Biochar addition indirectly affects N2O emissions via soil moisture and plant N uptake

Growing plants affect soil moisture, mineral N and organic C (Corg) availability in soil and may thus play an important role in regulating denitrification. The availability of the main substrates for denitrification (Corg and NO3-) is controlled by root activity and higher denitrification activity in rhizosphere soils has been reported. We hypothesized that (I) plant N uptake governs NO3- availability for denitrification leading to increased N2O and N2 emissions, when plant N uptake is low due to smaller root system or root senescence. (II) Denitrification is stimulated by higher Corg availability from root exudation or decaying roots increasing total gaseous N emissions while decreasing their N2O/(N2O+N2) ratios.We tested these assumptions in a double labeling pot experiment with maize (Zea mays L.) grown under three N fertilization levels S / M / L (no / moderate / high N fertilization) and with cup plant (Silphium perfoliatum L., moderate N fertilization). After 6 weeks, all plants were labeled with 0.1 g N kg-1 (Ca(15NO3)2, 60 at%), and the 15N tracer method was applied to estimate plant N uptake, N2O and N2 emissions. To link denitrification with available C in the rhizosphere, 13CO2 pulse labeling (5 g Na213CO3, 99 at%) was used to trace C translocation from shoots to roots and its release by roots into the soil. CO2 evolving from soil was trapped in NaOH for &#948;13C analyses, and gas samples were taken for analysis of N2O and N2 from the headspace above the soil surface every 12 h.Although pots were irrigated, changing soil moisture through differences in plant water uptake was the main factor controlling daily N2O+N2 fluxes, cumulative N emissions, and N2O production pathways. In addition, total N2O+N2 emissions were negatively correlated with plant N uptake and positively with soil N concentrations. Recently assimilated C released by roots (13C) was positively correlated with root dry matter, but we could not detect any relationship with cumulative N emissions. We anticipate that higher Corg availability in pots with large root systems did not lead to higher denitrification rates as NO3- was limited due to plant uptake. In conclusion, plant growth controlled water and NO3- uptake and, subsequently, formation of anaerobic hotspots for denitrification.

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Management of Native Soil Nitrogen for Reducing Nitrous Oxide Emissions and Higher Rice Production

Journal of Agriculture and Environment ◽

10.3126/aej.v9i0.2110 ◽

2009 ◽

Vol 9 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Keshav R. Pandey ◽

S. C. Shah ◽

M. Becker

Keyword(s):

Soil Moisture ◽

Grain Yield ◽

Green Manure ◽

N Uptake ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Soil N ◽

Management Options ◽

Native Soil ◽

Bare Fallow

Present production of rice is far below its reported potential yield because of being Ndeficiency, the major constraint. Because of poverty, small farmers have to rely on native soil N-supply. Between wheat harvest and rice transplanting, a dry-to-wet season transition (DWT) period exist with changing soil moisture from aerobic to anaerobic and a large amount of native soil N loss is hypothesized. To study soil N dynamism and possible management options for DWT, two years field experiments were conducted in Chitwan with four land management treatments like bare fallow, mucuna, mungbean and maize. Treatments were randomly allotted in 10 m2 plots. During DWT, building up of 50-75 kg of nitrate-N was observed at 60-75 % field capacity (FC) soil moisture but lost after flooding through leaching and denitrification, resulting in low grain yield and N uptake of succeeding rice. Growing cover crops during DWT, reduced leaching loss by half and N2O emissions by two thirds of those in the bare fallows. Atmospheric-N addition by legumes ranged from 27 to 56 kg ha-1 depending on the types of legumes and increased N uptake and grain yield by 24-42 kg N ha-1 yr-1 and 1.2-2.1 Mg ha-1 yr-1respectively. Thus, cultivation of grain/green manure legumes appears economically and ecologically beneficial.Key Words: bare fallow, crop N uptake, denitrification, green manure, leaching, nitrate catch crops, nitrificationThe Journal of Agriculture and Environment Vol:9, Jun.2008 Page: 1-9

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Mitigation of N2O emissions from surface-irrigated cropping systems using water management and the nitrification inhibitor DMPP

Soil Research ◽

10.1071/sr15315 ◽

2016 ◽

Vol 54 (5) ◽

pp. 481 ◽

Cited By ~ 5

Author(s):

Hizbullah Jamali ◽

Wendy Quayle ◽

Clemens Scheer ◽

Jeff Baldock

Keyword(s):

