scholarly journals Comparison of inorganic nitrogen uptake dynamics following snowmelt and at peak biomass in subalpine grasslands

2013 ◽  
Vol 10 (5) ◽  
pp. 8887-8917 ◽  
Author(s):  
N. Legay ◽  
F. Grassein ◽  
T. M. Robson ◽  
E. Personeni ◽  
M.-P. Bataillé ◽  
...  
Keyword(s):  
Land Use ◽  
Microbial Biomass ◽  
Microbial Communities ◽  
Plant Communities ◽  
N Uptake ◽  
Microbial Biomass N ◽  
Inorganic N ◽  
Peak Biomass ◽  
Biomass N ◽  
Subalpine Grasslands

Abstract. Subalpine grasslands are highly seasonal environments and likely subject to strong variability in nitrogen (N) dynamics. Plants and microbes typically compete for N acquisition during the growing season and particularly at plant peak biomass. During snowmelt, plants could potentially benefit from a decrease in competition by microbes because of greater plant N uptake associated with active growth and freeze-thaw cycles restricting microbial growth. In managed subalpine grasslands, we expect these interactions to be influenced by recent changes in agricultural land-use, and associated modifications in plant and microbial communities. At a subalpine grassland site in the Central French Alps, a pulse of 15N was added to the soil at the end of snowmelt, allowing us to compare the dynamics of inorganic N uptake in plants and microbes during this period with that previously reported at the peak biomass in July. In all grasslands, specific plant (per g of biomass) dissolved inorganic N (DIN) uptake was two to five times greater at snow-melt than at peak biomass, whereas the specific microbial DIN uptakes were similar between the two sampling dates. On an area basis, plant communities took more DIN than microbial communities at the end of snowmelt, and the intensity of this DIN uptake by plants differed across land use types. Consequently, N partitioning after snowmelt switches in favor of plant communities allowing them to support their growing capacities at this period of the year. Seasonal differences in microbial and plant N-related dynamics were also affected by past (terraced vs. unterraced) rather than current (mown vs. unmown) land use. In terraced grasslands, microbial biomass N remained similar across seasons, whereas in unterraced grasslands, microbial biomass N was higher and microbial C : N lower at the end of snowmelt as compared to peak biomass. Further investigations on microbial community composition and their organic N uptake dynamics are required to better understand the decrease in microbial DIN uptake.

scholarly journals Comparison of inorganic nitrogen uptake dynamics following snowmelt and at peak biomass in subalpine grasslands

2013 ◽  
Vol 10 (11) ◽  
pp. 7631-7645 ◽  
Author(s):  
N. Legay ◽  
F. Grassein ◽  
T. M. Robson ◽  
E. Personeni ◽  
M.-P. Bataillé ◽  
...  
Keyword(s):  
Land Use ◽  
Microbial Biomass ◽  
Plant Communities ◽  
Inorganic Nitrogen ◽  
N Uptake ◽  
Microbial Biomass N ◽  
Inorganic N ◽  
Peak Biomass ◽  
Biomass N ◽  
Subalpine Grasslands

Abstract. Subalpine grasslands are highly seasonal environments and likely subject to strong variability in nitrogen (N) dynamics. Plants and microbes typically compete for N acquisition during the growing season and particularly at plant peak biomass. During snowmelt, plants could potentially benefit from a decrease in competition by microbes, leading to greater plant N uptake associated with active growth and freeze-thaw cycles restricting microbial growth. In managed subalpine grasslands, we expect these interactions to be influenced by recent changes in agricultural land use, and associated modifications in plant and microbial communities. At several subalpine grasslands in the French Alps, we added pulses of 15N to the soil at the end of snowmelt, allowing us to compare the dynamics of inorganic N uptake in plants and microbes during this period with that previously reported at the peak biomass in July. In all grasslands, while specific shoot N translocation (per g of biomass) of dissolved inorganic nitrogen (DIN) was two to five times greater at snowmelt than at peak biomass, specific microbial DIN uptakes were similar between the two sampling dates. On an area basis, plant communities took more DIN than microbial communities at the end of snowmelt when aboveground plant biomasses were at least two times lower than at peak biomass. Consequently, inorganic N partitioning after snowmelt switches in favor of plant communities, allowing them to support their growing capacities at this period of the year. Seasonal differences in microbial and plant inorganic N-related dynamics were also affected by past (terraced vs. unterraced) rather than current (mown vs. unmown) land use. In terraced grasslands, microbial biomass N remained similar across seasons, whereas in unterraced grasslands, microbial biomass N was higher and microbial C : N lower at the end of snowmelt as compared to peak biomass. Further investigations on microbial community composition and their organic N uptake dynamics are required to better understand the decrease in microbial DIN uptake.

