Overwinter soil nitrogen dynamics in seasonally frozen soils

2000 ◽  
Vol 80 (4) ◽  
pp. 541-550 ◽  
Author(s):  
M. C. Ryan ◽  
R. G. Kachanoski ◽  
R. W. Gillham
Keyword(s):  
Soil Water ◽  
Microbial Biomass Carbon ◽  
Nitrogen Dynamics ◽  
Frozen Soil ◽  
Organic N ◽  
Soluble Nitrogen ◽  
Soil N ◽  
Freezing And Thawing ◽  
N Accumulation ◽  
Soil Microbial

An overwinter soil-monitoring study was conducted at two sites in southern Ontario. Soluble soil N accumulation at both sites occured in early winter, peaked when soil water was frozen, and then declined during the period that frozen soil water was present. The amount of soluble soil N accumulated was 48 ± 12 kg N ha−1 at one site, and 21 ± 6 kg N ha−1 at the other. In both cases, the overwinter accumulation approximately doubled the amount of soluble N in the soil. Similar trends were observed in both mineral and organic N, with 60 to 74% of the accumulation occurring in the organic form. No clear correlations between soluble nitrogen dynamics and soil extractable organic carbon or soil microbial biomass carbon dynamics were observed. Denitrification apparently occurred in shallow soil during the thaw period at one site. Since soil nitrate levels decreased before significant thawing occurred, leaching was probably not the primary dissipation mechanism. We hypothesize that the soluble N accumulation was due to death and lysis of soil microorganims during freezing and thawing. The presence of soil ice apparently decreased the lethality of the soil enviroment, allowing N dissipation to occur. Soil N dissipation could be due to gaseous losses, and is likely related to significant N2O fluxes commonly observed during spring thaw. Key words: Nitrogen, overwinter, soil ice

Dynamics of nitrogen and dry-matter partitioning and accumulation in broccoli (Brassica oleracea var. italica) in relation to extractable soil inorganic nitrogen

1999 ◽  
Vol 79 (2) ◽  
pp. 277-286 ◽  
Author(s):  
P. A. Bowen ◽  
B. J. Zebarth ◽  
P. M. A. Toivonen
Keyword(s):  
Dry Matter ◽  
N Fertilization ◽  
N Fertilizer ◽  
Organic N ◽  
Soil N ◽  
Inorganic N ◽  
N Accumulation ◽  
Spring Planting ◽  
Extractable Soil ◽  
Soil Inorganic

The effects of six rates of N fertilization (0, 125, 250, 375, 500 and 625 kg N ha−1) on the dynamics of N utilization relative to extractable inorganic N in the soil profile were determined for broccoli in three growing seasons. The amount of pre-existing extractable inorganic N in the soil was lowest for the spring planting, followed by the early-summer then late-summer plantings. During the first 2 wk after transplanting, plant dry-matter (DM) and N accumulation rates were low, and because of the mineralization of soil organic N the extractable soil inorganic N increased over that added as fertilizer, especially in the top 30 cm. From 4 wk after transplanting until harvest, DM and N accumulation in the plants was rapid and corresponded to a rapid depletion of extractable inorganic N from the soil. At high N-fertilization rates, leaf and stem DM and N accumulations at harvest were similar among the three plantings. However, the rates of accumulation in the two summer plantings were higher before and lower after inflorescence initiation than those in the spring planting. Under N treatments of 0 and 125 kg ha−1, total N in leaf tissue and the rate of leaf DM accumulation decreased while inflorescences developed. There was little extractable inorganic soil-N during inflorescence development in plots receiving no N fertilizer, yet inflorescence dry weights and N contents were ≥50 and ≥30%, respectively, of the maxima achieved with N fertilization. These results indicate that substantial N is translocated from leaves to support broccoli inflorescence growth under conditions of low soil-N availability. Key words: N translocation, N fertilizer

Validation of NBudget for estimating soil N supply in Australia's northern grains region in the absence of soil test data

Soil Research ◽  
2017 ◽  
Vol 55 (6) ◽  
pp. 590 ◽  
Author(s):  
David F. Herridge
Keyword(s):  
Soil Water ◽  
Organic N ◽  
Soil N ◽  
Limited Information ◽  
Available N ◽  
Support Tool ◽  
Grain Yields ◽  
N Supply ◽  
Nitrate N ◽  
Winter Crop

