Relationships between winter wheat yields and soil carbon under various tillage systems.

Soil quality and fertility are associated with its productivity, and this in turn is connected to the soil biological activity. To study these effects, well designed long-term field experiments that provide comprehensive data sets are the most applicable. Four treatments (tillage methods) were set up: (1) conventional tillage (CT); (2) no tillage (NT); (3) minimum tillage + straw (MTS), and (4) no tillage + mulch (NTM). Our objective was to assess the relationships between soil microbial characteristics and winter wheat yields under these different techniques of conser vation tillage within a field experiment, originally established in 1995. The differences in average grain yields over time period 2002–2009 between the variants were not statistically significant. Organic carbon in the topsoil was higher in plots with conservation tillage (NT, MTS, and NTM), than in the conventional tillage plots. There was a statistically significant correlation ( P ≤ 0.01) between the grain yields and organic C content in topsoil.