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Annette Cowie - One of the best experts on this subject based on the ideXlab platform.

  • impact of agricultural management practices on the nutrient supply potential of soil organic matter under long term farming systems
    Soil & Tillage Research, 2018
    Co-Authors: Jharna Rani Sarker, Bhupinder Pal Singh, W J Dougherty, Yunying Fang, Warwick Badgery, Frances C Hoyle, R C Dalal, Annette Cowie
    Abstract:

    Abstract Soil organic matter (SOM) has the potential to supply substantial quantities of nutrients [ i.e nitrogen (N), phosphorus (P) and sulphur (S)] for plant uptake. Yet there is little understanding of the impact of management on the nutrient supply potential in soils (particularly, P and S). To quantify N, P and S availability from SOM, surface soils (0–10 cm) were collected from 14 management practices across three long-term (16–46 years) experimental sites under semi-arid (Luvisol), Mediterranean (Luvisol) and sub-tropical (Vertisol) environments in Australia. The practices comprised conventional (CT) and reduced tillage (RT) with mixed farming, no-till with continuous cropping (NT), and perennial pasture (PP) in the semi-arid Luvisol, while in a Mediterranean direct-drilled continuous cropping system, stubble was either retained (SR) or burnt (SB). Practices on the Vertisol comprised a factorial combination of CT, NT, SR, SB with either 0 (0N) or 90 kg urea-N ha −1 (90N) in a continuous cropping system. Soils were incubated under controlled soil moisture and temperature, and cumulative organic C mineralised (C min ), and net available N, P and S were measured over 126 days. In the semi-arid Luvisol, CT and/or RT showed significantly higher C min and net available N, P and S than NT and PP. In the Mediterranean Luvisol, C min and net available P were not influenced by stubble management. In the Vertisol, CT-SR ( cf. CT-SB and NT-SR/SB) with or without N fertilisation significantly increased C min , and CT-SR and/or -SB with N fertilisation ( cf. CT-SR/SB without N fertilisation and NT-SR and/or -SB with or without N fertilisation) significantly increased net available N and P. This study found a continuous release of net available N (11–49 kg N ha −1 over 126 days) across all management practices, whereas, the release of available P and S was evident only during the first 30 days (6–74 kg P ha −1 , −4 to 22 kg S ha −1 ), after which microbial immobilisation or clay fixation of P and S predominated, particularly in the Vertisol. In conclusion, the results indicate that SOM is a ready source of plant available P and S (in addition to N), and tillage and stubble retention generally enhanced SOM mineralisation and nutrient release, which varied with soil type.

  • carbon and nutrient mineralisation dynamics in aggregate size classes from different tillage systems after input of canola and wheat residues
    Soil Biology & Biochemistry, 2018
    Co-Authors: Jharna Rani Sarker, Bhupinder Pal Singh, W J Dougherty, Yunying Fang, Annette Cowie, Damian Collins, Brajesh K Singh
    Abstract:

