• Authors:
    • Shu, X.
    • Xu, X. H.
    • Zhang, J. B.
    • Chen, X. M.
    • Zhu, A. N.
    • Yang, W. L.
  • Source: NUTRIENT CYCLING IN AGROECOSYSTEMS
  • Volume: 99
  • Issue: 1-3
  • Year: 2014
  • Summary: The backward Lagrangian stochastic (BLS) model and open-path tunable diode laser (OPTDL) analyzer were used to monitor ammonia (NH3) emissions from urea applied to winter wheat in the North China Plain. The high-temporal resolution measurements of ammonia concentrations provided an opportunity for estimating the diel patterns of ammonia emissions, as well as valuable information about the factors that influence NH3 emissions. The results showed both large diel variability and daily variability in NH3 volatilization, with NH3 emissions highest during the daytime. The diel pattern of ammonia volatilization depended mainly on the diel variation of wind speed and soil temperature, while the overall pattern of NH3 loss was strongly affected by soil moisture content, soil NH4 (+)-N concentration, wind speed and soil temperature. At the end of the measurement period, the cumulative NH3 loss was 12.21-16.43 kg N ha(-1), calculated based on different time scale average Q (BLS). Due to sensitivity of the OPTDL analyzer, the estimated total ammonia loss was still doubtful in this study.
  • Authors:
    • Rochette, P.
    • Morel, C.
    • Lalande, R.
    • Gagnon, B.
    • Angers, D. A.
    • Ziadi, N.
    • Chantigny, M. H.
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 3
  • Year: 2014
  • Summary: Adoption of conservation practices can induce beneficial changes to soil properties and related crop yields in which magnitude varies according to soil and climatic conditions but usually increases with time. A long-term field experiment was initiated in 1992 at L'Acadie in southern Quebec on a clay loam soil to evaluate the effect of tillage [mouldboard plow (MP) vs. conservation (CT)], synthetic N fertilization (0, 80, and 160 kg N ha -1) and synthetic P fertilization (0, 17.5, and 35 kg P ha -1) on soil functioning and grain yields of a corn-soybean rotation. Soil tillage was performed every year while synthetic fertilizers were applied only to the corn. Results obtained 12 to 20 yr after initiation of the study indicated that CT enhanced organic C accumulation, NO 3-N, P and K availability, microbial biomass and activity, and microbial community structure in the upper soil layer, likely due to leaving crop residues at the soil surface. The MP practice resulted in greater organic C content deeper, near the bottom of the plow layer, which promoted soil microbial activity at that depth. However, soil N 2O emissions were not affected by tillage. The N and P fertilization increased the availability of these nutrients, but had no significant effect on the soil microbial biomass, activity, and structure. Linear relationships were established between soil available P and cumulative P budgets obtained under MP or 0 kg P ha -1 under CT. Crop yields varied by year in this study but on average, MP yielded 10% more corn and 13% more soybeans than CT. Corn yield increased linearly with added synthetic N each year, whereas soybean yield was little affected by residual N, and both crops did not respond to fertilizer P. Response to N fertilization did not differ due to tillage or P. Despite higher costs associated with plowing, the profitability of MP was greater than CT on this clay loam soil due to greater yields. Specialized management practices (e.g., delayed planting, better herbicide selection, fall cover crop, in-row tillage) might help to improve CT performance on these cool, humid fine-textured soils.
  • Authors:
    • Basanta, M.
    • Costantini, A.
    • Alvarez, C. R.
    • Alvarez, C.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 142
  • Year: 2014
  • Summary: Soil management affects distribution and the stocks of soil organic carbon and total nitrogen. The aim of this study was to evaluate the effect of different crop sequences and tillage systems on the vertical distribution and stocks of soil carbon and nitrogen. We hypothesized that no-tillage promotes surface organic carbon and total nitrogen accumulation, but does not affect the C and N stocks, when compared with reduced tillage. In addition, the incorporation of maize in the crop sequence increases total organic carbon and total nitrogen stocks. Observations were carried out in 2010 in an experiment located in the semiarid Argentine Pampa, on an Entic Haplustoll. A combination of three tillage systems (no tillage, no tillage with cover crop in winter and reduced tillage) and two crop sequences (soybean-maize and soybean monoculture) were assessed. After 15 years of management treatments, soil samples to a depth of 100. cm at seven intervals, were taken and analyzed for bulk density, organic carbon and total nitrogen. Total organic carbon stock up to a depth of 100. cm showed significant differences between soils under different tillage systems (reduced tillage. <. no tillage = no tillage with cover crop), the last ones having 8% more than the reduced tillage treatment. Soybean-maize had 3% more organic C up to 100. cm depth than the soybean monoculture. Total nitrogen stock was higher under no-till treatments than under reduced tillage, both at 0-50 and 0-100. cm depths. Total organic carbon stratification ratios (0-5. cm/5-10. cm) were around 1.6 under no-till and lower under reduced tillage. The stratification ratio explains less than 40% of soil carbon stock. Tillage system had a greater impact on soil carbon stock than crop sequence. © 2014 Elsevier B.V.