scholarly journals A comparative account of the microbial biomass-N and N-mineralization of soils under natural forest, grassland and crop field from dry tropical region, India

2009 ◽  
Vol 55 (No. 6) ◽  
pp. 223-230 ◽  
Author(s):  
S. Singh Jay ◽  
D.P. Singh ◽  
A.K. Kashyap
Keyword(s):  
Soil Moisture ◽  
Microbial Biomass ◽  
N Mineralization ◽  
Mixed Forest ◽  
Microbial Biomass N ◽  
Tropical Region ◽  
Net N Mineralization ◽  
Inorganic N ◽  
Total N ◽  
Biomass N

This study investigated microbial biomass-N (MB-N) and N-mineralization in soils of four different vegetation systems including forest (sal), mixed forest, savanna and cropland ecosystems in the Vindhyan region, India. A change was noted in the above region due to physiographic differences and anthropogenic disturbances. Annually the soil moisture (SM) content across the different study sites ranged from 7.5 to 24.3% being maximum in forest sites compared to savanna and cropland sites. The NH<sub>4</sub><sup>+</sup>-N, NO <sup>-</sup><sub>3</sub> -N and MB-N concentrations varied from 4.3 to 10.2 &mu;g/g, 1.1 to 5.8 &mu;g/g and 21.3 to 90.2 &mu;g/g dry soil, respectively, with minimum values in the wet and maximum values in the dry season. The trend of seasonal variation in net N-mineralization was similar to that of moisture content but counter to the concentrations of inorganic-N and MB-N. The net N-mineralization rates at different investigated sites ranged from 4.5 to 37.6 &mu;g/g month. Cultivation reduced the N-mineralization and MB-N by 58.5% and 63.5%, respectively. Experiments showed that the percentage contribution of MB-N to total-N was 8.01 to 19.15%. MB-N was positively correlated with the inorganic-N (<i>n</i> = 180,<i>r</i>.80,<i>P</I> < 0.001) but negatively with soil moisture (<i>n</i> = 180, <i>r</i> = 0.79, <i>P</I> < 0.001) and net N-mineralization rates (<i>n</i> = 180, <i>r</i> = 0.92, <i>P</I> < 0.0001). The higher N-mineralization and MB-N in the soil of forest ecosystem was reported compared to savanna and cropland and the order of soil MB-N levels and net N-mineralization followed the sequence: forest (sal) > mixed forest > savanna > cropland.

Nitrogen uptake efficiency of maize in monoculture and intercropped with Brachiaria humidicola and Panicum maximum in a dystrophic Red-Yellow Latosol of the Brazilian Cerrado

2016 ◽  
Vol 67 (1) ◽  
pp. 47 ◽  
Author(s):  
Thais Rodrigues Coser ◽  
Maria Lucrécia Gerosa Ramos ◽  
Cícero Célio de Figueiredo ◽  
Segundo Urquiaga ◽  
Arminda Moreira de Carvalho ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Cover Crops ◽  
N Uptake ◽  
Microbial Biomass N ◽  
Panicum Maximum ◽  
No Tillage ◽  
Available N ◽  
Brachiaria Humidicola ◽  
Uptake Efficiency ◽  
Biomass N

No-tillage systems associated with intercropping practices of grains and forages as cover crops are increasing in the Cerrado agricultural areas. The aim of this study was to quantify the nitrogen (N) uptake efficiency of maize (Zea mays L.) grown as monoculture and intercropped with tropical forages under a no-tillage system by using the 15N isotope tracer in conjunction with measurements of soil microbial biomass N and available soil N. The experiment was conducted in the 2010–11 growing season, in a Dystrophic Red-Yellow Latosol (Typic Haplustox) in the Cerrado. The experiment was established in a complete randomised block design with three replicates with the following treatments: maize monoculture; maize intercropped with Panicum maximum Jacq. cv. Aruana; and maize intercropped with Brachiaria humidicola (Rendle) Schweick. Nitrogen was applied as ammonium sulfate at a rate of 100 kg ha–1 (30 kg N ha–1 was applied at planting and 70 kg N ha–1 as a side-dressing). The N-fertiliser uptake efficiency in maize and grain yield was not affected by the presence of the intercropped forages. The intercropped B. humidicola and P. maximum recovered 2.08% and 3.71% of the N fertiliser applied, respectively. The soil was the main N source for maize. Maize intercropped with P. maximum showed higher values of microbial biomass N and available N in the soil.

