scholarly journals Nitrogen dynamics after two years of elevated CO2 in phosphorus limited Eucalyptus woodland

2020 ◽  
Vol 150 (3) ◽  
pp. 297-312
Author(s):  
Louise C. Andresen ◽  
Yolima Carrillo ◽  
Catriona A. Macdonald ◽  
Laura Castañeda-Gómez ◽  
Samuel Bodé ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Nutrient Availability ◽  
N Mineralization ◽  
Free Amino ◽  
Organic N ◽  
Limiting Factor ◽  
N Availability ◽  
Available N ◽  
Gross N Mineralization ◽  
N Cycle

Abstract It is uncertain how the predicted further rise of atmospheric carbon dioxide (CO2) concentration will affect plant nutrient availability in the future through indirect effects on the gross rates of nitrogen (N) mineralization (production of ammonium) and depolymerization (production of free amino acids) in soil. The response of soil nutrient availability to increasing atmospheric CO2 is particularly important for nutrient poor ecosystems. Within a FACE (Free-Air Carbon dioxide Enrichment) experiment in a native, nutrient poor Eucalyptus woodland (EucFACE) with low soil organic matter (≤ 3%), our results suggested there was no shortage of N. Despite this, microbial N use efficiency was high (c. 90%). The free amino acid (FAA) pool had a fast turnover time (4 h) compared to that of ammonium (NH4+) which was 11 h. Both NH4-N and FAA-N were important N pools; however, protein depolymerization rate was three times faster than gross N mineralization rates, indicating that organic N is directly important in the internal ecosystem N cycle. Hence, the depolymerization was the major provider of plant available N, while the gross N mineralization rate was the constraining factor for inorganic N. After two years of elevated CO2, no major effects on the pools and rates of the soil N cycle were found in spring (November) or at the end of summer (March). The limited response of N pools or N transformation rates to elevated CO2 suggest that N availability was not the limiting factor behind the lack of plant growth response to elevated CO2, previously observed at the site.

scholarly journals The biodiversity - N cycle relationship: a 15N tracer experiment with soil from plant mixtures of varying diversity to model N pool sizes and transformation rates

2020 ◽  
Vol 56 (7) ◽  
pp. 1047-1061 ◽  
Author(s):  
Soni Lama ◽  
Thomas Kuhn ◽  
Moritz F. Lehmann ◽  
Christoph Müller ◽  
Odette Gonzalez ◽  
...  
Keyword(s):  
N Mineralization ◽  
Tracer Experiment ◽  
Soil Samples ◽  
N Cycling ◽  
Organic N ◽  
Autotrophic Nitrification ◽  
Gross N Mineralization ◽  
Jena Experiment ◽  
N Cycle ◽  
The Jena Experiment

Abstract We conducted a 15N tracer experiment in laboratory microcosms with field-fresh soil samples from a biodiversity experiment to evaluate the relationship between grassland biodiversity and N cycling. To embrace the complexity of the N cycle, we determined N exchange between five soil N pools (labile and recalcitrant organic N, dissolved NH4+ and NO3− in soil solution, and exchangeable NH4+) and eight N transformations (gross N mineralization from labile and recalcitrant organic N, NH4+ immobilization into labile and recalcitrant organic N, autotrophic nitrification, heterotrophic nitrification, NO3− immobilization, adsorption of NH4+) expected in aerobic soils with the help of the N-cycle model Ntrace. We used grassland soil of the Jena Experiment, which includes plant mixtures with 1 to 60 species and 1 to 4 functional groups (legumes, grasses, tall herbs, small herbs). The 19 soil samples of one block of the Jena Experiment were labeled with either 15NH4+ or 15NO3- or both. In the presence of legumes, gross N mineralization and autotrophic nitrification increased significantly because of higher soil N concentrations in legume-containing plots and high microbial activity. Similarly, the presence of grasses significantly increased the soil NH4+ pool, gross N mineralization, and NH4+ immobilization, likely because of enhanced microbial biomass and activity by providing large amounts of rhizodeposits through their dense root systems. In our experiment, previously reported plant species richness effects on the N cycle, observed in a larger-scale field experiment within the Jena Experiment, were not seen. However, specific plant functional groups had a significant positive impact on the N cycling in the incubated soil samples.

