scholarly journals Abiotic versus biotic controls on soil nitrogen cycling in drylands along a 3200 km transect

2017 ◽  
Vol 14 (4) ◽  
pp. 989-1001 ◽  
Author(s):  
Dongwei Liu ◽  
Weixing Zhu ◽  
Xiaobo Wang ◽  
Yuepeng Pan ◽  
Chao Wang ◽  
...  
Keyword(s):  
Arid Zone ◽  
N Cycling ◽  
Mean Annual Precipitation ◽  
N Availability ◽  
Soil N ◽  
Inorganic N ◽  
N Transformations ◽  
Soil Inorganic N ◽  
Soil Inorganic ◽  
Biotic Controls

Abstract. Nitrogen (N) cycling in drylands under changing climate is not well understood. Our understanding of N cycling over larger scales to date relies heavily on the measurement of bulk soil N, and the information about internal soil N transformations remains limited. The 15N natural abundance (δ15N) of ammonium and nitrate can serve as a proxy record for the N processes in soils. To better understand the patterns and mechanisms of N cycling in drylands, we collected soils along a 3200 km transect at about 100 km intervals in northern China, with mean annual precipitation (MAP) ranging from 36 to 436 mm. We analyzed N pools and δ15N of ammonium, dual isotopes (15N and 18O) of nitrate, and the microbial gene abundance associated with soil N transformations. We found that N status and its driving factors were different above and below a MAP threshold of 100 mm. In the arid zone with MAP below 100 mm, soil inorganic N accumulated, with a large fraction being of atmospheric origin, and ammonia volatilization was strong in soils with high pH. In addition, the abundance of microbial genes associated with soil N transformations was low. In the semiarid zone with MAP above 100 mm, soil inorganic N concentrations were low and were controlled mainly by biological processes (e.g., plant uptake and denitrification). The preference for soil ammonium over nitrate by the dominant plant species may enhance the possibility of soil nitrate losses via denitrification. Overall, our study suggests that a shift from abiotic to biotic controls on soil N biogeochemistry under global climate changes would greatly affect N losses, soil N availability, and other N transformation processes in these drylands in China.

scholarly journals Abiotic versus biotic controls on soil nitrogen cycling in drylands along a 3200 km transect

2016 ◽  
Author(s):  
Dongwei Liu ◽  
Weixing Zhu ◽  
Xiaobo Wang ◽  
Yuepeng Pan ◽  
Chao Wang ◽  
...  
Keyword(s):  
Arid Zone ◽  
N Cycling ◽  
Mean Annual Precipitation ◽  
N Availability ◽  
Soil N ◽  
Inorganic N ◽  
N Transformations ◽  
Soil Inorganic N ◽  
Soil Inorganic ◽  
Biotic Controls

Abstract. Nitrogen (N) cycling of drylands under changing climate is not well understood. Our understanding about N cycling over larger scales to date relies heavily on the measurement of bulk soil N, and the information about soil internal N transformations remains limited. The 15N natural abundance (δ15N) of ammonium and nitrate can serve as a proxy record for the N processes in soils. To better understand the patterns and mechanisms of water availability on soil N cycling in drylands, we collected soils along a 3200 km dryland transect at about 100 km intervals in northern China, with mean annual precipitation (MAP) from 36 mm to 436 mm. We analysed N pools and δ15N of ammonium, dual isotopes (15N and 18O) of nitrate, and the microbial gene abundance associated with soil N transformations. We found that the N status and their driven factors were different on the two sides of MAP = 100 mm. In the arid zone with MAP below 100 mm, soil inorganic N accumulated, with a large fraction being of atmospheric origin. Ammonia volatilization was strong because of the higher soil pH. The abundance of microbial genes associated with soil N transformations was also significantly low. In the semiarid zone with MAP above 100 mm, soil inorganic N concentrations were low and controlled mainly by biological processes, e.g., plant uptake and denitrification. The preference of soil ammonium to nitrate by the dominant plant species may enhance the possibility of soil nitrate loss via denitrification. Overall, our study suggest that the shifting from abiotic to biotic controls on soil N biogeochemistry under global climate changes would greatly affect N losses, soil N availability, and other N transformation processes in these drylands in China.

