Nitrogen fluxes in surface soils of 1 - 2-year-old eucalypt plantations in Tasmania

To improve our understanding of nitrogen (N) supply in eucalypt plantations in Tasmania, N fluxes were determined in surface soils (0–10 cm) at 4 sites supporting 1–2-year-old plantations of E. nitens. Net N mineralisation, nitrification, leaching, and uptake were measured by an in situ soil-core technique. Soils were derived from basalt (3 sites) or mudstone (1 site). Average rates of net N mineralisation ranged from 18 to 91 kg N/ha·year, and most mineralised N was nitrified and leached. There were significant linear relationships among net N mineralisation, nitrification, and leaching (r = 0·61–0·83). Annual rates of net N mineralisation varied as much within sites as between them, and rates in individual plots were significantly correlated with anaerobically mineralisable N (r = 0·82) or total N (r = 0·66), but were not correlated or only weakly correlated with C: N ratio, loss-on-ignition, organic C, water content, or temperature. Leaching was weakly correlated with effective rainfall (rainfall minus evaporation, r = 0·39). Soil contained most mineral N during February–April (i.e. late summer–early autumn) and least during October–November (i.e. late spring). We concluded that available N at these sites was highly variable spatially and temporally, and at a plot scale was closely related to concentrations of mineralisable substrate and not to soil water or temperature.

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Available Nitrogen in the Surface Mineral Layer of Natural Meadows

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis ◽

10.11118/actaun201765051483 ◽

2017 ◽

Vol 65 (5) ◽

pp. 1483-1492

Author(s):

Željko S. Dželetović ◽

Nevena Lj. Mihailović

Keyword(s):

N Availability ◽

Aerobic Incubation ◽

Mineral Layer ◽

Mineral N ◽

Total N ◽

Available N ◽

Organic C ◽

Wide Range ◽

Surface Mineral ◽

Total Organic C

Based on a greenhouse experiment, we evaluated nitrogen availability in the surface mineral layer of soil under various natural meadow stands by analyzing the following soil characteristics: total organic C, total N, initial content of easily available N inorganic forms, mineralized N content obtained by aerobic and anaerobic incubations and A-value. The experiment was performed on a test plant and through the application of urea enriched with 5.4 % 15N. The investigated soils under natural meadows are characterized with comparatively high mineralization intensity and high N availability indices. Contents of mineral N produced by aerobic incubation and the intensity of the mineralization correlate with the total organic C in the soil and the total N in the soil. Correlation of the availability index of the soil N produced by aerobic incubation with the total organic C and the total N in the soil under natural meadows is almost linear (r = 0.9981 and r = 0.9997, respectively). Contents of mineral N produced by anaerobic incubation, as well as the corresponding N availability and mineralization intensity indices correlate poorly with the mentioned parameters. Efficiency of nitrogen utilization from the applied N-fertilizer by the test crop varies within a wide range of values and correlates with the biomass yields of the test crop.

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Nitrogen fluxes in surface soils of young Eucalyptus nitens plantations in Tasmania

Soil Research ◽

10.1071/sr01024 ◽

2002 ◽

Vol 40 (3) ◽

pp. 543 ◽

Cited By ~ 11

Author(s):

M. T. Moroni ◽

P. J. Smethurst ◽

G. K. Holz

Keyword(s):

