scholarly journals Reviews and syntheses: measuring ecosystem nitrogen status – a comparison of proxies

2016 ◽  
Vol 13 (18) ◽  
pp. 5395-5403 ◽  
Author(s):  
Maya Almaraz ◽  
Stephen Porder
Keyword(s):  
N Mineralization ◽  
Nitrogen Availability ◽  
N Availability ◽  
Net N Mineralization ◽  
Tropical Regions ◽  
Net Nitrification ◽  
Kendall’S Τ ◽  
Soil Δ15n ◽  
N Status

Abstract. There are many proxies used to measure nitrogen (N) availability in watersheds, but the degree to which they do (or do not) correlate within a watershed has not been systematically addressed. We surveyed the literature for intact forest or grassland watersheds globally, in which several metrics of nitrogen availability have been measured. Our metrics included the following: foliar δ15N, soil δ15N, net nitrification, net N mineralization, and the ratio of dissolved inorganic to organic nitrogen (DIN : DON) in soil solution and streams. We were particularly interested in whether terrestrial and stream based proxies for N availability were correlated where they were measured in the same place. Not surprisingly, the strongest correlation (Kendall's τ) was between net nitrification and N mineralization (τ  =  0.71, p < 0.0001). Net nitrification and N mineralization were each correlated with foliar and soil δ15N (p < 0.05). Foliar and soil δ15N were more tightly correlated in tropical sites (τ  =  0.68, p < 0.0001), than in temperate sites (τ  =  0.23, p  =  0.02). The only significant correlations between terrestrial- and water-based metrics were those of net nitrification (τ  =  0.48, p  =  0.01) and N mineralization (τ  =  0.69, p  =  0.0001) with stream DIN : DON. The relationship between stream DIN : DON with both net nitrification and N mineralization was significant only in temperate, but not tropical regions. To our surprise, we did not find a significant correlation between soil δ15N and stream DIN : DON, despite the fact that both have been used to infer spatially or temporally integrated N status. Given that both soil δ15N and stream DIN : DON are used to infer long-term N status, their lack of correlation in watersheds merits further investigation.

scholarly journals Measuring ecosystem nitrogen status: a comparison of proxies

2016 ◽  
Author(s):  
Maya Almaraz ◽  
Stephen Porder
Keyword(s):  
N Mineralization ◽  
Organic Nitrogen ◽  
Nitrogen Availability ◽  
N Availability ◽  
Net N Mineralization ◽  
Net Nitrification ◽  
Soil Δ15n ◽  
Foliar Δ15n ◽  
N Status

Abstract. There are many proxies used to measure nitrogen (N) availability in watersheds, but the degree to which they do (or do not correlate) within a watershed has not been systematically addressed. We surveyed the literature for intact forest or grassland watersheds in which several metrics of nitrogen availability have been measured. Our metrics included: foliar δ15N, soil δ15N, net nitrification, net N mineralization, and the ratio of dissolved inorganic to organic nitrogen (DIN : DON) in soil solution and streams. Not surprisingly, the strongest correlation (Kendall's tau) was between net nitrification and N mineralization (τ = 0.61, p < 0.0001). Net nitrification was correlated with foliar and soil δ15N (p < 0.05), while net N mineralization was correlated with soil δ15N but not foliar δ15N. Foliar and soil δ15N were correlated across tropical sites (τ = 0.68, p < 0.0001), but not in temperate sites (τ = 0.02, p > 0.05). To our surprise, the only significant correlation we found between terrestrial- and water-based metrics was that of net N mineralization with stream DIN : DON (τ = 0.62, p = 0.004). Given both soil δ15N and stream DIN : DON are used to infer long-term N status, their lack of correlation in watersheds merits further investigation.

scholarly journals Nitrogen Availability in Biochar-Amended Soils with Excessive Compost Application

Agronomy ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 444 ◽  
Author(s):  
Chen-Chi Tsai ◽  
Yu-Fang Chang
Keyword(s):  
N Mineralization ◽  
Nitrogen Availability ◽  
Agricultural Soils ◽  
Inorganic Nitrogen ◽  
Clay Content ◽  
N Availability ◽  
Net N Mineralization ◽  
Mineral N ◽  
Mineralization Potential ◽  
The Impact