Cropping Systems ◽

N Uptake ◽

Nitrification Inhibitor ◽

Irrigation Scheduling ◽

Irrigated Agriculture ◽

N2o Emissions ◽

15N Recovery ◽

Plant N Uptake ◽

Moisture Deficit ◽

N Pool

Soils under irrigated agriculture are a significant source of nitrous oxide (N2O) owing to high inputs of nitrogen (N) fertiliser and water. This study investigated the potential for N2O mitigation by manipulating the soil moisture deficit through irrigation scheduling in combination with, and in comparison to, using the nitrification inhibitor, 3,4-dimethylpyrazole phosphate (DMPP). Lysimeter cores planted with wheat were fitted with automated chambers for continuous measurements of N2O fluxes. Treatments included conventional irrigation (CONV), reduced deficit irrigation (RED), CONV-DMPP and RED-DMPP. The total seasonal volume of irrigation water applied was constant for all treatments but the timing and quantity in individual irrigation applications varied among treatments. 15N-labelled urea was used to track the source of N2O emissions and plant N uptake. The majority of N2O emissions occurred immediately after irrigations began on 1 September 2014. Applying RED and DMPP individually slightly decreased N2O emissions but when applied in combination (RED-DMPP) the greatest reductions in N2O emissions were observed. There was no effect of treatments on plant N uptake, 15N recovery or yield possibly because the system was not N limited. Half of the plant N and 53% to 87% of N2O was derived from non-fertiliser sources in soil, highlighting the opportunity to further exploit this valuable N pool.

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Nitrate and water uptake, rather than rhizodeposition, control denitrification in the presence of growing plants

10.5194/egusphere-egu21-1223 ◽

2021 ◽

Author(s):

Pauline Sophie Rummel ◽

Reinhard Well ◽

Birgit Pfeiffer ◽

Klaus Dittert ◽

Sebastian Floßmann ◽

...

Keyword(s):

Soil Moisture ◽

Water Uptake ◽

Plant Root ◽

Oxygen Deficiency ◽

N Uptake ◽

Root Exudation ◽

Root Systems ◽

Plant N Uptake ◽

N Losses ◽

Double Labeling

The main prerequisites for denitrification are availability of nitrate (NO3-) and easily decomposable organic substances, and oxygen deficiency. Growing plants modify all these parameters and may thus play an important role in regulating denitrification. Previous studies investigating plant root effects on denitrification have found contradictive results. Both increased and decreased denitrification in the presence of plants have been reported and were associated with higher Corg or lower NO3- availability, respectively. Accordingly, it is still unclear whether growing plants stimulate denitrification through root exudation or restrict it through NO3- uptake. Furthermore, reliable measurements of N2 fluxes and N2O/(N2O+N2) ratios in the presence of plants are scarce.Therefore, we conducted a double labeling pot experiment with either maize (Zea mays L.) or cup plant (Silphium perfoliatum L.) of the same age but differing in size of their shoot and root systems. The 15N gas flux method was applied to directly quantify N2O and N2 fluxes in situ. To link denitrification with available C in the rhizosphere, 13CO2 pulse labeling was used to trace C translocation from shoots to roots and its release by roots into the soil.Plant water uptake was a main factor controlling soil moisture and, thus, daily N2O+N2 fluxes, cumulative N emissions, and N2O production pathways. However, N fluxes remained on a low level when NO3- availability was low due to rapid plant N uptake. Only when both N and water uptake were low, high NO3- availability and high soil moisture led to strongly increased denitrification-derived N losses.Total CO2 efflux was positively correlated with root dry matter, but there was no indication of any relationship between recovered 13C from root exudation and cumulative N emissions. We anticipate that higher Corg availability in pots with large root systems did not lead to higher denitrification rates, as NO3- was limiting denitrification due to plant N uptake. Overall, we conclude that root-derived C stimulates denitrification only when soil NO3- is not limited and low O2 concentrations enable denitrification. Thus, root-derived C may stimulate denitrification under small plants, while N and water uptake become the controlling factors with increasing plant and root growth.

