Variations in natural enrichment of 15N in the profiles of some Australian pasture soils

Soil Research ◽  
1984 ◽  
Vol 22 (2) ◽  
pp. 155 ◽  
Author(s):  
SF Ledgard ◽  
JR Freney ◽  
JR Simpson
Keyword(s):  
Soil Depth ◽  
Trifolium Subterraneum ◽  
Parent Material ◽  
Organic N ◽  
Soil N ◽  
Total N ◽  
Total Soil ◽  
Lateral Variations ◽  
Total Soil N ◽  
Natural Enrichment

Variability in the natural enrichment of 15N in total nitrogen (N) and several N fractions was examined for profiles of pasture soils differing in parent material and period under Trifolium subterraneum. The natural enrichment of 15N in the total N of surface soils (0-5 cm) within a 400 km2 catchment ranged from 2.55 to 6.79�(expressed as �15N with respect to atmospheric N2). There was no relationship with parent material, period under T. subterraneum or concentration of total N in the soil. In one soil, lateral variations in �15N over a 12 m2 grid were within the range of 5.01 to 7.95�. The �15N of total soil N always increased with depth in the soil profiles. This was associated with an increase in the stable clay-sized humus fraction, which had a higher �15N than the less humified organic N in sand and silt-sized fractions. One soil was separated into four depth layers in which �15N in the inorganic N, mineralizable N, plant-extractable N and total soil N were determined. The first three parameters all had lower �15N values than the total soil N. The �15N of total N increased with soil depth, whereas there was no change with depth in the other three parameters.

The effects of long-term applications of inorganic nitrogen fertilizer on soil nitrogen in the Broadbalk Wheat Experiment

1996 ◽  
Vol 127 (3) ◽  
pp. 347-363 ◽  
Author(s):  
M. J. Glendining ◽  
D. S. Powlson ◽  
P. R. Poulton ◽  
N. J. Bradbury ◽  
D. Palazzo ◽  
...  
Keyword(s):  
N Mineralization ◽  
Inorganic Nitrogen ◽  
Organic N ◽  
Soil N ◽  
Fertilizer N ◽  
Short Term ◽  
N Content ◽  
Total Soil ◽  
Total Soil N

SUMMARYThe Broadbalk Wheat Experiment at Rothamsted (UK) includes plots given the same annual applications of inorganic nitrogen (N) fertilizer each year since 1852 (48, 96 and 144 kg N/ha, termed N1 N2 and N3 respectively). These very long-term N treatments have increased total soil N content, relative to the plot never receiving fertilizer N (N0), due to the greater return of organic N to the soil in roots, root exudates, stubble, etc (the straw is not incorporated). The application of 144 kg N/ha for 135 years has increased total soil N content by 21%, or 570 kg/ha (0–23 cm). Other plots given smaller applications of N for the same time show smaller increases; these differences were established within 30 years. Increases in total soil N content have been detected after 20 years in the plot given 192 kg N/ha since 1968 (N4).There was a proportionally greater increase in N mineralization. Crop uptake of mineralized N was typically 12–30 kg N/ha greater from the N3 and N4 treatments than the uptake of c. 30 kg N/ha from the N0 treatment. Results from laboratory incubations show the importance of recently added residues (roots, stubble, etc) on N mineralization. In short-term (2–3 week) incubations, with soil sampled at harvest, N mineralization was up to 60% greater from the N3 treatment than from N0. In long-term incubations, or in soil without recently added residues, differences between long-term fertilizer treatments were much less marked. Inputs of organic N to the soil from weeds (principally Equisetum arvense L.) to the N0–N2 plots over the last few years may have partially obscured any underlying differences in mineralization.The long-term fertilizer treatments appeared to have had no effect on soil microbial biomass N or carbon (C) content, but have increased the specific mineralization rate of the biomass (defined as N mineralized per unit of biomass).Greater N mineralization will also increase losses of N from the system, via leaching and gaseous emissions. In December 1988 the N3 and N4 plots contained respectively 14 and 23 kg/ha more inorganic N in the profile (0–100 cm) than the N0 plot, due to greater N mineralization. These small differences are important as it only requires 23 kg N/ha to be leached from Broadbalk to increase the nitrate concentration of percolating water above the 1980 EC Drinking Water Quality Directive limit of 11·3mgN/l.The use of fertilizer N has increased N mineralization due to the build-up of soil organic N. In addition, much of the organic N in Broadbalk topsoil is now derived from fertilizer N. A computer model of N mineralization on Broadbalk estimated that after applying 144 kg N/ha for 140 years, up to half of the N mineralized each year was originally derived from fertilizer N.In the short-term, the amount of fertilizer N applied usually has little direct effect on losses of N over winter. In most years little fertilizer-derived N remains in Broadbalk soil in inorganic form at harvest from applications of up to 192 kg N/ha. However, in two very dry years (1989 and 1990) large inorganic N residues remained at harvest where 144 and 192 kg N/ha had been applied, even though the crop continued to respond to fertilizer N, up to at least 240 kg N/ha.