scholarly journals Nitrous oxide fluxes and nitrogen cycling along a pasture chronosequence in Central Amazonia, Brazil

2005 ◽  
Vol 2 (3) ◽  
pp. 499-535 ◽  
Author(s):  
B. Wick ◽  
E. Veldkamp ◽  
W. Z. de Mello ◽  
M. Keller ◽  
P. Crill
Keyword(s):  
Nitrous Oxide ◽  
Microbial Biomass ◽  
Dry Season ◽  
Microbial Biomass N ◽  
N Availability ◽  
Wet Season ◽  
Inorganic N ◽  
Forest Sites ◽  
Biomass N ◽  
Pasture Age

Abstract. We studied nitrous oxide (N2O) fluxes and soil nitrogen (N) cycling following forest conversion to pasture in the central Amazon near Santarém, Pará, Brazil. Two undisturbed forest sites and 27 pasture sites of 0.5 to 60 years were sampled once each during wet and dry seasons. In addition to soil-atmosphere fluxes of N2O we measured 27 soil chemical, soil microbiological and soil physical variables. Soil N2O fluxes were higher in the wet season than in the dry season. Fluxes of N2O from forest soils always exceeded fluxes from pasture soils and showed no consistent trend with pasture age. At our forest sites, nitrate was the dominant form of inorganic N both during wet and dry season. At our pasture sites nitrate generally dominated the inorganic N pools during the wet season and ammonium dominated during the dry season. Net mineralization and nitrification rates displayed large variations. During the dry season net immobilization of N was observed in some pastures. Compared to forest sites, young pasture sites (≤2 years) had low microbial biomass N and protease activities. Protease activity and microbial biomass N peaked in pastures of intermediate age (4 to 8 years) followed by consistently lower values in older pasture (10 to 60 years). The C/N ratio of litter was low at the forest sites (~25) and rapidly increased with pasture age reaching values of 60–70 at pastures of 15 years and older. Nitrous oxide emissions at our sites were controlled by C and N availability and soil aeration. Fluxes of N2O were negatively correlated to leaf litter C/N ratio, NH4+-N and the ratio of NO3--N to the sum of NO3--N + NH4+-N (indicators of N availability), and methane fluxes and bulk density (indicators of soil aeration status) during the wet season. During the dry season fluxes of N2O were positively correlated to microbial biomass N, β-glucosidase activity, total inorganic N stocks and NH4+-N. In our study region, pastures of all age emitted less N2O than old-growth forests, because of a progressive decline in N availability with pasture age combined with strongly anaerobic conditions in some pastures during the wet season.

scholarly journals Influence of legumes on N cycling in a heathland in northwest Spain

Web Ecology ◽  
2007 ◽  
Vol 7 (1) ◽  
pp. 87-93 ◽  
Author(s):  
A. Rodríguez ◽  
J. Durán ◽  
A. Gallardo
Keyword(s):  
Microbial Biomass ◽  
Nitrogen Availability ◽  
Soil Microbial Biomass ◽  
N Uptake ◽  
Microbial Biomass N ◽  
Natural Ecosystems ◽  
Mixed Stands ◽  
Soil Microbial ◽  
Soil Microbial Biomass N ◽  
Biomass N

Abstract. Nitrogen availability frequently limits plant growth in natural ecosystems. N-fixers should have a substantial competitive advantage in N-limited systems, and as a byproduct of their activity they should increase the quantity and availability of N in the system as a whole. However, this effect has rarely been quantified in natural ecosystems. Heathlands in northwest Spain are frequently occupied by legume scrubs. We tested whether the presence of these legumes affected the N cycle in these communities. Specifically, we addressed the following questions: is nitrogen availability higher beneath legume canopies than beneath non-legume canopies? Is soil microbial biomass acting as a sink of extra N mineralized beneath legume canopies? Does the presence of legume scrubs change the soil pools of labile N and P? Is N plant uptake different under N-fixer scrubs than under non-N-fixer scrubs? To answer these questions, we sampled soil beneath the canopy of randomly selected individuals of Erica umbellata, Ulex gallii, and Genista tridentata twice during the growing season. Soil samples were analyzed for organic matter, NH4-N, NO3-N, DON, PO4-P, N mineralization and nitrification rates, and soil microbial biomass-N. In addition, we estimated N uptake by plants and the N concentration in green tissue to compare internal N cycles between legume and non-legume scrubs. Nitrification rates, DON (dissolved organic nitrogen), soil NO3 concentration, and N uptake were significantly higher beneath legume canopies. However, soil microbial biomass-N and extractable-P were significantly lower under legumes. Our results showed that the presence of legume scrubs modify the size of N pools and the dominant form of available N for plants, increasing spatial heterogeneity in mixed stands.