  • Authors:
    • Kanampiu, F.
    • Kassie, M.
    • Vetter, S. H.
    • Stirling, C.
    • Bellarby, J.
    • Sonder, K.
    • Smith, P.
    • Hillier, J.
  • Source: AGRICULTURE ECOSYSTEMS & ENVIRONMENT
  • Volume: 197
  • Year: 2014
  • Summary: The world population is projected to increase to 9-10 billion by 2050, during which time it will be necessary to reduce anthropogenic greenhouse gas emissions to mitigate climate change. The particular challenge this places on agriculture is to identify practices which ensure stable and productive food supply that also have a low greenhouse gas (GHG) intensity. Maize is the principle staple crop in many parts of Africa with low and variable yields, averaging only 1.6. t/ha in sub-Saharan Africa (SSA). Food security and increasing crop yields are considered priorities in SSA over impacts of food production on GHG emissions. Here we describe an approach that can be used to inform a decision support tree for optimal interventions to obtain sufficient food production with low GHG intensity, and we demonstrate its applicability to SSA. We employed a derivative of the farm greenhouse gas calculator 'Cool Farm Tool' (CFT) on a large survey of Kenyan and Ethiopian smallholder maize-based systems in an assessment of GHG intensity. It was observed that GHG emissions are strongly correlated with nitrogen (N) input. Based on the relationship between yield and GHG emissions established in this study, a yield of 0.7. t/ha incurs the same emissions as those incurred for maize from newly exploited land for maize in the region. Thus, yields of at least 0.7. t/ha should be ensured to achieve GHG intensities lower than those for exploiting new land for production. Depending on family size, the maize yield required to support the average consumption of maize per household in these regions was determined to be between 0.3 and 2.0. t/ha, so that the desirable yield can be even higher from a food security perspective. Based on the response of the observed yield to increasing N application levels, average optimum N input levels were determined as 60 and 120. kg. N/ha for Kenya and Ethiopia, respectively. Nitrogen balance calculations could be applied to other countries or scaled down to districts to quantify the trade-offs, and to optimise crop productivity and GHG emissions. © 2014.
  • Authors:
    • Möller, A.
    • Ladd, B.
    • Siemens, J.
    • Borchard, N.
    • Amelung, W.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 144
  • Year: 2014
  • Summary: Adding biochar to tropical soils is a strategy for improving crop yield and mitigating climate change, but how various biochar types affect crop yield and the properties of temperate soils is still in dispute. Here, we evaluated how slow-pyrolysis charcoal and two biochars derived from energy production (gasification coke and flash-pyrolysis char) affected the growth of Zea mays L. and the related properties of sandy and silty soils within a 3-year mesocosm experiment. Fertilization was performed to optimize plant growth as would be done under common agricultural practice. Analyses included the monitoring of yield, plant and soil nutrients, aggregate stability, cation exchange and water holding capacity, and black carbon content. The results showed that the added biochars did not affect crop yield at an application rate of 15gbiocharkg-1 of soil. Increasing the application rate of slow-pyrolysis charcoal to 100gkg-1 resulted in decreased plant biomass in the second and third year of the experiment, likely as a result of nutrient imbalances and N-immobilization. We did not detect any degradation of the added black carbon; however, beneficial effects on plants were limited by the small and transient effect of these biochars on the physical and chemical properties of soil. Overall, our results indicate that the added carbon from biochars is stored in soil, but all treatments tested failed to improve plant yield for the studied temperate soils under the given application rates and common agricultural practice. © 2014 Elsevier B.V.
  • Authors:
    • Sauer, T. J.
    • Daigh, A. L.
    • Xiao, X.