Use of hot KCl-NH4-N to estimate fertilizer N requirements

1997 ◽  
Vol 77 (2) ◽  
pp. 161-166 ◽  
Author(s):  
C. A. Campbell ◽  
Y. W. Jamel ◽  
A. Jalil ◽  
J. Schoenau
Keyword(s):  
N Mineralization ◽  
Growth Models ◽  
Growing Season ◽  
Order Rate Constant ◽  
Weather Data ◽  
N Availability ◽  
Fertilizer N ◽  
Available N ◽  
Mineralizable N ◽  
Potentially Mineralizable N

We need an easy-to-use chemical index for estimating the amount of N that becomes available during the growing season, to improve N use efficiency. This paper discusses how producers may, in future, use crop growth models that incorporate indices of soil N availability, to make more accurate, risk-sensitive estimates of fertilizer N requirements. In a previous study, we developed an equation, using 42 diverse Saskatchewan soils, that related potentially mineralizable N (N0) to NH4N extracted with hot 2 M KCl (X), (i.e., N0 = 37.7 + 7.7X, r2 = 0.78). We also established that the first order rate constant (k) for N mineralization at 35°C is indeed a constant for arable prairie soils (k = 0.067 wk−1). We modified the N submodel of CERES-wheat to include k and N0 (values of N0 were derived from the hot KCl test). With long-term weather data (precipitation and temperature) as input, this model was used to estimate probable N mineralization during a growing season and yield of wheat (grown on fallow or stubble), in response to fertilizer N rates at Swift Current. The model output indicated that the amount of N mineralized in a growing season for wheat on fallow was similar to that for wheat on stubble, as we hypothesized. Further the model indicated that rate of fertilizer N had only minimal effect on N mineralized. We concluded that, despite the importance of knowing the Nmin capability of a soil, it is available water, initial levels of available N and rate of fertilizer N that are the main determinants of yield in this semiarid environment. The theoretical approach we have proposed must be validated under field conditions before it can be adopted for use. Key words: N mineralization, Hot KCl-NH4-N, potentially mineralizable N, CERES-wheat model

Empirical relationships between temperature and nitrogen availability across North American forests

1992 ◽  
Vol 22 (5) ◽  
pp. 707-712 ◽  
Author(s):  
Xiwei Yin
Keyword(s):  
N Mineralization ◽  
Regional Scale ◽  
Mineral Soil ◽  
Published Data ◽  
N Availability ◽  
Net N Mineralization ◽  
Soil N ◽  
Litter Fall ◽  
Available N ◽  
N Pool

Published data were analyzed to examine whether nitrogen (N) availability varies along macroclimatic gradients in North America. Extractable N produced during 8-week aerobic laboratory incubation was used as an index of potential net N mineralization. Mean extractable N during the growing season in the forest floor plus top mineral soil was used as an index of the available N pool. Using multiple regression, potential net N mineralization was shown to increase with available N and with litter-fall N (R2 = 0.722). Available N increased with increasing total soil N and with decreasing mean January and July air temperatures (R2 = 0.770). These relationships appeared to hold also for deciduous and coniferous forests separately across regions. Results suggest that net N mineralization output under uniform temperature and moisture conditions can be generally expressed by variations of N input (litter fall) and the available soil N pool, and that the available soil N pool is predictable along a temperature gradient at a regional scale.

scholarly journals Nitrogen Availability from High-nitrogen-containing Organic Fertilizers