scholarly journals Nitrous oxide fluxes and nitrogen cycling along a pasture chronosequence in Central Amazonia, Brazil

2005 ◽  
Vol 2 (2) ◽  
pp. 175-187 ◽  
Author(s):  
B. Wick ◽  
E. Veldkamp ◽  
W. Z. de Mello ◽  
M. Keller ◽  
P. Crill
Keyword(s):  
Nitrous Oxide ◽  
Microbial Biomass ◽  
Dry Season ◽  
Microbial Biomass N ◽  
N Availability ◽  
Wet Season ◽  
Inorganic N ◽  
Forest Sites ◽  
Biomass N ◽  
Pasture Age

Abstract. We studied nitrous oxide (N2O) fluxes and soil nitrogen (N) cycling following forest conversion to pasture in the central Amazon near Santarém, Pará, Brazil. Two undisturbed forest sites and 27 pasture sites of 0.5 to 60 years were sampled once each during wet and dry seasons. In addition to soil-atmosphere fluxes of N2O we measured 27 soil chemical, soil microbiological and soil physical variables. Soil N2O fluxes were higher in the wet season than in the dry season. Fluxes of N2O from forest soils always exceeded fluxes from pasture soils and showed no consistent trend with pasture age. At our forest sites, nitrate was the dominant form of inorganic N both during wet and dry season. At our pasture sites nitrate generally dominated the inorganic N pools during the wet season and ammonium dominated during the dry season. Net mineralization and nitrification rates displayed large variations. During the dry season net immobilization of N was observed in some pastures. Compared to forest sites, young pasture sites (≤2 years) had low microbial biomass N and protease activities. Protease activity and microbial biomass N peaked in pastures of intermediate age (4 to 8 years) followed by consistently lower values in older pasture (10 to 60 years). The C/N ratio of litter was low at the forest sites (~25) and rapidly increased with pasture age reaching values of 60-70 at pastures of 15 years and older. Nitrous oxide emissions at our sites were controlled by C and N availability and soil aeration. Fluxes of N2O were negatively correlated to leaf litter C/N ratio, NH4+-N and the ratio of NO3--N to the sum of NO3--N + NH4+-N (indicators of N availability), and methane fluxes and bulk density (indicators of soil aeration status) during the wet season. During the dry season fluxes of N2O were positively correlated to microbial biomass N, β-glucosidase activity, total inorganic N stocks and NH4+-N. In our study region, pastures of all age emitted less N2O than old-growth forests, because of a progressive decline in N availability with pasture age combined with strongly anaerobic conditions in some pastures during the wet season.

scholarly journals Nitrogen Immobilisation and Microbial Biomass Build-Up Induced by Miscanthus x giganteus L. Based Fertilisers

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1386
Author(s):  
Michael Stotter ◽  
Florian Wichern ◽  
Ralf Pude ◽  
Martin Hamer
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Triticum Aestivum L ◽  
Microbial Biomass C ◽  
Microbial Biomass N ◽  
Miscanthus X Giganteus ◽  
Organic Fertilisers ◽  
Biomass N ◽  
Set Up

Cultivation of Miscanthus x giganteus L. (Mis) with annual harvest of biomass could provide an additional C source for farmers. To test the potential of Mis-C for immobilizing inorganic N from slurry or manure and as a C source for soil organic matter build-up in comparison to wheat (Triticum aestivum L.) straw (WS), a greenhouse experiment was performed. Pot experiments with ryegrass (Lolium perenne L.) were set up to investigate the N dynamics of two organic fertilisers based on Mis at Campus Klein-Altendorf, Germany. The two fertilisers, a mixture of cattle slurry and Mis as well as cattle manure from Mis-bedding material resulted in a slightly higher N immobilisation. Especially at the 1st and 2nd harvest, they were partly significantly different compared with the WS treatments. The fertilisers based on Mis resulted in a slightly higher microbial biomass C and microbial biomass N and thus can be identified as an additional C source to prevent nitrogen losses and for the build-up of soil organic matter (SOM) in the long-term.