    • Horton, R.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 4
  • Year: 2014
  • Summary: The interest in bioenergy crops has raised questions as to the potential of management strategies to preserve soil C pools and soil quality. Since soilsurface CO2 effluxes are a major fate of soil C, knowledge of CO2 efflux's spatial and temporal trends among bioenergy crops will facilitate advances in research on improving terrestrial C-cycle models as well as decision support tools for policy and land-Management. Our objective was to evaluate spatial and temporal dynamics of soil-Surface CO2 effluxes in bioenergy-Based corn (Zea mays L.) and reconstructed prairie systems. Systems evaluated included continuous corn (harvested for grain and 50% of the corn stover) with and without a cover crop, mixed prairies (harvested for aboveground biomass) with and without N fertilization, and corn-soybean [Glycine max (L.) Merr.] rotations harvested for grain. Soil-Surface CO2 effluxes, soil temperature, and soil water contents were monitored weekly from July 2008 to September 2011 and hourly during portions of 2010 and 2011. Annual soil-Surface CO2 effluxes were greater in prairies than row crops and are attributed to greater plant root respiration. Soil-Surface CO2 effluxes spatially varied among intra-crop management zones only for continuous corn with stover removal. However, the cover crop reduced CO2 efflux spatial variability 70% of the time as compared to stover removal without a cover crop. Spatial variability of effluxes was not explained by soil physical properties or conditions. Temperature-induced diurnal fluctuations of CO 2 effluxes were not evident during apparent soil-water redistribution. Further research on the mechanisms behind this process is needed followed by incorporation of mechanisms into CO2 efflux models. © Soil Science Society of America, 5585 Guilford Rd., Madison WI 53711 USA.
  • Authors:
    • Hartman, D. C.
    • Briedis, C.
    • Lal, R.
    • Tivet, F.
    • De Moraes Sá, J. C.
    • dos Santos, J. Z.
    • dos Santos, J. B.
  • Source: Soil & Tillage Research
  • Volume: 136
  • Year: 2014
  • Summary: No-till (NT) cropping systems have been widely promoted in many regions as an important tool to enhance soil quality and improve agronomic productivity. However, knowledge of their long-term effects on soil organic carbon (SOC) stocks and functional SOC fractions linking soil resilience capacity and crop yield is still limited. The aims of this study were to: (i) assess the long-term (16 years) effects of tillage systems (i.e., conventional - CT, minimum - MT, no-till with chisel - NTch, and continuous no-till cropping systems - CNT) on SOC in bulk soil and functional C fractions isolated by chemical (hot water extractable organic C - HWEOC, permanganate oxidizable C - POXC) and physical methods (light organic C - LOC, particulate organic C - POC, mineral-associated organic C - MAOC) of a subtropical Oxisol to 40cm depth; (ii) evaluate the soil resilience restoration effectiveness of tillage systems, and (iii) assess the relationship between the SOC stock enhancement and crop yield. The crop rotation comprised a 3-year cropping sequence involving two crops per year with soybean (Glycine max, L. Merril) and maize (Zea mays L.) in the summer alternating with winter crops. In 2005, the soil under CNT contained 25.8, 20.9, and 5.3Mgha-1 more SOC (P<0.006) than those under CT, MT, and NTch in 0-40cm layer, representing recovery rates of 1.61, 1.31, and 0.33Mg Cha-1yr-1, respectively. The relative C conversion ratio of 0.398 at CNT was more efficient in converting biomass-C input into sequestered soil C than NTch (0.349), MT (0.136), and CT (0.069). The soil under CNT in 0-10cm depth contained ~1.9 times more HWEOC and POXC than those under CT (P<0.05), and concentrations of LOC and POC physical fractions of SOC were significantly higher throughout the year under CNT. Considering CT as the disturbance baseline, the resilience index (RI) increased in the order of MT (0.10)<NTch (0.43)<CNT (0.54). Grain yield was positively affected by increase in SOC stock, and an increase of 1Mg Cha-1 in 0-20cm depth resulted in an increase in yield equal to ~11 and 26kg grainha-1 of soybean (R2=0.97, P=0.03) and wheat (R2=0.96, P=0.03), respectively. The data presented emphasizes the role of labile fractions in the overall SOC accumulation processes in soils managed under CNT and their positive impacts on the soil resilience restoration and on agronomic productivity. © 2013 Elsevier B.V.
  • Authors:
    • Zhang, H. L.
    • Lal, R.
    • Chen, Z. D.
    • Dikgwatlhe ,S. B.
    • Chen, F.