scholarly journals Effect of soil covering on nitrogen availability of vineyards soils in Champagne area

OENO One ◽  
2005 ◽  
Vol 39 (4) ◽  
pp. 163
Author(s):  
Pascal Thiebeau ◽  
Christian Herré ◽  
Anne-France Doledec ◽  
André Perraud ◽  
Laurent Panigai ◽  
...  
Keyword(s):  
Organic Matter ◽  
N Mineralization ◽  
Farmyard Manure ◽  
N Availability ◽  
Soil N ◽  
Inorganic N ◽  
Growing Period ◽  
Soil Inorganic N ◽  
Soil Inorganic

<p style="text-align: justify;">We studied the effect of soil cover (bare soil, mulch of barks or composted organic materials, grass cover) on soil N dynamics in various experimental vineyards located in Champagne area (France). Soil cores were sampled periodically to measure water and mineral N in soil profile during autumn and winter. These measurements were used in a simple dynamic model (LIXIM) to calculate nitrate leaching and N mineralization. N mineralization potential of soils were also determined in laboratory incubations in controlled conditions. In most sites, soil inorganic N contents (0-75 cm) varied between 20 and 60 kg N ha-1, depending of the season. Soil inorganic N in plots receiving barks or composted barks or covered with grass did not differ significantly from control plots. Higher amounts of inorganic N were found in soils amended with refuse compost, peat or mixed compost (barks + farmyard manure) or composted farmyard manure. The model indicated that N leached varied from 8 to 77 kg N ha-1 and that the mean nitrate concentration in drained water was less than 50 mg NO3- L-1 except for plots receiving refuse compost or bark + farmyard manure compost. The calculated N mineralization varied from 9 to 45 kg N ha-1 over the autumn-winter period, i.e. 118 to 182 days. The N mineralization rate (Vp), expressed per 'normalised day' i.e. day at 15°C and field capacity, varied from 0.15 to 0.82 kg N ha-1 nd-1, including all sites and experimental treatments. Effect of organic matter addition on Vp was only observed for long-term experimental sites where large amounts of organic nitrogen had been added to soil using peat, refuse compost or compost mixtures with barks and farmyard manure. The Vp values measured in laboratory incubations showed the same trends and were in the same order of magnitude than those calculated with LIXIM model using in situ data. In average, the values measured in laboratory incubations underestimated the actual N mineralization in field conditions. The model was used to predict N mineralization and inorganic N in soil during the vegetative period using Vp values. It allowed to estimate the N uptake by vine: 10 ± 5 kg N ha-1 at flowering and 57 ± 5 kg N ha-1 over the whole growing period. These results show that soil N availability was sufficient to feed the vine during the whole growing period and that no inorganic N fertilisation was necessary, even in the grass covered soil. In this soil, water availability is probably the limiting factor when depressive effects are observed. On the long-term, it is necessary to manage the amount and quality of added organic matter since organic inputs may modify N availability and therefore vine behaviour, wine quality and environmental risks.</p>

PROPAGATION AND MANAGEMENT OF GLIRICIDIA SEPIUM PLANTED FALLOWS IN SUB-HUMID EASTERN ZAMBIA

2004 ◽  
Vol 40 (3) ◽  
pp. 341-352 ◽  
Author(s):  
R. CHINTU ◽  
P. L. MAFONGOYA ◽  
T. S. CHIRWA ◽  
E. KUNTASHULA ◽  
D. PHIRI ◽  
...  
Keyword(s):  
Biomass Production ◽  
Crop Yields ◽  
Gliricidia Sepium ◽  
N Availability ◽  
Inorganic N ◽  
Soil Inorganic N ◽  
Tree Survival ◽  
Maize Yields ◽  
Bare Root ◽  
Soil Inorganic

