Tillage and manure effects on soil and aggregate-associated carbon and nitrogen

• Published in: Soil Science Society of America journal Vol. 68; no. 3; pp. 809 - 816
• Main Authors: Mikha, M.M, Rice, C.W
• Format: Journal Article
• Language: English
• Published: Madison, WI Soil Science Society of America 01.05.2004; American Society of Agronomy
• Subjects: Aggregates; Agronomy. Soil science and plant productions; ammonium nitrate; animal manures; Biochemistry; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; conventional tillage; corn; Cropping systems. Cultivation. Soil tillage; Farming systems; fertilizer application; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; long term experiments; microaggregates; nitrogen; no-tillage; Organic matter; organic nitrogen compounds; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Silt loam; silt loam soils; Soil aggregates; Soil degradation; Soil erosion, conservation, land management and development; soil organic carbon; Soil organic matter; Soil science; Soil sciences; Soil testing; Soil tillage; Soils; Test methods; Tillage; Tillage. Tending. Growth control; Zea mays; Kansas; Organic matter; Monocotyledones; Cultivated soil; Soil quality; Zero tillage; Inorganic element; Cereal crop; Gramineae; Conventional tillage; Angiospermae; Soil science; Chemical composition; Soil chemistry; Partition; Soil tillage; Zea mays; Cropping system; Property of soil; Soil structure; Mollisols; Nitrogen; Carbon; Agroecosystem; Carbon cycle; Biogeochemistry; Nitrogen cycle; Silt loam soil; Conservation tillage; Soil biology; Spermatophyta; Aggregate
• ISSN: 0361-5995; 1435-0661; 1435-0661
• DOI: 10.2136/sssaj2004.0809

In agricultural systems, maintenance of soil organic matter (SOM) has long been recognized as a strategy to reduce soil degradation. No-tillage and manure amendments are management practices that can increase SOM content and improve soil aggregation. We investigated the effects of 10-yr of different tillage systems and N sources on soil aggregate-size distribution and aggregate-associated C and N. The study was a split-plot design replicated four times. The main plot treatment was tillage (no-tillage, NT; conventional tillage, CT) and the subplot treatment was N source (manure, M; NH4NO3 fertilizer, F). The experiment was established in 1990 on a moderately well-drained Kennebec silt loam (Fine-silty, mixed, superactive mesic Cumulic Hapludoll) with continuous corn (Zea mays L.). In 1999, soil samples were collected (0- to 5-cm depth) from the field treatments and separated into four aggregate-size classes (>2000, 250-2000, 53-250, and 20-53 micrometer) by wet sieving. Labile C and N content of all aggregate-size fractions were measured using 28-d laboratory incubations of intact and crushed aggregates. No-tillage and M treatments significantly increased total C and N and the formation of macroaggregates. Conventional tillage in comparison with NT significantly reduced macroaggregates with a significant redistribution of aggregates into microaggregates. Aggregate protected labile C and N were significantly greater for macroaggregates, (>2000 and 250-2000 micrometer) than microaggregates (53-250 and 20-53 micrometer) and greater for M than F indicating physical protection of labile C within macroaggregates. Notillage and M a lone each significantly increased soil aggregation and aggregate-associated C and N; however, NT and M together further improved soil aggregation and aggregate-protected C and N.