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Effect of N fertilisers and soil moisture levels on the N-gaseous losses and the plant N uptake in a maize pot experiment

Cereal Research Communications ◽

10.1556/crc.35.2007.2.172 ◽

2007 ◽

Vol 35 (2) ◽

pp. 853-856 ◽

Cited By ~ 1

Author(s):

Erika Nótás ◽

Katalin Debreczeni ◽

Katalin Berecz ◽

György Heltai

Keyword(s):

Soil Moisture ◽

N Uptake ◽

Pot Experiment ◽

Plant N Uptake ◽

N Fertilisers

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Optimizing Irrigation of Fresh Market Tomato Grown in the Mid-Atlantic United States

HortTechnology ◽

10.21273/horttech.23.6.859 ◽

2013 ◽

Vol 23 (6) ◽

pp. 859-867 ◽

Cited By ~ 1

Author(s):

Catherine S. Fleming ◽

Mark S. Reiter ◽

Joshua H. Freeman ◽

Rory Maguire

Keyword(s):

Soil Moisture ◽

N Uptake ◽

Cost Effective ◽

Residual Soil ◽

Soil Nitrate ◽

Fresh Market ◽

Plant N Uptake ◽

Irrigation Rate ◽

Growing Seasons ◽

Effective Water

Determining irrigation requirements for fresh market tomato (Solanum lycopersicum) production is essential to obtain optimum yields, cost-effective water use, and minimize nitrate leaching. The objective of this study was to determine the appropriate irrigation rate for polyethylene-mulched fresh market tomato grown in Virginia. This study investigated irrigation regimes by applying water based on evapotranspiration (ET) calculations in three spring and three fall seasons. Plants were grown using 0.0 × ET, 0.5 × ET, 1.0 × ET, 1.5 × ET, and 2.0 × ET. Additional irrigation treatments involved tensiometers installed at 12-inch depth in the bed, programmed to irrigate at soil moisture set points of −20, −40, and −60 kPa. Tensiometer treatments were able to irrigate up to nine times per day if soil moisture fell below the designated moisture set point. Measurements included fruit yield, plant and fruit nitrogen (N) uptake, and inorganic soil nitrate-N (NO3-N) at 0 to 10-, 10 to 20-, and 20 to 30-inch depths. Overall, the 0.5 × ET treatment provided optimum yields in all growing seasons except Spring 2010, which was unseasonably hot and dry. A tensiometer treatment (−40 kPa) provided optimum yields in all growing seasons, and was able to adjust irrigation in a hot and dry season. Residual soil NO3-N at 0 to 10 inches generally exhibited an inverse relationship with yield; greater yields resulted in less residual soil NO3-N. In most treatments throughout the duration of this study, plant N uptake + fruit N uptake accounted for most of the N fertilizer applied (68% to 151%). In conclusion, an irrigation rate of 0.5 × ET and a tensiometer treatment (−40 kPa) provided minimal irrigation inputs to obtain optimum marketable yields while also minimizing residual soil nitrate that may be prone to leaching after the season.

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Increased soil moisture content increases plant N uptake and the abundance of 15N in plant biomass

Plant and Soil ◽

10.1007/s11104-007-9477-0 ◽

2007 ◽

Vol 302 (1-2) ◽

pp. 263-271 ◽

Cited By ~ 16

Author(s):

Feike A. Dijkstra ◽

Weixin Cheng

Keyword(s):

Soil Moisture ◽

Moisture Content ◽

Soil Moisture Content ◽

Plant Biomass ◽

N Uptake ◽

Plant N Uptake

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Transformation of Nitrogen Fertilizers in Greenhouse Experiments

Agrokémia és Talajtan ◽

10.1556/agrokem.51.2002.1-2.18 ◽

2002 ◽

Vol 51 (1-2) ◽

pp. 147-156 ◽

Cited By ~ 2

Author(s):

Erika Nótás ◽

K. Debreczeni ◽

K. Fischl ◽

Keyword(s):

