Legumes regulate grassland soil N cycling and its response to variation in species diversity and N supply but not CO 2

Although increasing tropospheric ozone (O3) concentrations as well as precursor NO2 emissions and N deposition have been observed, the combination of their effects on deciduous trees is little understood. We therefore examined the growth and leaf injury response of a model tree (Populus ×euramericana (Dode) Guinier cuttings exposed before flush and until they reached a height of more than 1 m) to low and high soil N supply (105 or 315 mg N•L−1 substrate volume), to filtered air, and to filtered air with NO2 (sinusoidal daily course with a mean of 100 nL•L−1), with O3 (60 nL•L−1), or with a combination of both in climate-controlled chambers. High soil N increased total plant dry weight, leaf area, and xylem radius in plants fumigated with or without added NO2 or O3. The number of leaves increased with high soil N independent of added NO2. The stomatal density was influenced by soil N and by fumigations, but the appearance of leaf injury symptoms, leaf loss, specific leaf weight, and bark radius were not modified by the soil N regimes. NO2 alone, though applied in a sixfold ambient concentration, did not significantly increase plant growth. NO2 and O3 alone had opposite effects on specific leaf dry weight, stomatal density, and in the high fertilization regime, on the bark radius. The decrease in specific leaf dry weight and the appearance of early leaf symptoms were enhanced by NO2 added to O3. Visible leaf injury caused by O3 increased in parallel with microscopic changes in mesophyll cell walls, in the starch and protein patterns of mesophyll cells, in the bark cell content, and in the phloem sieve pores. NO2 enhanced the negative effect of O3 rather than compensated for a low soil N supply.

Download Full-text

Forest productivity under elevated CO2 and O3: positive feedbacks to soil N cycling sustain decade-long net primary productivity enhancement by CO2

Ecology Letters ◽

10.1111/j.1461-0248.2011.01692.x ◽

2011 ◽

Vol 14 (12) ◽

pp. 1220-1226 ◽

Cited By ~ 82

Author(s):

Donald R. Zak ◽

Kurt S. Pregitzer ◽

Mark E. Kubiske ◽

Andrew J. Burton

Keyword(s):

Elevated Co2 ◽

Primary Productivity ◽

Net Primary Productivity ◽

Forest Productivity ◽

N Cycling ◽

Soil N ◽

Positive Feedbacks ◽

Elevated Co2 And O3 ◽

Productivity Enhancement

Download Full-text

The soil N cycle: new insights and key challenges

SOIL ◽

10.5194/soil-1-235-2015 ◽

2015 ◽

Vol 1 (1) ◽

pp. 235-256 ◽

Cited By ~ 87

Author(s):

J. W. van Groenigen ◽

D. Huygens ◽

P. Boeckx ◽

Th. W. Kuyper ◽

I. M. Lubbers ◽

...

Keyword(s):

N Cycling ◽

Greenhouse Gas Mitigation ◽

Future Research ◽

N Fixation ◽

Gaseous Emissions ◽

Soil N ◽

Personal View ◽

Total N ◽

N Cycle ◽

Soil N Cycle

Abstract. The study of soil N cycling processes has been, is, and will be at the centre of attention in soil science research. The importance of N as a nutrient for all biota; the ever-increasing rates of its anthropogenic input in terrestrial (agro)ecosystems; its resultant losses to the environment; and the complexity of the biological, physical, and chemical factors that regulate N cycling processes all contribute to the necessity of further understanding, measuring, and altering the soil N cycle. Here, we review important insights with respect to the soil N cycle that have been made over the last decade, and present a personal view on the key challenges of future research. We identify three key challenges with respect to basic N cycling processes producing gaseous emissions: 1. quantifying the importance of nitrifier denitrification and its main controlling factors; 2. characterizing the greenhouse gas mitigation potential and microbiological basis for N2O consumption; 3. characterizing hotspots and hot moments of denitrification Furthermore, we identified a key challenge with respect to modelling: 1. disentangling gross N transformation rates using advanced 15N / 18O tracing models Finally, we propose four key challenges related to how ecological interactions control N cycling processes: 1. linking functional diversity of soil fauna to N cycling processes beyond mineralization; 2. determining the functional relationship between root traits and soil N cycling; 3. characterizing the control that different types of mycorrhizal symbioses exert on N cycling; 4. quantifying the contribution of non-symbiotic pathways to total N fixation fluxes in natural systems We postulate that addressing these challenges will constitute a comprehensive research agenda with respect to the N cycle for the next decade. Such an agenda would help us to meet future challenges on food and energy security, biodiversity conservation, water and air quality, and climate stability.