Gliricidia sepium features prominently as a soil replenishment tree in planted coppicing fallows in eastern Zambia. Its usual method of propagation, through nurseryseedlings, is costly and may possibly hinder wider on-farm adoption. We compared fallows propagated by potted and bare root seedlings, direct seeding and stem cuttings, in terms of tree coppice biomass production, soil inorganic N availability and post-fallow maize yields under semi-arid conditions. We hypothesized that cutting fallows initially in May (off-season) would increase subsequent seasonal coppice biomass production as opposed to cutting them in November (at cropping). The tree survival and biomass order after two years was: potted = bare root > direct > cuttings. The post-fallow maize productivity sequence was: fertilized maize = potted = bare root > direct > cuttings = no-tree unfertilized controls, across seasons. However, farmers may prefer directly seeded fallows owing to their cost effectiveness. Soil inorganic N and maize yield were significantly higher in May-cut than in November-cut fallows. Preseason topsoil inorganic N and biomass N input correlated highly with maize yields. This implies that bothparameters may be used to predict post-fallow crop yields.

scholarly journals The strength of the biotic compartment to retain nitrogen additions prevents nitrogen losses from a Mediterranean maquis

2011 ◽  
Vol 8 (4) ◽  
pp. 8041-8065
Author(s):  
T. Dias ◽  
M. A. Martins-Loução ◽  
L. Sheppard ◽  
C. Cruz
Keyword(s):  
Initial Response ◽  
Ecosystem Functions ◽  
N Availability ◽  
Inorganic N ◽  
N Losses ◽  
Total N ◽  
Soil Inorganic N ◽  
Mediterranean Maquis ◽  
N Additions ◽  
Soil Inorganic

Abstract. Nitrogen (N) is one of the nutrients most limiting to ecosystem productivity. However, N availability is increasing globally, which may affect ecosystem functions and stability. To understand the role of each ecosystem compartment in the cycling of increased N, we studied the initial response of a nutrient-poor ecosystem, a Mediterranean maquis, to increased N. N availability (dose and forms) was modified by three N additions along the year (spring, summer and middle autumn/winter). Soil inorganic N pools (nitrate in particular) strongly reflected the N additions in autumn, almost matching the total N added along the three additions. Cistus ladanifer, the dominant plant species, responded to the increased N (cover and N concentration in leaves and litter), and given that leaf shedding occurs in the summer, the importance of this N pool returning to the soil through litter decomposition on the total soil inorganic N in autumn was investigated. Data suggest that living plants and litter have a crucial role in preventing N losses from Mediterranean maquis. This is the first integrated field study on how European Mediterranean ecosystems retain increased N of different forms and doses, however longer-term studies are needed to explore the generality of this study's observations.

scholarly journals Interrelationships among soil nitrogen transformation rates, functional gene abundance and soil properties in a tropical forest with exogenous N inputs

2019 ◽  
Author(s):  
Yanxia Nie ◽  
Xiaoge Han ◽  
Jie Chen ◽  
Mengcen Wang ◽  
Weijun Shen
Keyword(s):  
N Deposition ◽  
N Cycling ◽  
Functional Gene ◽  
Soil N ◽  
Wet Season ◽  
Inorganic N ◽  
N Transformations ◽  
Gene Abundance ◽  
Functional Gene Abundance ◽  
N Additions

