Goddard, T.

Malhi, S.S.

Nyborg, M.

Puurveen, D.

English

eCommons@USASK

Long-term tillage, straw, and N rate effects on quantity and quality of organic C and N in a Gray Luvisol soil

University of Saskatchewan Research Archive

 1  Long-term Tillage, Straw and N Rate Effects on Quantity and Quality of Organic C and N in a Gray Luvisol Soil S. S. Malhi1, M. Nyborg2, T. Goddard3 and D. Puurveen2 1Agriculture and Agri-Food Canada, P.O. Box 1240, Melfort, Saskatchewan, Canada S0E 1A0; 2Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada T6G 2E3; 3Alberta Agriculture, Food and Rural Development, Edmonton, Alberta, Canada  T6H 5T6  Background • With recent developments, such as the Kyoto protocol, there is a desire to identify best management practices to enhance carbon (C) sequestration.  • Soil organic matter is the primary source and temporary sink for plant nutrients and it maintains soil tilth, aids air and water movement, promotes water retention and reduces soil erosion.  • Soil organic carbon (SOC) reserves in western Canada have diminished considerably since the initial cultivation of native prairie grasslands 100 or more years ago, especially with tilled summer fallow.  • Adoption of better management strategies such as continuous cropping, reduced tillage, improved fertilization, application of organic amendments and crop rotations including perennial forage can increase the amount of organic C and/or N stored in the soil. • Soil, crop and fertilizer management practices alter soil properties, but the magnitude of change depends on soil type and climatic conditions. Objective • To determine the long-term (19 or 27 years – 1980 to 1998 or 2006) effects of tillage, straw management and N fertilizer on total organic C (TOC) and N (TON), light fraction organic C (LFOC) and N (LFON), macro organic matter C (MOM-C) and N (MOM-N), microbial biomass C (MB-C), and mineralizable C (Cmin) and N (Nmin), pH, extractable P, ammonium-N and nitrate-N in a Gray Luvisol (Typic Cryoboralf) loam soil. Materials and Methods • A field experiment conducted from 1980 to 1998 or 2006 with barley-wheat-canola rotation on a Gray Luvisol (Typic Cryoboralf) loam (pH 6.6 and initial TOC 13.75 g C kg-1) at Breton, Alberta, Canada.  • Treatments (Table 1) included two tillages (zero tillage [ZT] and conventional tillage [CT]), two straw managements (straw removed [SRem] and straw retained [SRet]) and four N fertilizer rates (0, 50 and 100 kg N ha-1 in SRet, and 0 kg N ha-1 in SRem plots).   2 • Individual plots were 2.8 m x 6.9 m. Plots under CT were tilled twice, once in autumn and once in spring (chisel cultivator). The ZT plots did not undergo any disturbance, except for seeding drill.  • Crop was harvested from 1980 to 2006 for seed and straw yield.  • In autumn 1998, and in spring 2007, soil samples were taken from each plot after growing wheat. The soil samples were then analyzed for various organic C and N fractions and some chemical properties. • Total organic C (TOC) and N (TON), light fraction organic C (LFOC) and N (LFON), macro organic matter C (MOM-C) and N (MOM-N), microbial biomass C (MB-C), and mineralizable C (Cmin) and N (Nmin) measured in 0-7.5 and 7.5-15 cm or 0-5, 5-10 and 10-15 cm layers.  • pH, extractable P, ammonium-N and nitrate-N in 0-7.5, 7.5-15, 15-30 and 30-40 cm or 0-15, 15-30, 30-60, 60-90 and 90-120 cm layers. Summary • Zero tillage, SRet and N fertilizer treatments usually had higher mass of TOC, TON, LFOC, LFON, Cmin and Nmin compared to the corresponding CT, SRem and zero-N control treatment, especially in the surface soil layers, but no consistent effect of these treatments on MB-C (Tables 2 and 3).  • MOM-C in both 0-7.5 and 7.5-15 cm layers and MOM-N in 0-7.5 cm layer generally higher with SRet than SRem, also higher with N fertilizer than zero-N, and tended to be higher under ZT than CT treatments (Table 3).  • There were close and significant correlations among most soil organic C or N fractions in most cases, except MB-C which correlated only with MOM-N at P ≤ 0.10, and Nmin did not correlate with MOM-C (Table 4). Linear regressions between crop residue or C input and soil organic C or N were significant in most cases, except for MB-C, or Nmin (P ≤ 0.16) (Tables 5 and 6).   • In the 0-15 cm soil layer, pH was depressed slightly with N application, and extractable P was higher with SRet than SRem and under ZT than CT, but decreased with N application ((Table 7).  • In this layer, nitrate-N (though quite low) increased with application of N, but no effect of treatments on ammonium-N (Table 7). There was usually no effect of treatments on any soil parameters at depths below 15 cm.  • Compared to the 1979, the TOC concentrations in the 0-15 cm layer indicated a loss in the CTSRem0 treatment in 1998, and in the CTSRem0, CTSRet0 and ZTSRem0 treatments in 2007 (Table 8).  Conclusion • Elimination of tillage, straw retention and N application all improved organic C and N in soil, and generally differences were more pronounced for light fraction organic C and N, and between the most extreme treatments (CTSRem0 vs. ZTSRet100) for each dynamic organic fraction. This will be better for the long-term sustainability of soil quality, fertility, and productivity.  3 Acknowledgements • The authors would like to thank Z. Zhang and K. Strukoff for technical help, D. Leach for preparing and Erin Cadieu for graphic design of the poster.   Table 1. Description of treatments sampled in autumn 1998 and spring 2007 at Breton, Alberta, Canada (Gray Luvisol soil, experiment established in autumn 1979)         Table 2. Effect of long-term tillage, straw and N rate on mass of total organic C (TOC), total organic N (TON), light fraction organic C (LFOC) and light fraction organic N (LFON) in soil depth 0-15 cm, spring 2007 at Breton, Alberta, Canada (Gray Luvisol soil, experiment established in autumn 1979)         Treatment No. ID  Tillage system  Straw management  Rate of N (kg N ha-1) 1 ZTSRem0 Zero Straw removed 0 4 ZTSRet0 Zero Straw retained 0 3 ZTSRet50 Zero Straw retained 50 6 ZTSRet100 Zero Straw retained 100 2 CTSRem0 Conventional Straw removed 0 5 CTSRet0 Conventional Straw retained 0 8 CTSRet50 Conventional Straw retained 50 7 CTSRet100 Conventional Straw retained 100   (Mg  ha-1)   (kg C ha-1)  Treatment (tillage/straw/kg N ha-1)   TOC TON  LFOC  LFON  ZTSRem0  21.95 2.476  936 29.6 ZTSRet0  25.49 2.799  977 31.4 ZTSRet50  31.80 3.229  1456 49.9 ZTSRet100  32.47 3.352  2335 92.3 CTSRem0  20.11 2.390  756 23.6 CTSRet0  21.09 2.582  865 27.4 CTSRet50  25.44 2.804  1508 49.4 CTSRet100  30.57 3.143  1436 53.0 LSD0.05  8.03 0.578  374 16.3 SEMy  2.647* 0.1906*  123.3*** 5.4***          4 Table 3. Effect of long-term tillage, straw and N rate on mass of mineralizable and microbial biomass C and N in soil depth 0-15 cm, autumn 1998 at Breton, Alberta, Canada (Gray Luvisol soil, experiment established in autumn 1979)            Table 4. Relationships among soil organic C or N fractions (TOC, TON, LFOC, LFON, MOM-C, MOM-N, MB-C, mineralizable C [Cmin] and mineralizable N [Nmin]) in autumn 1998 and in spring 2007at Breton, Alberta, Canada (Gray Luvisol soil, experiment established in autumn, 1979)      Mineralizable mass    Microbial biomass  Cmin Nmin MB-C MOM-C MOM-N Treatment (tillage/straw/kg N ha-1)  (kg C ha-1) (kg N ha-1)  (kg C ha-1) (kg C ha-1) (kg N ha-1) ZTSRem0  303 25.2  917 267 11.1 ZTSRet0  367 30.7  1063 464 18.9 ZTSRet50  424 37.5  888 595 20.7 ZTSRet100  416 37.6  1002 377 15.7 CTSRem0  259 14.7  943 316 8.1 CTSRet0  261 17.9  997 299 10.8 CTSRet50  349 23.8  1089 591 23.1 CTSRet100  390 28.4  1085 762 27.4 LSD0.05  129 12.0  268 290 12.6 SEMy  42.4• 3.95**  88.4ns 95.7* 4.14*          Parameter     Correlation coefficients   Relationships among soil organic C or N fractions                           1998     TOC   TON   LFOC   LFON   MOM -C   MOM -N   MB - C   Cmin   Nmin                         TOC       0.997***   0.806*   0.810*   0.595•   0.635•   - 0.017 ns   0.932***   0.893**   TON         0.813*   0.827*   0.612•   0.661•   0.049 ns   0.940***   0.890**   LFOC           0.986***   0.934***   0.941***   0.310 ns   0.817*   0.643•   LFON             0.930***   0.965***   0.427 ns   0.843**   0.662•   MOM -C               0.961***   0.493 ns   0.656•   0.403 ns   MOM -N                 0.590•   0.736*   0.519 ns   MB - C                   0.156 ns   - 0. 