Relationships between biological and chemical measures of N supplying power and total soil N at field scale

1999 ◽  
Vol 79 (2) ◽  
pp. 353-366 ◽  
Author(s):  
F. Selles ◽  
C. A. Campbell ◽  
B. G. McConkey ◽  
S. A. Brandt ◽  
D. Messer
Keyword(s):  
Spatial Structure ◽  
Bulk Density ◽  
Multiple Regression ◽  
Geometric Mean ◽  
Transport Processes ◽  
Organic N ◽  
Soil N ◽  
Total Soil ◽  
Mineralizable N ◽  
Total Soil N

Producers and scientists are seeking more accurate methods for estimating the N-supplying power of soil at the field level. This has become more urgent as new management technologies, such as precision farming, gain popularity on the Canadian Prairies. We characterized the N status of the soil on an 18-ha site on which a new long-term alternative farming experiment was being initiated at Scott, Saskatchewan, by taking 160 cores in a systematic manner in June 1994. In these cores we determined: i) total soil N; and ii) the N-supplying power of the soil by determining mineralizable N by aerobic incubation at optimum temperature and moisture, and by extracting NH4–N with 2 M KCl at 100°C. Because the field had been fertilized shortly before sampling, residual fertilizer N severely affected the quality of determinations of N supplying power at the 0- to 7.5-cm depth. Consequently, we limited our investigation to the 7.5- to 15-cm depth. We also determined pH, bulk density, and particle size distribution. Using geostatistics, simple correlations, and multiple regression analyses, we demonstrated a close association between the biological and chemical measures of N-supplying power of the soil. Semivariograms revealed that the spatial structure of the variance of both variables was similar, with about 70% of the variance resulting from unidentified processes, and the rest explained by spatial structure. Field maps prepared with block-kriged estimates, revealed that these two measures of N-supplying power were similarly distributed throughout the landscape, and followed closely the spatial distribution of total soil N throughout most of the field. However, we identified two areas of the field where the two estimators of N-supplying power had a weak association with total soil N. Multiple regression and cluster analysis indicated that this disparity was a function of differences in soil pH, bulk density, and geometric mean diameter of soil particles, suggesting that soil erosion-transport processes may have altered the nature of organic N in areas of the field. The relationship between N mineralized during a 24-wk incubation and NH4–N extracted with hot KCl was not affected by these differences, suggesting that the biological and chemical procedures tested were accessing similar pools of soil N. We concluded that hot KCl NH4–N should prove useful for quantifying the N supplying power of soils. Key words: Geostatistics, estimation, kriging, spatial variability, mineralizable N

scholarly journals Bermudagrass Management in the Southern Piedmont U.S. IV. Soil Surface Nitrogen Pools

2001 ◽  
Vol 1 ◽  
pp. 673-681 ◽  
Author(s):  
Alan J. Franzluebbers ◽  
John A. Stuedemann
Keyword(s):  
Cynodon Dactylon ◽  
Soil Surface ◽  
N Fertilization ◽  
Organic N ◽  
Soil N ◽  
Crimson Clover ◽  
Total Soil ◽  
Soil N Pools ◽  
Total Soil N