Abstract. Elevated nitrogen (N) deposition affects soil N transformations in the N-rich soil of tropical forests. However, the change in soil functional microorganisms responsible for soil N cycling remains largely unknown. Here, we investigated the variation in soil inorganic N content, net N mineralization (Rm), net nitrification (Rn), inorganic N leaching (Rl), N2O efflux and N-related functional gene abundance in tropical forest soil over a two-year period with four levels of N addition. The responses of soil N transformations (in situ Rm, Rn and Rl) to N additions were delayed during the first year of N inputs. The Rm, Rn, and Rl increased with the medium nitrogen (MN) and high nitrogen (HN) treatments relative to the control treatments in the second year of N additions. Furthermore, the Rm, Rn, and Rl were higher in the wet season than in the dry season. The Rm and Rn were predominately driven by the lower C : N ratio under N addition in the dry season but by higher microbial biomass in the wet season. Throughout the study period, high N additions increased the annual N2O emissions by 78 %. Overall, N additions significantly facilitated soil N availability (Rm and Rn) and N loss (Rl and N2O emission), which had a stimulating effect on N transformations. In addition, the MN and HN treatments increased the ammonia-oxidizing archaea (AOA) abundance by 17.3 % and 7.5 %, respectively. Meanwhile, the HN addition significantly increased the abundance of nirK-denitrifiers but significantly decreased the abundance of ammonia-oxidizing bacteria (AOB) and nosZ-containing N2O reducers. To some extent, the variation in functional gene abundance was related to the corresponding N transformation processes. Partial least squares path modelling (PLS-PM) indicated that inorganic N contents had significant negative direct effects on the abundances of N-related functional genes in the wet season, implying that chronic N deposition would have a negative effect on the N-cycling-related microbes and the function of N transformation.

Whole-season grass response to and recovery of nitrogen applied at various rates and distributions in a high rainfall environment

1998 ◽  
Vol 78 (3) ◽  
pp. 445-451 ◽  
Author(s):  
S. Bittman ◽  
C. G. Kowalenko
Keyword(s):  
Crude Protein ◽  
Forage Yield ◽  
Soil N ◽  
Inorganic N ◽  
High Rainfall ◽  
Yield And Quality ◽  
Soil Inorganic N ◽  
Herbage Yield ◽  
Nitrate Concentrations ◽  
Soil Inorganic

High rates of nitrogen (N) fertilizer are often used on perennial grass in the coastal region of British Columbia and the Pacific Northwest, but there is little information on optimum rates for abundant high-quality yields and on their environmental implications. A field trial was conducted in each of 3 yr to determine the effect of rates and distributions of N on whole-season herbage yield and quality, and pre- and post-season extractable inorganic N in the soil. Yearly rates were 100, 200 and 400 kg N ha−1 applied to each of four cuts in the following distributions: 1.00/0/0/0, 0.50/0.25/0.25/0 and 0.25/0.25/0.25/0.25. Whole-season yield was increased by increasing rates of N in all three trials, but the increase varied from 17% (Trial 1) to 127% (Trial 3). Distributing the N uniformly through the season resulted in only a 5% increase in yield compared with applying all of the N at the beginning of the season. Rate of N had a substantial effect on average herbage crude protein and nitrate concentrations, but the distribution effect was greater on herbage N constituents than on yield. Increasing rates of N consistently increased average herbage nitrate concentrations, and crude protein in two of three trials. Applying all of the N at the beginning of the season increased average herbage crude protein and nitrate concentrations more than distributing it evenly through the season. Extractable inorganic N in the soil at the end of the season increased only at 400 kg N ha−1 rate and was not affected by distribution. Although distribution pattern influenced herbage yield and nitrogen concentrations, distribution did not influence total herbage N uptake or recovery in herbage plus soil. Rates and distributions of N on grass influenced herbage yield and quality, and soil extractable inorganic N in different ways; therefore, compromises in N management are required to optimize forage yield and quality, and soil nitrate concentrations. Autumn soil inorganic N testing may be useful as feedback information for fertilizer recommendations in the subsequent season. Spring soil inorganic N testing was a poor predictor of crop response to fertilizer in the high rainfall environment of the study. Key words: Nitrogen, plant crude protein, plant nitrate, forage yield, forage quality, apparent N recovery, residual soil N, soil N test