Effective management of fertiliser nitrogen (N) inputs by farmers will generally have beneficial productivity, economic and environmental consequences. The reality is that farmers may be unsure of plant-available N levels in cropping soils at sowing and make decisions about how much fertiliser N to apply with limited information about existing soil N supply. NBudget is a Microsoft (Armonk, NY, USA) Excel-based decision support tool developed primarily to assist farmers and/or advisors in Australia’s northern grains region manage N. NBudget estimates plant-available (nitrate) N at sowing; it also estimates sowing soil water, grain yields, fertiliser N requirements for cereals and oilseed crops and N2 fixation by legumes. NBudget does not rely on soil testing for nitrate-N, organic carbon or soil water content. Rather, the tool relies on precrop (fallow) rainfall data plus basic descriptions of soil texture and fertility, tillage practice and information about paddock use in the previous 2 years. Use is made of rule-of-thumb values and stand-alone or linked algorithms describing, among other things, rates of mineralisation of background soil organic N and fresh residue N. Winter and summer versions of NBudget cover the 10 major crops of the region: bread wheat, durum, barley, canola, chickpea and faba bean in the winter crop version; sorghum, sunflower, soybean and mung bean in the summer crop version. Validating the winter crop version of NBudget estimates of sowing soil nitrate-N against three independent datasets (n=65) indicated generally close agreement between measured and predicted values (y=0.91x+16.8; r2=0.78). A limitation of the tool is that it does not account for losses of N from waterlogged or flooded soils. Although NBudget also predicts grain yields and fertiliser N requirements for the coming season, potential users may simply factor predicted soil N supply into their fertiliser decisions, rather than rely on the output of the tool. Decisions about fertiliser N inputs are often complex and are based on several criteria, including attitudes to risk, history of fertiliser use and costs. The usefulness and likely longevity of NBudget would be enhanced by transforming the current Excel-based tool, currently available on request from the author, to a stand-alone app or web-based tool.

scholarly journals EFFECT OF WATER AVAILABILITY ON SOIL MICROBIAL BIOMASS IN SECONDARY FOREST IN EASTERN AMAZONIA

2015 ◽  
Vol 39 (2) ◽  
pp. 377-384 ◽  
Author(s):  
Lívia Gabrig Turbay Rangel-Vasconcelos ◽  
Daniel Jacob Zarin ◽  
Francisco de Assis Oliveira ◽  
Steel Silva Vasconcelos ◽  
Cláudio José Reis de Carvalho ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Microbial Biomass ◽  
Soil Water ◽  
Water Availability ◽  
Soil Microbial Biomass ◽  
Secondary Forest ◽  
Microbial Biomass Carbon ◽  
Basal Respiration ◽  
Soil Water Availability ◽  
Soil Microbial

Soil microbial biomass (SMB) plays an important role in nutrient cycling in agroecosystems, and is limited by several factors, such as soil water availability. This study assessed the effects of soil water availability on microbial biomass and its variation over time in the Latossolo Amarelo concrecionário of a secondary forest in eastern Amazonia. The fumigation-extraction method was used to estimate the soil microbial biomass carbon and nitrogen content (SMBC and SMBN). An adaptation of the fumigation-incubation method was used to determine basal respiration (CO2-SMB). The metabolic quotient (qCO2) and ratio of microbial carbon:organic carbon (CMIC:CORG) were calculated based on those results. Soil moisture was generally significantly lower during the dry season and in the control plots. Irrigation raised soil moisture to levels close to those observed during the rainy season, but had no significant effect on SMB. The variables did not vary on a seasonal basis, except for the microbial C/N ratio that suggested the occurrence of seasonal shifts in the structure of the microbial community.