047 ns   Cmin                     0.946***   Nmin                                             2007     TOC   TON   LFOC   LFON                                   TOC       0.990***   0.840**   0.835*             TON         0.863**   0.860**             LFOC           0.994***             LFON                                                5 Table 5. Relationships between crop residue or crop residue C input from 1980 to 1998 or 2006 growing seasons and soil organic C or N stored in soil sampled in autumn 1998 and in spring 2007at Breton, Alberta, Canada (Gray Luvisol soil, experiment established in autumn, 1979)            Table 6. Linear regressions for relationships between crop residue or crop residue C input from 1980 to 1998 or 2006 growing seasons and soil organic C or N (TOC, TON, LFOC, LFON, MOM-C, MOM-N, MB-C, mineralizable C [Cmin] and mineralizable N [Nmin]) stored in soil sampled in autumn 1998 and in spring 2007at Breton, Alberta, Canada (Gray Luvisol soil, experiment established in autumn, 1979)            Parameter     Correlation coefficients       Relationships  between crop residue or crop residue C input  and soil organic C or N fractions                           1980 to 1998     TOC   TON   LFOC   LFON   MOM - C   MOM - N   MB - C   Cmin   Nmin                         Crop residue  or C input     0.813*   0.832 *   0.851**   0.885**   0.797*   0.797*   0.348 ns   0.744*   0. 541 0.16                         1980 to 2006     TOC   TON   LFOC   LFON                                   Crop residue  or C input     0.820*   0.815*   0.772*   0.744*                                       Crop parameter (X)   Soil C or N parameter (Y)   Linear regression (Y = a + bX)   R 2       1980  to 1998             Crop residue C input   TOC   Y = 22.17 + 0.4204X    0.6609*         TON   Y = 2.287 + 0.0358X    0.6930*         LFOC   Y = 385.6 + 30.893X    0.7244**         LFON   Y = 15.41 + 1. 2000X    0.7828**         MOM - C   Y = 174.9 + 14.220X    0.6347*         MOM - N   Y = 6.128 + 0.5431X    0.6354*         MB - C   Y = 943.6 + 2.7222X    0.1210 ns         Cmin   Y = 247.5 + 4.9361X    0.5539*         Nmin   Y = 17.85 + 0.4570X    0.2934 0.16                   1980  to 2006             Crop residue C input   TOC   Y = 17.47 + 0.2704X    0.6726*         TON   Y = 2.222 + 0.0195X    0.6648*         LFOC   Y = 432.8 + 22.596X    0.5964*         LFON   Y = 8.977 + 1.1128X    0.5447*        6 Table 7 Effect of long-term tillage, straw and N rate on nitrate-N, extractable P and pH in soil in spring 2007 at Breton, Alberta, Canada (Gray Luvisol soil, experiment established in autumn, 1979)          Table 8 Total organic C (TOC) concentration in 0-15 cm soil in1979, 1990, 1998 and spring 2007 for each treatment at Breton, Alberta, Canada (Gray Luvisol soil, experiment established in autumn 1979 - mean total organic C concentration was 13.75 g C kg-1 in 1979)   Nitrate-N (kg N ha-1)  Extractable P  (kg P ha-1)  pH Treatmentz (tillage/straw/kg N ha-1)  0-15 cm 15-30 cm  0-15 cm  0-5 cm 5-10 cm ZTSRem0  2.0 2.0  35.6  5.94 5.80 ZTSRet0  2.7 2.5  44.1  6.08 5.90 ZTSRet50  6.2 2.2  41.9  5.55 5.48 ZTSRet100  7.1 3.1  28.1  5.44 5.34 CTSRem0  2.6 2.0  41.7  6.92 5.86 CTSRet0  3.4 2.3  48.8  6.03 5.96 CTSRet50  3.5 3.1  16.5  5.55 5.48 CTSRet100  5.7 3.8  27.7  5.49 5.40 LSD0.05  3.5 1.29  20.7  0.21 0.28 SEMy  1.14* 0.39*  6.81•  0.068*** 0.091***  TOC concentration (g C kg-1)  Treatment 1979 1990 1998 2007 ZTSRem0 13.75 12.59 12.22 10.51 ZTSRet0 13.75 13.92 13.72 12.18 ZTSRet50 13.75 17.89 16.76 15.80 ZTSRet100 13.75 17.39 16.49 15.22 CTSRem0 13.75 13.41 10.17 9.57 CTSRet0 13.75 13.41 11.96 10.06 CTSRet50 13.75 16.46 12.99 12.27 CTSRet100 13.75 16.58 15.62 13.37  

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Long-term tillage, straw, and N rate effects on quantity and quality of organic C and N in a Gray Luvisol soil

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