Vegetation recovery alters soil N status in subtropical karst plateau area: Evidence from natural abundance δ15N and δ18O

The use of leaf total nitrogen concentration as an indicator for nutritional diagnosis has some limitations. The objective of this study was to determine the reliability of total N concentration as an indicator of N status for eucalyptus clones, and to compare it with alternative indicators. A greenhouse experiment was carried out in a randomized complete block design in a 2 × 6 factorial arrangement with plantlets of two eucalyptus clones (140 days old) and six levels of N in the nutrient solution. In addition, a field experiment was carried out in a completely randomized design in a 2 × 2 × 2 × 3 factorial arrangement, consisting of two seasons, two regions, two young clones (approximately two years old), and three positions of crown leaf sampling. The field areas (regions) had contrasting soil physical and chemical properties, and their soil contents for total N, NH+4-N, and NO−3-N were determined in five soil layers, up to a depth of 1.0 m. We evaluated the following indicators of plant N status in roots and leaves: contents of total N, NH+4-N, NO−3-N, and chlorophyll; N/P ratio; and chlorophyll meter readings on the leaves. Ammonium (root) and NO−3-N (root and leaf) efficiently predicted N requirements for eucalyptus plantlets in the greenhouse. Similarly, leaf N/P, chlorophyll values, and chlorophyll meter readings provided good results in the greenhouse. However, leaf N/P did not reflect the soil N status, and the use of the chlorophyll meter could not be generalized for different genotypes. Leaf total N concentration is not an ideal indicator, but it and the chlorophyll levels best represent the soil N status for young eucalyptus clones under field conditions.

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The potential of using 15N natural abundance in changing ammonium-N and nitrate-N pools for studying in situ soil N transformations

Journal of Soils and Sediments ◽

10.1007/s11368-019-02478-1 ◽

2020 ◽

Vol 20 (3) ◽

pp. 1323-1331 ◽

Cited By ~ 1

Author(s):

Dianjie Wang ◽

Zhihong Xu ◽

Timothy J. Blumfield ◽

Jacinta Zalucki

Keyword(s):

15N Natural Abundance ◽

Natural Abundance ◽

Soil N ◽

N Transformations ◽

Nitrate N ◽

Ammonium N

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Nitrogen Uptake of Field-grown Cotton. II. Nitrate Reductase Activity and Petiole Nitrate Concentration as Indicators of Plant Nitrogen Status

Experimental Agriculture ◽

10.1017/s0014479700010565 ◽

1983 ◽

Vol 19 (1) ◽

pp. 103-109 ◽

Cited By ~ 14

Author(s):

D. M. Oosterhuis ◽

G. C. Bate

Keyword(s):

Nitrate Reductase ◽

Seasonal Changes ◽

Nitrate Reductase Activity ◽

Nitrate Concentration ◽

Reductase Activity ◽

Soil N ◽

Plant Nitrogen ◽

Petiole Nitrate Concentration ◽

Leaf Nitrate ◽

N Status

SUMMARYThe possibility of using seasonal changes in leaf nitrate reductase activity (NRA) as a reliable and sensitive indicator of plant nitrogen (N) status has been investigated in field-grown cotton. These changes were compared with those in nitrate concentration in petioles and variations in soil-N concentration. We conclude that NRA in the uppermost, fully-expanded sympodial leaves may provide a more convenient, sensitive and reliable indicator of plant-N status than measurements of nitrate concentrations in petioles.

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Natural abundance of 15N of a spruce forest ecosystem under acid rain and manipulated clean rain field conditions

Journal of Forest Science ◽

10.17221/36/2008-jfs ◽

2008 ◽

Vol 54 (No. 8) ◽

pp. 377-387

Author(s):

P. Sah S ◽

R. Brumme ◽

N. Lamersdorf

Keyword(s):

Forest Floor ◽

Forest Ecosystems ◽

Soil Depth ◽

Mineral Soil ◽

Control Plot ◽

Natural Abundance ◽

Spruce Forest ◽

Litter Fall ◽

Bulk Precipitation ◽

N Status

We analysed stable isotopes of N in a spruce forest under ambient rainfall (no further manipulation of the atmospheric input) and clean rain application (10 years of reduced inorganic N- and acid-constituent input). The objectives of the study were to assess whether or not the natural 15N abundance would function as an indicator for the N-status of our forest ecosystems. For this purpose, natural 15N abundance values were measured in needles, litter fall, roots, soil, bulk precipitation, throughfall and soil water of both plots. In the bulk precipitation and throughfall the δ15N values of NO3-N were in the range reported by other studies (–16 to + 23‰). In both plots, the throughfall was greatly depleted of 15N compared to the bulk precipitation and this was attributed to nitrification in the canopy leaves, leading to δ15N-depleted nitrate production in the leaves that leaches down the soil surface. Nitrate in seepage water showed a general increase in δ15N values when it passes through the upper mineral soil (10 cm soil depth) and infiltrates into deeper mineral soil horizons (100 cm soil depth), similar to the δ15N enrichment of total nitrogen in the mineral soil. We observed 15N depletion in both green needles and litter fall at the clean rain plot, compared to the N-saturated control plot. We assumed it to be due to increased mycorrhizal N-uptake under N limited, i.e. clean rain conditions which are indicated by relatively lower N concentrations of green needles. With respect to the vertical gradient of the 15N abundance in the forest floor, both plots differ from each other, showing an untypical peak of δ15N depletion in the humus layer, which is more pronounced at the control plot. In contrast to the mineral soil where mineralisation is a dominant process for fractionation we attribute the δ15N pattern in the forest floor to additional processes like litter input and immobilisation. We conclude that the δ15N natural abundance analysis is helpful for interpreting the N-status of forest ecosystems but further research is needed especially with respect to the soil-root interface.

