scholarly journals Plant and soil nitrogen in oligotrophic boreal forest habitats with varying moss depths: does exclusion of large grazers matter?

Oecologia ◽  
2021 ◽  
Author(s):  
Maria Väisänen ◽  
Maria Tuomi ◽  
Hannah Bailey ◽  
Jeffrey M. Welker
Keyword(s):  
Boreal Forest ◽  
Vascular Plant ◽  
Soil N ◽  
Inorganic N ◽  
N Dynamics ◽  
N Content ◽  
Feather Moss ◽  
Foliar N ◽  
Plant Soil ◽  
Plant Soil Interactions

AbstractThe boreal forest consists of drier sunlit and moister-shaded habitats with varying moss abundance. Mosses control vascular plant–soil interactions, yet they all can also be altered by grazers. We determined how 2 decades of reindeer (Rangifer tarandus) exclusion affect feather moss (Pleurozium schreberi) depth, and the accompanying soil N dynamics (total and dissolvable inorganic N, δ15N), plant foliar N, and stable isotopes (δ15N, δ13C) in two contrasting habitats of an oligotrophic Scots pine forest. The study species were pine seedling (Pinus sylvestris L.), bilberry (Vaccinium myrtillus L.), lingonberry (V. vitis-idaea L.), and feather moss. Moss carpet was deeper in shaded than sunlit habitats and increased with grazer exclusion. Humus N content increased in the shade as did humus δ15N, which also increased due to exclusion in the sunlit habitats. Exclusion increased inorganic N concentration in the mineral soil. These soil responses were correlated with moss depth. Foliar chemistry varied due to habitat depending on species identity. Pine seedlings showed higher foliar N content and lower foliar δ15N in the shaded than in the sunlit habitats, while bilberry had both higher foliar N and δ15N in the shade. Thus, foliar δ15N values of co-existing species diverged in the shade indicating enhanced N partitioning. We conclude that despite strong grazing-induced shifts in mosses and subtler shifts in soil N, the N dynamics of vascular vegetation remain unchanged. These indicate that plant–soil interactions are resistant to shifts in grazing intensity, a pattern that appears to be common across boreal oligotrophic forests.

scholarly journals 605 Evaluation of How Cover Crop, Tillage, and N Fertilization Affect Nitrogen Sufficiency in Watermelons

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 551D-551
Author(s):  
Anthony F. Silvernail ◽  
Gary R. Cline
Keyword(s):  
Cover Crop ◽  
Citrullus Lanatus ◽  
N Fertilization ◽  
Soil N ◽  
Inorganic N ◽  
Vicia Villosa ◽  
Testing Procedures ◽  
Foliar N ◽  
No Till ◽  
Spad Readings

The effects of cover crop, tillage, and N fertilization on yields of `Paladin' watermelon (Citrullus lanatus) were analyzed by determining available soil N levels, foliar N content, and relative greenness with a SPAD-502 chlorophyll meter. Analyses from all three analytical procedures identified N deficiencies in watermelon with their respected measurements. Available soil N analyses indicated that soil N levels below 40 mg·kg–1 at vining caused dramatic decreases in yields, while the level needed to ensure maximal yields during the same period was 100 mg·kg–1. Results from foliar and SPAD tests indicated that plants with foliar N levels below 42 g·kg–1 and SPAD readings below 40 SPAD units at anthesis will have suppressed yields. Optimal foliar N levels and SPAD readings required for maximum yields were 50 g·kg –1 and 48 SPAD units, respectively. The main difference among all three N testing procedures was that available soil N analysis was able to detect possible deficiencies two to three weeks before either the foliar or SPAD analysis. Differences in yield between plants from conventionally tilled plots and no-till plots were not significant. However, inorganic N fertilization significantly increased yields in watermelon following both rye (Secale cereale) and mix cover crop treatments. Watermelon yields of plants following the hairy vetch (Vicia villosa) cover crop treatment showed no response to inorganic N fertilization. Of the three cover crop treatments, the addition of N fertilizer had the most effect in the rye treatment.

scholarly journals Belowground rhizomes in paleosols: The hidden half of an Early Devonian vascular plant