2006 ◽  
Vol 16 (1) ◽  
pp. 39-42 ◽  
Author(s):  
T.K. Hartz ◽  
P.R. Johnstone
Keyword(s):  
Blood Meal ◽  
Nitrogen Availability ◽  
Organic Fertilizers ◽  
Organic N ◽  
N Availability ◽  
Vegetable Production ◽  
Feather Meal ◽  
Available N ◽  
Organic Vegetable Production ◽  
Seabird Guano

Limited soil nitrogen (N) availability is a common problem in organic vegetable production that often necessitates in-season fertilization. The rate of net nitrogen mineralization (Nmin) from four organic fertilizers (seabird guano, hydrolyzed fish powder, feather meal, and blood meal) containing between 11.7% and 15.8% N was compared in a laboratory incubation. The fertilizers were mixed with soil from a field under organic management and incubated aerobically at constant moisture at 10, 15, 20, and 25 °C. Nmin was determined on samples extracted after 1, 2, 4, and 8 weeks. Rapid Nmin was observed from all fertilizers at all temperatures; within 2 weeks between 47% and 60% of organic N had been mineralized. Temperature had only modest effects, with 8-week Nmin averaging 56% and 66% across fertilizers at 10 and 25 °C, respectively. Across temperatures, 8-week Nmin averaged 60%, 61%, 62%, and 66% for feather meal, seabird guano, fish powder, and blood meal, respectively. Cost per unit of available N (mineralized N + initial inorganic N) varied widely among fertilizers, with feather meal the least and fish powder the most expensive.

scholarly journals Nutrient Availability under Lettuce Grown in Rye Mulch in Histosols

Nitrogen ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 137-150
Author(s):  
Jacynthe Dessureault-Rompré ◽  
Alexis Gloutney ◽  
Jean Caron
Keyword(s):  
Nutrient Availability ◽  
Crop Production ◽  
Growing Season ◽  
Organic N ◽  
N Availability ◽  
Long Term Effects ◽  
Vegetable Crop ◽  
Conservation Practice ◽  
Lettuce Growth ◽  
The Impact

Vegetable crop production, which is expanding worldwide, is managed extremely intensively and is therefore raising concerns about soil degradation. The objective of this study was to analyze the impact of using rye mulch as a conservation practice on nutrient availability for lettuce grown in histosols. The rye cover crop was established in the fall of 2018 at two cultivated peatland sites. The following summer, lettuce crops were planted at both sites on the rye mulch cover and on control plots. Lysimeters were used to extract the soil solution once a week during lettuce growth. Various soil properties were analyzed in the soil sampled at the end of the lettuce growing season. The rye yield was higher at site 1 than at site 2 and the lettuce growth was reduced at site 1 under the rye mulch treatment. The rye mulch reduced mineral N and dissolved organic N availability at both sites. The N dynamics in histosols might be fast enough to supply the lettuce needs; however, the implantation difficulties must first be overcome to confirm that hypothesis. At the end of the lettuce growth period, soil total and active C pools and soluble organic soil N in the rye mulch treatment sample were significantly higher at site 1 than at site 2. The presence of rye mulch improved the carbon pool over a single growing season. The use of rye mulch as a soil conservation practice for vegetable crop production appears promising for histosols; however, more work is needed to gain a better understanding on the long-term effects of decomposing rye mulch and roots on soil nutrient availability, soil health and C sequestration, and on the nitrogen uptake pathways and growth of cash crops. Future works which would include consecutive years of study at multiple sites are also needed to be able to confirm and generalize the observations found in the present work.

