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Long‐Term Changes in Soil Carbon and Nitrogen Pools in Wheat Management Systems
Author(s) -
Franzluebbers A. J.,
Hons F. M.,
Zuberer D. A.
Publication year - 1994
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/sssaj1994.03615995005800060009x
Subject(s) - agronomy , loam , tillage , soil carbon , crop residue , mineralization (soil science) , soil water , chemistry , crop rotation , cropping system , soil organic matter , environmental science , crop , biology , soil science , agriculture , ecology
Crop management strategies that alter the timing, placement, quantity, and quality of crop residue input can affect the size, turnover, and vertical distribution of the active and passive pools of soil organic matter (SOM). Our objectives were to quantify long‐term changes in soil organic, soil microbial biomass (SMB), and mineralizable C and N in continuous wheat ( Triticum aestivum L.), continuous wheat/soybean [ Glycine max (L.) Merr.], and wheat/soybean‐sorghum [ Sorghum bicolor (L.) Moench.] sequences under conventional tillage (CT) and no tillage (NT) with and without N fertilizer. A Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas was collected from a 9‐yr field study. Soil microbial biomass C (SMBC) and N (SMBN) were determined with the chloroform fumigation‐incubation method and mineralizable C and N were determined from 10‐d aerobic incubations at 25°C. More crop residue C input was retained as soil organic C (SOC), SMBC, and mineralizable C under NT than under CT. Soil organic C, SMBC, and mineralizable C at a depth of 0 to 50 mm were 33 to 125% greater under NT than under CT. Increasing cropping intensity increased SOC up to 22%, SMBC up to 31%, and mineralizable C up to 27% under NT. Differences in crop management systems significantly altered SMB and the associated mineralizable N level, which supplies crops with mineral N. High clay content soils of central Texas can be effectively managed to increase the active and passive pools of SOM using minimal fallow with NT.