Forest Site ◽

N Availability ◽

Soil Core ◽

Eucalyptus Nitens ◽

Surface Soils ◽

Mineral N ◽

Eucalypt Plantations ◽

Wide Range ◽

Study Sites

Nitrogen (N) fluxes in surface soils (0–10 cm) were measured by an in situ soil-core technique at 5 sites supporting 1- to 4-year-old Eucalyptus nitens plantations in Tasmania. Rates of net N mineralisation (NNM) ranged from 13 to 188 kg N/ha.year. The highest rate was from an ex-pasture site, which was almost double the highest rate of NNM measured on an ex-forest site. Although there was a tendency towards lower rates of NNM in uncultivated versus cultivated soils, and in the final versus previous year or two of measurement, these differences were not significant. Concentrations of mineral N, however, decreased at all study sites during the first 3–4 years, significantly at 4 of these sites. Within the errors of measurement, most N that was mineralised was also nitrified and leached. Seasonal patterns in NNM and concentrations of nitrate (NO3–) occurred only at one site, which also had the highest annual rate of NNM. The balance of mineral N remaining in surface soil each October was 2–17 kg N/ha. We concluded that there was little evidence of a decrease in rates of NNM between 1 and 4 years after planting, and that high rates of NNM at some sites were accompanied by high rates of leaching that limited the accumulation of mineral N. Sitespecific management of N fertiliser may be warranted to compliment the wide range of N availability in eucalypt plantations. mineralisation, nitrification, leaching, uptake, forests, Australia.

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Nitrogen mineralisation indices in ferrosols under eucalypt plantations of North-Western Tasmania: association with previous land use

Soil Research ◽

10.1071/sr9960925 ◽

1996 ◽

Vol 34 (6) ◽

pp. 925 ◽

Cited By ~ 9

Author(s):

XJ Wang ◽

PJ Smethurst ◽

GK Holz

Keyword(s):

Land Use ◽

C:N Ratio ◽

Nitrogen Mineralisation ◽

Mineral N ◽

Total N ◽

Organic C ◽

Eucalypt Plantations ◽

Highly Correlated ◽

North Western ◽

Eucalyptus Delegatensis

Potentially mineralisable N was studied in the laboratory and in the held in ferrosols from eucalypt plantations and pastures in north-western Tasmania. The plantation sites previously supported either Pinus radiata plantations (ex-pine), mixed eucalypt-myrtle forest (ex-mixed), or open Eucalyptus delegatensis forest with a grass understory (ex-dele). Ranges of concentrations of organic C and total N, and C to N ratio, were 6.9-13.6%, 0.297-0.978%, and 10.3-30.4, respectively. The concentration of organic C was independent of previous land use, but rankings for total N, anaerobically mineralisable N, and extractable N in hot KCl were pasture > to ex-dele = ex-mixed > ex-pine. The ratio C:N in theex-pine group (23.6) was higher than ratios in other groups (13.1-15.6). Anaerobically mineralisable N ranged from 49 to 214 �g/g, and was highly correlated with total N and extractable N in hot KCl at 95�C for 16 h (r = 0.83 for both cases, P < 0.001). The C:N ratio was negatively correlated with total N and anaerobically mineralisable N (r = 0.56 and 0.70, P < 0.01). The results indicated that the pasture soils had greater availability of mineral N, and that total N, C:N ratio, and anaerobically mineralisable N may provide useful information for assessing N mineralisation in these soils.

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Effects of green-manure and tillage management on soil microbial community composition, nutrients and tree growth in a walnut orchard

Scientific Reports ◽

10.1038/s41598-021-96472-8 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Ningguang Dong ◽

Guanglong Hu ◽

Yunqi Zhang ◽

Jianxun Qi ◽

Yonghao Chen ◽

...

Keyword(s):

Microbial Community ◽

Green Manure ◽

Rhizosphere Soil ◽

Green Manures ◽

Hairy Vetch ◽

Mineral N ◽

Total N ◽

Organic C ◽

Nutrient Contents ◽

Walnut Tree

AbstractThis study characterized the effect of green manures (February orchid, hairy vetch, rattail fescue and a no-green-manure control) and the termination method (flail or disk) on nutrient contents, enzyme activities, microbial biomass, microbial community structure of rhizosphere soil and vegetative growth of walnut tree. All three selected green manures significantly enhanced the water content, organic C, total N and available P. The rattail fescue significantly decreased the mineral N. Total organic C, total N, mineral N and available P were significantly greater under flail than under disk. Hairy vetch and February orchid significantly improved levels of soil β-glucosidase, N-acetyl-glucosaminidase and acid phosphatase activity, whereas rattail fescue improved only β-glucosidase activity. All of the green manures significantly decreased phenoloxidase activity. β-glucosidase, N-acetyl-glucosaminidase and acid phosphatase activities were significantly greater under flail relative to disk. The termination method had no significant effect on phenoloxidase activity. The different types of green manures and termination methods significantly altered the soil microbial biomass and microbial community structure. The green-manure treatments were characterized by a significantly greater abundance of Gram-positive (Gram +) bacteria, total bacteria and saprophytic fungi compared to the control. Hairy vetch significantly decreased the abundance of arbuscular mycorrhizal fungi (AMF) while February orchid and rattail fescue increased their abundance compared to the no-green-manure treatment. The abundance rates of Gram+ bacteria, actinomycetes, saprophytic fungi and AMF were significantly greater in soils under flail than under disk. In terms of vegetative growth of walnut tree, hairy vetch showed the greatest positive effects. The growth of walnut tree was significantly greater under flail relative to disk. Our results indicate that green-manure application benefits the rhizosphere soil micro-ecology, rhizosphere soil nutrient contents and tree growth. Overall, the hairy vetch and flail combined treatment is recommended for walnut orchards in northern China.