The fate of nitrogen (N) applied in forage-based agricultural systems is important for understanding the long-term production and environmental impacts of a particular management strategy. We evaluated the factorial combination of three types of N fertilization (inorganic, crimson clover [Trifolium incarnatum L.] cover crop plus inorganic, and chicken [Gallus gallus] broiler litter pressure and four types of harvest strategy (unharvested forage, low and high cattle [Bos Taurus] grazing pressure, and monthly haying in summer) on surface residue and soil N pools during the first 5 years of ̒Coastal̓ bermudagrass (Cynodon dactylon [L.] Pers.) management. The type of N fertilization used resulted in small changes in soil N pools, except at a depth of 0 to 2 cm, where total soil N was sequestered at a rate 0.2 g ‧ kg–1‧ year–11 greater with inorganic fertilization than with other fertilization strategies. We could account for more of the applied N under grazed systems (76–82%) than under ungrazed systems (35–71%). As a percentage of applied N, 32 and 48% were sequestered as total soil N at a depth of 0 to 6 cm when averaged across fertilization strategies under low and high grazing pressures, respectively, which was equivalent to 6.8 and 10.3 g ‧ m–2‧ year–1. Sequestration rates of total soil N under the unharvested-forage and haying strategies were negligible. Most of the increase in total soil N was at a depth of 0 to 2 cm and was due to changes in the particulate organic N (PON) pool. The greater cycling of applied N into the soil organic N pool with grazed compared with ungrazed systems suggests an increase in the long-term fertility of soil.

CHANGES IN NATURAL 15N ABUNDANCE OF SOILS ASSOCIATED WITH TILLAGE PRACTICES

1984 ◽  
Vol 64 (3) ◽  
pp. 345-354 ◽  
Author(s):  
F. SELLES ◽  
R. E. KARAMANOS ◽  
K. E. BOWREN
Keyword(s):  
Particle Size ◽  
Conventional Tillage ◽  
Soil N ◽  
Zero Tillage ◽  
Total N ◽  
Size Fractions ◽  
Particle Size Fractions ◽  
Tillage Practices ◽  
Total Soil ◽  
Total Soil N

The objective of this study was to determine changes in N dynamics in an Orthic Black Chernozem as a result of two tillage practices (conventional and zero tillage) using the variations in the natural 15N abundance of different soil-N fractions. After 14 yr, no significant differences in isotope composition of total soil-N between the two tillage practices could be found. However, changes were detected in the natural 15N abundance of the acid-hydrolyzable N and various organo-mineral size fractions which led to useful comparisons of the nature of N under the two systems. The N-content of the hydrolyzable-N fraction was similar at the 0- to 4- and 8- to 16-cm depth under both tillage practices, while it was significantly different at the 4- to 8-cm depth. The δa15N of this fraction was consistently higher than that of total soil N at all depths only under zero tillage. This was associated with the presence of more labile N compounds under zero tillage. No differences in the isotopic composition of the organomineral size fractions were found at the 0- to 4-cm depth. At the 4- to 8- and 8- to 16-cm depths, the δa15N values of the finer particle size fractions were higher under zero tillage than under conventional tillage. This indicates a more labile nature of the N associated with these size fractions under zero tillage. Key words: δa15N, conventional tillage, zero tillage, total N, acid-hydrolyzable fraction, particle size fractions

scholarly journals Effects of two wood-based biochars on the fate of added fertilizer nitrogen—a 15N tracing study

2021 ◽  
Author(s):  
Subin Kalu ◽  
Gboyega Nathaniel Oyekoya ◽  
Per Ambus ◽  
Priit Tammeorg ◽  
Asko Simojoki ◽  
...  
Keyword(s):  
Plant Uptake ◽  
Plant Biomass ◽  
Application Rate ◽  
Control Treatment ◽  
Organic N ◽  
N Leaching ◽  
Soil N ◽  
Mineral N ◽  
Total N ◽  
Application Rates

AbstractA 15N tracing pot experiment was conducted using two types of wood-based biochars: a regular biochar and a Kon-Tiki-produced nutrient-enriched biochar, at two application rates (1% and 5% (w/w)), in addition to a fertilizer only and a control treatment. Ryegrass was sown in pots, all of which except controls received 15N-labelled fertilizer as either 15NH4NO3 or NH415NO3. We quantified the effect of biochar application on soil N2O emissions, as well as the fate of fertilizer-derived ammonium (NH4+) and nitrate (NO3−) in terms of their leaching from the soil, uptake into plant biomass, and recovery in the soil. We found that application of biochars reduced soil mineral N leaching and N2O emissions. Similarly, the higher biochar application rate of 5% significantly increased aboveground ryegrass biomass yield. However, no differences in N2O emissions and ryegrass biomass yields were observed between regular and nutrient-enriched biochar treatments, although mineral N leaching tended to be lower in the nutrient-enriched biochar treatment than in the regular biochar treatment. The 15N analysis revealed that biochar application increased the plant uptake of added nitrate, but reduced the plant uptake of added ammonium compared to the fertilizer only treatment. Thus, the uptake of total N derived from added NH4NO3 fertilizer was not affected by the biochar addition, and cannot explain the increase in plant biomass in biochar treatments. Instead, the increased plant biomass at the higher biochar application rate was attributed to the enhanced uptake of N derived from soil. This suggests that the interactions between biochar and native soil organic N may be important determinants of the availability of soil N to plant growth.

