Differences in natural abundance of 15N in the extractable mineral nitrogen of cropped and fallowed surface soils

1987 ◽  
Vol 38 (1) ◽  
pp. 15 ◽  
Author(s):  
GL Turner ◽  
RR Gault ◽  
L Morthorpe ◽  
DL Chase ◽  
FJ Bergersen
Keyword(s):  
Total Nitrogen ◽  
Soil Nitrogen ◽  
Mineral Nitrogen ◽  
Natural Abundance ◽  
Mineral N ◽  
Plant Nitrogen ◽  
Red Earth ◽  
Time Courses ◽  
Soil Nitrogen Cycle ◽  
Made In

The natural abundances (S15N with reference to atmospheric N2) of the stable isotope of nitrogen (15N) in the total nitrogen and in KCl-extractable mineral nitrogen (typically 96% NO-3-N and 4% NH+4-N) were measured in the surface 10 cm of a transitional red earth at Yanco, N.S.W., and of a grey soil of heavy texture at Trangie, N.S.W. Measurements were made in Autumn (May), prior to planting crops of winter oats, at the time of harvest (October) and in December, using both cropped and continuously fallowed soils. At Trangie, additional measurements were made in September, near the beginning of rapid growth in spring. Despite differences in soil type, pH .and location, both sites showed: (i) S15N in extractable mineral nitrogen varied with time (decreasing from 18.7 to 6.0% in fallowed soil at Yanco, and increasing from 5.8 to 12.0%~ under oats at Trangie), and in cropped versus fallowed treatments (12.0 and 5.3% respectively in December at Trangie), and values were different from those of the total soil nitrogen, in which S15N remained virtually unchanged (over all times and sites, S15N = 8.2 � 0.2 at Trangie); (ii) after removal of the crop, S15N in increments of extractable mineral nitrogen were higher than in the total nitrogen of previously cropped soils, whilst in the continuously fallowed soils, S15N of extractable mineral nitrogen was lower than in the total nitrogen. In addition, at Trangie, S15N in the extractable mineral nitrogen was highest late in growth of the oat crop, and this was reflected in the values for S15N of nitrogen assimilated in the crop. Values of the S15N of plant nitrogen agreed well with the S15N of extractable mineral N when the former were determined in increments of plant N during fixed periods of growth and plotted appropriately (the mid-point between sampling times) in relation to the time courses of changes in the mineral N. These results are discussed in relation to the use of 15N natural abundance techniques for estimating nitrogen fixation by nodulated legumes and in the study of other aspects of soil nitrogen cycle processes.

Effects of soil nitrogen status and rate of inoculation on the establishment of populations of Bradyrhizobium japonicum and on the nodulation of soybeans

1989 ◽  
Vol 40 (4) ◽  
pp. 753
Author(s):  
J Brockwell ◽  
RR Gault ◽  
LJ Morthorpe ◽  
MB Peoples ◽  
GL Turner ◽  
...  
Keyword(s):  
Glycine Max ◽  
Soil Nitrogen ◽  
Bradyrhizobium Japonicum ◽  
Clay Soil ◽  
Mineral Nitrogen ◽  
Soil Mineral ◽  
Soil Mineral Nitrogen ◽  
Nitrogen Status ◽  
Mineral N ◽  
Glycine Max L

Soybeans (Glycine max [L.] Merrill cv. Forrest) were grown under irrigation on a well-structured grey clay soil, previously free of Bradyrhizobium japonicum and containing relatively high levels of mineral N, at Trangie, N.S.W. There were two soil pretreatments, pre-cropped (which had the effect of reducing the level of mineral nitrogen in the soil) and pre-fallowed, and four rates of inoculation (B. japonicum CB 1809 - nil, 0.01 X, 1.OX [=normal] and 100X).Mineral nitrogen (0-10 cm) initially was higher in pre-fallowed soil than in pre-cropped soil (37.6 v. 18.5 mg N per kg). Depletion of mineral nitrogen occurred more rapidly in pre-fallowed treatments, so that, 7 days after harvest, mineral-N in pre-cropped soil was significantly higher than in pre-fallowed soil (14.4 v. 10.6 mg per kg).With high levels of soil mineral nitrogen, colonization of seedling rhizospheres by rhizobia and plant nodulation were diminished. These effects were ameliorated but not eliminated by increased rates of inoculation. The development of the symbiosis was also impeded by lower rates of inoculation (0.01 X, 1.OX).

