Soil physical properties of agricultural systems in a large-scale study

Abstract

The extent to which findings from small-scale field studies can be used to make agricultural recommendations or management decisions is a concern because of natural influential processes that occur only at a large-scale. A large-scale field study was conducted to determine the effects of agricultural management systems on soil physical properties, including their spatial and temporal variations. Three replicates of the systems were based on soil type in an area that had been intensively mapped and were established in 1998 at the Center for Environmental Farming Systems, Goldsboro, NC. Agricultural management systems include five treatments which were best management practices (BMP: with subplots conventional tillage – BCT and no-tillage – BNT), organic crop production (OCP), integrated crop–animal (ICA), plantation forestry-woodlot (PFW), and abandoned-field succession (AFS). Soil physical properties of bulk density (Db), saturated hydraulic conductivity (Ksat), field capacity (FC), saturated water content (SWC), total porosity (TP), micro- and macroporosity (MicP, MacP), and water stable aggregation (WSA) were measured in multiple years within the period 1999–2007. The experimental methods successfully produced data with acceptable levels of variability, discernable soil property differences between systems, and unambiguous relationships between soil properties. Blocking areas with large portions of a diagnostic soil maintained the homogeneity of experimental plots and produced acceptable error terms in statistical procedures. The sampling scheme used prevented sample collection in previously sampled areas. Tilled systems BCT and OCP did not differ in soil physical properties and their properties remained rather constant with time. The BNT, PFW and AFS systems had similar properties with higher Db, lower TP, higher MicP and higher FC than tilled systems. The ICA sub-treatments developed a post-grazing higher Db, lower TP and lower MacP.