Quantifying short-term effects of crop rotations on soil organic carbon in southwestern Saskatchewan

Campbell, C. A.; Zentner, R. P.; Selles, F.; Biederbeck, V. O.; McConkey, B.G.; Blomert, B.; Jefferson, P. G.

doi:10.4141/s99-045

Cited by 98 publications

(70 citation statements)

References 19 publications

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“…This experiment has been described in detail previously (Zentner et al 2003(Zentner et al , 2004(Zentner et al , 2006Campbell et al 2000b); thus, we present only a brief description of the techniques used, and additional information and data specific to the objectives of this paper.…”

Section: Experimental Datamentioning

confidence: 99%

“…However, we measured bulk densities in the fall of 1996 and, assuming that density had not changed since 1990, we used the 1996 values to convert SOC concentrations to mass for 1990and 1996(Campbell et al 2000b. Because bulk density in the 7.5-to 15-cm depth was generally constant among all treatments (average 1.39 Mg m -3 ), we used this mean value to estimate the SOC mass for this segment.…”

Section: Monitoring Soil Organic Carbonmentioning

confidence: 99%

“…Consequently, the new study used reduced (minimum) tillage instead of conventional tillage; all treatments were fertilized with N and P based on soil tests; the stubble was cut tall at harvest to enhance snow trapping, increase available spring soil water and reduce evapotranspiration as the crop grew (Campbell et al 2000b;Zentner et al 2006). The treatments tested in this study included a legume green manure (LGM) system, a comparison of a high-yielding wheat vs. a standard hard red spring wheat; a flexible rotation that was fallowed only if stored soil water in the spring was below a certain minimum, a grass (hay) treatment, and cropping frequency.…”

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confidence: 99%

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Quantifying carbon sequestration in a minimum tillage crop rotation study in semiarid southwestern Saskatchewan

Campbell¹,

VandenBygaart²,

Zentner³

et al. 2007

Can. J. Soil. Sci.

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. Quantifying carbon sequestration in a minimum tillage crop rotation study in semiarid southwestern Saskatchewan. Can. J. Soil Sci. 87: 235-250. Scientists and the agricultural community require methods of quantifying C sequestration in soils. This is important in assessing the impact of crop management practices on emission of greenhouse gases and for "C trading". Using simulation models may be a more effective method of quantification as compared with in situ measurements. A 17-yr crop rotation experiment being conducted on a medium-textured Orthic Brown Chernozem at Swift Current, Saskatchewan, in which soil organic C (SOC) was being monitored periodically, was used to assess the effect on C sequestration of cropping frequency, wheat class, legume green manure (LGM), flexible cropping based on available water, and regrassing of crop land. Prior to the study, the experimental site had been cropped to fallow-wheat (F-W) for the previous 60 yr. Crop management in this experiment involved minimum tillage, snow trapping, and N + P fertilization based on soil tests. Three models [Century, the Introductory C Balance model (ICBM), and the Campbell model] were tested for their effectiveness in simulating SOC trends. Because growing season precipitation was average to above average, yields, and thus C inputs from residue, were also above average, and consequently SOC increased in most systems for the first 10 yr before reaching a new steady state. SOC gains (kg ha -1 yr -1 ) in the 0-to 15-cm depth in 17 yr were directly proportional to cropping frequency (F-W-W = 135, F-W-W-W = 332, and Cont W = 441);LGM-W-W gained SOC at a much higher rate than F-W-W (329 vs. 135 kg ha -1 yr -1 ); Canada Western Red Spring (CWRS) wheat (Triticum aestivum L.), although it yielded 26% less than Canada Prairie Spring (CPS) wheat, gained SOC at a higher rate than CPS wheat (135 vs. 0 kg ha -1 yr -1 ). Further, 2 yr of conventionally-tilled fallow in 17 yr (flexible system) markedly suppressed SOC gain by 46% compared with Cont W (441 vs. 236 kg ha -1 yr -1 ). There was a 282 kg ha -1 yr -1 gain in SOC under crested wheatgrass (Agropyron cristatum L.) (CWG) but most of this gain occurred in the last 7 yr. Though having their inherent weaknesses, the ICBM and Campbell models performed equally well in simulating SOC trends (r 2 = 0.55 ** ), but Century was less effective (r 2 = 0.21 * ), in part because of its limited ability to simulate yields. Because C input, and thus yield, is one of the main factors influencing SOC gains, and since measured yields are used in the ICBM and Campbell models, while simulated yields are used by Century, the ICBM and Campbell models have an advantage over the Century model in this comparison. Efficiencies of conversion of input C to SOC increased with cropping frequency, and were higher for LGM-W-W than for F-W-W, and for systems with CWRS wheat rather than CPS wheat. Efficiency of conversion was 8% for F-W-W, 15% for LGM-W-W and 21% for Cont W.Key words: ICBM model, Century model, Campbell model, C sequest...

