Premium
Tillage and Nitrogen Fertilizer Influence on Carbon and Soluble Silica Relations in a Pacific Northwest Mollisol
Author(s) -
Gollany H. T.,
Allmaras R. R.,
Copeland S. M.,
Albrecht S. L.,
Douglas C. L.
Publication year - 2005
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2004.0284
Subject(s) - mollisol , tillage , loam , soil carbon , randomized block design , plough , fertilizer , zoology , chemistry , nitrogen , agronomy , conventional tillage , soil science , soil water , environmental science , biology , organic chemistry
Long‐term experiments are ideal for evaluating the influence of agricultural practices on soil organic carbon (SOC) accretion. Little is known about the influence of tillage and N fertilization on SOC distribution and silica (Si) movement in a soil. This study: (i) determined the effect of tillage and N fertilizer on SOC accretion in a Walla Walla silt loam (coarse‐silty, mixed, superactive, mesic Typic Haploxeroll), and (ii) examined the subsequent influence of fine organic matter (FOM) on Si movement. A long‐term wheat ( Triticum aestivum L.)–fallow experiment was established in 1940, in a randomized block with split‐plot design. Soil cores (2‐cm increments) from two tillages (moldboard plow, MP; and sweep, SW) and two N rates (45 and 180 kg N ha −1 ) were used to measure coarse organic matter (COM), FOM, pH, bulk density (ρ b ), water‐soluble C (C ws ), and water‐soluble Si (Si ws ). The FOM fraction (6.6 kg C m −2 ) in SW was 14% higher (5.8 kg C m −2 ) than in MP for the 180 kg N ha −1 rate. After 44 yr of N additions, the SOC storage (6.2 kg C m −2 ) for the 180 kg N ha −1 rate increased 3% above that for the 45 kg N ha −1 (6.0 kg C m −2 ). Total Si ws in the B horizon were 34 and 39% greater than in the Ap horizon for the MP and SW systems, respectively. Interaction of tillage and N with Si ws suggests that SOC provides a mechanism to suppress Si solubility, which impacts siliceous pan formation, reduces soil mechanical resistance, and enhances drainage and plant growth.