Download Full-text

Impact of irrigation management on paddy soil N supply and depth distribution of abiotic drivers

Agriculture Ecosystems & Environment ◽

10.1016/j.agee.2018.03.015 ◽

2018 ◽

Vol 261 ◽

pp. 12-24 ◽

Cited By ~ 4

Author(s):

Masuda Akter ◽

Heleen Deroo ◽

Ahammad Mostafa Kamal ◽

Mohammed Abdul Kader ◽

Elizabeth Verhoeven ◽

...

Keyword(s):

Paddy Soil ◽

Depth Distribution ◽

Irrigation Management ◽

Soil N ◽

N Supply

Download Full-text

Correction: Conversion of monoculture cropland and open grassland to agroforestry alters the abundance of soil bacteria, fungi and soil-N-cycling genes

PLoS ONE ◽

10.1371/journal.pone.0220713 ◽

2019 ◽

Vol 14 (7) ◽

pp. e0220713

Author(s):

Keyword(s):

Soil Bacteria ◽

N Cycling ◽

Soil N

Download Full-text

Elevated CO2, but not defoliation, enhances N cycling and increases short-term soil N immobilization regardless of N addition in a semiarid grassland

Soil Biology and Biochemistry ◽

10.1016/j.soilbio.2011.07.017 ◽

2011 ◽

Vol 43 (11) ◽

pp. 2247-2256 ◽

Cited By ~ 6

Author(s):

Feike A. Dijkstra ◽

Gordon L. Hutchinson ◽

Jean D. Reeder ◽

Daniel R. LeCain ◽

Jack A. Morgan

Keyword(s):

Elevated Co2 ◽

N Cycling ◽

N Immobilization ◽

Soil N ◽

N Addition ◽

Short Term ◽

Semiarid Grassland

Download Full-text

Validation of NBudget for estimating soil N supply in Australia's northern grains region in the absence of soil test data

Soil Research ◽

10.1071/sr16336 ◽

2017 ◽

Vol 55 (6) ◽

pp. 590 ◽

Cited By ~ 4

Author(s):

David F. Herridge

Keyword(s):

Soil Water ◽

Organic N ◽

Soil N ◽

Limited Information ◽

Available N ◽

Support Tool ◽

Grain Yields ◽

N Supply ◽

Nitrate N ◽

Winter Crop

Effective management of fertiliser nitrogen (N) inputs by farmers will generally have beneficial productivity, economic and environmental consequences. The reality is that farmers may be unsure of plant-available N levels in cropping soils at sowing and make decisions about how much fertiliser N to apply with limited information about existing soil N supply. NBudget is a Microsoft (Armonk, NY, USA) Excel-based decision support tool developed primarily to assist farmers and/or advisors in Australia’s northern grains region manage N. NBudget estimates plant-available (nitrate) N at sowing; it also estimates sowing soil water, grain yields, fertiliser N requirements for cereals and oilseed crops and N2 fixation by legumes. NBudget does not rely on soil testing for nitrate-N, organic carbon or soil water content. Rather, the tool relies on precrop (fallow) rainfall data plus basic descriptions of soil texture and fertility, tillage practice and information about paddock use in the previous 2 years. Use is made of rule-of-thumb values and stand-alone or linked algorithms describing, among other things, rates of mineralisation of background soil organic N and fresh residue N. Winter and summer versions of NBudget cover the 10 major crops of the region: bread wheat, durum, barley, canola, chickpea and faba bean in the winter crop version; sorghum, sunflower, soybean and mung bean in the summer crop version. Validating the winter crop version of NBudget estimates of sowing soil nitrate-N against three independent datasets (n=65) indicated generally close agreement between measured and predicted values (y=0.91x+16.8; r2=0.78). A limitation of the tool is that it does not account for losses of N from waterlogged or flooded soils. Although NBudget also predicts grain yields and fertiliser N requirements for the coming season, potential users may simply factor predicted soil N supply into their fertiliser decisions, rather than rely on the output of the tool. Decisions about fertiliser N inputs are often complex and are based on several criteria, including attitudes to risk, history of fertiliser use and costs. The usefulness and likely longevity of NBudget would be enhanced by transforming the current Excel-based tool, currently available on request from the author, to a stand-alone app or web-based tool.

Download Full-text