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Section: Experimental Datamentioning

confidence: 99%

Section: Monitoring Soil Organic Carbonmentioning

confidence: 99%

mentioning

confidence: 99%

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Quantifying carbon sequestration in a minimum tillage crop rotation study in semiarid southwestern Saskatchewan

Campbell¹,

VandenBygaart²,

Zentner³

et al. 2007

Can. J. Soil. Sci.

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“…Further, if the lentil was the reason for the under-estimation, the difference between measured and estimated values should be diverging over time with more cycles of the legume-containing system, but this has not happened. Campbell et al (1995Campbell et al ( , 2000b have shown that, because of the large spatial variability that often exists, even on landscapes that are level and uniform looking, accurate quantification of C changes requires that repeated measurements be made in the same plots over time. Assumptions that SOC is constant in contiguous areas of a field can lead to large discrepancies (Campbell et al , 2000b.…”

Section: Estimating Soc Using Equationmentioning

confidence: 99%

“…Campbell et al (1995Campbell et al ( , 2000b have shown that, because of the large spatial variability that often exists, even on landscapes that are level and uniform looking, accurate quantification of C changes requires that repeated measurements be made in the same plots over time. Assumptions that SOC is constant in contiguous areas of a field can lead to large discrepancies (Campbell et al , 2000b. However, if initial measurements are not available we are often left with little choice but to make assumptions and hope for the best.…”

Section: Estimating Soc Using Equationmentioning

confidence: 99%

Evaluation of a simple model to describe carbon accumulation in a Brown Chernozem under varying fallow frequency

Campbell¹,

Zentner²,

Selles³

et al. 2001

Can. J. Soil. Sci.

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. 2001. Evaluation of a simple model to describe carbon accumulation in a Brown Chernozem under varying fallow frequency. Can. J. Soil Sci. 81: 383-394. Soil organic C (SOC) is readily influenced by crop management practices, such as summerfallowing. On the Canadian prairies, the area summerfallowed has decreased significantly in recent years. Our objectives were to determine the influence of fallow frequency on the rate of change in SOC in an Orthic Brown Chernozem, and to test the effectiveness of an empirical equation developed in an earlier study for estimating SOC changes in these rotations over 33-yr period. The rotations, which were initiated in 1967, all received adequate N and P fertilizers. They were (i) fallow-spring wheat (Triticum aestivum L.) (F-W), F-W-W, F-W-W-W-W-W and Wlentil (Lens culinaris L.) (W-Lent). Soil organic C was measured in the 0-to 15-cm and 15-to 30-cm depths in 1976, 1981, 1984, 1990, 1993, 1996 and 1999. No measurements of SOC were made in 1967; we estimated SOC starting values to be 30.5 Mg ha -1 in the 0-to 15-cm depth. In the period 1967 to 1990, when growing season precipitation was near normal for this semiarid region, SOC in the four rotations approached a steady state. However, a decade of much more favourable growing season precipitation in the 1990s increased C inputs, which resulted in a marked increase in SOC in the treatments. The empirical equation suggests, and the F-W and W-Lent rotations appear to confirm, that these rotations are approaching a new steady state at a higher level of SOC, reflecting the decade of favourable precipitation. Measured SOC levels were quite variable, emphasizing the difficulty of relying on measurements made over short time frames (e.g., 5-6yr) when quantifying SOC changes. The equation effectively simulated the trends in SOC changes in all rotations, but consistently underestimated SOC levels in the W-Lent rotation by about 2 Mg ha -1 . Estimates of difference in SOC between treatments were generally similar whether expressed on a mass/fixed depth or a mass/equivalent depth basis. Based on the estimates derived by the empirical equation, we estimated rates of SOC sequestration during the 1967-1990 period to be 0.03 Mg ha -1 yr -1 for F-W, 0.10 Mg ha -1 yr -1 for F-W-W, and 0.15 Mg ha -1 yr -1 for W-Lent. If we include the decade of more favourable precipitation , the rates were between 0.05 Mg ha -1 yr -1 for F-W and 0.20 Mg ha -1 yr -1 for W-Lent. These values are much higher than those estimated by others using the CENTURY model. We concluded that (i) simple models, such as that used in this study, are very useful for estimating management effects on SOC changes, and (ii) we must be cautious in extrapolating C sequestration estimates based on data from short-term experiments because future weather conditions are not easily predicted and weather can have an important impact on C sequestration. 1976, 1981, 1984, 1990, 1993, 1996 et 1999. Elle n'avait toutefois pas été évaluée en 1967. Les auteurs estiment que la CCOS s'établissait ...

