• Authors:
    • Liu, S. G.
    • Tan, Z. X.
  • Source: Applied and Environmental Soil Science
  • Volume: 2013
  • Issue: 2013
  • Year: 2013
  • Summary: Terrestrial carbon (C) sequestration through optimizing land use and management is widely considered a realistic option to mitigate the global greenhouse effect. But how the responses of individual ecosystems to changes in land use and management are related to baseline soil organic C (SOC) levels still needs to be evaluated at various scales. In this study, we modeled SOC dynamics within both natural and managed ecosystems in North Dakota of the United States and found that the average SOC stock in the top 20 cm depth of soil lost at a rate of 450 kg C ha -1 yr -1 in cropland and 110 kg C ha -1 yr -1 in grassland between 1971 and 1998. Since 1998, the study area had become a SOC sink at a rate of 44 kg C ha -1 yr -1. The annual rate of SOC change in all types of lands substantially depends on the magnitude of initial SOC contents, but such dependency varies more with climatic variables within natural ecosystems and with management practices within managed ecosystems. Additionally, soils with high baseline SOC stocks tend to be C sources following any land surface disturbances, whereas soils having low baseline C contents likely become C sinks following conservation management.
  • Authors:
    • Nyiraneza, J.
    • Gagnon, B.
    • Ziadi, N.
  • Source: Canadian Journal of Soil Science
  • Volume: 93
  • Issue: 3
  • Year: 2013
  • Summary: Les biosolides papetiers (BP) en combinaison avec les residus industriels alcalins pourraient beneficier aux sols agricoles tout en les detournant des sites d'enfouissement. Une etude en serre a ete menee afin d'evaluer l'effet de trois types de BP a des taux de 0,30, et 60 Mg humide ha(-1), ainsi que cinq sous-produits chaulants a 3 Mg humide ha(-1) avec 30 Mg BP ha(-1) stir le rendement des cultures, l'accumulation des elements nutritifs et les proprietes du sol. Des biosolides de desencrage (BD, C/N de 65) ont ete appliques au soya [Glycine max (L.) Merr.], et deux BP mixtes (BPI, C/N de 31; et BP2, C/N de 14) ont ete appliqu s a du haricot sec (Phaseolus vulgaris L.) et de l'orge (Hordettm vulgare L.), respectivement. Les sous-produits chaulants incluaient des boues de chaux (BC), des cendres de bois de papetieres, de la chaux calcique commerciale (CC), des sous-produits de dissolution magnesien, et des residus de Mg provenant du travail de la fonte et d'electrolyse (MgFE). Par rapport au temoin, BP2 a augment& le rendement de l'orge et l'accumulation totale en Mg et Na, et les deux BP ont augmente l'accumulation du N, P et Ca dans les plants d'orge et de haricot. L'impact des BD sur le soya a ete limite. L'ajout de sous-produits chaulants a BD ou BP n'a pas eu d'incidence sur les parametres culturaux a l'exception de la combinaison avec MgFE qui a fortement reduit la croissance du haricot sec et, dans une moindre mesure, le soya. Le NO3-N du sol a ete immobilise suite a l'application de BD alors qu'il y a eu un relachement net avec les deux BP. La combinaison BP et sous-produits chaulants a produit les plus grands changements dans les proprietes du sol a la recolte. En regle generale, BC et CC ont augmente le pH et le Ca extrait au Mehlich-3, et MgFE a cause une forte augmentation du Mehlich-3 Mg et Na et du Cl soluble a l'eau. Lorsqu'ils sont utilises avec des cultures appropriees, les biosolides de papetieres et les residus alcalins autres que MgFE peuvent ameliorer efficacement la fertilite des sols en fournissant du C organique et des elements nutritifs majeurs pour equilibrer la fertilisation des cultures.
  • Authors:
    • Arbuckle,J. Gordon, Jr.