Soil resources and the growth and nutrition of tree seedlings near harvest gap – forest edges in interior cedar–hemlock forests of British Columbia

2006 ◽  
Vol 36 (1) ◽  
pp. 62-76 ◽  
Author(s):  
Michael B Walters ◽  
Cleo C Lajzerowicz ◽  
K David Coates
Keyword(s):  
Soil Water ◽  
Seedling Growth ◽  
N Mineralization ◽  
Forest Edge ◽  
Organic N ◽  
Tree Seedlings ◽  
Net N Mineralization ◽  
Soil N ◽  
Forest Edges ◽  
Mineral N

Observations of tree seedlings with chlorotic foliage and stunted growth near harvest gap – forest edges in interior cedar–hemlock forests inspired a study addressing the following questions: (1) Do seedling foliar chemistry, foliar nitrogen (N) versus growth relationships, and fertilizer responses suggest N-limited seedling growth? (2) Are patterns in soil characteristics consistent with N limitation, and can interrelationships among these characteristics infer causality? Our results suggest that seedling growth near gap–forest edges was colimited by N and light availability. Soil mineral N and dissolved organic N (DON) concentrations, in situ net N mineralization, and water generally increased from forest to gap, whereas N mineralization from a laboratory incubation and total N and carbon did not vary with gap–forest position. Interrelations among variables and path analysis suggest that soil water and total soil N positively affect DON concentration and N mineralization, and proximity to mature gap–forest edge trees negatively impacts mineral N concentration and water. Collectively, our results suggest that soil N levels which limit seedling growth near gap edges can be partially explained by the direct negative impacts of gap–forest edge trees on mineral N concentrations and their indirect impacts on N cycling via soil water, and not via effects on substrate chemistry.

Modelling the impact of soil processes on the N and O isotope signatures of nitrate in groundwater

2021 ◽  
Author(s):  
Neus Otero ◽  
Mathieu Sebilo ◽  
Bernhard Mayer ◽  
Daren Gooddy ◽  
Dan Lapworth ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Isotope Composition ◽  
Organic N ◽  
Soil Biology ◽  
Soil N ◽  
Plant System ◽  
Soil Microbial ◽  
The Impact ◽  
Loire Valley ◽  
N Pool

<p>Stable isotope fingerprinting is widely applied to plant-soil-groundwater systems in an aim to identify and even quantify the sources of nitrates found in groundwater. Frequently, in such studies, the <em>δ</em><sup>15</sup>N and <em>δ</em><sup>18</sup>O values of nitrogen sources, such as inorganic fertilizers and manure, are directly compared to the isotope signatures of nitrate encountered in groundwater bodies below agricultural watersheds. We submit that the underlying assumptions (conservative behavior of isotope composition, rapid transfer from surface to groundwater) may only be realistic under very specific conditions whereas, in most cases, significant isotope effects exerted by the soil-microbial-plant system on the <em>δ</em><sup>15</sup>N and <em>δ</em><sup>18</sup>O values of nitrate need to be taken into account when attempting a quantitative apportionment of sources of groundwater nitrate.</p><p>We hypothesise that the isotopic signature of nitrate exported from below the root zone and migrating towards the groundwater will reflect the nitrogen isotope composition of the soil organic N pool, rather than the isotope composition of source fertilizer or organic amendments, due to processes that reset source isotope compositions within soil N pools. We test this hypothesis using empirical observations from a diversity of settings, in France, Spain and Canada with a relatively constant historic anthropogenic N source or a simple and well constrained landuse history. Furthermore, through the use of a process-based model (SIMSONIC, Billy et al., 2010) we estimate to what extent the isotopic composition of the predominant N input to the soil-microbial-plant system and the soil N pool has been modified in an attempt to consider these changes in source apportionment studies elucidating the sources of groundwater nitrate.</p><p>This research was supported through the Consortium award MUTUAL, by the LE STUDIUM® Loire Valley Institute for Advanced Studies via its SMART LOIRE VALLEY (SLV) fellowship programme, co-funded by the H2020 Marie Sklodowska-Curie programme, Contract No. 665790.</p><p> </p><p>Billy C., Billen G., Sebilo M., Birgand F., Tournebize J. (2010) Nitrogen isotopic composition of leached nitrate and soil organic matter as an indicator of denitrification in a sloping drained agricultural plot and adjacent uncultivated riparian buffer strips. Soil Biology and Biochemistry, 42, 108-117.</p>

scholarly journals Freezing and thawing cycles affect nitrous oxide emissions in rain-fed lucerne (Medicago sativa) grasslands of different ages