  • Source: SOIL & TILLAGE RESEARCH
  • Volume: 144
  • Year: 2014
  • Summary: The importance of soil organic carbon (SOC) and nitrogen (N) sequestration in agricultural soils as climate-change-mitigating strategy has received robust attention worldwide in relation to soil management. This study was conducted to determine the temporal effects of different tillage systems and residue management on distribution, storage and stratification of SOC and N under wheat (Triticum aestivum L.) - maize (Zea mays L.) cropping systems in the North China Plain (NCP). Four tillage systems for winter wheat established in 2001 were: moldboard plow tillage with maize residues removed (PT0), moldboard plow tillage with maize residues incorporated (PT), rotary tillage with maize residues incorporated (RT), and no-till with maize residues retained on the soil surface (NT). Compared with PT0 and PT, significantly higher SOC and N concentrations were observed in the surface layer (0-10cm depth) under NT and RT. In 2004, the SOC stocks were lower (PRT>PT>PT0 in both years. Compared with other treatments, SOC and N stocks were the lowest (P<0.05) under PT0. Therefore, crop residues play an important role in SOC and N management, and improvement of soil quality. The higher SOC stratification was observed under NT and RT than under PT and PT0, whereas the C:N ratio was higher (P<0.05) under PT and PT0 than under NT and RT systems. Therefore, the notion that NT leads to higher SOC stocks than plowed systems requires cautious scrutiny. Nonetheless, some benefits associated with NT present a greater potential for its adoption in view of the long-term environmental sustainability under wheat-maize double-cropping system in the NCP. © 2014 Elsevier B.V.
  • Authors:
    • Oelbermann, M.
    • Dil, M.
    • Xue Wei
  • Source: Canadian Journal of Soil Science
  • Volume: 94
  • Issue: 4
  • Year: 2014
  • Summary: Biochar can enhance soil fertility, plant nutrient uptake and crop production. Using a potted study, we quantified the effects of adding biochar at 1 t ha -1 (Char), biochar pre-conditioned with urea ammonium nitrate [UAN (Char +)], or UAN only to a control (Contr) with no amendments on maize (Zea mays L.) biomass production, tissue carbon (C) and nitrogen (N) concentrations, N uptake (NU), N utilization efficiency (NUtE), and soil chemistry and biology in coarse-, medium- and fine-textured soils over 6 wk. Soil pH decreased (P<0.05) in Char + and UAN treatments for all soil textures. Soil organic carbon (SOC) increased ( P<0.05) in the coarse and medium textured soil in Char and Char + treatments. Soil ammonium and soil nitrate were different (P<0.05) among treatments; increasing or decreasing depending upon soil texture. Soil microbial biomass C was lowest (P<0.05) in the UAN treatment for all soil textures. Soil potential microbial activity was significantly greater in the coarse-textured soil in only the Char and Char + treatments. Maize biomass, tissue N concentration, and NU increased (P<0.05) in soils amended with Char + or UAN only. NUtE was lower (P<0.05) in Char + and UAN treatments in the coarse- and medium-textured soils, but this was reversed for the fine-textured soil.
  • Authors:
    • Al-Kaisi, M. M.
    • Guzman, J. G.
  • Source: SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
  • Volume: 78
  • Issue: 2
  • Year: 2014
  • Summary: Agriculture management practices can significantly affect soil C storage through changes in C inputs and losses. This study investigated the shortterm effects of tillage (no-tillage [NT] and conventional tillage [CT]), residue removal (0, 50, and 100%), and N rates of 0, 170, and 280 kg N ha-1 on soil C storage. Studies were established in 2008 to 2011 on a Nicollet clay loam (fine-loamy, mixed superactive, mesic Aquic Hapludolls) and Canisteo clay loam (Fine-loamy, mixed, superactive, calcareous, mesic Typic Endoaquolls) soil association at Ames, central Iowa site (AC) and a Marshall silty clay loam (Fine-silty, mixed, superactive, mesic Typic Hapludolls) soil association at Armstrong, southwest Iowa site (ASW) in continuous corn (Zea Mays L.). Findings from the C budget show that under CT and N rate of 170 kg N ha-1 in continuous corn, there was no significant change in net soil C with no residue removal. Increasing N rate from 170 to 280 kg N ha-1 resulted in greater potential C inputs from above and belowground biomass, although C losses were not significantly different, especially with NT. Thus, a portion of soil surface residue could be removed without causing a net loss of soil C. Converting from CT to NT led to lower soil C losses, but C inputs varied due to soil temperature and water content differences and seasonal variability in a given year. Consequently, averaged across both tillage systems and at 280 kg ha-1 N rate for continuous corn approximately 5.10 and 4.18 Mg ha-1 of the residue should remain on the field to sustain soil C in 2010 and 5.23 and 5.18 Mg ha-1 in 2011 for AC and ASW sites, respectively. These finding suggest that residue removal needs to be approached on yearly basis with particular consideration to site's yield potential and weather condition as the residue biomass production can be variable. © Soil Science Society of America.