The mobility and transformation of soil nitrogen and the relationships between soil and plant nitrogen and yield at different times following application of various nitrogen fertilizers to sweet corn

1992 ◽  
Vol 43 (7) ◽  
pp. 1643 ◽  
Author(s):  
AA Salardini ◽  
LA Sparrow ◽  
RJ Holloway
Keyword(s):  
Soil Nitrogen ◽  
Sweet Corn ◽  
Nitrogen Fertilizers ◽  
Yield Response ◽  
Strongly Correlated ◽  
Mineral N ◽  
N Application ◽  
Plant Nitrogen ◽  
Highly Correlated ◽  
Sampling Times

The concentration of NH4-N, NO3-N and their sum (mineral N) were monitored 12 times in 1 or 2 weekly intervals in the soil under a sweet corn crop. The samples were taken on the fertilizer band and to depths of 200, 400 and 600 mm. The NO3-N concentration of the sap expressed from the midrib of the leaf opposite and immediately above the primary cob (sap NO3-N) and that of midrib dry matter (midrib NO3-N) were determined weekly. Under the low rainfall and optimized irrigation of this trial the concentration of mineral N in soil to the depth of 400 mm or more was a good predictor of yield response to application of N at 10 of the 12 sampling times. The concentration of either NH4-N or NO3-N in the soil to any depth and the concentration of mineral N in the surface 200 mm correlated with the yield at only a few times of sampling. The concentration of mineral N in the top 200 mm of soil 1 or 2 weeks after top-dressing of N was highly correlated to yield. The concentration of sap NOS-N and midrib NO3-N decreased continuously until harvest. Both these concentrations were significantly correlated with the rates of basal and top-dressed N in most sampling times. These were also strongly correlated to yield 1 or 2 weeks after N top-dressing. Ammonium sulfate, ammonium nitrate and urea gave similar responses in sap NO3-N and midrib NO3-N and in soil nitrogen after 5 weeks when nitrification of fertilizer NH4-N was complete. These observations indicated that soil mineral N, sap NO3-N and midrib NO3-N all offer potential as techniques to predict the yield response of sweet corn to N application. The sap NO3-N test was simpler, quicker, cheaper and more consistent than other tests.

Nitrogen availability in a Darling Downs soil following cereal, oilseed and grain legume crops. 1. Soil nitrogen accumulation

1986 ◽  
Vol 26 (3) ◽  
pp. 347 ◽  
Author(s):  
WM Strong ◽  
J Harbison ◽  
RGH Nielsen ◽  
BD Hall ◽  
EK Best
Keyword(s):  
Soil Nitrogen ◽  
Nitrogen Availability ◽  
Grain Legumes ◽  
Mineral Nitrogen ◽  
Grain Legume ◽  
Nitrogen Accumulation ◽  
Soil Mineral N ◽  
Soil Mineral ◽  
Soil Mineral Nitrogen ◽  
Mineral N

Available soil mineral nitrogen (N) was determined in a Darling Downs clay at intervals of 4-6 weeks throughout summer and autumn after harvest of two cereals (wheat and oats), two oilseeds (rapeseed and linseed), and four grain legumes (chickpea, fieldpea, lupin and lathyrus). Soil mineral N (0-1.2 m) at 40,68, 107, 150 and 185 days after harvest was affected (P < 0.05) by the prior crop. At 40 days it was generally higher following grain legumes (34-76 kg/ha N) than following oilseeds or cereals (16-30 kg/ha N). Net increase during the next 145 days was in the order of cereals (2 1-27 kg/ha N) < oilseeds (40 kg/ha N) <grain legumes (53-85 kg/ha N). These differences are partly accounted for by differences in the quantities of N removed in the grain of these crops. However, a large quantity of mineral N accumulated following lupin even though a large quantity (80 kg/ha) was removed in the grain.