Strip Intercropping of Rye–Vetch Mixtures: Effects on Weed Growth and Competition in Strip-tilled Sweet Corn

Weed Science ◽  
2019 ◽  
Vol 67 (1) ◽  
pp. 114-125 ◽  
Author(s):  
Carolyn J. Lowry ◽  
Daniel C. Brainard
Keyword(s):  
Sweet Corn ◽  
N Uptake ◽  
Corn Yield ◽  
N Availability ◽  
Hairy Vetch ◽  
Inorganic N ◽  
Cereal Rye ◽  
Soil Inorganic N ◽  
Strip Intercropping ◽  
Soil Inorganic

AbstractStrip-intercropping of functionally diverse cover crop mixtures including cereal rye (Secale cerealeL.) and hairy vetch (Vicia villosaRoth) is one mechanism by which nitrogen (N) banding can be applied to an organic, strip-tilled system to increase crop competitiveness over weeds. We hypothesized that by targeting hairy vetch, a low C:N legume, to the tilled strip directly in row with future crop establishment, and cereal rye, a high C:N grass, to the untilled strip directly between future crop rows, that N would be preferentially available to the crop. We conducted a field study between 2011 to 2013 in southwest Michigan to examine the effects of rye–vetch mixture spatial arrangement (strip intercropping vs. full-width mixture) on (1) soil inorganic N; (2) weed biomass; and (3) sweet corn (Zea maysL.) biomass, yield, and competitiveness against weeds. We found that as the proportion of vetch biomass in the crop row (in-row, IR) increased, we also saw increasing levels of IR soil inorganic N and greater early sweet corn N uptake and growth relative to weeds. However, sweet corn yield and final biomass were more responsive to vetch biomass across the whole plot (WP) and did not respond to rye and vetch segregation into strips. Increasing vetch WP biomass increased sweet corn final biomass across both years, but only increased corn competitiveness against weeds in 1 out of 2 years and decreased sweet corn competitiveness in the other year. Strip-intercropping of cereal rye and hairy vetch has potential to increase soil N availability to the crop, thereby increasing early crop competitiveness, which may lower weed management costs.

scholarly journals The strength of the biotic compartment in retaining nitrogen additions prevents nitrogen losses from a Mediterranean maquis

2012 ◽  
Vol 9 (1) ◽  
pp. 193-201 ◽  
Author(s):  
T. Dias ◽  
M. A. Martins-Loução ◽  
L. Sheppard ◽  
C. Cruz
Keyword(s):  
Initial Response ◽  
Ecosystem Functions ◽  
N Availability ◽  
Inorganic N ◽  
N Losses ◽  
Total N ◽  
Soil Inorganic N ◽  
Mediterranean Maquis ◽  
N Additions ◽  
Soil Inorganic

Abstract. Nitrogen (N) is one of the nutrients most limiting to ecosystem productivity. However, N availability is increasing globally, which may affect ecosystem functions and stability. To understand the role of each ecosystem compartment in the cycling of increased N, we studied the initial response of a nutrient-poor ecosystem, a Mediterranean maquis, to increased N deposition. N availability (dose and form) was modified by three N additions over the year (middle autumn/winter, spring and summer). Soil inorganic N pools (nitrate in particular) strongly reflected the N additions in autumn, almost matching the total N added over the three additions. Cistus ladanifer, the dominant plant species, responded to the increased N (cover and N concentration in leaves and litter). Given that leaf shedding occurs in the summer, the importance of this N pool returning to the soil through litter decomposition on the total soil inorganic N in autumn was investigated. Data suggest that living plants and litter have a crucial role in preventing N losses from Mediterranean maquis. This is the first integrated field study on how European Mediterranean ecosystems retain increased N of different forms and doses, however longer-term studies are needed to explore the generality of this study's observations.

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