Comparison of rotations in which barley for grain follows woollypod vetch or forage barley

1987 ◽  
Vol 108 (3) ◽  
pp. 609-615 ◽  
Author(s):  
I. Papastylianou ◽  
Th. Samios
Keyword(s):  
Grain Yield ◽  
Dry Matter ◽  
Nitrogen Concentration ◽  
N Balance ◽  
Dry Matter Yield ◽  
Soil N ◽  
Fertilizer N ◽  
Total Soil ◽  
Using Data ◽  
Total Soil N

SummaryUsing data from rotation studies in which barley or woollypod vetch were included, both cut for hay and preceding barley for grain, it is shown that forage barley gave higher dry-matter yield than woollypod vetch (3·74 v. 2·92 t/ha per year). However, the latter gave feedingstuff of higher nitrogen concentration and yield (86 kg N/ha per year for vetch v. 55 kg N/ha per year for barley). Rainfall was an important factor in controlling the yield of the two forages and the comparison between them in different years and sites. Barley following woollypod vetch gave higher grain yield than when following forage barley (2·36 v. 1·91 t/ha). Rotation sequences which included woollypod vetch had higher output of nitrogen (N) than input of fertilizer N with a positive value of 44–60 kg N/ha per year. In rotations where forage barley was followed by barley for grain the N balance between output and input was 5–6 kg N/ha. Total soil N was similar in the different rotations at the end of a 7-year period.

Seasonal Dynamics of Fertilizer-Derived Hydrolysable NH3 in an Arable Soil of Northeast China

2012 ◽  
Vol 496 ◽  
pp. 502-506
Author(s):  
Hui Jie Lü ◽  
Hong Bo He ◽  
Xu Dong Zhang
Keyword(s):  
Early Stage ◽  
Grain Filling ◽  
Anthropogenic Sources ◽  
Organic N ◽  
Soil N ◽  
Fertilizer N ◽  
Maize Crop ◽  
Total N ◽  
Growing Period ◽  
Residual Fertilizer N

Fertilizer applications to soil are widely known to be the most important anthropogenic sources to influence soil N turnover in agricultural ecosystems. More information is required on the relationships between soil organic N (SON) forms in order to predict the maintenance, transformation and stability of soil N. Accordingly, 15N-labeled (NH4)2SO4 (totally 200 kg N/ha) was applied to a maize crop throughout the entire growing period to investigate the distribution and the dynamics of fertilizer-derived N in hydrolyzable-NH3 fraction by measuring the labeled N in them. The accumulation of 15N in hydrolyzable-NH3 fraction was time-dependent although the total N concentration changed only slightly. The transformation of the residual fertilizer N to hydrolyzable-NH3-15N was maximal during the silking and grain filling stages, suggesting the fertilizer N was immobilized at an early stage during the growing period. The rapid decrease of 15N in hydrolyzable-NH3 pool indicated that hydrolyzable-NH3-15N was a temporary pool for fertilizer N retention and was able to release fertilizer N for uptake by the current crop

scholarly journals Nitrogen Management in Organic Processing Tomato Production: Nitrogen Sufficiency Prediction Through Early-season Soil and Plant Monitoring

HortScience ◽  
2015 ◽  
Vol 50 (7) ◽  
pp. 1055-1063 ◽  
Author(s):  
S. Castro Bustamante ◽  
T.K. Hartz
Keyword(s):  
Management Practices ◽  
Nitrogen Management ◽  
Net N Mineralization ◽  
Soil N ◽  
Early Season ◽  
Processing Tomato ◽  
Total Soil ◽  
N Management ◽  
Total Soil N ◽  
Leaf N

