Volume 5
Issue 2
Agronomy
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
Available Online: http://www.ejpau.media.pl/volume5/issue2/agronomy/art-02.html
IMPACT OF NITROGEN (15 N) APPLICATION TIME ON ITS UPTAKE AND DISTRIBUTION IN SPRING BARLEY PLANT PARTS
Stanisław Kalembasa, Dorota Kalembasa
The aim of the pot experiment was to determine the impact of timing of nitrogen application in the form of ammonium nitrate enriched with the 15N isotope, on the uptake of 15N by spring barley plant and its distribution in grain, awns, leaves, straw, and roots. 1.21 g of N per pot containing 10 kg of the soil was applied at two doses: 2/3 before the sowing, and 1/3 at the tillering phase or at the stalk-shooting phase. The distribution of the applied nitrogen, assumed as 100%, was the highest in grain (61.5%), and the lowest in roots (4%). The mean nitrogen utilisation coefficient value (%) measured with the difference method was 86.9 %, and that for the isotope dilution method – 61.0%. Postponing the time of nitrogen application from the tillering to the stalk-shooting phase differentiated the nitrogen utilisation coefficient value, which was higher for the difference method than for the isotope dilution method and it amounted to +32.3% at the tillering pha
Key words:
the 15N isotope, application timing, uptake and distribution of N in a plant, spring barley.
INTRODUCTION
The share of cereal crops in the agricultural production is considerable, accounting for 65-75% of the total crop production. Proper fertilisation regime, especially with nitrogen, results in achieving maximum crop yields of the highest technological quality. In barley fertilisation, several systems and time periods of nitrogen application are suggested [7]. The most commonly recommended method involves applying of nitrogen at two or three times: before sowing, and then at tillering phase and/or stalk-shooting phase. Earlier fertilisation with nitrogen increases the growth and development of vegetative parts in a plant, whereas a later time period of application affects protein accumulation in grain.
High prices of mineral nitrogen fertilisers and uptake of the applied nitrogen in crops as effectively as possible to reduce the environment pollution bring about the importance of estimating nitrogen utilisation coefficient value in an undertaken research on method and timing of nitrogen fertilisation. The value may be calculated with the difference method or the isotopic dilution method, the latter involving 15N or13 N nitrogen isotopes [5]. According to Hauck [2], the nitrogen utilisation coefficient value calculated with the difference method is higher by 6-7% than that arrived at the isotopic dilution method. Westerman and Kurtz [11] corroborated Hauck’s findings, establishing even a higher difference, 17-34%.
The difference in nitrogen utilisation coefficient values has large practical and theoretical consequences for calculating nitrogen doses applied in mineral fertilisation with due attention paid to time periods and techniques of its application. The aim of the pot experiment was to determine the uptake of 15N and its distribution in the spring barley plants.
MATERIAL AND METHODS
The 10 kg of soil for filling the pots was drawn from the humus layer of a lessive soil, good rye soil agricultural suitability complex. The soil contained 6.29 g.kg-1 of C in organic compounds and 0.56 g.kg-1 of total nitrogen as well as following available quantities of: P – 10.2 mg, of K - 14.1 mg, of Mg - 5.2 mg in 100 g of soil; pH in KCl 1mol.dm-3 – 6.2.
20 grains of ‘Goma’ spring barley cultivar were sown per pot, and after the emergence, 5 plants were uprooted and left to decay in the pot, whereas the remaining 15 plants were allowed to grow and develop. Against the fertilisation regime involving P – 0.56 g.pot –1, K – 0.82 g.pot –1, Mg – 1.20 g.pot –1 and S – 0.20 g.pot –1, 1.21 g of N was applied at two doses: a) two thirds before the sowing and one third at the tillering phase; b) two thirds before the sowing and one third at the stalk-shooting phase. The nitrogen isotope NH4NO3, applied before the sowing and as a top fertiliser, contained 2.51 at %15N.