Adding biochar to excessive compost amendments may affect compost mineralization rate and nitrogen (N) availability. The objective of this 371-day incubation study was to evaluate the effects of four proportions of woody biochar (0%, 0.5%, 1.0%, and 2.0%) from lead tree (Leucaena leucocephala (Lam.) de. Wit) biochar produced at 750 °C through dynamic mineral N and N mineralization rates in three rural soils (one Oxisol and two Inceptisols). In each treatment, 5% poultry–livestock manure compost was added to serve as an excessive application. The results indicated that the biochar decreased available total inorganic nitrogen (TIN) (NO3−-N+NH4+-N) by on average 6%, 9% and 19% for 0.5%, 1.0% and 2.0% treatments, respectively. The soil type strongly influenced the impact of the biochar addition on the soil nitrogen mineralization potential, especially the soil pH and clay content. This study showed that the co-application of biochar and excessive compost benefited the agricultural soils by improving NO3−-N retention in agroecosystems. The application of biochar to these soils to combine it with excessive compost appeared to be an effective method of utilizing these soil amendments, as it diminished the net N mineralization potential and reduced the nitrate loss of the excessive added compost.

Improving nitrogen availability indicators by emphasizing correlations between gross nitrogen mineralization and the quality and quantity of labile soil organic matter fractions

2012 ◽  
Author(s):  
Mike J. Castellano ◽  
Abraham G. Shaviv ◽  
Raphael Linker ◽  
Matt Liebman
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
N Mineralization ◽  
Nitrogen Availability ◽  
N Availability ◽  
Net N Mineralization ◽  
N Dynamics ◽  
Organic Matter Fractions ◽  
N Fertility ◽  
Labile Soil Organic Matter

A major goal in Israeli and U.S. agroecosystems is to maximize nitrogen availability to crops while minimizing nitrogen losses to air and water resources. This goal has presented a significant challenge to global agronomists and scientists because crops require large inputs of nitrogen (N) fertilizer to maximize yield, but N fertilizers are easily lost to surrounding ecosystems where they contribute to water pollution and greenhouse gas concentrations. Determination of the optimum N fertilizer input is complex because the amount of N produced from soil organic matter varies with time, space and management. Indicators of soil N availability may help to guide requirements for N fertilizer inputs and are increasingly viewed as indicators of soil health To address these challenges and improve N availability indicators, project 4550 “Improving nitrogen availability indicators by emphasizing correlations between gross nitrogen mineralization and the quality and quantity of labile organic matter fractions” addressed the following objectives: Link the quantity and quality of labile soil organic matter fractions to indicators of soil fertility and environmental quality including: i) laboratory potential net N mineralization ii) in situ gross N mineralization iii) in situ N accumulation on ion exchange resins iv) crop uptake of N from mineralized soil organic matter sources (non-fertilizer N), and v) soil nitrate pool size. Evaluate and compare the potential for hot water extractable organic matter (HWEOM) and particulate organic matter quantity and quality to characterize soil N dynamics in biophysically variable Israeli and U.S. agroecosystems that are managed with different N fertility sources. Ultimately, we sought to determine if nitrogen availability indicators are the same for i) gross vs. potential net N mineralization processes, ii) diverse agroecosystems (Israel vs. US) and, iii) management strategies (organic vs. inorganic N fertility sources). Nitrogen availability indicators significantly differed for gross vs. potential N mineralization processes. These results highlight that different mechanisms control each process. Although most research on N availability indicators focuses on potential net N mineralization, new research highlights that gross N mineralization may better reflect plant N availability. Results from this project identify the use of ion exchange resin (IERs) beads as a potential technical advance to improve N mineralization assays and predictors of N availability. The IERs mimic the rhizosphere by protecting mineralized N from loss and immobilization. As a result, the IERs may save time and money by providing a measurement of N mineralization that is more similar to the costly and time consuming measurement of gross N mineralization. In further search of more accurate and cost-effective predictors of N dynamics, Excitation- Emission Matrix (EEM) spectroscopy analysis of HWEOM solution has the potential to provide reliable indicators for changes in HWEOM over time. These results demonstrated that conventional methods of labile soil organic matter quantity (HWEOM) coupled with new analyses (EEM) may be used to obtain more detailed information about N dynamics. Across Israeli and US soils with organic and inorganic based N fertility sources, multiple linear regression models were developed to predict gross and potential N mineralization. The use of N availability indicators is increasing as they are incorporated into soil health assessments and agroecosystem models that guide N inputs. Results from this project suggest that some soil variables can universally predict these important ecosystem process across diverse soils, climate and agronomic management. BARD Report - Project4550 Page 2 of 249 