    • Morton,Lois Wright
    • Hobbs,Jon
  • Source: Climatic Change
  • Volume: 118
  • Issue: 3-4
  • Year: 2013
  • Summary: Agriculture is both vulnerable to climate change impacts and a significant source of greenhouse gases. Increasing agriculture's resilience and reducing its contribution to climate change are societal priorities. Survey data collected from Iowa farmers are analyzed to answer the related research questions: (1) do farmers support adaptation and mitigation actions, and (2) do beliefs and concerns about climate change influence those attitudes. Results indicate that farmers who were concerned about the impacts of climate change on agriculture and attributed it to human activities had more positive attitudes toward both adaptive and mitigative management strategies. Farmers who believed that climate change is not a problem because human ingenuity will enable adaptations and who did not believe climate change is occurring or believed it is a natural phenomenon-a substantial percentage of farmers-tended not to support mitigation.
  • Authors:
    • Oberson,A.
    • Frossard,E.
    • Buehlmann,C.
    • Mayer,J.
    • Maeder,P.
    • Luescher,A.
  • Source: Plant and Soil
  • Volume: 371
  • Issue: 1-2
  • Year: 2013
  • Summary: Symbiotic dinitrogen (N-2) fixation is the most important external N source in organic systems. Our objective was to compare symbiotic N-2 fixation of clover grown in organically and conventionally cropped grass-clover leys, while taking into account nutrient supply gradients. We studied leys of a 30-year-old field experiment over 2 years in order to compare organic and conventional systems at two fertilization levels. Using N-15 natural abundance methods, we determined the proportion of N derived from the atmosphere (PNdfa), the amount of Ndfa (ANdfa), and the transfer of clover N to grasses for both red clover (Trifolium pratense L.) and white clover (Trifolium repens L.). In all treatments and both years, PNdfa was high (83 to 91 %), indicating that the N-2 fixation process is not constrained, even not in the strongly nutrient deficient non-fertilized control treatment. Annual ANdfa in harvested clover biomass ranged from 6 to 16 g N m(-2). At typical fertilizer input levels, lower sward yield in organic than those in conventional treatments had no effect on ANdfa because of organic treatments had greater clover proportions. In two-year-old leys, on average, 51 % of N taken up by grasses was transferred from clover. Both, organically and conventionally cropped grass-clover leys profited from symbiotic N-2 fixation, with high PNdfa, and important transfer of clover N to grasses, provided sufficient potassium- and phosphorus-availability to sustain clover biomass production.
  • Authors:
    • Sheng,Min
    • Lalande,Roger
    • Hamel,Chantal
    • Ziadi,Noura
  • Source: Web Of Knowledge
  • Volume: 369
  • Issue: 1-2
  • Year: 2013
  • Summary: Evidence shows that tillage modifies soil properties, especially phosphorus (P) dynamics. Our objective was to disentangle long-term effects of P-fertilization and tillage on arbuscular mycorrhizal fungal (AMF) proliferation and community structure. Changes in the community structure of AMF and in the density of their hyphae and spores induced by moldboard plow (MP) or no till (NT), and fertilization with 0, 17.5, or 35 kg P ha(-1) were sought in the 0-15 cm and 15-30 cm soil layers after soybean harvest, at a long-term (17 years) experimental site in a humid continental zone of eastern Canada. The relationships among AMF, soil and plant attributes were examined. The 0-15 cm and 15-30 cm soil layers had different properties under NT, but were similar under MP, after 17 years, and MP increased soil available P levels. Phosphorus fertilization increased P levels in soil and in soybean. Treatment effects on AMF spore and hyphal density at 0-15 cm were greater than that at 15-30 cm, whereas effects on AMF community structure did not change with soil depths. At 0-15 cm, P-fertilization increased AMF spore density and reduced AMF hyphal density, and MP reduced AMF spore density. A total of eight AMF phylotypes were detected. Phosphorus fertilization reduced AMF phylotype richness and Shannon diversity index. Soil P availability increased under MP and hence the influence of P-fertilization treatments on the frequency of AMF phylotype detection varied with tillage system; it declined with P-fertilization under MP, but increased under NT. Phosphorus fertilization shifts resource partitioning in AMF propagules rather than in their hyphae, and degrades the genetic diversity of AMF in soil; tillage increases soil P availability and hence aggravates the impact of P-fertilization.