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12216
Author(s):  
Yuan Li ◽  
Yuying Shen ◽  
Tao Wang
Keyword(s):  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Depth ◽  
Denitrifying Bacteria ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Soil Microbial ◽  
Freezing And Thawing Cycles

Lucerne (Medicago sativa L.) is a major component of the crops used in dry-land farming systems in China and its management is associated with notable nitrous oxide (N2O) emissions. A high proportion of these emissions is more likely to occur during periods when the soil undergoes freezing and thawing cycles. In this study, the effects of freeze/thaw cycles on N2O emissions and related factors were investigated in lucerne grasslands. The hypothesis was tested whether increased emissions resulted from a disruption of nitrification or denitrification caused by variations in soil temperatures and water contents. Three days (3 × 24 h) were chosen, where conditions represented freezing and thawing cycles. N2O emissions were measured for a fallow control (F) and two grasslands where lucerne had been cultivated for 4 and 11 years. Soil temperature, soil water content, soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), soil ammonium nitrogen (NH4+-N), and soil nitrate nitrogen (NO3−-N) contents were measured. Moreover, the quantities of soil nitrification and denitrification microbes were assessed. Variations in N2O emissions were strongly affected by freeze/thaw cycles, and emissions of 0.0287 ± 0.0009, 0.0230 ± 0.0019, and 0.3522 ± 0.0029 mg m−2 h−1 were found for fallow, 4-year-old, and 11-year-old grasslands, respectively. Pearson correlation analyses indicated that N2O emissions were significantly correlated with the soil water content, temperature, NH4+-N content, and the number of nitrosobacteria and denitrifying bacteria at a soil depth of 0–100 mm. The numbers of nitrosobacteria and denitrifying bacteria correlated significantly with soil temperature at this soil depth. MBN and soil NH4+-N contents correlated significantly with soil water content at this depth. Principal component analysis highlighted the positive effects of the number of denitrifying bacteria on N2O emissions during the freeze/thaw period. Furthermore, soil temperature and the number of nitrosobacteria at the tested soil depth (0−100 mm) also played a significant role. This shows that soil freeze/thaw cycles strongly impacted both N2O emissions and the diurnal range, and the number of denitrifying bacteria was mainly influenced by soil temperature and soil NH4+-N content. The number of denitrifying bacteria was the dominant variable affecting N2O emissions from lucerne grasslands during the assessed soil freeze/thaw period on the Loess Plateau, China.

scholarly journals Compound-specific <sup>15</sup>N stable isotope probing of N assimilation by the soil microbial biomass: a new methodological paradigm in soil N cycling

2015 ◽  
Vol 2 (2) ◽  
pp. 1135-1160
Author(s):  
A. F. Charteris ◽  
T. D. J. Knowles ◽  
K. Michaelides ◽  
R. P. Evershed
Keyword(s):  
Stable Isotope ◽  
Microbial Biomass ◽  
Soil Microbial Biomass ◽  
Stable Isotope Probing ◽  
N Cycling ◽  
Organic N ◽  
Soil N ◽  
Soil Microbial ◽  
Incubation Experiments ◽  
N Assimilation

Abstract. A compound-specific nitrogen-15 stable isotope probing (15N-SIP) technique is described which allows investigation of the fate of inorganic- or organic-N amendments to soils. The technique uses gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) to determine the δ15N values of individual amino acids (AAs; determined as N-acetyl, O-isopropyl derivatives) as proxies of biomass protein production. The δ15N values are used together with AA concentrations to quantify N assimilation of 15N-labelled substrates by the soil microbial biomass. The utility of the approach is demonstrated through incubation experiments using inorganic 15N-labelled substrates ammonium (15NH4+) and nitrate (15NO3-) and an organic 15N-labelled substrate, glutamic acid (15N-Glu). Assimilation of all the applied substrates was undetectable based on bulk soil properties, i.e. % total N (% TN), bulk soil N isotope composition and AA concentrations, all of which remained relatively constant throughout the incubation experiments. In contrast, compound-specific AA δ15N values were highly sensitive to N assimilation, providing qualitative and quantitative insights into the cycling and fate of the applied 15N-labelled substrates. The utility of this 15N-AA-SIP technique is considered in relation to other currently available methods for investigating the microbially-mediated assimilation of nitrogenous substrates into the soil organic N pool. This approach will be generally applicable to the study of N cycling in any soil, or indeed, in any complex ecosystem.