Long-term effects of repeated N fertilization and straw application in a jack pine forest. 3. Nitrogen availability in the forest floor

1995 ◽  
Vol 25 (12) ◽  
pp. 1991-1996 ◽  
Author(s):  
C.E. Prescott ◽  
B.E. Kishchuk ◽  
G.F. Weetman
Keyword(s):  
Nitrogen Availability ◽  
Jack Pine ◽  
N Fertilization ◽  
Ground Vegetation ◽  
N Availability ◽  
Net N Mineralization ◽  
Long Term Effects ◽  
Forest Floors ◽  
Straw Application

A long-term increase in N availability was evident in higher rates of net N mineralization and lower C/N ratios in jack pine (Pinusbanksiana Lamb.) forest floors that received 672 kg N•ha−1 in six applications or a single application of straw. There was no evidence of increased N availability in plots that received P and K in addition to N. Litter N concentrations were higher in N-fertilized and straw-treated plots, but rates of C mineralization and litter decomposition were not increased. Additions of N in repeated small applications or in conjunction with readily decomposable C in straw likely resulted in high retention of N in the ecosystem. The long-term increase in N availability was attributed to increased recycling of N, retention of added N in the ecosystem, and reductions in the ericaceous ground vegetation.

scholarly journals Effects of experimental freezing on soil nitrogen dynamics in soils from a net nitrification gradient in a nitrogen-saturated hardwood forest ecosystem

2010 ◽  
Vol 40 (3) ◽  
pp. 436-444 ◽  
Author(s):  
Frank S. Gilliam ◽  
Adam Cook ◽  
Salina Lyter
Keyword(s):  
N Mineralization ◽  
Soil Freezing ◽  
N Saturation ◽  
Net N Mineralization ◽  
N Dynamics ◽  
Net Nitrification ◽  
Soil Nitrogen Dynamics ◽  
Soil N Cycle ◽  
N Mineralization Potential ◽  
Fernow Experimental Forest

This study examined effects of soil freezing on N dynamics in soil along an N processing gradient within a mixed hardwood dominated watershed at Fernow Experimental Forest, West Virginia. Sites were designated as LN (low rates of N processing), ML (moderately low), MH (moderately high), and HN (high). Soils underwent three 7-day freezing treatments (0, –20, or –80 °C) in the laboratory. Responses varied between temperature treatments and along the gradient. Initial effects differed among freezing treatments for net N mineralization, but not nitrification, in soils across the gradient, generally maintained at LN < ML ≤ MH < HN for all treatments. Net N mineralization potential was higher following freezing at –20 and –80 °C than control; all were higher than at 0 °C. Net nitrification potential exhibited similar patterns. LN was an exception, with net nitrification low regardless of treatment. Freezing response of N mineralization differed greatly from that of nitrification, suggesting that soil freezing may decouple two processes of the soil N cycle that are otherwise tightly linked at our site. Results also suggest that soil freezing at temperatures commonly experienced at this site can further increase net nitrification in soils already exhibiting high nitrification from N saturation.

scholarly journals Incubation methods for assessing mineralizable nitrogen in soils under sugarcane

2013 ◽  
Vol 37 (2) ◽  
pp. 450-461 ◽  
Author(s):  
Eduardo Mariano ◽  
Paulo Cesar Ocheuze Trivelin ◽  
José Marcos Leite ◽  
Michele Xavier Vieira Megda ◽  
Rafael Otto ◽  
...  
Keyword(s):  
N Mineralization ◽  
Standard Technique ◽  
Extraction Methods ◽  
N Fertilization ◽  
Chemical Extraction ◽  
Net N Mineralization ◽  
Anaerobic Incubation ◽  
Aerobic Incubation ◽  
Mineralizable N