An evaluation of indices of available soil nitrogen

1970 ◽  
Vol 10 (42) ◽  
pp. 89 ◽  
Author(s):  
RR Storrier ◽  
AT Hanly ◽  
HI Nicol
Keyword(s):  
Soil Nitrogen ◽  
Nitrogen Uptake ◽  
Dry Matter ◽  
Mineral Nitrogen ◽  
Soluble Nitrogen ◽  
Dry Matter Yield ◽  
Soil Tests ◽  
Plant Nitrogen ◽  
Matter Production ◽  
Nitrate Fertilizer

Various chemical and biological measures of available soil nitrogen were evaluated as potential soil tests by estimating their relationship with the dry matter production and nitrogen uptake of ryegrass (Lolium perenne) from twelve soils treated with several rates of nitrate fertilizer. The response of the ryegrass to fertilizer was similar for all soils, and did not show any relationship with the soil tests. However, the mean dry matter yield and mean nitrogen uptake for all treatments were significantly related to some of these tests. Generally, soil nitrogen indices that measured total mineral nitrogen at planting or included this value with an estimate of the potentially available organic nitrogen gave the higher correlations. Incubation nitrogen values gave lower correlations. The best index of available soil nitrogen was based on a multiple regression involving total mineral nitrogen and alkali-permanganate soluble nitrogen. It accounted for 92 and 96 per cent of the variation in dry matter yield and plant nitrogen uptake respectively.

The natural abundance of 15N in an irrigated soybean crop and its use for the calculation of nitrogen fixation

1985 ◽  
Vol 36 (3) ◽  
pp. 411 ◽  
Author(s):  
FJ Bergersen ◽  
GL Turner ◽  
RR Gault ◽  
DL Chase ◽  
J Brockwell
Keyword(s):  
Soil Nitrogen ◽  
N2 Fixation ◽  
Plant Size ◽  
Natural Abundance ◽  
Available Nitrogen ◽  
Plant Nitrogen ◽  
Residual Nitrogen ◽  
Stages Of Growth ◽  
Plant Available Nitrogen ◽  
Grain Nitrogen

In a field experiment at Leeton, N.S.W., Chaffey soybeans were grown with irrigation at various plant spacings and with various inoc~ilation treatments and two pre-planting soil treatments. Uninoculated plants were almost completely non-nodulated. Measurements of the natural abundance of 15N (S15N) in the total nitrogen of the plants were made at all stages of growth and in the grain at harvest. The 6lSN in all nodulated treatments declined progressively with time in comparison with un-nodulated plants, due to the incorporation of atmospheric N2 of lower 15N concentration than the soil nitrogen. This enabled calculation of the proportions of plant-nitrogen obtained from the soil and by symbiotic N2-fixation. The main findings were as follows: There was a gradient of S15N in plant-available nitrogen across the experimental area. Therefore, treatments were compared by using the nearest non-nodulated plot for the estimate of S15N in plantavailable soil nitrogen. Despite large differences in plant size due to plant spacing, S15N in mature nonnodulated plants did not differ significantly, indicating that the natural abundance of 15N in plantavailable soil nitrogen was uniform in root zones of different sizes. In well-nodulated plants, the proportion (p) of shoot nitrogen derived from N2-fixation increased with time, reaching approximately 70% and 90% in previously fallowed and previously cropped soil respectively, during a period of rapid growth between 78 and 98 d& after planting. The fixed N, in the best-nodulated treatments at (114 days) was 143 and 244 kg N ha-1 respectively for previously fallowed and previously cropped soil. There were consistent trends for increased N2 fixation with increased inoculation rates. In non-nodulated plants, nitrogen recovered in the grain represented most of that present in the shoots at maturity. In well-nodulated treatments, grain nitrogen, although similar in S15N to that of shoots + fruits, represented only 47 and 59% of the 406 and 348 kg N ha-1 present at maturity in shoots + fruits from previously fallowed and previously cropped soils respectively. After harvesting more than 3 t ha-1 of grain, the nitrogen balance in the previously cropped soil, if all of the residual nitrogen in the soybeans could have been retained in the soil, was positive. In the previously fallowed soil there could have been a net depletion of soil nitrogen.