scholarly journals Green Manuring Effect on Changes of Soil Nitrogen Fractions, Maize Growth, and Nutrient Uptake

Agronomy ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 261 ◽  
Author(s):  
Lu Yang ◽  
Jinshun Bai ◽  
Jia Liu ◽  
Naohua Zeng ◽  
Weidong Cao
Keyword(s):  
Green Manure ◽  
N Uptake ◽  
Partial Substitution ◽  
Organic N ◽  
Soil N ◽  
Path Modeling ◽  
Mineral N ◽  
N Accumulation ◽  
Maize Growth ◽  
N Fractions

Green manure is a promising, at least partial, substitution for chemical fertilizer in agriculture, especially for nitrogen (N), which in soil can be radically changed by exogenous input. However, it is not well understood how, after green manure incorporation, soil N changes coordinate with crop N uptake and consequently contribute to fertilizer reduction in a maize–green manure rotation. A four-year field study was performed consisting of (1) control, no fertilization; (2) F100, recommended inorganic fertilization alone; (3) G, green manure incorporation alone; (4) F70 + G (70% of F100 plus G); (5) F85 + G; and (6) F100 + G. The results show that treatments with 15–30% reduction of inorganic fertilizer (i.e., F70 + G and F85 + G) had similar grain yield, dry matter (DM) accumulation, and N uptake as F100 treatment. F100 + G maize had 17% greater DM and 15% more N uptake at maturity relative to F100. Of the five soil N fractions examined, dissolved organic N (DON) and mineral N (Nmin) explained over 70% of the variation of maize DM and N accumulation. Partial least squares path modeling further revealed that soil N fractions had positive indirect effects on DM production through N uptake, which might be coordinated with improved DON and Nmin status at both early and mid-late stages of maize growth. Overall, the results highlight enhanced maize production with reduced fertilizer inputs based on green manure incorporation in temperate regions.

scholarly journals Effects of two wood-based biochars on the fate of added fertilizer nitrogen—a 15N tracing study

2021 ◽  
Author(s):  
Subin Kalu ◽  
Gboyega Nathaniel Oyekoya ◽  
Per Ambus ◽  
Priit Tammeorg ◽  
Asko Simojoki ◽  
...  
Keyword(s):  
Plant Uptake ◽  
Plant Biomass ◽  
Application Rate ◽  
Control Treatment ◽  
Organic N ◽  
N Leaching ◽  
Soil N ◽  
Mineral N ◽  
Total N ◽  
Application Rates

AbstractA 15N tracing pot experiment was conducted using two types of wood-based biochars: a regular biochar and a Kon-Tiki-produced nutrient-enriched biochar, at two application rates (1% and 5% (w/w)), in addition to a fertilizer only and a control treatment. Ryegrass was sown in pots, all of which except controls received 15N-labelled fertilizer as either 15NH4NO3 or NH415NO3. We quantified the effect of biochar application on soil N2O emissions, as well as the fate of fertilizer-derived ammonium (NH4+) and nitrate (NO3−) in terms of their leaching from the soil, uptake into plant biomass, and recovery in the soil. We found that application of biochars reduced soil mineral N leaching and N2O emissions. Similarly, the higher biochar application rate of 5% significantly increased aboveground ryegrass biomass yield. However, no differences in N2O emissions and ryegrass biomass yields were observed between regular and nutrient-enriched biochar treatments, although mineral N leaching tended to be lower in the nutrient-enriched biochar treatment than in the regular biochar treatment. The 15N analysis revealed that biochar application increased the plant uptake of added nitrate, but reduced the plant uptake of added ammonium compared to the fertilizer only treatment. Thus, the uptake of total N derived from added NH4NO3 fertilizer was not affected by the biochar addition, and cannot explain the increase in plant biomass in biochar treatments. Instead, the increased plant biomass at the higher biochar application rate was attributed to the enhanced uptake of N derived from soil. This suggests that the interactions between biochar and native soil organic N may be important determinants of the availability of soil N to plant growth.

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