  • Authors:
    • Smith,Lydia J.
    • Torn,Margaret S.
  • Source: Climatic Change
  • Volume: 118
  • Issue: 1
  • Year: 2013
  • Summary: Terrestrial biological atmospheric carbon dioxide removal (BCDR) through bioenergy with carbon capture and storage (BECS), afforestation/reforestation, and forest and soil management is a family of proposed climate change mitigation strategies. Very high sequestration potentials for these strategies have been reported, but there has been no systematic analysis of the potential ecological limits to and environmental impacts of implementation at the scale relevant to climate change mitigation. In this analysis, we identified site-specific aspects of land, water, nutrients, and habitat that will affect local project-scale carbon sequestration and ecological impacts. Using this framework, we estimated global-scale land and resource requirements for BCDR, implemented at a rate of 1 Pg C y(-1). We estimate that removing 1 Pg C y(-1) via tropical afforestation would require at least 7 x 10(6) ha y(-1) of land, 0.09 Tg y(-1) of nitrogen, and 0.2 Tg y(-1) of phosphorous, and would increase evapotranspiration from those lands by almost 50 %. Switchgrass BECS would require at least 2 x 10(8) ha of land (20 times U.S. area currently under bioethanol production) and 20 Tg y(-1) of nitrogen (20 % of global fertilizer nitrogen production), consuming 4 x 10(12) m(3) y(-1) of water. While BCDR promises some direct (climate) and ancillary (restoration, habitat protection) benefits, Pg C-scale implementation may be constrained by ecological factors, and may compromise the ultimate goals of climate change mitigation.
  • Authors:
    • Huffman, T.
    • Coote, D. R.
    • Green, M.
  • Source: Canadian Journal of Soil Science
  • Volume: 92
  • Issue: 3
  • Year: 2012
  • Summary: Agricultural soils that are covered by vegetation or crop residue are less susceptible to degradation by wind and water erosion, organic matter depletion, structural degradation and declining fertility. In general, perennial crops, higher yields, reduced tillage and continuous cropping provide more soil cover than annual crops, lower yields, intensive tillage, residue harvesting and fallowing. This study presents a model for estimating the number of days in a year that the soil surface is protected and demonstrates its application on the Canadian prairies over the period from 1981 to 2006. Over the 25-yr study period, the average soil cover on Canadian prairie soils increased by 4.8% overall. The improvement came primarily as a result of widespread adoption of no-till and a decline in the use of summerfallow, but the gains were offset to a great deal by a shift from higher-cover crops such as wheat, oats and barley to more profitable but lower-cover crops such as canola, soybeans and potatoes. The implication of these trends is that, even though protection of prairie agricultural soils has improved over the past 25 yr, soil cover could decline dramatically over the next several decades if crop changes continue, the adoption of conservation tillage reaches a peak and residue harvesting for biofuels becomes more common.
  • Authors:
    • Huffman, T.
    • Green, M.
    • Coote, D.
  • Source: Canadian Journal of Soil Science
  • Volume: 92
  • Issue: 3
  • Year: 2012
  • Summary: Agricultural soils that are covered by vegetation or crop residue are less susceptible to degradation by wind and water erosion, organic matter depletion, structural degradation and declining fertility. In general, perennial crops, higher yields, reduced tillage and continuous cropping provide more soil cover than annual crops, lower yields, intensive tillage, residue harvesting and fallowing. This study presents a model for estimating the number of days in a year that the soil surface is protected and demonstrates its application on the Canadian prairies over the period from 1981 to 2006. Over the 25-yr study period, the average soil cover on Canadian prairie soils increased by 4.8% overall. The improvement came primarily as a result of widespread adoption of no-till and a decline in the use of summerfallow, but the gains were offset to a great deal by a shift from higher-cover crops such as wheat, oats and barley to more profitable but lower-cover crops such as canola, soybeans and potatoes. The implication of these trends is that, even though protection of prairie agricultural soils has improved over the past 25 yr, soil cover could decline dramatically over the next several decades if crop changes continue, the adoption of conservation tillage reaches a peak and residue harvesting for biofuels becomes more common.