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Indices of soil nitrogen availability in five Tasmanian Eucalyptus nitens plantations

Soil Research ◽

10.1071/sr03145 ◽

2004 ◽

Vol 42 (7) ◽

pp. 719 ◽

Cited By ~ 5

Author(s):

M. T. Moroni ◽

P. J. Smethurst ◽

G. K. Holz

Keyword(s):

Soil Solution ◽

Nitrogen Availability ◽

Native Forest ◽

N Availability ◽

Eucalyptus Nitens ◽

Soil Nitrogen Availability ◽

Mineral N ◽

Total N ◽

Available N ◽

Total P

Several soil analyses were used to estimate available N in surface soils (0–10 cm) over a 2-year period at 5 sites that supported 1- to 4-year-old Eucalyptus nitens plantations, and once in subsoils (10–120 cm) at 3 of these sites. Soils were derived from basalt (1 site previously pasture, 1 Pinus radiate, and 2 native forest) or siltstone (previously native forest). Soil analyses examined were total N, total P, total C, anaerobically mineralisable N (AMN), hot KCl-extractable N (hot KCl-N), and NH4+ and NO3– in soil solution and KCl extracts. AMN, KCl-extractable NH4+ and NO3–, and soil solution NH4+ and NO3– varied considerably with time, whereas hot KCl-N, total N, total P, and total C were temporally stable except for a gradual decline in total C with time at one site. Only total P was correlated with net N mineralisation (NNM) across all sites (r2 = 0.91, P < 0.05, n = 5). At 2–3 years after planting, soil solution and KCl-extractable NO3– dropped below 0.1 mm N and 1 μg N/g soil, respectively, at sites with NNM ≤24 kg N/ha.year (n = 3). Sites with NNM ≤24 kg N/ha.year also had ≤0.8 Mg P/ha. Although concentrations of indices of soil N availability decreased with depth, the contribution of subsoil (10–120 cm depth) to total profile N availability was estimated to be at least twice that of the top 10 cm. At an ex-pasture site, high concentrations of mineral N were found at 75–105 cm depths (KCl-extractable N, 289.3 μg N/g soil; 2.8 mm mineral N in soil solution), which may have become available to plantations as their root systems developed.

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The influence of the soil matrix on nitrogen mineralisation and nitrification. I. Spatial variation and a hierarchy of soil properties

Soil Research ◽

10.1071/s97102 ◽

1998 ◽

Vol 36 (3) ◽

pp. 429 ◽

Cited By ~ 10

Author(s):

D. T. Strong ◽

P. W. G. Sale ◽

K. R. Helyar

Keyword(s):

