Soil organic carbon and 13C abundance as related to tillage, crop residue, and nitrogen fertilization under continuous corn management in Minnesota
Introduction
Soil organic carbon (SOC) storage is sensitive to tillage systems, crop residue return (or harvest of straw/silage), and nitrogen (N) management — each of these main effects and their interactions may have a significant impact on soil physical, chemical, and biological properties either directly or associated with changes in SOC. We report SOC storage in a Waukegan silt loam, a well drained Haplic Chernozem soil in the northern Corn Belt with no calcareous accumulation above 60 cm. The site had a high level of SOC characteristic of alfalfa (Medicago sativum L.) and oat (Avena sativa L.) in rotation pasture, with some manure applications, before continuous corn (Zea mays L.) provided the sole source of C additions and created a C4-type input for tracing 13C natural abundance. Accumulated SOC storage and the 13C abundance in the soil derived from the corn stover allowed the separate accounting for the two C pools: (1) that in the soil before the corn (relic C) and (2) that derived from the corn (corn-derived C).
Tillage effects on SOC storage have been characterized either as a single factor or in combination with crop residue management, N fertilization, or both (Havlin et al., 1990; Franzluebbers et al., 1994; Ismail et al., 1994; Lal et al., 1994; Rasmussen and Parton, 1994; Paustian et al., 1997; Reeves et al., 1997; Salinas-Garcia et al., 1997; Dao, 1998). Storage of SOC in shallow soil depths <7.5 cm is usually greater with no-till than in annually-tilled systems when sweep, chisel, disk, or moldboard are the primary tillage tool. However, SOC storage below 7.5 cm can be greater in annually-tilled systems, as shown in two Ohio soils where SOC storage was greater in the no-till system near the surface, but below 7.5 cm the SOC storage was equal to or less than in the moldboard system (Dick and Durkalski, 1987). Wander et al. (1998) demonstrated that tillage system (no-till compared to moldboard) effects on SOC storage near the soil surface and deeper in the traditional Ap layer depended on which one of the three Illinois soils were tested. For comparing SOC storage the sampling depth for all treatments should be at least as deep as the maximum depth of tillage (Ellert and Bettany, 1995).
Perhaps more important than SOC storage in many studies with no-till was the impact of decomposing residue on infiltration, run-off, and soil erosion, because the residues were on or near the soil surface. Allmaras et al. (1988) demonstrated nearly identical depth distributions of coarse organic matter and SOC as controlled by tillage systems in a long-term field experiment in Oregon. Microbial biomass is commonly linked to decomposing organic matter (Martin and Haider, 1986), therefore suggesting more bioactive impact on water stable aggregation where there is a larger storage of SOC near the surface in non-moldboard systems.
The position and quantity of crop residue as well as N fertilization have variable influences on SOC storage (Paustian et al., 1997). When more crop residues are on or near the surface, the storage of SOC has been increased (Larson et al., 1972; Rasmussen et al., 1980; Havlin et al., 1990) but when incorporated by moldboard tillage the quantity of crop residue has had little or no influence on SOC storage (Huggins et al., 1998). Nitrogen fertilization can have variable effects ranging from significantly increased SOC (Blevins et al., 1977; Ismail et al., 1994; Salinas-Garcia et al., 1997) to only small increases of SOC storage (Havlin et al., 1990). Paustian et al. (1997) suggest numerous mechanisms for variable SOC storage response to crop residue return and N fertilization, but conclude that much unexplained variation exists among field experiments.
Recently, studies on SOC storage and turnover have employed 13C natural abundance as an in situ marker of relic and recent SOC pools (Balesdent et al., 1987, Balesdent et al., 1988, Balesdent et al., 1990; Angers et al., 1995; Gregorich et al., 1996; Huggins et al., 1998; Liang et al., 1998). Mass concentrations of both SOC and 13C are sufficient to calculate the amount of SOC coming from a C4 (e.g., corn) crop or from a C3 [e.g., soybean, Glycine max (L.) Merr.] crop. Angers et al. (1995) found that corn-derived SOC was evenly distributed with depth in a moldboard plow treatment and accumulated near the soil surface in shallow reduced-tillage treatments, but total SOC storage from corn residue in the 0–24 cm layer was reduced and not significantly affected by tillage when the stover was harvested. Storage of SOC in the study of Balesdent et al. (1990) was shallow tine tillage>no-till>moldboard tillage when stover was returned and N was not limiting. Gregorich et al. (1996) reported significant SOC turnover as influenced by long-term N fertilization of continuous corn. Total organic C and 13C measurements indicated that fertilized soils had more SOC than unfertilized soils, the difference was accounted for by more C4-derived C in fertilized soils. About 22–30% of the SOC in the Ap layer had turned over and was derived from corn in the fertilized soils; in unfertilized soils only 15–20% was derived from corn. Liang et al. (1998) showed a larger change in SOC storage in a coarse-textured than in a fine-textured soil as related to N fertilization and quantity of residue returned. They noted a fast SOC turnover early and a very small turnover after 12 years of continuous corn.
