|Allan, D - UNIVERSITY OF MINNESOTA|
|Huggins, David - UNIVERSITY OF MINNESOTA|
Submitted to: Advances in Soil Science
Publication Type: Book / Chapter
Publication Acceptance Date: June 13, 1997
Publication Date: N/A
Interpretive Summary: Society's desire for food security is a driving force behind a large portion of soil research. Society is now beginning to ask agriculturists to verify that production practices such as tillage maintain soil quality and, therefore, the sustainability of food production. In this regard, it is acknowledged that sustaining soil organic matter is extremely important for maintaining soil quality. A farming system with the ability to accrue carbon is favored to maintain soil quality. Soils under four tillage systems including conventional tillage, conservation tillage, ridge tillage and minimum tillage within a continuous corn and a corn/soybean rotation, were tested for soil carbon components and structural properties to assess each system's ability to sustain soil organic matter. Evidence suggests that organic matter increased slightly or was maintained under systems that are less aggressively tilled the than moldboard plow, however carbohydrate content of soils increased with increasing tillage. The band of information from which farmers make decisions in regard to production practices, such as tillage, will be expanded by the data compiled from our research on soil quality.
Technical Abstract: Society's desire for food security prompts agriculturists to verify that production practices maintain soil quality and, therefore, the sustainability of food production. In this regard, it is acknowledged that sustaining soil organic matter is extremely important for maintaining soil quality. The transformation of fresh crop residue into soil organic matter rinvolves a variety of carbon pools which may indicate the direction of accumulations or depletions in a shorter time frame than the measurement of total organic matter. The effects of tillage and crop rotation on soil structure and carbon dynamics was determined in a long term tillage study on a well drained silt loam soil (typic hapludoll). Four tillage systems ranging from conventional tillage to minimum tillage were studied. The measured carbon pools were; total carbon, particulate organic matter, biomass carbon, and carbohydrates. Measurements also included: aggregate stability, soil moisture, bulk density, and soil nitrates. Samples were taken on three dates and from 2 depths. Evidence is apparent that total carbon increases slightly under the tillage treatments that have less aggressive tillage than moldboard plowing. Carbohydrate content of soils increased with more intensive tillage. Nitrate concentrations were less effected by tillage than crop rotation, increasing significantly at shallow depths following soybeans. Carbon dynamics are highly affected by tillage systems and the long term impact on soil organic matter can be assessed by short term measurements.