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United States Department of Agriculture

Agricultural Research Service

Title: Incorporated Source Carbon and Nitrogen Fertilization Effects on Carbon Storage and Soluble Silica in a Haploxeroll

Authors
item Gollany, Hero
item Allmaras, Raymond - ARS-RETIRED
item Copeland, Stephen
item Albrecht, Stephan
item Douglas, Jr, Clyde - ARS-RETIRED

Submitted to: Soil Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 23, 2006
Publication Date: August 15, 2006
Citation: Gollany, H.T., Allmaras, R.R., Copeland, S.M., Albrecht, S.L., Douglas, Jr, C.D. 2006. Incorporated source carbon and nitrogen fertilization effects on carbon storage and soluble silica in a haploxeroll. Soil Science 171(8).

Interpretive Summary: Crop production systems that promote carbon storage and improve soil properties, such as enhanced drainage and root penetration, improve plant growth and production. Long-term experiments with repeat additions of manure and crop residue are ideal for evaluating the influence of incorporated carbon sources on soil organic carbon accumulation and its interaction with soil constituents. A long-term wheat-fallow experiment with several crop residue management practices (no burn; spring burn; and fall burn), three nitrogen rates (0, 40, and 80 lb N/acre), and organic amendments (10 tons/acre/year manure; and 1 ton/acre/year pea vines) was established in 1931 on a Walla Walla silt loam soil. The objectives were to: 1) determine the effect of crop residue management, N fertilizer, and organic amendments on soil organic carbon storage; and 2) evaluate the influence of organic amendments on soil organic matter interaction with soluble silica. The soil organic carbon storage for the manure treatment was 25% higher than for the fall burned wheat residue treatment without N fertilization. In the top 20 inches of soil, N fertilizer application decreased water soluble silica by 17% while applied manure or pea vines increased water soluble silica by 10%. Nitrogen application for 52 years acidified the topsoil and increased silica solubility and leaching from the topsoil. This movement and concentration of silica below the topsoil results in the development of a hard layer below the plow depth that reduces water infiltration. Silica solubilization and movement was greater in the absence of organic amendments or reduced crop residue returns. Increased soil organic carbon storage derived from amendments or N fertilization with retention of crop residues is important for preventing siliceous pan formation and associated impaired infiltration and internal drainage in these soils.

Technical Abstract: Long-term field experiments with repeat additions of incorporated carbon sources are ideal to examine soil organic carbon (SOC) storage and its interaction with soil constituents. The objectives were to: i) determine the effect of crop residue management, N fertilizer, and organic amendments on SOC storage; and ii) evaluate the influence of source C on fine organic matter (FOM) interaction with soluble silica (Si). A long-term wheat (Triticum aestivum L.)-fallow experiment with several crop residue management practices (NB, no burn; SB, spring burn; and FB, fall burn), three N rates (0, 45, and 90 kg N ha-1), and organic amendments (NBM, 11.2 t ha-1 yr-1 manure; and NBPV, 1.12 t ha-1 yr-1 pea vines) was established in 1931 on a Walla Walla silt loam (coarse-silty, mixed, superactive, mesic Typic Haploxeroll). The experiment is an ordered block. Soil cores (2-cm depth increments) were used to measure coarse organic matter (COM), FOM, pH, bulk density ('b), water-soluble C (Cws) and water-soluble Si (Siws). The SOC storage for the NBM (5.78 kg C m-2) was 25% higher than for the FB0 (4.62 kg C m-2) in the 0- to 50-cm depth. Nitrogen fertilizer application (45 or 90 kg N ha-1) decreased Siws by 17% while applied manure or pea vines increased Siws by 10%. Silica solubilization and movement in response to reduced pH was greater in the absence of organic amendments or reduced crop residue returns. Increased SOC storage derived from amendments or N fertilization with retention of crop residues is important for preventing siliceous pan formation and associated impaired infiltration and internal drainage. Phytolith processes could enhance soil C sequestration.

Last Modified: 10/25/2014
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