    Abstract Aggregate-size classes may have different microbial accessibility and therefore different decomposability of aggregate-associated soil organic matter (SOM). However, processes and mechanisms of soil organic carbon (SOC) mineralisation and availability of nutrients [nitrogen (N), phosphorus (P) and sulphur (S)] in different aggregate-size classes, and particularly, the interaction of aggregates with tillage intensity and crop residue type in contrasting soils is poorly understood. Soil samples from conventional tillage (CT) and reduced tillage (RT) systems under mixed wheat–pasture farming, and no-till (NT) under continuous cereal–cover cropping in a Luvisol, and from CT and NT under continuous wheat cropping in a Vertisol, were separated into three dry aggregate classes of different sizes [mega-aggregates (>2–6.5 mm), macro-aggregates (0.25–2 mm) and micro-aggregates ( 13 C 124 and 460‰, respectively) were added into each of the three aggregate class samples from Luvisol (δ 13 C −24.7‰) and Vertisol (δ 13 C −18.5‰). Total CO 2 -C, δ 13 C in CO 2 -C, microbial biomass C (MBC), and plant available N, P and S were measured periodically during the 126-day incubation. The results showed that crop residue input increased native SOC mineralisation ( via positive priming), MBC and microbial metabolic quotient in all three aggregate-size classes from different tillage systems in both soils. Native SOC mineralisation was 1.5–3.7 and 0.6–2.8 times higher in the canola and wheat residue-amended ( cf . control, non-amended) aggregates, respectively. Native SOC mineralisatiion and MBC were higher in the macro- and micro- than mega-aggregates in both soils. However, priming of native SOC mineralisation, relative to the control, was similar across the aggregates, except for the CT in the Luvisol where priming was higher in the macro- than micro- and mega-aggregates. Native SOC mineralisation among the aggregate-size classes was 26–114% higher under CT or RT cf . NT in the Luvisol but was similar under CT and NT in the Vertisol. Net available N was significantly higher in the residue-amended than the control aggregates, particularly in the CT and/or RT versus the NT at day 30 only, and mainly in the Luvisol. Further, substantial amounts of available P and S were released from the residue-amended versus the control aggregates at day 126, with Vertisol releasing 2–3 times more available P than Luvisol. In conclusion, our findings showed the importance of returning crop residues to enhance nutrient availability from all aggregate-size classes in different soils and farming systems. In particular, the tillage ( versus no-till) and canola ( versus wheat) residue induced a greater release of nutrients, generally in the pattern of micro- ≥ macro- > mega-aggregates. Clearly, the input of crop residues enhanced the release of SOM-bound nutrients, possibly via positive priming, and may have mobilised mineral-bound nutrients, such as P and S in each aggregate-size class, with tillage intensity and soil type modulating these processes.

Jharna Rani Sarker - One of the best experts on this subject based on the ideXlab platform.

  • impact of agricultural management practices on the nutrient supply potential of soil organic matter under long term farming systems
    Soil & Tillage Research, 2018
    Co-Authors: Jharna Rani Sarker, Bhupinder Pal Singh, W J Dougherty, Yunying Fang, Warwick Badgery, Frances C Hoyle, R C Dalal, Annette Cowie
    Abstract:

    Abstract Soil organic matter (SOM) has the potential to supply substantial quantities of nutrients [ i.e nitrogen (N), phosphorus (P) and sulphur (S)] for plant uptake. Yet there is little understanding of the impact of management on the nutrient supply potential in soils (particularly, P and S). To quantify N, P and S availability from SOM, surface soils (0–10 cm) were collected from 14 management practices across three long-term (16–46 years) experimental sites under semi-arid (Luvisol), Mediterranean (Luvisol) and sub-tropical (Vertisol) environments in Australia. The practices comprised conventional (CT) and reduced tillage (RT) with mixed farming, no-till with continuous cropping (NT), and perennial pasture (PP) in the semi-arid Luvisol, while in a Mediterranean direct-drilled continuous cropping system, stubble was either retained (SR) or burnt (SB). Practices on the Vertisol comprised a factorial combination of CT, NT, SR, SB with either 0 (0N) or 90 kg urea-N ha −1 (90N) in a continuous cropping system. Soils were incubated under controlled soil moisture and temperature, and cumulative organic C mineralised (C min ), and net available N, P and S were measured over 126 days. In the semi-arid Luvisol, CT and/or RT showed significantly higher C min and net available N, P and S than NT and PP. In the Mediterranean Luvisol, C min and net available P were not influenced by stubble management. In the Vertisol, CT-SR ( cf. CT-SB and NT-SR/SB) with or without N fertilisation significantly increased C min , and CT-SR and/or -SB with N fertilisation ( cf. CT-SR/SB without N fertilisation and NT-SR and/or -SB with or without N fertilisation) significantly increased net available N and P. This study found a continuous release of net available N (11–49 kg N ha −1 over 126 days) across all management practices, whereas, the release of available P and S was evident only during the first 30 days (6–74 kg P ha −1 , −4 to 22 kg S ha −1 ), after which microbial immobilisation or clay fixation of P and S predominated, particularly in the Vertisol. In conclusion, the results indicate that SOM is a ready source of plant available P and S (in addition to N), and tillage and stubble retention generally enhanced SOM mineralisation and nutrient release, which varied with soil type.