The objective of this study was to determine the main and interaction effects of tillage, stover harvest, and N fertilization on SOC storage, the δ13C label, and corn-derived SOC in the soil within several depths of the tilled layer during a 13-year field experiment with continuous corn, a C4 crop with a −12‰ δ13C label. A separate characterization of the relic and corn-derived C afforded the opportunity to assess the impact of these three management treatments on SOC storage.
Section snippets
Long-term field experiment
Soil samples for this study were taken from a field experiment, initiated in 1980, at the University of Minnesota Research and Outreach Center in Rosemount, Minnesota to investigate tillage, crop residue management, and N fertilization (Clay et al., 1989). The experiment consisted of eight tillage by residue (stover harvest or return) treatments, each on a randomly allocated, separate block 18×50 m. Each tillage by residue treatment, as a separate block, was subdivided into 12 plots, to give
Soil bulk density
Profiles of soil BD (Fig. 1) indicate tillage depths consistent with those observed in an adjacent experiment where the same machinery was used (Allmaras et al., 1996). The means in Fig. 1 averaged over the N treatments have a standard error of the mean <0.03 g cm−3. Within the depth of annual tillage (17 cm in CH and 23 cm in MB), the BD of treatments with incorporated stover were somewhat less than when stover was removed. Earthworm burrowing, casting, and residue incorporation activity (observed
SOC dynamics mediated by the 13C:12C label
Five characteristics of SOC dynamics were measured in each of the 12 treatment inputs (N variable, stover harvest option, and three tillage systems) as derived from δ13C and total C in continuous corn. The original δ13C label in the soil reflected a strong C3 input of −19.8 and −18.0‰ in the 0–15 and 15–30 cm layers, respectively. The mean SOC mass in the 0–30 cm depth was relatively high in 1980 because of past management history.
The mass of SOC increased in all three tillage treatments only
Summary and conclusions
SOC and natural abundance 13C, as measured in long-term field experiments, are sensitive to tillage, stover and N management. The 13-year field experiment on a Waukegan silt loam soil involved three tillage systems (NT, MB, and CH), two stover options (returned or harvested), and two N rates (0 and 200 kg N ha−1).
- 1.
All three tillage treatments showed a distinctly lower BD at lower depths when the stover was returned, with no effect of N rate; nearer to the surface, BD were somewhat higher where
Acknowledgements
We thank Steve Copeland, Christara Hormann, and Margaret Miller for technical assistance. This is contribution No. 991250077 of the Minnesota Agric. Exp. Stn. Journal Series.
References (34)
- et al.
Major contribution of roots to soil carbon storage inferred from maize cultivated soils
Soil Biol. Biochem.
(1996) - et al.
Natural 13C abundance as a tracer for studies of soil organic matter dynamics
Soil Biol. Biochem.
(1987) - et al.
A method for measuring incorporated crop residue and associated soil properties
Soil Sci. Soc. Am. J.
(1988) - et al.
Spatial relations between oat residue and ceramic spheres when incorporated sequentially by tillage
Soil Sci. Soc. Am. J.
(1996) - et al.
Dynamics of soil organic matter and corn residues affected by tillage practices
Soil Sci. Soc. Am. J.
(1995) - et al.
Soil organic matter turnover in long-term field experiments as revealed by 13C natural abundance
Soil Sci. Soc. Am. J.
(1988) - et al.
Effect of tillage on soil organic carbon mineralization estimated from 13C abundance in maize fields
J. Soil Sci.
(1990) - et al.
Crop carbon contribution to the soil with different cropping and livestock systems
J. Soil Water Conserv.
(1994) - et al.
Inflence of no-tillage and nitrogen fertilization on certain soil properties after 5 years of continuous corn
Agron. J.
(1977) - et al.
Post-harvest residue input to cropland
Plant Soil
(1986)
Nitrogen-tillage-residue management: 3. Observed and simulated interactions among soil depth, nitrogen mineralization, and corn yield
Soil Sci.
Tillage and crop residue effects on carbon-dioxide evolution and carbon storage in a Paleustoll
Soil Sci. Soc. Am. J.
Calculation of organic matter and nutrients stored in soils under contrasting management regimes
Can. J. Soil. Sci.
Long-term changes in soil carbon and nitrogen pools in wheat management systems
Soil Sci. Soc. Am. J.
Nitrogen effects on conservation of carbon during corn residue decomposition in soil
Soil Sci. Soc. Am. J.
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