Soil Properties ◽

Water Content ◽

Organic N ◽

Small Field ◽

N Mineralisation ◽

Mineral N ◽

Conceptual Tool ◽

Soil Matrix ◽

Total N ◽

Soil Variables

Natural heterogeneity of soil properties was used to explore their influence on nitrogen (N) mineralisation and nitrification in undisturbed small soil volumes (soil cells; c. 1 · 7 cm3 ) sampled from a small field plot (2 m by 3 m). Soil cells (840) were randomly ascribed to 1 of 6 treatments in which soils were retained continuously moist (M10 and M30 treatments) and amended with organic N from clover (Cl10 and Cl30 treatments), dried and rewetted (DW10), or treated with urea (Ur10) (subscripts indicate soil incubation at matric potential - 10 or - 30 kPa). After 20 days of incubation at 24C, each soil cell was analysed for NO-3 -N, NH + 4 -N, pH, bulk density (BD), volumetric water content (θv), water content at - 490 kPa (θv490), and pH buffer capacity (pHBC). On 25 soil cells from each treatment, % clay, % silt, % sand, total N (% N), organic carbon (% C), and 7 cations and anions were also determined. Net N mineralisation and net nitrification occurred in all treatments, and the total mineral N at the end of the incubation was 497, 81, 73, 31, 27, and 31 µg N/g in the Ur10 Cl10, Cl30, M10, M30, and DW10 treatments, respectively. Net N mineralisation in the M30 treatment was 84% of that in the M10 treatment, and net N mineralisation in the Cl30 treatment was 86% of that in the Cl10 treatment. Fluctuations in soil pH varied markedly between treatments and over time, and it was apparent that alkaline processes were occurring in all soil cells. The heterogeneity between soil samples was substantial for all of the soil variables. Soil variables were classified in a hierarchy from the least to the most fundamental based on their stability through time. This ranking provides a conceptual tool for understanding interrelationships between soil properties and for interpreting results of regression analyses. The sampling approach adopted in this study was designed to harness the natural heterogeneity of soil properties in the small field site while keeping other properties and environmental factors, that usually vary over larger distances, constant. Both the extent of heterogeneity of soil properties and the nature of their correlations with NO-3 -N suggested that this technique would be useful in the exploration of how soil properties influence N mineralisation and nitrification.

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Organic amendment effects on tuber yield, plant N uptake and soil mineral N under organic potato production

Renewable Agriculture and Food Systems ◽

10.1017/s1742170508002330 ◽

2008 ◽

Vol 23 (03) ◽

pp. 250-259 ◽

Cited By ~ 24

Author(s):

Derek H. Lynch ◽

Zhiming Zheng ◽

Bernie J. Zebarth ◽

Ralph C. Martin

Keyword(s):

N Uptake ◽

N Availability ◽

Residual Soil ◽

Soil Mineral ◽

Soil Mineral Nitrogen ◽

Mineral N ◽

Total N ◽

Available N ◽

Organic Potato ◽

Certified Organic

AbstractThe market for certified organic potatoes in Canada is growing rapidly, but the productivity and dynamics of soil N under commercial organic potato systems remain largely unknown. This study examined, at two sites in Atlantic Canada (Winslow, PEI, and Brookside, NS), the impacts of organic amendments on Shepody potato yield, quality and soil mineral nitrogen dynamics under organic management. Treatments included a commercial hog manure–sawdust compost (CP) and pelletized poultry manure (NW) applied at 300 and 600 kg total N ha−1, plus an un-amended control (CT). Wireworm damage reduced plant stands at Brookside in 2003 and those results are not presented. Relatively high tuber yields (~30 Mg ha−1) and crop N uptake (112 kg N ha−1) were achieved for un-amended soil in those site-years (Winslow 2003 and 2004) when soil moisture was non-limiting. Compost resulted in higher total yields than CT in one of three site-years. Apparent recovery of N from CP was negligible; therefore CP yield benefits were attributed to factors other than N availability. At Winslow, NW300, but not NW600, significantly increased total and marketable yields by an average of 5.8 and 7.0 Mg ha−1. Plant available N averaged 39 and 33% for NW300 and NW600, respectively. Soil (0–30 cm) NO3−-N at harvest was low (<25 kg N ha−1) for CT and CP, but increased substantially both in season and at harvest (61–141 kg N ha−1) when NW was applied. Most leaching losses of NO3−-N occur between seasons and excessive levels of residual soil NO3-N at harvest, as obtained for NW600, must be avoided. Given current premiums for certified organic potatoes, improving yields through application of amendments supplying moderate rates of N or organic matter appears warranted.

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Wheat response after temperate crop legumes in south-eastern Australia

Australian Journal of Agricultural Research ◽

10.1071/ar9910031 ◽

1991 ◽

Vol 42 (1) ◽

pp. 31 ◽

Cited By ~ 51

Author(s):

J Evans ◽

NA Fettell ◽

DR Coventry ◽

GE O'Connor ◽

DN Walsgott ◽

...