Nitrogen fixation in grazed and ungrazed subterranean clover pasture in south-west Australia assessed by the 15N natural abundance technique

1995 ◽  
Vol 46 (7) ◽  
pp. 1427 ◽  
Author(s):  
P Sanford ◽  
JS Pate ◽  
MJ Unkovich ◽  
AN Thompson
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
15N Natural Abundance ◽  
Natural Abundance ◽  
Shoot Biomass ◽  
Pasture Grass ◽  
Mineral N ◽  
Plant Nitrogen ◽  
Winter Depression ◽  
Grazed Pasture

The progress of N2 fixation by subterranean clover (Trifolium subterraneum L.) was followed throughout a growing season in adjacent grazed and ungrazed portions of a pasture at Mount Barker, W.A. Proportions of plant nitrogen derived from the atmosphere (%Ndfa) were determined at a sequence of sampling times using the 15N natural abundance technique with capeweed (Arctotheca calendula L.) as non-fixing reference species. Cumulative yields of fixed N by above ground biomass of clover were determined from %Ndfa values, concurrent estimates of dry matter (DM) yields, and percentage nitrogen in clover shoot DM. Seasonal DM yields of clover, capeweed and mixed grasses were in the approximate ratio 60 : 20: 20. Total herbage yields were 11.8 and 7.8 t ha-1 for the grazed and ungrazed swards respectively. Poorer performance of the latter was attributed to shading by taller grasses late in the season. Starting from a low value of 58%, Ndfa of the ungrazed sward became uniformly high (73-88%) for the rest of the season. Clover of the more productive grazed sward behaved similarly except for a significant mid winter depression to 55%Ndfa, probably caused by excessive defoliation through overgrazing. Fixed N recovered from clover shoot biomass was 103 and 188 kg N ha-1 for ungrazed and grazed pasture respectively. Mineral N under the grazed sward first consisted mostly of nitrate, and then predominantly of ammonium. Soil-derived N was utilized roughly equally by clover, grasses and capeweed and a field study of %Ndfa of subterranean clover grown in varying proportion with either the main pasture grass (Lolium rigidum Gaudin) or capeweed indicated the grass to be the more effective competitor for soil N against the clover. The data suggested that reliable estimates of seasonal accumulation of fixed N by pastures would be obtained from assessments of cumulative biomass yield of clover N with a single determination of %Ndfa at peak productivity in mid to late spring.

A survey of proportional dependence of subterranean clover and other pasture legumes on N2 fixation in south-west Australia utilizing 15N natural abundance

1994 ◽  
Vol 45 (1) ◽  
pp. 165 ◽  
Author(s):  
P Sanford ◽  
JS Pate ◽  
MJ Unkovich
Keyword(s):  
Soil Ph ◽  
Coastal Region ◽  
Subterranean Clover ◽  
15N Natural Abundance ◽  
Natural Abundance ◽  
Mineral N ◽  
Pasture Production ◽  
Total N ◽  
Study Region ◽  
Plant Nitrogen

In an attempt to understand why pasture production in southern Australia has declined markedly in recent years a survey of the symbiotic performance of the legume component of annual pastures on 81 farms (243 sites) was undertaken in the southern coastal region of Western Australia. The 15N natural abundance technique was used to determine the percentage of plant nitrogen derived from the atmosphere (%Ndfa) using capeweed (Arctotheca calendula) as principal non-fixing reference species. %Ndfa values were then related to edaphic and management information, e.g. soil total nitrogen, soil pH, stocking rates and cropping history of the sites. The principal legume species encountered exhibited similar mean %Ndfa values but substantial variation in symbiotic performance was evident across the sites, viz, Trifolium subterraneum 72%Ndfa (n = 184, range of values encountered 0-100%), Medicago spp. 7l%Ndfa (n = 24, range 7-l00%), Lotus spp. 8l%Ndfa (n = 15, range 1-l00%), Ornithopus compressus 76%Ndfa (n = 15, range 25-100%) and Trifolium balansae 69%Ndfa (n = 7, range 0-100%). In the case of subterranean clover, the most widely occurring species, almost one third (29%) of sites surveyed recorded %Ndfa values within the range 0-65%, suggesting that symbiotic performance might well be quite widely limiting to herbage production in the study region. Of the 24 edaphic and management factors evaluated, only one, %A1 in shoot, DM showed a significant relationship with %Ndfa, with 40% of the pastures surveyed deemed at risk in terms of acidity related aluminium toxicity. Correlations of %Ndfa with soil pH and soil total N produced examples of high values %Ndfa for sub-clover being associated with very low soil pH or high soil N, suggesting possible adaptation of symbiotic partnerships to acidity or high mineral N.