Availability of nitrogen in solid manure amendments with different C:N ratios

2002 ◽  
Vol 82 (2) ◽  
pp. 219-225 ◽  
Author(s):  
P. Qian ◽  
J. J. Schoenau
Keyword(s):  
Anion Exchange ◽  
N Mineralization ◽  
N Uptake ◽  
C:N Ratio ◽  
Anion Exchange Membrane ◽  
N Availability ◽  
Short Term ◽  
Available N ◽  
Manure Amendments ◽  
Exchange Membrane

Manures behave differently as sources of available N due to differences in the amounts and forms of N in the manure. The C:N ratio is an important factor affecting the rate of mineralization and release of available N from manures in which the majority of N is contained in organic forms. In order to ascertain the effect of manure C:N ratio on N mineralization in manure-amended soils, 13 solid manures with a large range in C:N ratio were applied to two Saskatchewan soils (Haverhill sandy loam and Blaine Lake clay loam) at 100 mg N kg-1 along with control (no manure) treatments. A growth chamber experiment was conducted to evaluate the relationship between manure C:N ratio and canola yield and N uptake, and a laboratory incubation was conducted to measure how the addition of manures with different C:N ratios affected the pattern of N release in the soils as measured by supply rates to anion exchange membrane (PRSTM) probes placed directly in the soil. Canola (Brassica napus var. Sprint) was grown under the same environmental conditions to maturity, and yield and nutrient contents were determined. A significant increase in canola yield and N uptake was observed over the control in both soils only when amended with poultry manure (C:N 7.6) or a pelletized form of hog manure that was supplemented with fertilizer N (C:N 6.6). A significant negative correlation was found between cattle manure organic C:N ratio and N mineralization. Overall, the manures showed limited release of available N over the short-term (67 d) when the organic C:N ratio was in the range of 13–15 and tended to decrease N availability in the short-term if the organic C:N ratio was over 15. The C:N ratio appears to be a useful parameter to measure when attempting to predict the effects of solid manure amendments on short-term N availability. Key words: Nitrogen availability, mineralization, manure, C:N ratio, anion exchange membrane

scholarly journals Nitrogen Dynamics Associated with Organic and Inorganic Inputs to Substrate Commonly Used on Rooftop Farms

HortScience ◽  
2015 ◽  
Vol 50 (6) ◽  
pp. 806-813 ◽  
Author(s):  
Angela Y.Y. Kong ◽  
Cynthia Rosenzweig ◽  
Joshua Arky
Keyword(s):  
The United States ◽  
Organic N ◽  
N Availability ◽  
Inorganic N ◽  
Available N ◽  
Nutrient Runoff ◽  
Swiss Chard ◽  
Rooftop Farming ◽  
N Input ◽  
Synthetic Fertilizer

Employing rooftops for the cultivation of crops in limited urban space has garnered interest in densely populated cities in the United States, where there is a growing demand for locally sourced vegetable products. Fertility management recommendations for rooftop farming, however, are scant. With insufficient research on nutrient cycling within rooftop farming systems, which tend to use soilless substrates with low organic matter content, the potential tradeoffs between the negative impacts (e.g., nutrient runoff) and the benefits (e.g., increased locally produced vegetables, stormwater retention, etc.) associated with rooftop farms are unclear. The objective of this study was to evaluate the effects of organic and inorganic nitrogen (N) inputs on the N dynamics within substrate typically used on rooftop farms. Substrate without added N inputs (control) was compared with substrates receiving N sources that are both realistic for and/or reflective of amendments currently applied on urban rooftop farms: a synthetic fertilizer (Osmocote® 14N–4.2P–11.6K), and three organic N inputs—composted poultry manure, municipal green waste (MGW) compost, and vermicompost. Aboveground crop biomass and yields of Beta vulgaris (swiss chard), along with inorganic N availability (ammonium: and nitrate: ), potentially mineralizable nitrogen (PMN), leachate-inorganic N concentrations, and pH and electrical conductivity (EC) levels were measured during an 8-week greenhouse experiment. Despite differences in carbon-to-nitrogen ratios (C:N), few differences in N cycling and yields were found among the treatments receiving organic N inputs. Crop yields from the synthetic fertilizer and MGW compost treatments were higher than the other organic N input treatments. Inorganic N levels in the synthetic fertilizer treatment decreased from 129 mg N/L at the start of the season to 113 mg N/L at the end of the season, while nearly 10-fold decreases of inorganic N concentrations in the substrate of the control and organic N input treatments from week 0 (79.5–117.8 mg N/L) to week 8 (12.8–16.6 mg N/L) were observed. Greater N availability at critical periods during the season may have promoted greater crop N uptake efficiency and, therefore, higher yields in the system receiving synthetic fertilizer. However, the greatest losses of and via leachate were also measured from this treatment. Our results show that the type of N input influenced plant-available N and yields and that the MGW compost treatment best achieved the balance between higher yields and reduced N losses to potential roof runoff. Furthermore, additional N inputs to these systems, particularly to the treatments receiving organic composts, will likely be necessary if a high N-demanding crop (such as swiss chard) is to be grown in the same substrates for more than 8 weeks. Rooftop farming is an emergent component of urban agriculture; regulations and guidelines for nutrient management of rooftop farms are necessary to optimize productivity and long-term benefits and to minimize negative environmental impacts.