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Trends in grain yields and soil organic C in a long‐term fertilization experiment in the China Loess Plateau

Fan

Song

et al. 2008

Z. Pflanzenernähr. Bodenk.

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Changes in grain yields and soil organic carbon (SOC) from a 26 y dryland fertilization trial in Pingliang, Gansu, China, were recorded. Cumulative C inputs from straw and root and manure for fertilizer treatments were estimated. Mean wheat (Triticum aestivum L.) yields for the 18 y ranged from 1.72 t ha -1 for the unfertilized plots (CK) to 4.65 t ha -1 for the plots that received manure (M) annually with inorganic N and P fertilizers (MNP). Corn (Zea mays L.) yields for the 6 y averaged 2.43 and 5.35 t ha -1 in the same treatments. Yields declined with year except in the CK for wheat. Wheat yields for N only declined with time by 117.8 kg ha -1 y -1 that was the highest decrease among all treatments, and that for NP declined by 84.7 kg ha -1 y -1 , similar to the declines of 77.4 kg ha -1 y -1 for the treatment receiving straw and N annually and P every second year (SNP). Likewise, the corn yields declined highly for all treatments, and the declined amounts ranged from 108 to 258 kg ha -1 y -1 which was much higher than in wheat. These declined yields were mostly linked to both gradual dry weather and nutrients depletion of the soil. The N only resulted in both P and K deficiency in the soil, and soil N and K negative balances in the NP and MNP were obvious. Soil organic carbon (SOC) in the 0-20 cm soil layer increased with time except in the CK and N treatments, in which SOC remained almost stable. In the MNP and M treatments, 24.7% and 24.0% of the amount of cumulative C input from organic sources remained in the soil as SOC, but 13.7% of the C input from straw and root in the SNP, suggesting manure is more effective in building soil C than straw. Across the 26 y cropping and fertilization, annual soil-C sequestration rates ranged from 0.014 t C ha -1 y -1 for the CK to 0.372 t C ha -1 y -1 for the MNP. We found a strong linear relationship (R 2 = 0.74, p = 0.025) between SOC sequestration and cumulative C input, with C conversion-to-SOC rate of 16.9%, suggesting these dryland soils have not reached an upper limit of C sequestration.

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Quantifying short-term effects of crop rotations on soil organic carbon in southwestern Saskatchewan

Cited by 98 publications

References 19 publications

Quantifying carbon sequestration in a minimum tillage crop rotation study in semiarid southwestern Saskatchewan

Quantifying carbon sequestration in a minimum tillage crop rotation study in semiarid southwestern Saskatchewan

Evaluation of a simple model to describe carbon accumulation in a Brown Chernozem under varying fallow frequency

Trends in grain yields and soil organic C in a long‐term fertilization experiment in the China Loess Plateau

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