Understanding the effect of long-term soil tillage management on soil physical properties, biochemical transformation and microbiological properties is essential to adjustment of soil test recommendations and improved fertilizer nutrient management. Nutrient stratification in no-till (NT) and minimum till (MT) systems can be of concern in soils with limited hydraulic conductivities. Studies have been conducted on Victoria clay and Orelia sandy clay loam soils that have been variably tilled for 18 and25 years, respectively, to compare various tillage intensities for effects on soil chemical, physical and microbiological properties and profile distribution of nitrogen (N), and phosphorus (P). Tillage variables included NT, deep moldboard (MLB), chisel and conventional tillage (CT). Additional studies were also conducted on an Orelia sand clay loam soil with emphasis on soil physical properties. The objective of these additional studies was to evaluate effects of long-term variable tillage intensities on certain soil physical properties including soil aggregation, soil bulk densities and soil water retention.
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