Carbon sequestration in a Brown Chernozem as affected by tillage and rotation

Self Cite

H. 2003. Effect of tillage and crop rotations on the light fraction organic carbon and carbon mineralization in Chernozemic soils of Saskatchewan. Can J. Soil Sci. 83: 65-72. Light fraction of soil organic C (LFOC) represents a major portion of labile soil organic C (SOC) and is a key attribute of soil quality. Soil respiration (C min ) is an important index depicting the potential activity of the labile SOC. Six field experiments, varying in duration (8 to 25 yr), in location (Brown, Dark Brown and Black Chernozemic soil zones of Saskatchewan) and soil texture, were conducted to evaluate the impact of tillage and crop rotations on crop production and soil quality. We sampled the 0-7.5-cm depth of soil in these experiments to determine the treatment effects on LFOC, the proportion of LFOC in the SOC (LFOC/SOC) and C min . Increasing the frequency of summer fallow in cropping systems decreased the LFOC in all soil zones; it also decreased the proportion of LFOC in SOC and C min . Tillage had little impact on LFOC in the Brown and Dark Brown Chernozemic soil zones, although it significantly decreased LFOC in the Black Chernozemic soil zone. Thus, crop rotation had a greater impact on LFOC than tillage. Tillage did not influence C min in any soil zone. Because adoption of no-till management increased SOC in all soil zones, we concluded that LFOC was not a sensitive indicator of the impact of tillage on this soil quality attribute for these Chernozemic soils in Saskatchewan. We also found that LFOC/SOC is directly proportional to sand content. This relationship may assist us in partitioning SOC pools with differing turnover times when modeling SOC dynamics.Key words: Soil organic C, light fraction organic C, tillage, crop rotations, texture, mineralizable C Liang, B. C., McConkey, B. G., Schoenau, J., Curtin, D., Campbell, C. A., Moulin, A. P., Lafond, G. P., Brandt, S. A. et Wang, H. 2003. Incidence du travail du sol et de l'assolement sur la fraction légère du carbone organique et sur la minéralisation du carbone dans les sols tchernozémiques de la Saskatchewan. Can. J. Soil Sci. 83: 65-72. La fraction légère du C organique du sol (FLCO) constitue une part importante du C organique du sol (COS) labile et elle figure parmi les principaux paramètres qualitatifs du sol. La respiration (C min ) est un indice important caractérisant l'activité potentielle du COS labile. Les auteurs ont entrepris six expériences d'une durée variable (de 8 à 25 ans), à divers endroits (zones de sols bruns, de sols brun foncé et de sols noirs tchernozémiques de la Saskatchewan) et sur des sols de texture différente, afin d'évaluer l'incidence du travail du sol et de l'assolement sur la production végétale et la qualité du sol. Ils ont prélevé des échantillons de sol à une profondeur de 0 à 7,5 cm et déterminé l'effet des traitements sur la FLCO, la proportion de FLCO dans le COS (FLCO/COS) et la C min . Des jachères d'été plus fréquentes réduisent la FLCO dans toutes les zones de sols; elles diminuent aussi le rapport FLCO/COS et la C m...

Section: Effect Of Crop Rotationmentioning

confidence: 96%

Effect of tillage and crop rotations on the light fraction organic carbon and carbon mineralization in Chernozemic soils of Saskatchewan

Liang¹,

McConkey²,

Schoenau³

et al. 2003

Self Cite

“…Nonetheless, as we have shown for CT systems (Campbell and Biederbeck 1982), and even for ZT situations (Campbell et al 1995(Campbell et al , 1996, most of the microbial and soil biochemical changes in soil, under Canadian prairie conditions, occur in the top 7.5 cm. Although some workers report that microbial activity is greater near the soil surface of ZT systems and the reverse is true for CT systems, this phenomenon is mostly observed where tillage involves inversion of the soil, such as with the moldboard plow (Doran and Smith 1987).…”

Section: Carbon and Nitrogen Mineralizationmentioning

confidence: 99%

Tillage effects on soil microbial and biochemical characteristics in a fallow-wheat rotation in a Dark Brown soil