Plant phenols contents and their changes with nitrogen availability in peatlands of northeastern China

2020 ◽  
Vol 13 (6) ◽  
pp. 713-721
Author(s):  
Di Wu ◽  
Xian-Wei Wang ◽  
Shi-Qi Xu ◽  
Chong-Juan Chen ◽  
Rong Mao ◽  
...  
Keyword(s):  
Climate Warming ◽  
Nutrient Availability ◽  
Nitrogen Availability ◽  
Resource Competition ◽  
N Deposition ◽  
Northeastern China ◽  
Organic N ◽  
N Availability ◽  
Boreal Peatlands ◽  
Leaf N

Abstract Aims Climate warming and increasing nitrogen (N) deposition have influenced plant nutrient status and thus plant carbon (C) fixation and vegetation composition in boreal peatlands. Phenols, which are secondary metabolites in plants for defense and adaptation, also play important roles in regulating peatland C dynamics due to their anti-decomposition properties. However, how the phenolic levels of different functional types of plants vary depending on nutrient availability remain unclear in boreal peatlands. Methods Here, we investigated total phenols contents (TPC) and total tannins contents in leaves of 11 plant species in 18 peatlands of the Great Hing’an Mountains area in northeastern China, and examined their variations with leaf N and phosphorus (P) and underlying mechanisms. Important Findings Shrubs had higher TPC than graminoids, indicating less C allocation to defense and less uptake of organic N in faster-growing and nonmycorrhizal graminoids than in slower-growing and mycorrhizal shrubs. For shrubs, leaf TPC decreased with increasing N contents but was not influenced by changing leaf phosphorus (P) contents, which suggested that shrubs would reduce the C investment for defense with increasing N availability. Differently, leaf TPC of graminoids increased with leaf N contents and decreased with leaf P contents. As graminoids are more N-limited and less P-limited, we inferred that graminoids would increase the defensive C investment under increased nutrient availability. We concluded that shrubs would invest more C in growth than in defense with increasing N availability, but it was just opposite for graminoids, which might be an important mechanism to explain the resource competition and encroachment of shrubs in boreal peatlands in the context of climate warming and ever-increasing N deposition.

C and N mineralization of composted and anaerobically stored ruminant manure in differently textured soils

2000 ◽  
Vol 135 (2) ◽  
pp. 151-159 ◽  
Author(s):  
INGRID K. THOMSEN ◽  
JØRGEN E. OLESEN
Keyword(s):  
N Mineralization ◽  
Storage Period ◽  
Clay Content ◽  
Organic N ◽  
Net N Mineralization ◽  
Turnover Rates ◽  
Inorganic N ◽  
Available N ◽  
C Pools ◽  
Anaerobic Storage