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Crop Mass and N Status as Prerequisite Covariables for Unraveling Nitrogen Use Efficiency across Genotype-by-Environment-by-Management Scenarios: A Review

Plants ◽

10.3390/plants9101309 ◽

2020 ◽

Vol 9 (10) ◽

pp. 1309 ◽

Cited By ~ 2

Author(s):

Gilles Lemaire ◽

Ignacio Ciampitti

Keyword(s):

Growth Rate ◽

Plant Growth ◽

Nitrogen Use Efficiency ◽

Soil N ◽

Nitrogen Use ◽

Genotype By Environment ◽

N Supply ◽

Fertilizer Application Rate ◽

Use Efficiency ◽

N Status

Due to the asymptotic nature of the crop yield response curve to fertilizer N supply, the nitrogen use efficiency (NUE, yield per unit of fertilizer applied) of crops declines as the crop N nutrition becomes less limiting. Therefore, it is difficult to directly compare the NUE of crops according to genotype-by-environment-by-management interactions in the absence of any indication of crop N status. The determination of the nitrogen nutrition index (NNI) allows the estimation of crop N status independently of the N fertilizer application rate. Moreover, the theory of N dilution in crops indicates clearly that crop N uptake is coregulated by (i) soil N availability and (ii) plant growth rate capacity. Thus, according to genotype-by-environment-by-management interactions leading to variation in potential plant growth capacity, N demand for a given soil N supply condition would be different; consequently, the NUE of the crop would be dissimilar. We demonstrate that NUE depends on the crop potential growth rate and N status defined by the crop NNI. Thus, providing proper context to NUE changes needs to be achieved by considering comparisons with similar crop mass and NNI to avoid any misinterpretation. The latter needs to be considered not only when analyzing genotype-by-environment-by-management interactions for NUE but for other resource use efficiency inputs such as water use efficiency (colimitation N–water) under field conditions.

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Soil and residue management effects on cropping conditions and nitrous oxide fluxes under controlled traffic in Scotland2. Nitrous oxide, soil N status and weather

Soil and Tillage Research ◽

10.1016/s0167-1987(99)00081-1 ◽

1999 ◽

Vol 52 (3-4) ◽

pp. 191-201 ◽

Cited By ~ 40

Author(s):

B Ball

Keyword(s):

Nitrous Oxide ◽

Residue Management ◽

Soil N ◽

N Status ◽

Management Effects ◽

Controlled Traffic

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Rate and time of fertilizer nitrogen application on yield, protein and apparent efficiency of fertilizer nitrogen use of spring wheat

Canadian Journal of Plant Science ◽

10.4141/cjps06001 ◽

2007 ◽

Vol 87 (4) ◽

pp. 709-718 ◽

Cited By ~ 15

Author(s):

B. J. Zebarth ◽

E. J. Botha ◽

H. Rees

Keyword(s):

Triticum Aestivum ◽

Grain Yield ◽

Spring Wheat ◽

N Mineralization ◽

Grain Protein ◽

Soil N ◽

Fertilizer N ◽

N Application ◽

Fertilizer Nitrogen ◽

N Status

Use of an in-season measurement of crop nitrogen (N) status to optimize fertilizer N management has been proposed as a means of optimizing yield of spring wheat while minimizing environmental N losses. This study determined the effect of the rate and time of fertilizer N application on the grain yield, grain protein, and apparent recovery of fertilizer N in grain and in the above-ground plant for spring wheat (Triticum aestivum L.) in 2001–2003, and evaluated the use of a SPAD-502 meter to measure crop N status in spring wheat. Sixteen N fertility treatments were used, including application of different rates of fertilizer N (0–160 kg N ha-1) applied pre-seeding (ZGS 0), at tillering (ZGS 21) and at shooting (ZGS 32) as ammonium nitrate. Split N application provided no benefit in terms of grain yield or apparent recovery of fertilizer N. Application of fertilizer N at ZGS 32 reduced crop yield and apparent recovery of fertilizer N compared with N application at ZGS 0. Application of fertilizer N at ZGS 21 reduced yield and apparent recovery of fertilizer N in grain in 2 of 3 yr, but had no effect on apparent recovery of fertilizer N in the above-ground plant. Delayed fertilizer N application generally increased grain protein. Fertilizer N can be applied at ZGS 21 as required to optimize grain yield provided at least some fertilizer N is applied prior to seeding; however, crop N status cannot reliably be assessed at this time using a SPAD-502 meter. Crop N status can be assessed at ZGS 32 using a SPAD-502 meter; however, fertilizer N application at this time primarily influences grain protein rather than grain yield. These results highlight the need for a means of predicting soil N mineralization potential in order to optimize grain yield in humid environments where carry-over of soil nitrate from the previous growing season is limited. Key words: Triticum aestivum; N mineralization; soil N supply; SPAD-502 meter, leaf chlorophyll index

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