  • carbon and nutrient mineralisation dynamics in aggregate size classes from different tillage systems after input of canola and wheat residues
    Soil Biology & Biochemistry, 2018
    Co-Authors: Jharna Rani Sarker, Bhupinder Pal Singh, W J Dougherty, Yunying Fang, Annette Cowie, Damian Collins, Brajesh K Singh
    Abstract:

    Abstract Aggregate-size classes may have different microbial accessibility and therefore different decomposability of aggregate-associated soil organic matter (SOM). However, processes and mechanisms of soil organic carbon (SOC) mineralisation and availability of nutrients [nitrogen (N), phosphorus (P) and sulphur (S)] in different aggregate-size classes, and particularly, the interaction of aggregates with tillage intensity and crop residue type in contrasting soils is poorly understood. Soil samples from conventional tillage (CT) and reduced tillage (RT) systems under mixed wheat–pasture farming, and no-till (NT) under continuous cereal–cover cropping in a Luvisol, and from CT and NT under continuous wheat cropping in a Vertisol, were separated into three dry aggregate classes of different sizes [mega-aggregates (>2–6.5 mm), macro-aggregates (0.25–2 mm) and micro-aggregates ( 13 C 124 and 460‰, respectively) were added into each of the three aggregate class samples from Luvisol (δ 13 C −24.7‰) and Vertisol (δ 13 C −18.5‰). Total CO 2 -C, δ 13 C in CO 2 -C, microbial biomass C (MBC), and plant available N, P and S were measured periodically during the 126-day incubation. The results showed that crop residue input increased native SOC mineralisation ( via positive priming), MBC and microbial metabolic quotient in all three aggregate-size classes from different tillage systems in both soils. Native SOC mineralisation was 1.5–3.7 and 0.6–2.8 times higher in the canola and wheat residue-amended ( cf . control, non-amended) aggregates, respectively. Native SOC mineralisatiion and MBC were higher in the macro- and micro- than mega-aggregates in both soils. However, priming of native SOC mineralisation, relative to the control, was similar across the aggregates, except for the CT in the Luvisol where priming was higher in the macro- than micro- and mega-aggregates. Native SOC mineralisation among the aggregate-size classes was 26–114% higher under CT or RT cf . NT in the Luvisol but was similar under CT and NT in the Vertisol. Net available N was significantly higher in the residue-amended than the control aggregates, particularly in the CT and/or RT versus the NT at day 30 only, and mainly in the Luvisol. Further, substantial amounts of available P and S were released from the residue-amended versus the control aggregates at day 126, with Vertisol releasing 2–3 times more available P than Luvisol. In conclusion, our findings showed the importance of returning crop residues to enhance nutrient availability from all aggregate-size classes in different soils and farming systems. In particular, the tillage ( versus no-till) and canola ( versus wheat) residue induced a greater release of nutrients, generally in the pattern of micro- ≥ macro- > mega-aggregates. Clearly, the input of crop residues enhanced the release of SOM-bound nutrients, possibly via positive priming, and may have mobilised mineral-bound nutrients, such as P and S in each aggregate-size class, with tillage intensity and soil type modulating these processes.

Paulina Schuller - One of the best experts on this subject based on the ideXlab platform.