  • Authors:
    • Hussain, I.
    • Olson, K. R.
  • Source: Pakistan Journal of Botany
  • Volume: 44
  • Issue: 2
  • Year: 2012
  • Summary: Adoption of conservation tillage resulted in changes in soil properties, soil organic matter, soil nutrients. These soil variables were strongly correlated and could not be explained independently by the univariate analysis. The objectives of the study were to use the factor analysis for the identification of the factor pattern in soil properties and to examine the changes in factor scores in no-till (NT), chisel plow (CP) and moldboard plow (MP) tillage systems at different depths after 8 years of the tillage application and planting of corn and soybean on a sloping and previously eroded with a root restricting fragipan Grantsburg soil. The soil samples from the 0 to -5 and -5 to -15 cm soil depths were analyzed for the Ca, Mg, K, P, aggregate stability, particulate organic C, N and humified organic C and N. With factor analysis, 13 highly correlated soil variables were grouped into three different uncorrelated factors, which accounted for the 78% total variance of the data. The soil organic factor had high variable loading on aggregate stability, soil organic C and N contents in soil, POM and humified organic fractions. This factor varied between tillage and represented the accumulation of soil organic matter and its effect on aggregation because of the adoption of tillage. The soil exchange factor had high variable loading for the extractable Ca, Mg and CEC, and varied with tillage and depth because of mixing due to plowing and stratification due to use of no-till treatment. The soil nutrient factor had high variable loading on soil K and P and soil pH and varied between tillage treatments. The nutrient factor scores were also affected by fertilizer application and its mixing by plowing in CP and MP. No-till, which lacks mixing, resulted in decrease in availability of nutrients. This technique enables us to combine the correlated soil variables into three different groups and assess the impact of soil management systems, soil depths and sampling years on these factors. In the NT, lack of tillage, resulted in stratification of exchangeable bases, reduced availability of nutrients. However, it contributed to the maintenance of soil organic matter and soil aggregation. The mixing of soil with plowing resulted in the uniform nutrient availability and exchange capacity of soil in plow layer with the CP and MP systems. The plowing affected soil aggregation adversely due to decomposition of soil organic matter and making soil more susceptible to erosion. The crop yield of maize and soybean were higher with NT system than with CP and MP systems.
  • Authors:
    • Martins, M. dos R.
    • Angers, D. A.
    • Cora, J. E.
  • Source: Soil Science Society of America Journal
  • Volume: 76
  • Issue: 2
  • Year: 2012
  • Summary: In no-till systems, plants play a substantial role in soil physical conditioning because physical management is otherwise confined to sowing operations. We performed a study to determine the effect of 28 different crop sequences on soil water-stable aggregation, soil organic C (SOC), and the neutral carbohydrate composition of the surface layer (0-5-cm depth) of an Oxisol under no-till. Summer crop sequences with corn ( Zea mays L.) on a continuous basis or in rotation with soybean [ Glycine max (L.) Merr.] showed a higher mean weight diameter (MWD) of water-stable aggregates than those with a rice ( Oryza sativa L.)-bean ( Phaseolus vulgaris L.)-cotton ( Gossypium hirsutum L.) rotation. Among winter crops, pearl millet [ Pennisetum americanum (L.) Leeke] or grain sorghum [ Sorghum bicolor (L.) Moench] were associated with a higher MWD than oilseed radish ( Raphanus sativus L. var. oleiformis Pers.). Plant tissues of Poaceae species (corn, pearl millet, and sorghum) were enriched in pentoses relative to other plant species. A principal component analysis showed a close positive relationship of the soil aggregate MWD with the soil xylose content, but not with other soil monosaccharide and SOC contents, and a positive relationship with the amount of pentose input to the soil, notably from aboveground plant materials. A possible explanation is that pentosans are used as an energy source by filamentous microorganisms, which play a well-known role in stabilizing soil aggregates. Our results suggest that plant-derived carbohydrates mediate crop species effects on soil structure under no-till conditions, and this effect appears to be independent of changes in total SOC.