Tillage, crop residue and crop sequence effects on nitrogen availability in a legume-based cropping system

2004 ◽  
Vol 84 (4) ◽  
pp. 421-430 ◽  
Author(s):  
Y. K. Soon ◽  
M. A. Arshad
Keyword(s):  
Crop Yield ◽  
Crop Residue ◽  
N Uptake ◽  
Microbial Biomass N ◽  
Fertilizer N ◽  
Inorganic N ◽  
Soil Inorganic N ◽  
Crop Sequence ◽  
Extractable Soil ◽  
Soil Inorganic

A field study was conducted to determine the effects and interactions of crop sequence, tillage and residue management on labile N pools and their availability because such information is sparse. Experimental treatments were no-till (NT) vs. conventional tillage (CT), and removal vs. retention of straw, imposed on a barley (Hordeum vulgare L.)-canola (Brassica rapa L.)-field pea (Pisum sativum L.) rotation. 15N-labelling was used to quantify N uptake from straw, below-ground N (BGN), and fertilizer N. Straw retention increased soil microbial biomass N (MBN) in 2 of 3 yr at the four-leaf growth stage of barley, consistent with observed decreases in extractable soil inorganic N at seeding. However, crop yield and N uptake at maturity were not different between straw treatments. No tillage increased soil MBN, crop yield and N uptake compared to CT, but had no effect on extractable soil inorganic N. The greater availability of N under NT was probably related to soil moisture conservation. Tillage effects on soil and plant N were mostly independent of straw treatment. Straw and tillage treatments did not influence the uptake of N from its various sources. However, barley following pea (legume/non-legume sequence) derived a greater proportion of its N from BGN (13 to 23% or 9 to 23 kg N ha-1) than canola following barley (nonlegumes) (6 to 16% or 3 to 9 kg N ha-1). Fertilizer N constituted 8 to 11% of barley N uptake and 23 to 32% of canola N uptake. Straw N contributed only 1 to 3% of plant N uptake. This study showed the dominant influence of tillage on N availability, and of the preceding crop or cropping sequence on N uptake partitioning among available N sources. Key words: Crop residue, crop sequence, labile nitrogen, nitrogen uptake, pea, tillage

scholarly journals Maturity indices of composting plant materials with Trichoderma asperellum as activator

2020 ◽  
Vol 53 (1) ◽  
pp. 19-27
Author(s):  
Adenike Fisayo Komolafe ◽  
Christopher Olu Adejuyigbe ◽  
Adeniyi Adebowale Soretire ◽  
Isaac OreOluwa Olatokunbo Aiyelaagbe
Keyword(s):  
Microbial Biomass ◽  
Microbial Biomass N ◽  
Cow Dung ◽  
Trichoderma Asperellum ◽  
Plant Materials ◽  
Total N ◽  
Compost Maturity ◽  
Randomized Design ◽  
Maturity Indices ◽  
Biomass N

AbstractCompost maturity is a major factor in its use for nutrient supply without adverse effect on crop germination. Composting may be accelerated with inclusion of some microorganisms as activators. This study was conducted to determine the effect of Trichoderma asperellum and length of composting of different plant materials and cattle manure on compost maturity in Ibadan, Nigeria. Composting of two plant materials with cow dung at ratio 3:1 was done in triplicate with or without Trichoderma activation to obtain twelve heaps of four different types of composts; Panicum-based compost with Trichoderma, Tridax-based compost with Trichoderma, Panicum-based compost without Trichoderma and Tridax-based compost without Trichoderma. The process was a 2×2 factorial experiment, laid out a completely randomized design. The Trichoderma activated compost (TAC) at four weeks of composting (4WC) had 56% total N, 21% organic matter, 38% total K, 51% total P and 66.6% microbial biomass N increase over non-activated compost (NAC). Carbon to nitrogen ratio was within the ideal range (10–20) in TAC while it was greater than it in NAC. Microbial biomass and lignin contents had a 56% and 41% increase, respectively, in NAC over TAC. Trichorderma-activated compost has a potential to hasten maturation and makes the compost ready for field on or before four weeks without posing a threat to crop germination.

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