2016 ◽  
Vol 113 (34) ◽  
pp. 9451-9456 ◽  
Author(s):  
Jinzhuang Xue ◽  
Zhenzhen Deng ◽  
Pu Huang ◽  
Kangjun Huang ◽  
Michael J. Benton ◽  
...  
Keyword(s):  
Vascular Plants ◽  
Soil Stabilization ◽  
Early Stage ◽  
Vascular Plant ◽  
Deep Roots ◽  
Early Devonian ◽  
Landscape Modification ◽  
Plant Soil ◽  
Floodplain Sediments ◽  
Plant Soil Interactions

The colonization of terrestrial environments by rooted vascular plants had far-reaching impacts on the Earth system. However, the belowground structures of early vascular plants are rarely documented, and thus the plant−soil interactions in early terrestrial ecosystems are poorly understood. Here we report the earliest rooted paleosols (fossil soils) in Asia from Early Devonian deposits of Yunnan, China. Plant traces are extensive within the soil and occur as complex network-like structures, which are interpreted as representing long-lived, belowground rhizomes of the basal lycopsidDrepanophycus. The rhizomes produced large clones and helped the plant survive frequent sediment burial in well-drained soils within a seasonal wet−dry climate zone. Rhizome networks contributed to the accumulation and pedogenesis of floodplain sediments and increased the soil stabilizing effects of early plants. Predating the appearance of trees with deep roots in the Middle Devonian, plant rhizomes have long functioned in the belowground soil ecosystem. This study presents strong, direct evidence for plant−soil interactions at an early stage of vascular plant radiation. Soil stabilization by complex rhizome systems was apparently widespread, and contributed to landscape modification at an earlier time than had been appreciated.

scholarly journals Short-Term Litter Manipulations have Strong Impact on Soil Nitrogen Dynamics in Larix gmelinii Forest of Northeast China

Forests ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1205
Author(s):  
Ruihan Xiao ◽  
Xiuling Man ◽  
Beixing Duan ◽  
Tijiu Cai
Keyword(s):  
Soil Layer ◽  
Net N Mineralization ◽  
Soil N ◽  
Inorganic N ◽  
Short Term ◽  
N Dynamics ◽  
Litter Addition ◽  
Litter Manipulation ◽  
Soil Inorganic N ◽  
Soil N Dynamics

Changes in above-ground litterfall can influence below-ground biogeochemical processes in forests, which substantially impacts soil nitrogen (N) and nutrient cycling. However, how these soil processes respond to the litter manipulation is complex and poorly understood, especially in the N-limiting boreal forest. We aimed to examine how soil N dynamics respond to litter manipulations in a boreal larch forest. A litter manipulation experiment including control, litter exclusion, and litter addition was performed in the Larix gmelinii forest on the north of the Daxing’an Mountains in China. Monthly soil inorganic N, microbial biomass and the rate of net N mineralization in both 0–10 cm and 10–20 cm layers, and N2O flux were analyzed from May 2018 to October 2018. In 0–20 cm soil layer the average soil inorganic N contents, microbial biomass N (MBN) contents, the rate of net N mineralization (Rmin), and the soil N2O emission in the litter addition plot were approximately 40.58%, 54.16%, 128.57%, and 38.52% greater, respectively than those in the control. While litter exclusion reduced those indexes about 29.04%, 19.84%, 80.98%, and 31.45%, respectively. Compared with the dynamics of the 10–20 cm soil layer, the N dynamics in 0–10 cm soil were more sensitive to litter manipulation. Rmin and N2O emissions were significantly correlated with MBN in most cases. Our results highlight the short-term effects of litter manipulations on soil N dynamics, which suggests that the influence of litter on soil N process should be considered in the future defoliation management of the boreal larch forest.

scholarly journals Effects of Cover Crops, Nitrogen, and Tillage on Sweet Corn

2002 ◽  
Vol 12 (1) ◽  
pp. 118-125 ◽  
Author(s):  
Gary R. Cline ◽  
Anthony F. Silvernail
Keyword(s):  
Cover Crops ◽  
Sweet Corn ◽  
Winter Rye ◽  
No Tillage ◽  
Population Densities ◽  
Inorganic N ◽  
N Content ◽  
Foliar N ◽  
Winter Cover ◽  
Winter Cover Crops