  • Radiocaesium transfer from volcanic soils to Swiss chard, cabbage and sweet corn.
    Journal of environmental radioactivity, 2018
    Co-Authors: Paulina Schuller, Alejandra Castillo, Gabriele Voigt, Natalia Semioshkina
    Abstract:

    Abstract The root uptake of radiocaesium by different plant parts of Swiss chard (Beta vulgaris L. var. cicla), cabbage (Brassica oleracea L. var. capitata) and sweet corn (Zea mays L. var. saccharata ) and the potential influence of K-fertilising on the transfer behaviour was studied in allophanic volcanic soils (umbric andosol and dystric Fluvisol) in Chile under temperate climate and heavy rainfall conditions (∼2660 mm y −1 ) over several vegetation periods. The soils were spiked homogeneously to 0.20 m depth with 100 kBq 134 Cs m −2 and activity concentrations measured. The transfer factor (TF, on a dry mass basis) to Swiss chard had a clear exponential decrease within each crop year for both soil types, either K-fertilised or unfertilised. The highest values of the TFs to Swiss chard were at the beginning of the harvests, and the half-times of TF decrease ranged between 52 and 137 d for umbric andosol and between 40 and 164 d for dystric Fluvisol. Over the five seasons there was no consistent ageing effect based on TF in either soil types for the three studied crops. The effect of 134 Cs foliar uptake by Swiss chard from resuspended soil was estimated to account for about 70% (external leaves) and 30% (internal leaves) increase in the TF for the K-unfertilised umbric andosol, and showed an ambiguous behaviour for the K-fertilised umbric andosol. Consequently foliar uptake does not explain the 370 and 500% increase of the TF to Swiss chard leaves determined during the third growing period in the umbric andosol without and with K-fertilisation, respectively. Therefore an uncertainty factor of 3–5 is recommended to be taken into account when using this parameter for dose calculations. The TF to Swiss chard was found to be higher than previously reported values. The TF to cabbage and sweet corn plant parts was found to be within the range of previously reported values. Normal K-fertilisation resulted in about 2.4-fold reduction in 134 Cs TF to Swiss chard, 2.3-fold to sweet corn and 3.0-fold to cabbage.

  • seasonal variation of the radiocaesium transfer soil to swiss chard beta vulgaris var cicla l in allophanic soils from the lake region chile
    Journal of Environmental Radioactivity, 2004
    Co-Authors: Paulina Schuller, K Bunzl, G Voigt, A Krarup, Alejandra Castillo
    Abstract:

    Abstract The transfer factor (TF) of radiocaesium from soil-to-Swiss chard ( Beta vulgaris var. cicla L.) was studied in two different characteristic allophanic soils (umbric andosol and dystric Fluvisol) of the Lake Region, an important agricultural region situated in central-south Chile. To investigate especially the time dependence and the effect of K-fertilisation on the TF, field experiments were conducted. Plots of 7.6 m 2 were labelled with 100 kBq 134 Cs m −2 at Santa Rosa Experiment Station close to the city of Valdivia characterised by a temperate climate and high precipitation rates. The variation in time of the radiocaesium TF soil-to-Swiss chard was observed during two consecutive years after soil contamination by sequential harvests and radiocaesium analyses of the plants. The TFs showed no significant ageing effect, but a pronounced seasonal decrease with effective half-lives of about 140 and 160 days for the umbric andosol without and with K-fertilisation, respectively, and of 50 and 60 days for the dystric Fluvisol without and with K-fertilisation, respectively. The effect of K-fertilisation on the absolute values of the TF was determined by the ratio between the median TF values obtained for corresponding dates without and with use of K-fertiliser. A ratio of TF without K TF with K =1.8 for the umbric andosol and TF without K TF with K =2.9 for the dystric Fluvisol was obtained, indicating a reduction of the TF by applying 90 kg K ha −1 . The maximal values of the TF to chard predicted by the equation characterising the seasonal decrease of the TF at the beginning of the harvest periods are 0.19 for the umbric andosol and 0.11 for the dystric Fluvisol, both values for soil treated with common K-fertilisation.

Alejandra Castillo - One of the best experts on this subject based on the ideXlab platform.