Organic processing tomato (Solanum lycopersicum L.) production is a significant industry in California, yet little nitrogen (N) fertility research is available to guide N management. A total of 37 certified organic processing tomato fields in the Sacramento Valley of California were monitored during the 2012 and 2013 production seasons, with two objectives: 1) to document current N management practices and 2) to investigate the utility of early-season soil and plant N monitoring techniques in predicting seasonal crop N sufficiency. Between ≈3 and 11 weeks after transplanting (WAT) soil mineral N (SMN), leaf N and petiole NO3-N were determined every other week. In 22 fields, whole plant N concentration at ≈11 WAT was determined as a measure of crop N sufficiency. Growers were surveyed regarding N management practices used and fruit yields achieved. Net N mineralization (Nmin) was measured for 20 fields soils by aerobic laboratory incubation. Carbon mineralization (Cmin) in 24 hours following rewetting of air-dried soil and water extractable organic nitrogen (WEON) and carbon (WEOC) were also determined and evaluated as predictors of Nmin. Nitrogen management was primarily based on the application of manure or manure compost in the fall. Organic fertilizers were applied mainly in spring (pre- and post-transplanting). SMN in the top 60 cm at 3 WAT ranged from 6 to 32 mg·kg−1. About 30% of fields were N deficient by 11 WAT. Sensitivity analysis showed that SMN (whether measured from 0 to 30 or 0 to 60 cm) and leaf N at 5 WAT correctly predicted late-season plant N status in >60% of the fields. Nmin in 28 days ranged from 8 to 31 mg·kg−1, representing an average of 2% of total soil N. Correlation between Nmin and Cmin was weak (r = 0.44, P = 0.051) while stronger correlations were observed between Nmin and WEOC, WEON and total soil N (r = 0.63, 0.61 and 0.51, respectively, all P < 0.03). A multiple linear regression model that used 3 WAT SMN (0–30 cm) and WEON as independent variables improved Nmin prediction (adj. R2 = 0.67). Significant fruit yield increase with sidedress N application of feather meal at 5–6 WAT was observed in 2 of 4 field trials, demonstrating the ability to remedy a soil N limitation identified by early-season N monitoring.

Influence of growing various crops in five different fixed rotations on the changes in nitrate and total nitrogen content of soils

1985 ◽  
Vol 104 (3) ◽  
pp. 609-613 ◽  
Author(s):  
K. N. Sharma ◽  
A. L. Bhandari ◽  
M. L. Kapur ◽  
D. S. Rana
Keyword(s):  
Nitrogen Content ◽  
Total Nitrogen ◽  
Soil Nitrogen ◽  
Nitrate Nitrogen ◽  
Balance Sheet ◽  
Total Nitrogen Content ◽  
Soil N ◽  
Total N ◽  
Soil Layers ◽  
Total Soil N

SummaryThe results on the influence of various crops in five different fixed rotations on the ohanges in nitrate and total N content of soils are reported. Groundnut contributed largely to the accumulation of nitrate nitrogen in the soil profile (to a depth of 120 cm). Bajra fodder exhausted the soil nitrogen reserve to a great extent. Wheat and maize, in a rotation, reduced nitrate leaching to deeper soil layers. Summer moong also left a large amount of unabsorbed nitrate in the profile. Total nitrogen content of the soil decreased after the harvest of cereals. Maximum depletion occurred after the harvest of bajra crop. Potato (a crop which received a heavy dressing of N fertilizer) and legumes contributed to the soil N reserve. A balance sheet of N indicated net gains of total soil N in four of the five cropping sequences. A net loss of 75 kg N/ha was observed in bajra fodder-potato-wheat rotation.

Nitrogen cycling in a semi-arid Mediterranean region: changes in soil N and organic matter under several crop/livestock production systems

1994 ◽  
Vol 45 (6) ◽  
pp. 1293 ◽  
Author(s):  
PF White ◽  
NK Nersoyan ◽  
S Christiansen
Keyword(s):  
Organic Matter ◽  
Organic Matter Content ◽  
Farming Systems ◽  
Matter Content ◽  
Soil N ◽  
Livestock Farming ◽  
Mineral N ◽  
North West ◽  
Total Soil ◽  
Total Soil N

There is a need to quantify the effects on soil N of introducing different legumes into the farming systems of West Asia and North Africa. This paper presents 6 years results from an on-going experiment aimed at examining the productivity of several crop/livestock farming systems in north west Syria. Changes in total soil N and organic matter when either medic pasture (3 stocking rates), vetch, lentil, fallow or watermelon were rotated yearly with wheat were examined. In addition, in the sixth year of the experiment, mineral N levels in the soil and the N content of the wheat and legumes shoots were determined in order to formulate a simple N balance for each rotation. Medic pasture and vetch rotations increased total soil N and the organic matter content of the soil. Lentil had no effect on total soil N or the organic matter content. Total soil N also remained constant in the fallow rotation, but organic matter content of the soil tended to decrease. The changes in soil properties had implications for the long term production from the different rotations, and highlighted the importance of retaining legume residues for maintaining fertility.

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