Effects of tillage, inorganic N, and winter cover crops on sweet corn (Zea mays) were examined in 1994, 1995, and 1996. Tillage treatments were tillage or no tillage, and N treatments were the addition of inorganic N at 0 (N0) or 200 (N+) kg·ha-1 (0 or 179 lb/acre). Winter cover crops included hairy vetch (Vicia villosa), winter rye (Secale cereale), and a vetch/rye biculture. In the N0, rye treatment, the soil was N deficient in 1994 and highly N deficient in 1995 and 1996. When vetch shoot N content was ≥150 kg·ha-1 (134 lb/acre) (1994 and 1995), addition of inorganic N did not increase corn yields, and it only increased corn foliar N concentrations by 8%. Reductions in corn yields (29%) and foliar N concentrations (24%) occurred when vetch shoot N content was only 120 kg·ha-1 (107 lb/acre) (1996) and inorganic N was not supplied. In 1994, the vetch/rye biculture supplied sufficient N for maximum corn yields, but addition of inorganic N increased yields by more than 50% in 1995 and 1996. Under tilled conditions, the vetch N contribution to corn appeared to equal (1996) or exceed (1994 and 1995) 82 kg·ha-1 (73 lb/acre) of N supplied as ammonium nitrate, whereas a mean value of 30 kg·ha-1 (27 lb/acre) was obtained for the biculture cover crop (1995 and 1996). No significant effects of tillage on sweet corn population densities were detected following vetch, but no-tillage significantly reduced corn population densities following rye (17%) or biculture (35%) cover crops compared to tillage. No-tillage did not reduce yields from emerged seedlings (per plant basis) for any cover crops. Vetch appeared to be a satisfactory N source for sweet corn when vetch N content was ≥150 kg·ha-1, and it could be used with no-tillage without yield reductions.

scholarly journals Agriculture Model Comparison Framework and MyGeoHub Hosting: Case of Soil Nitrogen

Inventions ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 25
Author(s):  
Anupam Bhar ◽  
Benjamin Feddersen ◽  
Robert Malone ◽  
Ratnesh Kumar
Keyword(s):  
Soil Nitrogen ◽  
Field Data ◽  
Model Comparison ◽  
Test Model ◽  
Soil N ◽  
N Dynamics ◽  
Benchmark Model ◽  
C Dynamics ◽  
Comparison Results ◽  
Speed Up

To be able to compare many agricultural models, a general framework for model comparison when field data may limit direct comparison of models is proposed, developed, and also demonstrated. The framework first calibrates the benchmark model against the field data, and next it calibrates the test model against the data generated by the calibrated benchmark model. The framework is validated for the modeling of the soil nutrient nitrogen (N), a critical component in the overall agriculture system modeling effort. The nitrogen dynamics and related carbon (C) dynamics, as captured in advanced agricultural modeling such as RZWQM, are highly complex, involving numerous states (pools) and parameters. Calibrating many parameters requires more time and data to avoid underfitting. The execution time of a complex model is higher as well. A study of tradeoff among modeling complexities vs. speed-up, and the corresponding impact on modeling accuracy, is desirable. This paper surveys soil nitrogen models and lists those by their complexity in terms of the number of parameters, and C-N pools. This paper also examines a lean soil N and C dynamics model and compares it with an advanced model, RZWQM. Since nitrate and ammonia are not directly measured in this study, we first calibrate RZWQM using the available data from an experimental field in Greeley, CO, and next use the daily nitrate and ammonia data generated from RZWQM as ground truth, against which the lean model’s N dynamics parameters are calibrated. In both cases, the crop growth was removed to zero out the plant uptake, to compare only the soil N-dynamics. The comparison results showed good accuracy with a coefficient of determination (R2) match of 0.99 and 0.62 for nitrate and ammonia, respectively, while affording significant speed-up in simulation time. The lean model is also hosted in MyGeoHub cyberinfrastructure for universal online access.