Biederbeck¹,

Campbell²,

Hunter³

1997

Self Cite

As the adoption of reduced tillage increases on the prairies, so too does the use of herbicides and society's concern regarding their possible negative impact on the environment. Two experiments were conducted on Regina heavy clay, an Orthic, Dark Brown Chernozem, at Regina, Saskatchewan, for up to 21 yr, to determine the influence of tillage on yields of hard red spring wheat (Triticum aestivum L.) in a fallow–wheat (F–W) rotation. The treatments used to control weeds in the fallow phase were conventional mechanical tillage (CT) vs. zero tillage (i.e., herbicides only or ZT). In one experiment, glyphosate was the herbicide used; in the other, paraquat (plus Buctril M) was used. In 1991 (the 21st yr), soil sampled from the 0- to 5-cm depth of each rotation phase was used to determine the possible long-term effect of these treatments on selected soil microbial populations and soil biochemical characteristics. The samples were taken in early June (prior to herbicide application), in mid July (3 wk after the 21st herbicide application), and in early September (11 wk after the 21st herbicide application). Generally, the herbicides had no long-term or short-term (in the 21st yr) deleterious effects on soil microbial populations (bacteria, actimonycetes, fungi, nitrifiers, denitrifiers), nor on microbial biomass or potential C or N mineralization. Compared with ZT, CT had a negative impact on most soil characteristics. Microbial activity was primarily a function of crop residue inputs and growing season weather conditions near the time of sampling. Key words: Zero tillage, glyphosate, paraquat, microbial biomass, mineralization

“…Total and organic C and total N were determined by an automated combustion equipment (Carlo Erba TM , Milan, Italy) (Campbell et al 1996). Mineralizable-N (N min ) was determined by incubating a soil-sand mixture at 35°C and measuring cumulative nitrate-and ammonium-N generated during 24 wk, by leaching intermittently (weeks 2, 4, 6, 8, 12, 16, 20 and 24) with 0.01 M CaCl 2 followed by a minus- For personal use only.…”

Section: Soil Biochemical Analysesmentioning

confidence: 99%

Seasonal trends in soil biochemical attributes: Effects of crop management on a Black Chernozem

Campbell¹,

Lafond²,

Biederbeck³

et al. 1999

Self Cite

. 1999. Seasonal trends in soil biochemical attributes: Effects of crop management on a Black Chernozem. Can. J. Soil Sci. 79: 85-97. Knowledge of the response of soil biochemical attributes to crop management and growing season weather is important for assessing soil quality and fertility. Long-term (38-39 yr) crop rotations on a Black Chernozem at Indian Head, Saskatchewan, were sampled (0-to 7.5-cm depth) between early May and mid-October, 11 times in 1995 and 9 times in 1996. We assessed the effect of cropping frequency [fallow-wheat (Triticum aestivum L.) (F-W) vs. F-W-W, vs. Continuous (Cont) W], fertilizers (unfertilized vs. N + P applied), straw harvesting, legume green-manure (GM) in GM-W-W (unfertilized), and legume-grass hay (H) in F-W-W-H-H-H (unfertilized) systems. Changes in organic C and total N (OC, TN), microbial biomass C (MBC), light fraction C and N (LFC and LFN), mineralizable C and N (C min and N min ), and water-soluble organic C (WSOC) were monitored. Organic C and TN were constant and unaffected by rotation phase during the season, but most of the other more labile soil biochemical attributes varied during the season. Much of this temporal variability was associated with changes in soil moisture, temperature and precipitation, and with rhizodeposition in some cases. Whenever conditions favoured rapid decomposition in situ (e.g., high moisture, temperature and/or precipitation) we obtained lower values for the more labile attributes in subsequent laboratory measurements. Seasonal trends in the more labile attriutes were more pronounced in 1995 (a much wetter year) than in 1996, and the proportion of the variability attributable to weather conditions was greater in 1995 than in 1996 (viz., R 2 ranged from 20 to 44% in 1996 and from 37 to 60% in 1995). Seasonal variability was greater in the more fertile treatments [e.g., Cont W (Fert) and F-W-W-H-H-H) than in F-W or Cont W (Unfert). Seasonal variability in LF was unaffected by cropping. Light fraction was lower in 1995 than 1996 because of faster decomposition in 1995 (335 mm of growing season precipitation compared to 157 mm in 1996). Microbial biomass was not influenced by cropping in 1996, but in 1995 it was higher in cropped than in fallow phases of the rotations, suggesting a positive effect of rhizodeposition. Water-soluble organic C was greatest in the more fertile treatments and in cropped than in fallow phases. Mineralizable C and N were greater in cropped than in fallow rotation phases in 1995, but unaffected by cropping in 1996. Further, C min and N min were higher in 1996 than in 1995, likely due to more rapid decomposition in the wetter 1995. Over the last 10 yr of this experiment LFC and C min have increased markedly in the more fertile treatments [e.g., Cont W (Fert), F-W-W-H-H-H], but have hardly changed in the less fertile treatments such as F-W or Cont W (Unfert). In this period the less labile attributes (e.g., OC) have hardly changed in any treatment.Key words: Microbial biomass, carbon, nitrogen, mineralization, water-...