Seasonal variation in the suitability of different methods for estimating biological nitrogen fixation by grain legumes under rainfed conditions

1996 ◽  
Vol 47 (7) ◽  
pp. 1061 ◽  
Author(s):  
AM McNeill ◽  
CJ Pilbeam ◽  
HC Harris ◽  
RS Swift
Keyword(s):  
Nitrogen Fixation ◽  
Isotope Dilution ◽  
Biological Nitrogen Fixation ◽  
N Uptake ◽  
Isotope Dilution Method ◽  
Dilution Method ◽  
First Year ◽  
Soil N ◽  
A Value ◽  
Biological Nitrogen

Biological nitrogen fixation (BNF) by legume crops was estimated in a Mediterranean environment at ICARDA in northern Syria for 3 consecutive seasons beginning in 1991-92. Using the classical isotope dilution technique (NID), estimates ranged from 32 to 82 kg N/ha for chickpea and from 18 to 82 kg N/ha for lentil. In comparison the simple N-difference method gave lower, sometimes negative, estimates for BNF by both crops in the latter 2 seasons but a higher estimate for chickpea in the first year. Discrepancies in the estimates from N-difference were correlated with differences in the amount of soil N taken up by the legume and the non-fixing wheat reference crop. Since soil N uptake by lentil in the first year was similar to wheat, the estimates of BNF from the 2 methods for that season were similar. The indirect effects of an interaction of added N fertiliser on N derived from the soil and thus on N uptake and estimated BNF are discussed in relation to the use of the isotope dilution method with A-value modification (NAV). Despite some significant differences in A-value for soils receiving different amounts of fertiliser it is demonstrated that the A-value method used in this study, with fertiliser rates of 10 kg N/ha to the legume and 30 kg N/ha to the non-legume, resulted in BNF estimates for lentil similar to those obtained using classical isotope dilution. However, this was not the case for chickpea where a direct inhibitory effect of fertiliser N at 30 kg N/ha resulted in lower estimates of BNF from NID than NAV. Since the reference crops derived as much as 90% of their N from the soil, it is recommended that future BNF studies using isotope dilution techniques for lentil and chickpea crops at ICARDA use a fertiliser rate lower than that used in this study. An isotope dilution method utilising a slow-release source of 15N or the natural abundance technique for estimating BNF are suggested as potentially useful alternatives. The need for a basic understanding of the soil N dynamics pertinent to each site as a prerequisite for choosing an appropriate method for estimating BNF is highlighted.

scholarly journals Mineral Fertilizer Demand for Optimum Biological Nitrogen Fixation and Yield Potentials of Legumes in Northern Ethiopia

2020 ◽  
Vol 12 (16) ◽  
pp. 6449 ◽  
Author(s):  
Shimbahri Mesfin ◽  
Girmay Gebresamuel ◽  
Mitiku Haile ◽  
Amanuel Zenebe ◽  
Girma Desta
Keyword(s):  
Nitrogen Fixation ◽  
Faba Bean ◽  
Biological Nitrogen Fixation ◽  
Cropping Systems ◽  
Mineral Fertilizer ◽  
Field Pea ◽  
Northern Ethiopia ◽  
Soil N ◽  
Combined Application ◽  
Biological Nitrogen

Farmers in Northern Ethiopia integrate legumes in their cropping systems to improve soil fertility. However, biological nitrogen fixation (BNF) potentials of different legumes and their mineral nitrogen (N) and phosphorus (P) demands for optimum BNF and yields are less studied. This study aimed to generate the necessary knowledge to enable development of informed nutrient management recommendations, guide governmental public policy and assist farmer decision making. The experiment was conducted at farmers’ fields with four N levels, three P levels, and three replications. Nodule number and dry biomass per plant were assessed. Nitrogen difference method was used to estimate the amount of fixed N by assuming legume BNF was responsible for differences in plant N and soil mineral N measured between legume treatments and wheat. The result revealed that the highest grain yields of faba bean (2531 kg ha−1), field pea (2493 kg ha−1) and dekeko (1694 kg ha−1) were recorded with the combined application of 20 kg N ha−1 and 20 kg P ha−1. Faba bean, field pea and dekeko also fixed 97, 38 and 49 kg N ha−1, respectively, with the combined application of 20 kg N ha−1 and 20 kg P ha−1; however, lentil fixed 20 kg ha−1 with the combined application of 10 kg N ha−1 and 10 kg P ha−1. The average BNF of legumes in the average of all N and P interaction rates were 67, 23, 32 and 16 kg N ha−1 for faba bean, field pea, dekeko and lentil, respectively. Moreover, faba bean, field pea, dekeko and lentil accumulated a surplus soil N of 37, 21, 26 and 13 kg ha−1, respectively, over the wheat plot. The application of 20 kg N ha−1 and 20 kg P ha−1 levels alone and combined significantly (p < 0.05) increased the nodulation, BNF and yield of legumes; however, 46 kg N ha-1 significantly decreased BNF. This indicated that the combination of 20 kg N ha−1 and 20 kg P ha−1 levels is what mineral fertilizer demands to optimize the BNF and yield of legumes. The results of this study can lead to the development of policy and farmer guidelines, as intensification of the use of legumes supplied with starter N and P fertilizers in Northern Ethiopian cropping systems has the multiple benefits of enhancing inputs of fixed N, improving the soil N status for following crops, and becoming a sustainable option for sustainable soil fertility management practice.