The moisture of the soil over the barley-growing season was kept at the level of 60% total water-holding capacity. The barley plants were harvested at the full ripeness phase. Grain, awns, leaves, straw, and roots were isolated from each plant. Nitrogen content in the separated parts of the plants was measured with the modified Kjeldahl method, which allows to take fully into account the N03 ion [6]. Total nitrogen content was determined by distilling ammonia off to 2% boracic acid with the mixed tracer, and then back titration was applied using the 0.25 mol.dm-3 solution of H2SO4. The sample for determining the isotopic composition was provided by the third distillate, from which ammonia was distilled off and fixed by HCl of 0.1 mol.dm-3 concentration. The enrichment with the 15N isotope of total nitrogen, contained in the separated parts of the plants, was estimated by determining 14N and 15N with the method of emission spectrometry on the emission spectrometer, releasing N2 nitrogen molecules containing 14N2, 14N, 15N and 15N2 from the sample by the “dry method” [5].
Values of the nitrogen utilisation coefficient were calculated with:
- the difference method, according to the formula:
- the isotopic dilution method, according to the formula:
 |
where:
WWN – value of nitrogen utilisation coefficient,
TNF – quantity of nitrogen uptake by the plants (the parts) subjected to nitrogen fertilisation,
TNC – quantity of nitrogen uptake by the plants (the parts) not subjected to nitrogen fertilisation,
NA – quantity of nitrogen applied,
B – at%15N in the plants (the parts) treated with 15N nitrogen,
C – at%15N in the plants (the parts) not treated with 15N nitrogen,
D – enrichment of nitrogen with 15N expressed at%15N.
The significance of differences in the mean total nitrogen contents, 15N enrichment and in the nitrogen utilisation coefficients in separate spring barley plants were estimated with ANOVA procedures (the F Fischer-Snedecor test), whereas LSD0.05 was calculated with the Tukey test. Relationships between the examined features were established on the basis of correlation coefficients and simple regression equations.
RESULTS
Nitrogen fertilisation has been the most influential factor in increasing the yield of the examined barley cultivar (Table 1). The application of nitrogen, irrespective of when it had been carried out, led to significant increase in dry matter yield from all the parts of the plant, compared to that obtained for the control. Delaying of nitrogen fertilisation until the stalk-shooting phase brought about a significant decrease in straw and roots dry matter yields, while for the other barley parts the decrease was not significant. Out of all the analysed barley plant parts, as a result of delayed nitrogen application, the largest decrease in dry matter yield was observed for straw (3.24 g.pot -1), and the least – for leaves (0.1 g.pot -1). Nitrogen fertilisation and its application time differed the nitrogen content in the analysed barley parts. A significant difference in the content of this element was noted in roots, whereas grain was not significantly affected by the examined factors. For the remaining barley plant parts, only nitrogen fertilisation itself led to a significant increase in nitrogen content, whereas the time of its application was irrelevant. The enrichment with the 15N isotope of total nitrogen content, determined for the separate parts of the barley plants, was significantly differentiated by the date of nitrogen application and varied according to each represented part. Delaying the time of nitrogen application led to a significant increase in 15N content in all the analysed barley parts with the exception of roots, where it was lower than that achieved by applying nitrogen at the tillering phase. The highest increase of the 15N isotope enrichment as a result of delayed nitrogen application was found in leaves (+ 0.070 at %15N), while the lowest – in straw (+ 0.010 at %15N).