Soil Moisture ◽

Difference Method ◽

N Uptake ◽

First Year ◽

Fertilizer N ◽

Plant N Uptake ◽

Mineral N ◽

After Effect ◽

Gaseous Loss ◽

The Difference

The primary (1 st year) and the after-effects (2 nd , 3 rd year) of N fertilizers (KNO 3 , NH 4 Cl) on the soil-plant-atmosphere system were studied in a three-year greenhouse pot experiment with and without maize plants. The two- and three-year balances of the fertilizer N uptake and gaseous N losses were also analyzed. The cumulative values of the gaseous losses showed a similar trend in all years, significant differences were not obtained. On the basis of the three-year balance, the gaseous loss in the planted and unplanted pots was 18-22% and about 37-39%, respectively. Consequently, there was a 50% decrease in denitrificated gaseous losses of fertilizer N due to plant N uptake. The cumulative gaseous loss, calculated by the difference method, was significantly higher in cases of KNO 3 applications than in NH 4 Cl treatments, as an assumed consequence of the intensive denitrification. It was found that the gaseous loss was not influenced by soil moisture. In contrast to the gaseous losses, the values of plant N uptake and soil mineral N content showed significant differences in the years studied, as a result of the quick transformation of mineral N to organic N, the non-complete homogenization of the total soil amount, the seasonal climatic differences in the greenhouse during the years studied, and consequently the different microbiological activity. The plant N uptake was found to depend significantly on the fertilizer N form. Results obtained by the difference method and the 15 N-tracer technique were very similar. In the case of KNO 3 treatment and higher soil moisture (WHC = 80%) plant N uptake was more intensive, ranging between 48-57% (calculated by the difference method), and 35-51% (calculated by the 15 N- tracer method) in the first year (1993). It can be concluded that 60-100% of the fertilizer N was used from the soil by plant uptake and gaseous losses, which depends mainly on the treatments and the soil moisture during the first year. These values changed between 7-17% in the 1 st year after-effect and between 1-5% in the 2 nd year after-effect.

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Biochar and urease inhibitor mitigate NH3 and N2O emissions and improve wheat yield in a urea fertilized alkaline soil

Scientific Reports ◽

10.1038/s41598-021-96771-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Khadim Dawar ◽

Shah Fahad ◽

M. M. R. Jahangir ◽

Iqbal Munir ◽

Syed Sartaj Alam ◽

...

Keyword(s):

Nitrous Oxide ◽

Grain Yield ◽

Block Design ◽

N Uptake ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Urease Inhibitor ◽

Alkaline Soil ◽

Total N ◽

N Assimilation

AbstractIn this study, we explored the role of biochar (BC) and/or urease inhibitor (UI) in mitigating ammonia (NH3) and nitrous oxide (N2O) discharge from urea fertilized wheat cultivated fields in Pakistan (34.01°N, 71.71°E). The experiment included five treatments [control, urea (150 kg N ha−1), BC (10 Mg ha−1), urea + BC and urea + BC + UI (1 L ton−1)], which were all repeated four times and were carried out in a randomized complete block design. Urea supplementation along with BC and BC + UI reduced soil NH3 emissions by 27% and 69%, respectively, compared to sole urea application. Nitrous oxide emissions from urea fertilized plots were also reduced by 24% and 53% applying BC and BC + UI, respectively, compared to urea alone. Application of BC with urea improved the grain yield, shoot biomass, and total N uptake of wheat by 13%, 24%, and 12%, respectively, compared to urea alone. Moreover, UI further promoted biomass and grain yield, and N assimilation in wheat by 38%, 22% and 27%, respectively, over sole urea application. In conclusion, application of BC and/or UI can mitigate NH3 and N2O emissions from urea fertilized soil, improve N use efficiency (NUE) and overall crop productivity.

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Simulating Long-Term Development of Greenhouse Gas Emissions, Plant Biomass, and Soil Moisture of a Temperate Grassland Ecosystem under Elevated Atmospheric CO2

Agronomy ◽

10.3390/agronomy10010050 ◽

2019 ◽

Vol 10 (1) ◽

pp. 50

Author(s):

Ralf Liebermann ◽

Lutz Breuer ◽

Tobias Houska ◽

David Kraus ◽

Gerald Moser ◽

...

Keyword(s):

Soil Moisture ◽

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Elevated Co2 ◽

Biomass Production ◽

Atmospheric Co2 ◽

N2o Emissions ◽

Gas Emissions ◽

Co2 Concentrations

The rising atmospheric CO2 concentrations have effects on the worldwide ecosystems such as an increase in biomass production as well as changing soil processes and conditions. Since this affects the ecosystem’s net balance of greenhouse gas emissions, reliable projections about the CO2 impact are required. Deterministic models can capture the interrelated biological, hydrological, and biogeochemical processes under changing CO2 concentrations if long-term observations for model testing are provided. We used 13 years of data on above-ground biomass production, soil moisture, and emissions of CO2 and N2O from the Free Air Carbon dioxide Enrichment (FACE) grassland experiment in Giessen, Germany. Then, the LandscapeDNDC ecosystem model was calibrated with data measured under current CO2 concentrations and validated under elevated CO2. Depending on the hydrological conditions, different CO2 effects were observed and captured well for all ecosystem variables but N2O emissions. Confidence intervals of ensemble simulations covered up to 96% of measured biomass and CO2 emission values, while soil water content was well simulated in terms of annual cycle and location-specific CO2 effects. N2O emissions under elevated CO2 could not be reproduced, presumably due to a rarely considered mineralization process of organic nitrogen, which is not yet included in LandscapeDNDC.

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