scholarly journals Quantification of Biologically Fixed Nitrogen by White Lupin (Lupins albus L.) and Its Subsequent Uptake by Winter Wheat Using the 15N Isotope Dilution Method

Agronomy ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1392
Author(s):  
Stanisław Kalembasa ◽  
Jerzy Szukała ◽  
Agnieszka Faligowska ◽  
Dorota Kalembasa ◽  
Barbara Symanowicz ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Isotope Dilution ◽  
Crop Residues ◽  
Lupinus Albus ◽  
N Fertilization ◽  
White Lupin ◽  
Isotope Dilution Method ◽  
Dilution Method ◽  
First Year ◽  
Lupin Seeds

A field experiment was carried out in 2016–2018 in a white lupin (Lupinus albus L.)-winter wheat (Triticum aestivum cv. ‘Bogatka’) crop rotation. The aim of this study was to determine the amount of nitrogen (N) that was biologically fixed by the white lupin crop in the first year of the rotation and to estimate how much of this N was then taken up from the lupin residues by winter wheat in the second and third years of the rotation. Biologically fixed N was determined by the isotope-dilution method (ID15N) by applying 30 kg N ha−1 of 15N-labeled fertilizer (15NH4)2SO4 (containing 20.1 at.% 15N) to the white lupin and the reference plant spring wheat. The yields of white lupin seeds and crop residues were 3.92 t ha−1 and 4.30 t ha−1, respectively. The total amount of N in the white lupin biomass was 243.2 kg ha−1, which included 209.3 kg ha−1 in the seeds and 33.9 kg ha−1 in the residues. The 15N-labeled residue of white lupin was cut and ploughed into soil. Our results indicate that 111.2 kg N ha−1 was fixed from the atmosphere by the lupin plants, with 93.7 kg ha−1 found in the seeds and 17.5 kg ha−1 in the residues. In the second and third years of the rotation when winter wheat was cultivated, the plots were divided into two groups of subplots (1) without N-fertilization (control) and (2) with an application of 100 kg N ha−1. In the first year of winter wheat cultivation, 20.0% and 21.0% of N from the crop residues was taken up by the control and N-fertilization plots, respectively, while in the second year, uptake was lower at 7.12% and 9.27% in the control and N-fertilized plots, respectively.

Use of residual fertiliser 15N in soil for isotope dilution estimates of N2 fixation by grain legumes

1998 ◽  
Vol 49 (5) ◽  
pp. 821 ◽  
Author(s):  
C. J. Pilbeam ◽  
H. C. Harris ◽  
R. S. Swift ◽  
A. M. McNeill
Keyword(s):  
Isotope Dilution ◽  
Soil Depth ◽  
N Uptake ◽  
The Other ◽  
Isotope Dilution Method ◽  
Dilution Method ◽  
N Fixation ◽  
Available N ◽  
15N Abundance ◽  
N Pool

Estimates of the proportion of nitrogen (N) derived from the atmosphere (pNatm) by chickpea and lentil in the alternate phase of a cereal-legume 2-year rotation, for each of 3 seasons (1993, 1994, and 1995) in northern Syria, were obtained from isotope dilution methodology using residual fertiliser 15N in the soil (IDres). The 15N had been immobilised, during the year antecedent to the legume, from 15N-enriched fertiliser which had been applied at sowing to wheat in the cereal phase of the rotation at 30 kg N/ha. For lentil in 1994, and for chickpea in 1993 and 1994, the IDres estimates of pNatm were compared with those obtained by using the classical 15N isotope dilution method (ID) where 15N-enriched fertiliser (either 30 or 10 kg N/ha) was added at sowing to both the legume and non-fixing reference crops. Estimates of pNatm for 1994 from the 2 methodological approaches were significantly (P < 0 ·01) different for lentil, with ID resulting in a higher estimate than IDres (0·92 v. 0·85). For chickpea in the same season (1994) the IDres estimate was significantly higher than the ID estimate (0· 88 v. 0·78) at 30 kgN/ha because the N fertiliser inhibited biological N fixation (BNF). However, using a lower fertiliser rate (10 kg N/ha) for ID the estimate of pNatm obtained for chickpea in 1994 was 0·91, which was slightly higher than the IDres estimate. Proportional reliance on BNF was estimated to be greater in spring than at harvest for both lentil and chickpea. The estimates of p Natm obtained at harvest were greatest (>0·82) for both crops in 1994 and less, but similar, for both crops (0·64-0·79) in the other 2 seasons (1993 and 1995). Although substantial amounts of residual fertiliser N were present in the soil, only a small proportion of the original fertiliser N added (<5%) was utilised by plant uptake plus any losses in the residual year, indicative of a slow remineralisation rate for the immobilised labelled N. Nevertheless, the crops in the residual year were suciently enriched to allow for estimation of pNatm. The 15N abundance, at harvest, of wheat shoots from the 15N IDres method was similar to that of the soil nitrate and ammonium pools, suggesting that plant N uptake through the season had been from an N pool of reasonably constant enrichment. This was in contrast to wheat receiving 15N-labelled fertiliser at sowing, where the shoots at harvest had a higher 15N abundance than the plant-available N pool, indicating a declining15N enrichment of plant-available N in the soil through the season. Furthermore, variability in the 15N abundance of plant-available N with soil depth was also demonstrated to be greater where the 15N IDres method was used, for ammonium N at least. These differences in 15N enrichment patterns of the plant-available N pool for the 2 methods resulted in significantly different estimates for pNatm of lentil in 1994 but for all the other comparisons there were no major differences between estimates obtained using either ID or IDres.

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