Considering nitrogen mineralization (N) of soil organic matter is a key aspect for the efficient management of N fertilizers in agricultural systems. Long-term aerobic incubation is the standard technique for calibrating the chemical extraction methods used to estimate the potentially mineralizable N in soil. However, the technique is laborious, expensive and time-consuming. In this context, the aims of this study were to determine the amount of soil mineralizable N in the 0-60 cm layer and to evaluate the use of short-term anaerobic incubation instead of long-term aerobic incubation for the estimation of net N mineralization rates in soils under sugarcane. Five soils from areas without previous N fertilization were used in the layers 0-20, 20-40 and 40-60 cm. Soil samples were aerobically incubated at 35 ºC for 32 weeks or anaerobically incubated (waterlogged) at 40 ºC for seven days to determine the net soil N mineralization. The sand, silt and clay contents were highly correlated with the indexes used for predicting mineralizable N. The 0-40 cm layer was the best sampling depth for the estimation of soil mineralizable N, while in the 40-60 cm layer net N mineralization was low in both incubation procedures. Anaerobic incubation provided reliable estimates of mineralizable N in the soil that correlated well with the indexes obtained using aerobic incubation. The inclusion of the pre-existing NH4+-N content improved the reliability of the estimate of mineralizable N obtained using anaerobic incubation.

scholarly journals Effect of 50 Years of No-Tillage, Stubble Retention, and Nitrogen Fertilization on Soil Respiration, Easily Extractable Glomalin, and Nitrogen Mineralization

Agronomy ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 151
Author(s):  
Pramod Jha ◽  
Kuntal M. Hati ◽  
Ram C. Dalal ◽  
Yash P. Dang ◽  
Peter M. Kopittke ◽  
...  
Keyword(s):  
Soil Respiration ◽  
N Mineralization ◽  
Positive Impact ◽  
N Fertilization ◽  
N Fertilizer ◽  
N Availability ◽  
Soil Microbial ◽  
Stubble Retention ◽  
No Till

In subtropical regions, we have an incomplete understanding of how long-term tillage, stubble, and nitrogen (N) fertilizer management affects soil biological functioning. We examined a subtropical site managed for 50 years using varying tillage (conventional till (CT) and no-till (NT)), stubble management (stubble burning (SB) and stubble retention (SR)), and N fertilization (0 (N0), 30 (N30), and 90 (N90) kg ha−1 y−1) to assess their impact on soil microbial respiration, easily extractable glomalin-related soil protein (EEGRSP), and N mineralization. A significant three-way tillage × stubble × N fertilizer interaction was observed for soil respiration, with NT+SB+N0 treatments generally releasing the highest amounts of CO2 over the incubation period (1135 mg/kg), and NT+SR+N0 treatments releasing the lowest (528 mg/kg). In contrast, a significant stubble × N interaction was observed for both EEGRSP and N mineralization, with the highest concentrations of both EEGRSP (2.66 ± 0.86 g kg−1) and N mineralization (30.7 mg/kg) observed in SR+N90 treatments. Furthermore, N mineralization was also positively correlated with EEGRSP (R2 = 0.76, p < 0.001), indicating that EEGRSP can potentially be used as an index of soil N availability. Overall, this study has shown that SR and N fertilization have a positive impact on soil biological functioning.

Effect of landscape position on N mineralization and nitrification in a forested watershed in the Adirondack Mountains of New York

1999 ◽  
Vol 29 (4) ◽  
pp. 497-508 ◽  
Author(s):  
Kiyokazu Ohrui ◽  
Myron J Mitchell ◽  
Joseph M Bischoff
Keyword(s):  
New York ◽  
N Mineralization ◽  
Forest Floor ◽  
Landscape Position ◽  
Nitrification Rate ◽  
Forested Watershed ◽  
Net N Mineralization ◽  
Adirondack Mountains ◽  
Net Nitrification ◽  
Intermediate Rate

Within a forest ecosystem in the Adirondack Mountains of New York, net N mineralization and nitrification rates were measured at different landscape positions (zones). Net N mineralization rates (0-15 cm depth) were less (39 kg N·ha-1 per year) within a wetland without alder and with a coniferous overstory than an upland conifer zone (82 kg N·ha-1 per year) and an upland hardwood zone (107 kg N·ha-1 per year). Net N mineralization rates (39 to 82 kg N·ha-1 per year) and the forest floor N concentrations (2.3 to 2.5%) were higher than values reported (1.2-29 kg N·ha-1 and 1.1-2.12%, respectively) for other spruce forests. The net nitrification rates were higher at the upland hardwood zone (29 kg N·ha-1 per year) than the upland conifer zone (2 kg N·ha-1 per year). The wetland conifer zone without alders had an intermediate rate of net nitrification (13 kg N·ha-1 per year) compared with the upland zones. The presence of white alder (Alnus incana (L.) Moench) in the wetland increased the NO3- content and net nitrification rate of the soil.

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.

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