feedback, legacy
effects of plant species and species mixtures can be employed for
sustainable management of agro-ecosystems. Biomass and nitrogen
concentration of plants returned to the soil stimulate subsequent plant
productivity. Winter cover crop quantity and quality are both manipulable
with mixtures. The specificity of spatial and temporal diversity effects
warrants consideration of plant species choice in mixtures and rotations
for optimal employment of beneficial legacy effects.