Three animal manures cross-labelled with 15N in either the urine, faeces or straw fractions were prepared. After a storage period of 86 days when the manures were exposed to either composting or to anaerobic storage, portions of the manures were incubated in six differently textured soils with clay contents ranging from 11 to 45%. Evolved CO2-C was determined during a 266 day incubation and inorganic N and 15N in soil were measured at the termination of the incubation. The mineralization of C was analysed using first-order kinetics, and two C pools with fast (P1) and slow (P2) turnover rates were estimated. The total conversion of added C (Ps) was estimated as Ps=P1+P2.The cumulated CO2 production was considerably higher from soils incubated with anaerobically stored manure compared with soils amended with composted manure. CO2 production levelled off after c. 60 days in the three sandier soils whereas CO2 continued to be produced throughout the incubation from the three soils with the highest clay content. More C was assigned to the easily decomposable P1 pool in the sandiest soils whereas the more recalcitrant P2 pool was larger in the soils with higher clay content. Because of the different relationships between soil texture and C pools, Ps ended up being similar for five of the six soils. When taking C losses during the preceding storage into account, the accumulated C losses during storage and after incubation in soil accounted for 60 and 54% of C initially present in the composted and anaerobically stored manure, respectively.Net N mineralization which averaged 16% of applied organic N took place in all soils amended with composted manure. Soils with anaerobically stored manure showed net immobilization after the 266 days of incubation. The amount of N immobilized accounted for up to 30% of the inorganic N applied with the manure. As anaerobically stored manure generally loses less inorganic N during storage, it may contain more inorganic N than composted manure at the time of field application. Because of the immobilization that takes place after application of anaerobically stored manure to soil, the immediate levels of plant available N in soil may not be as different from soil supplied with composted manure as could be expected from the inorganic N content in the two types of manure. However, when considering the manure as a N resource, anaerobic storage is superior to composting.

scholarly journals Subcritical water extraction to isolate kinetically different soil nitrogen fractions

2013 ◽  
Vol 10 (11) ◽  
pp. 7435-7447 ◽  
Author(s):  
S. Sleutel ◽  
M. A. Kader ◽  
K. Demeestere ◽  
C. Walgraeve ◽  
J. Dewulf ◽  
...  
Keyword(s):  
Bonding Strength ◽  
N Mineralization ◽  
Subcritical Water ◽  
Water Extraction ◽  
Organic N ◽  
Soil N ◽  
Subcritical Water Extraction ◽  
Available N ◽  
Upland Soils ◽  
N Fractions

Abstract. Soil organic N is largely composed of inherently biologically labile proteinaceous N and its persistence in soil is mainly explained by stabilization through binding to minerals and other soil organic matter (SOM) components at varying strengths. In order to separate kinetically different soil N fractions we hypothesize that an approach which isolates soil N fractions on the basis of bonding strength is required, rather than employing chemical agents or physical methods. We developed a sequential subcritical water extraction (SCWE) procedure at 100, 150 and 200 °C to isolate SOM fractions. We assessed these SCWE N fractions as predictors for aerobic and anaerobic N mineralization measured from 25 paddy soil cores in incubations. SCWE organic carbon (SCWE OC) and N (SCWE N) increased exponentially with the increase of temperature and N was extracted preferentially over OC. The efficiency of SCWE and the selectivity towards N were both lower in soils with increasingly reactive clay mineralogy. Stepwise linear regression found no relations between the SCWE fractions and the anaerobic N mineralization rate but instead with pH and a model parameter describing the temperature dependency of SCWE extraction. Both were linked to texture, mineralogy and content of pedogenic oxides, which suggests an indirect relation between anaerobic NH4+ release and these edaphic soil factors. N mineralization appeared to be largely decoupled from SOM quantity and quality. From the present study on young paddy soils low in pedogenic oxides and with high fixed NH4+ content we cannot infer the performance of SCWE to isolate bio-available N in more developed upland soils. There may be potential to separate kinetically different SOM pools from upland soils because 1° for aerobic N mineralization at 100–150 °C SCWE N was the best predictor; and 2° SCWE selectively extracted N over C and this preference depended on the mineralogical composition. Hence N fractions differing in bonding strength with minerals or SOM might be isolated at different temperatures, and specifically this association has frequently been found a prominent stabilization mechanism of N in temperate region cropland soils.

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