EFFECTS OF GRAZING ON MICROBIAL FUNCTIONAL GROUPS INVOLVED IN SOIL N DYNAMICS

2005 ◽  
Vol 75 (1) ◽  
pp. 65-80 ◽  
Author(s):  
A. K. Patra ◽  
L. Abbadie ◽  
A. Clays-Josserand ◽  
V. Degrange ◽  
S. J. Grayston ◽  
...  
Keyword(s):  
Functional Groups ◽  
Soil N ◽  
N Dynamics ◽  
Microbial Functional Groups ◽  
Soil N Dynamics

Enhancing Soil Fertility through Intercropping, Inoculation and Fertilizer

2016 ◽  
Vol 59 (1) ◽  
pp. 1-5
Author(s):  
Muhammad Arshad Ullah ◽  
Nazir Hussain ◽  
Helge Schmeisky ◽  
Muhammad Rasheed
Keyword(s):  
Plant Uptake ◽  
Field Experiments ◽  
Fertilizer Application ◽  
Research Centre ◽  
Vicia Sativa ◽  
Soil N ◽  
N Content ◽  
Seed Inoculation ◽  
Crop Harvest ◽  
Total Soil N

The present study was conducted to investigate the effects of intercropping grass (Panicummaximum) and legumes (Vicia sativa and cowpeas) alone or coupled with inoculation or fertilizer on soilfertility. The study comprised of two field experiments conducted under rain fed conditions for two years(June, 2005 to September, 2007) at National Agriculture Research Centre, Islamabad, Pakistan. In oneexperiment intercropping (33, 50 and 67%) of grass and legumes alone as well as coupled with seedinoculation were studied while, same set of treatments was combined with fertilizer application at the ratesof 25, 75 and 50 kg/ha (N, P2O5 and K2O) in the second experiment. Total soil N increased by 0.008% dueto symbiotic fixation in addition to plant uptake under best treatment when compared with grass alonewhile, soil organic matter increased by 0.19%. After crop harvest soil N content was determined to behigher in all the treatments of the experiment compared with growing grass alone. Legumes caused rhizobialN fixation that caused an increase in soil N. Similarly, intercropping and inoculation increased this soilcharacteristic that was found to be non-significant in the first crop but later on became significant, especiallywhen intercropping of grass with legumes after seed inoculation was investigated or fertilizer wassupplemented to the crops. Thus, not only grass used the symbiotically fixed N by companion legumesbut also enhanced the soil N content. The effect of fertilizer was not measurable statistically in case of soilorganic matter. This parameter, in general, was not affected significantly when assessed after first cropharvest. Nevertheless, legumes alone or intercropped within grass increased this important soil constituent.Inoculation proved further beneficial in this regard but combination of intercropping (especially 67%)either with seed inoculation or application of fertilizer was found as the best technique for increasing soilorganic matter.

Dynamics of nitrogen and dry-matter partitioning and accumulation in broccoli (Brassica oleracea var. italica) in relation to extractable soil inorganic nitrogen

1999 ◽  
Vol 79 (2) ◽  
pp. 277-286 ◽  
Author(s):  
P. A. Bowen ◽  
B. J. Zebarth ◽  
P. M. A. Toivonen
Keyword(s):  
Dry Matter ◽  
N Fertilization ◽  
N Fertilizer ◽  
Organic N ◽  
Soil N ◽  
Inorganic N ◽  
N Accumulation ◽  
Spring Planting ◽  
Extractable Soil ◽  
Soil Inorganic

The effects of six rates of N fertilization (0, 125, 250, 375, 500 and 625 kg N ha−1) on the dynamics of N utilization relative to extractable inorganic N in the soil profile were determined for broccoli in three growing seasons. The amount of pre-existing extractable inorganic N in the soil was lowest for the spring planting, followed by the early-summer then late-summer plantings. During the first 2 wk after transplanting, plant dry-matter (DM) and N accumulation rates were low, and because of the mineralization of soil organic N the extractable soil inorganic N increased over that added as fertilizer, especially in the top 30 cm. From 4 wk after transplanting until harvest, DM and N accumulation in the plants was rapid and corresponded to a rapid depletion of extractable inorganic N from the soil. At high N-fertilization rates, leaf and stem DM and N accumulations at harvest were similar among the three plantings. However, the rates of accumulation in the two summer plantings were higher before and lower after inflorescence initiation than those in the spring planting. Under N treatments of 0 and 125 kg ha−1, total N in leaf tissue and the rate of leaf DM accumulation decreased while inflorescences developed. There was little extractable inorganic soil-N during inflorescence development in plots receiving no N fertilizer, yet inflorescence dry weights and N contents were ≥50 and ≥30%, respectively, of the maxima achieved with N fertilization. These results indicate that substantial N is translocated from leaves to support broccoli inflorescence growth under conditions of low soil-N availability. Key words: N translocation, N fertilizer

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