Management Impacts on SOM and Related Soil Properties in a Long-Term Farming Systems Trial in Pennsylvania: 1981–1991
Management-induced changes in soil carbon (C) and nitrogen contents were difficult to document in these soils because much of the observed difference in soil organic matter (SOM) levels was due to the heterogeneity of texture and drainage characteristics. The kinds and amounts of soil amendments applied and plant residues returned impact SOM and related characteristics by their effect on microorganisms, on the supply of plant-available nutrients, and on soil structure. The amount of C translocated to the roots of each plant species in a crop rotation and the structure of these root systems could be the most important factor affecting SOM dynamics. An integral component of a sustainable agroecosystem is the presence of a continual supply of SOM to provide substrate for an active, healthy soil biological community, an environment for vigorous plant-root development which resists soil erosion, and adequate nutrients for plant growth.