  • Radiocaesium transfer from volcanic soils to Swiss chard, cabbage and sweet corn.
    Journal of environmental radioactivity, 2018
    Co-Authors: Paulina Schuller, Alejandra Castillo, Gabriele Voigt, Natalia Semioshkina
    Abstract:

    Abstract The root uptake of radiocaesium by different plant parts of Swiss chard (Beta vulgaris L. var. cicla), cabbage (Brassica oleracea L. var. capitata) and sweet corn (Zea mays L. var. saccharata ) and the potential influence of K-fertilising on the transfer behaviour was studied in allophanic volcanic soils (umbric andosol and dystric Fluvisol) in Chile under temperate climate and heavy rainfall conditions (∼2660 mm y −1 ) over several vegetation periods. The soils were spiked homogeneously to 0.20 m depth with 100 kBq 134 Cs m −2 and activity concentrations measured. The transfer factor (TF, on a dry mass basis) to Swiss chard had a clear exponential decrease within each crop year for both soil types, either K-fertilised or unfertilised. The highest values of the TFs to Swiss chard were at the beginning of the harvests, and the half-times of TF decrease ranged between 52 and 137 d for umbric andosol and between 40 and 164 d for dystric Fluvisol. Over the five seasons there was no consistent ageing effect based on TF in either soil types for the three studied crops. The effect of 134 Cs foliar uptake by Swiss chard from resuspended soil was estimated to account for about 70% (external leaves) and 30% (internal leaves) increase in the TF for the K-unfertilised umbric andosol, and showed an ambiguous behaviour for the K-fertilised umbric andosol. Consequently foliar uptake does not explain the 370 and 500% increase of the TF to Swiss chard leaves determined during the third growing period in the umbric andosol without and with K-fertilisation, respectively. Therefore an uncertainty factor of 3–5 is recommended to be taken into account when using this parameter for dose calculations. The TF to Swiss chard was found to be higher than previously reported values. The TF to cabbage and sweet corn plant parts was found to be within the range of previously reported values. Normal K-fertilisation resulted in about 2.4-fold reduction in 134 Cs TF to Swiss chard, 2.3-fold to sweet corn and 3.0-fold to cabbage.

  • seasonal variation of the radiocaesium transfer soil to swiss chard beta vulgaris var cicla l in allophanic soils from the lake region chile
    Journal of Environmental Radioactivity, 2004
    Co-Authors: Paulina Schuller, K Bunzl, G Voigt, A Krarup, Alejandra Castillo
    Abstract:

    Abstract The transfer factor (TF) of radiocaesium from soil-to-Swiss chard ( Beta vulgaris var. cicla L.) was studied in two different characteristic allophanic soils (umbric andosol and dystric Fluvisol) of the Lake Region, an important agricultural region situated in central-south Chile. To investigate especially the time dependence and the effect of K-fertilisation on the TF, field experiments were conducted. Plots of 7.6 m 2 were labelled with 100 kBq 134 Cs m −2 at Santa Rosa Experiment Station close to the city of Valdivia characterised by a temperate climate and high precipitation rates. The variation in time of the radiocaesium TF soil-to-Swiss chard was observed during two consecutive years after soil contamination by sequential harvests and radiocaesium analyses of the plants. The TFs showed no significant ageing effect, but a pronounced seasonal decrease with effective half-lives of about 140 and 160 days for the umbric andosol without and with K-fertilisation, respectively, and of 50 and 60 days for the dystric Fluvisol without and with K-fertilisation, respectively. The effect of K-fertilisation on the absolute values of the TF was determined by the ratio between the median TF values obtained for corresponding dates without and with use of K-fertiliser. A ratio of TF without K TF with K =1.8 for the umbric andosol and TF without K TF with K =2.9 for the dystric Fluvisol was obtained, indicating a reduction of the TF by applying 90 kg K ha −1 . The maximal values of the TF to chard predicted by the equation characterising the seasonal decrease of the TF at the beginning of the harvest periods are 0.19 for the umbric andosol and 0.11 for the dystric Fluvisol, both values for soil treated with common K-fertilisation.

Jingkuan Wang - One of the best experts on this subject based on the ideXlab platform.