Keyword(s):

New South ◽

Wheat Yield ◽

Wheat Crop ◽

First Year ◽

Mineral N ◽

Total N ◽

Available N ◽

Relative Contribution ◽

South Wales ◽

Eastern Australia

At 15 sites in the cereal belt of New South Wales and Victoria, wheat after lupin or pea produced more biomass and had a greater nitrogen (N) content than wheat after wheat or barley; on average these crops assimilated 36 kg N/ha more. The improved wheat yield after lupin averaged 0 . 9 t/ha and after pea 0.7 t/ha, increases of 44 and 32% respectively. The responses were variable with site, year and legume. Soil available N was increased by both lupin and pea and the levels of surface inorganic N measured at the maturity of first year crops was often related to N in wheat grown in the following year. Of two possible sources of additional N for wheat after legumes, namely mineral N conserved in soil by lupin or pea (up to 60 kg N/ha) and the total N added in the residues of these legumes (up to 152 kg N/ha), both were considered significant to the growth of a following wheat crop. Their relative contribution to explaining variance in wheat N is analysed, and it is suggested wheat may acquire up to 40 kg N/ha from legume stubbles. Non-legume break crops also increased subsequent wheat yield but this effect was not as great as the combined effect of added N and disease break attained with crop legumes.

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Soil nitrogen mineralisation and organic matter composition revealed by 13C NMR spectroscopy under repeated prescribed burning in eucalypt forests of south-east Queensland

Soil Research ◽

10.1071/s97034 ◽

1999 ◽

Vol 37 (1) ◽

pp. 123 ◽

Cited By ~ 42

Author(s):

D. F. Guinto ◽

Z. H. Xu ◽

P. G. Saffigna ◽

A. P. N. House ◽

M. C. S. Perera

Keyword(s):

Organic Matter ◽

Nmr Spectroscopy ◽

13C Nmr ◽

Prescribed Burning ◽

13C Nmr Spectroscopy ◽

High Ratio ◽

N Mineralisation ◽

Total N ◽

Organic C ◽

Organic Matter Composition

The effects of burning on in situ extractable nitrogen (NH+4-N+NO-3-N) and net Nmineralisation following scheduled fuel reduction burns in repeatedly burnt dry and wet sclerophyll forest sites in south-east Queensland were assessed. In addition, soil organic matter composition in the wet sclerophyll site was assessed by 13C NMR spectroscopy. The results showed that at the dry sclerophyll site, extractable N and net N mineralisation for 1 year were largely unaffected by burning, while at the wet sclerophyll site, these parameters decreased. 13C NMR analysis of soil samples from the wet sclerophyll site revealed that there was a significant reduction in the proportion of O-alkyl (alkoxy/carbohydrate) C with increasing burning frequency. Statistically significant effects on the other chemical shift regions were not detected. The ratio of alkyl C to O-alkyl C, a proposed index of organic matter decomposition, increased with increasing burning frequency. A high ratio of alkyl C to O-alkyl C suggests low amounts of carbohydrates relative to waxes and cutins, which could in turn lead to slower mineralisation. The findings are in accord with this hypothesis. There were significant linear relationships between cumulative N mineralisation for 1 year and the proportions of alkyl C and O-alkyl C, and the ratio of alkyl C/O-alkyl C. Thus, in addition to reductions in substrate quantity (low organic C and total N for burnt soils), there was also an alteration of substrate quality as revealed by 13C NMR spectroscopy which is reflected in low N mineralisation.

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NO3- uptake and C exudation – do plant roots stimulate or inhibit denitrification?

10.5194/egusphere-egu2020-19445 ◽

2020 ◽

Author(s):

Pauline Sophie Rummel ◽

Reinhard Well ◽

Birgit Pfeiffer ◽

Klaus Dittert ◽

Sebastian Floßmann ◽

...

Keyword(s):

Soil Moisture ◽

N Uptake ◽

Root Exudation ◽

Soil Surface ◽

N Fertilization ◽

Plant N Uptake ◽

Mineral N ◽

Double Labeling ◽

Total N ◽

Organic C

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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