Corrigendum - Effects of soil nitrogen status and rate of inoculation on the establishment of populations of Bradyrhizobium japonicum and on the nodulation of soybeans

1989 ◽  
Vol 40 (4) ◽  
pp. 753 ◽  
Author(s):  
J Brockwell ◽  
RR Gault ◽  
LJ Morthorpe ◽  
MB Peoples ◽  
GL Turner ◽  
...  
Keyword(s):  
Glycine Max ◽  
Soil Nitrogen ◽  
Bradyrhizobium Japonicum ◽  
Clay Soil ◽  
Mineral Nitrogen ◽  
Soil Mineral ◽  
Soil Mineral Nitrogen ◽  
Nitrogen Status ◽  
Mineral N ◽  
Glycine Max L

Soybeans (Glycine max [L.] Merrill cv. Forrest) were grown under irrigation on a well-structured grey clay soil, previously free of Bradyrhizobium japonicum and containing relatively high levels of mineral N, at Trangie, N.S.W. There were two soil pretreatments, pre-cropped (which had the effect of reducing the level of mineral nitrogen in the soil) and pre-fallowed, and four rates of inoculation (B. japonicum CB 1809 - nil, 0.01 X, 1.OX [=normal] and 100X).Mineral nitrogen (0-10 cm) initially was higher in pre-fallowed soil than in pre-cropped soil (37.6 v. 18.5 mg N per kg). Depletion of mineral nitrogen occurred more rapidly in pre-fallowed treatments, so that, 7 days after harvest, mineral-N in pre-cropped soil was significantly higher than in pre-fallowed soil (14.4 v. 10.6 mg per kg).With high levels of soil mineral nitrogen, colonization of seedling rhizospheres by rhizobia and plant nodulation were diminished. These effects were ameliorated but not eliminated by increased rates of inoculation. The development of the symbiosis was also impeded by lower rates of inoculation (0.01 X, 1.OX).

EFFECT OF VARIOUS PERIODS OF SEED-DOWN TO ALFALFA AND BROMEGRASS ON SOIL NITROGEN

1971 ◽  
Vol 51 (1) ◽  
pp. 65-73 ◽  
Author(s):  
W. S. FERGUSON ◽  
B. J. GORBY
Keyword(s):  
Total Nitrogen ◽  
Soil Nitrogen ◽  
Nitrogen Loss ◽  
Nitrogen Absorption ◽  
Aerobic Incubation ◽  
Available Nitrogen ◽  
Plant Nitrogen ◽  
Acid Hydrolysate ◽  
Total Soil ◽  
Total Soil Nitrogen

Total soil nitrogen decreased substantially during the 12-year period (1954 to 1965) in a coarse-textured Chernozemic soil located at Brandon, Manitoba. The amount of nitrogen loss was related to cropping practices. The loss was 24% when the soils were continuously summerfallowed and 16% when the soil was producing alfalfa, during eight of the 12 years. Other perennial crops (bromegrass, and a mixture of bromegrass and alfalfa) had similar effects on total nitrogen to those of alfalfa. The loss of soil nitrogen was inversely proportional to the intensity of cropping during the 12-year period. The availability of soil nitrogen, as assessed for wheat production during the four-year period 1966 to 1969, was directly proportional to the intensity of cropping during 1954 to 1965, and was increased by alfalfa production. The total nitrogen absorbed by three crops of wheat was closely related to the amount of nitrate nitrogen in the soil to a depth of 122 cm at the beginning of the three years of production. It was not related to total soil nitrogen. The protein content of the grain was related to intensity of cropping and alfalfa production. The change in the amount of nitrogen in the amino acid, hexosamine, ammonia, and unidentified fractions of an acid hydrolysate of these soils was proportional to the change in total soil nitrogen. It did not appear to be related to changes in available nitrogen as measured by soil nitrate, plant nitrogen absorption or nitrate released on aerobic incubation.

Concerning the Heterogeneity of the Natural Abundance of 15N in Soil Nitrogen

1981 ◽  
Vol 45 (2) ◽  
pp. 450-451 ◽  
Author(s):  
Daniel H. Kohl ◽  
Barbara A. Bryan ◽  
Georgia Shearer ◽  
Ross A. Virginia
Keyword(s):  
Soil Nitrogen ◽  
Natural Abundance
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