| Table 1. Crop yield, nitrogen content and 15N enrichment for the particular spring barley parts |
|
Object |
Spring barley plant parts |
Total |
||||
|
grain |
awns |
leaves |
straw |
roots |
||
|
Yield, g.pot –1 |
||||||
|
PK PKNk PKNs |
9.97 29.30 28.37 |
0.91 3.84 3.50 |
6.33 15.80 15.70 |
3.93 13.10 9.86 |
0.91 8.97 6.73 |
22.05 71.01 64.16 |
|
LSD 0.05 |
4.32 |
0.69 |
1.89 |
2.06 |
1.12 |
10.2 |
|
Nitrogen content, g.kg-1 Mean |
||||||
|
PK PKNk PKNs |
28.9 29.2 30.1 |
7.90 15.2 14.4 |
12.5 19.7 18.0 |
8.9 16.4 17.0 |
17.9 9.0 11.8 |
15.2 17.9 18.3 |
|
LSD0.05 |
ns |
1.9 |
2.5 |
1.8 |
2.2 |
1.9 |
15N enrichment, at %15N |
||||||
|
PK 15Nk PK 15Ns |
0.208 0.233 |
0.169 0.224 |
0.160 0.230 |
0.194 0.204 |
0.162 0.148 |
|
|
PK 15NS PK15 NK |
+ 0.025 |
+ 0.055 |
+ 0.070 |
+ 0.010 |
- 0.014 |
|
|
LSD0.05 |
0.017 |
0.029 |
0.031 |
0.009 |
0.010 |
|
| ns – difference non-significant PKNK - phosphorus-potassium fertilisation + 1/3 nitrogen dose at the tillering phase PKNS - phosphorus-potassium fertilisation + 1/3 nitrogen dose at the stalk-shooting phase |
The nitrogen utilisation coefficient value (%) arrived with both methods was significantly different: it was higher for the difference method than for the isotope dilution method (Table 2). The differentiation occurred irrespective of when nitrogen had been applied, and it was higher for nitrogen application at the tillering phase (+32.3%) than at the stalk-shooting phase (+19.4%). The nitrogen utilisation coefficient value (%) for the separate barley parts was differentiated by the method of its estimation and by nitrogen application time. For the difference method, nitrogen application time did not affect its value in grain and roots. The largest differences were established for leaves and straw, with the preponderant result of nitrogen application at the tillering phase. For the isotopic dilution method, delayed nitrogen application brought about an increase in the N utilisation coefficient in grain and leaves, and its decrease in straw.
| Table 2. Values of nitrogen utilisation coefficients arrived at the difference and the isotopic dilution methods |
|
Method and time |
Spring barley plant parts |
|||||
|
grain |
awns |
leaves |
straw |
roots |
total |
|
|
A. Difference method tillering phase stalk-shooting phase |
46.8 46.7 |
4.2 3.5 |
19.2 16.9 |
14.9 11.0 |
5.4 5.2 |
90.5 83.3 |
|
B. Isotopic dilution tillering phase stalk-shooting phase |
35.4 39.6 |
2.0 2.2 |
9.9 13.0 |
8.3 6.8 |
2.6 2.3 |
58.2 63.9 |
|
A1 – B1 A2 – B2 |
+ 11.4 + 7.1 |
+ 2.2 + 1.3 |
+ 9.3 + 3.9 |
+ 6.6 + 4.2 |
+ 2.8 + 2.9 |
+ 32.3 + 19.4 |
The distribution of nitrogen applied in the form of ammonium nitrate enriched with the 15N isotope in the particular parts of the barley plant depended on the time of N application (Table 3). Nitrogen applied at the stalk-shooting phase was accumulated in large quantities in leaves and awns, and in still larger quantities in grain, whereas when applied at the tillering phase – in straw and roots. Correlation coefficient values for the analysed features were found to be significant and as follows:
r = +0.97** and Y = - 12.4 + 2.40x, for the correlation between dry matter yields from the separate barley parts and the distribution of nitrogen from ammonium nitrate,
r = +0.95** and Y = - 37.3 + 3.17x, for the correlation between nitrogen content in the separate barley parts and the distribution of nitrogen from ammonium nitrate;
r = +0.91** and Y = 8.92 + 0.68x, for the correlation between crop yield and nitrogen content in the separate barley parts.
| Table 3. Distribution (%) of ammonia nitrogen (=100%) in particular parts of spring barley plants analysed with the isotopic dilution method |
|
Plant development phase of NH4NO3 application |
Spring barley plant parts |
|||||
|
grain |
awns |
leaves |
straw |
roots |
total |
|
|
- tillering - stalk-shooting |
60.9 62.0 |
3.3 3.5 |
17.0 20.3 |
14.3 10.6 |
4.5 3.6 |
100 100 |
|
LSD0.05 |
ns |
ns |
2.6 |
1.5 |
ns |
- |
DISCUSSION
The nitrogen utilisation coefficient value (%), higher for the difference method than for the isotopic dilution method determined in the present study, corroborates the findings obtained under different conditions and for other tested plants [4,11]; however some other researches proved the reversed relation [8]. Higher nitrogen utilisation coefficient values arrived with the difference method may result in the accelerated and augmented mineralisation of the soil organic matter as a result of higher nitrogen quantities brought into the soil in ammonium nitrate. This phenomenon has already been described in the literature [5] and called “the priming effect” [1,3,10]. As a result of this process more nitrogen available to plants appears in the soil. Its quantity is in direct proportion to nitrogen content in organic compounds contained in the soil, as well as to nitrogen doses applied in mineral fertilisation [5].
CONCLUSIONS
Nitrogen fertilisation significantly increased the dry matter yields in all the analysed parts of the barley plants.
Postponing the application of one third of the total nitrogen dose from the tillering phase to the stalk-shooting phase resulted in a significant decrease in straw yield and root biomass.
Dose and time of nitrogen fertilisation did not affect significantly nitrogen content in grain, whereas in the other parts of the spring barley plants they effect was significant.
Delaying the time of nitrogen applying in the form of 15N led to its higher enrichment in the analysed spring barley parts.
Values of nitrogen utilisation were found to be higher when arrived at the difference method than those provided by the isotopic dilution, irrespective of nitrogen application time. The difference was +32.3%, when applying one third of the total nitrogen dose at the tillering phase, and +19.4%, when nitrogen was applied at the stalk-shooting phase.
The distribution of nitrogen uptake from ammonium nitrate by the barley plant parts differed considerably; the highest uptake was observed in grain (61.5%) and the lowest one in roots (4%).
REFERENCES
Broadbent F.E., Nokashima T., 1971. Effect of added soils on nitrogen mineralization in three California soils. Soil Sci. Soc. Am. Proc. 35, 457-460. Hauck R.D., 1971. Nitrogen – 15. In: Soil – Plant Studies. IAEA Vienna, 65-80. Jenkinson D.S., Fox R.H., Rayner J.H., 1985. Interactions between fertilizer nitrogen and soil nitrogen – the so-called priming effect. J. Soil Sci. 36, 425-444. Kalembasa S., 1989. A comparison between the difference method and the isotopic dilution method for assessing the coefficient utilization of nitrogen by oat when applied in top dressing as potassium nitrate. Polish J. Soil Sci. 22 (2), 73-78. Kalembasa S., 1995. Wykorzystanie azotu 15N i 13N w badaniach gleboznawczych i chemiczno-rolniczych [Using of 15N and 13N in soil science and chemical and physical analysis]. WNT Warszawa [in Polish]. Kalembasa S., Carlson R.W., Kalembasa D., 1989. A new method for the reduction of nitrates in total nitrogen determination according to the Kjeldahl method. Polish J. Soil Sci. 20 (2), 21-26. Kalembasa S., Kalembasa D., Król M., 1993. Wpływ dawek azotu i terminów jego stosowania na plon ziarna i białka jęczmienia jarego [Effects of date and dose of nitrogen application on spring barley grain and total protein yields]. Rocz. Nauk Roln. 109 A (4), 97-104 [in Polish]. Kocoń A., Skiba T., Sykut M., Próchniak A., 1999. Wykorzystanie azotu stosowanego dolistnie lub doglebowo w plonie pszenicy jarej i ozimej [Spring and winter wheat utilisation of nitrogen applied on top and soil]. Fragm. Agron. 4, 90-99 [in Polish]. Rutkowska A., 2002. Wykorzystanie azotu przez pszenicę ozim± z póĽno podanych dawek nawozów z zastosowaniem 15N [Winter wheat utilisation of nitrogen from late-applied fertilisers containing 15N]. Nawozy i nawożenie 1, 90-99 [in Polish]. Westerman R.L., Kurtz L.T., 1973. Priming effect of 15N labelled fertilisers on soil nitrogen in field experiments. Soil Sci. Soc. Am. Proc. 36, 727-727. Westerman R.L., Kurtz L.T., 1974. Isotopic and non-isotopic estimations of fertilisers nitrogen uptake by sudangroos in field experiments. Soil Sci. Soc. Am. Proc. 38, 107-109.
Stanisław Kalembasa, Dorota Kalembasa
Department of Soil Science and Agricultural Chemistry
Podlasie University
Prusa 14, 08-110 Siedlce, Poland
e-mail: kalembasa@ap.siedlce.pl
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