A new approach to quantifying the N benefit from pasture legumes to succeeding wheat

1998 ◽  
Vol 49 (3) ◽  
pp. 427 ◽  
Author(s):  
Ann M. McNeill ◽  
Chunya Zhu ◽  
Ian R. P. Fillery
Keyword(s):  
Subterranean Clover ◽  
Bulk Soil ◽  
Residual Fraction ◽  
15N Tracer ◽  
Soil Columns ◽  
Total N ◽  
Plant Soil ◽  
Soil Systems ◽  
Peak Biomass ◽  
Below Ground

Vegetative subterranean clover (Trifolium subterraneum L.) and serradella (Ornithopus compressus L.), growing in 1-m soil columns under glasshouse conditions during 1994, were fed 15N tracer by immersion of individual leaves (5 per plant) in a 0·4% (w/w) solution of labelled urea (99·6 atom% 15N). Four replicate soil-plant systems were harvested in late October 1994 at legume peak biomass (41 days after labelling) and in early December 1994 at maturity (90 days after labelling). The shoots were removed and the soil columns fractionated into clean macro-root, residual (root/soil) fraction, and bulk soil; the shoots from the remaining replicates were also harvested at maturity leaving the labelled soil columns intact. These intact columns were kept dry for 5 months during the summer then rewetted and planted with wheat in June 1995. Four replicate soil-plant systems were harvested at planting, tillering, anthesis, and maturity of the wheat and fractionated as before. Mean recovery of fed 15N by the plant{soil systems was 42% for subterranean clover and 64% for serradella. Proportional distribution of the recovered 15N was similar for both plant-soil systems: 67-69% recovered above-ground and 31-33% recovered below-ground for subterranean clover compared with 71-75% above-ground and 25-29% below-ground for serradella. Uniform labelling of below-ground nitrogen (BG N) enabled estimation of total BG N accumulation, under undisturbed conditions, for the two pasture species. Less than 60% of the total legume BG N for both species was recovered as macro-root, with up to 17% recovered in the residual fraction and 33-51% in the bulk soil. Subterranean clover increased its total amount of BG N from 174 to 218 mg/plant between peak biomass and maturity with >65% of this located in the top 10 cm of the soil. Total BG N for serradella was similar at peak biomass (172 mg/plant) and not only decreased slightly by maturity (160 mg/plant) but was also redistributed to depth between the 2 sampling times. The ratio of shoot N to total BG N at peak biomass was 1 : 0·68 for subterranean clover and 1 : 0·60 for serradella. Recovery of labelled legume BG N at harvest by wheat following subterranean clover was 25% and after serradella was 18%. Root residues from subterranean clover appeared to decompose more rapidly than those from serradella, manifest by rapid uptake by the succeeding wheat so that 66% of the total N benefit had accrued by tillering, whereas only 44% of the N benefit from serradella roots had accrued by tillering and 72% by anthesis.

Use of in situ 15N-labelling to estimate the total below-ground nitrogen of pasture legumes in intact soil - plant systems

1997 ◽  
Vol 48 (3) ◽  
pp. 295 ◽  
Author(s):  
Ann M. McNeill ◽  
Chunya Zhu ◽  
Ian R. P. Fillery
Keyword(s):  
Subterranean Clover ◽  
Bulk Soil ◽  
Vegetative Stage ◽  
Residual Fraction ◽  
N Fixation ◽  
15N Labelling ◽  
Below Ground ◽  
Sampling Procedures ◽  
Intact Soil

A leaf-feeding technique for in situ 15N-labelling of intact soil–pasture plant systems was assessed, using subterranean clover (Trifolium subterraneum L.) and serradella (Ornithopus compressus L.) grown under glasshouse conditions. Total recoveries of fed 15N were 87–100% following leaf-feeding of plants at flowering but were lower (74–84%) following the feed at the vegetative stage. Below-ground recovery of fed 15N ranged from 7 to 26%, with serradella partitioning a greater proportion of labelled N below ground than subterranean clover. Additionally, plants of both species fed at the vegetative stage accumulated a greater proportion of the 15N label below ground than did those fed at flowering. Dry sampling procedures, which utilised freeze-drying, enabled fractionation of the below-ground portion of the system into ‘clean’ nodulated macro-roots with no adhering soil, residual uncleaned root, rhizosphere, and bulk soil. Calculated specific enrichment for the ‘clean’ roots at different depths demonstrated a relatively uniform distribution of 15N label in the subterranean clover roots, whereas the presence of large indeterminate nodules in the crown region of serradella roots contributed to apparent uneven distribution of label. Approximately half of the N in the residual fraction of both species consisted of labelled material, postulated to be mostly fine root. Additionally, 5–20% of the rhizosphere N and 0·5–3% of the N in bulk soil was legume root-derived, with some 15N detected in the extractable total soluble N and microbial N pools. Rhizodeposition of N represented approximately 10% of total plant N and 17–24% of total below-ground N for subterranean clover, whereas values for serradella were 20 and 34–37%, respectively. Estimated total below-ground N of subterranean clover reached a maximum value of 177 mg N/plant at 98 days after sowing, which corresponded with a peak shoot N of 243 mg N. Maximum below-ground N for serradella attained 196 mg N/plant 84 days after sowing with a corresponding shoot biomass of 225 mg N. There was a decline in the total below-ground N of serradella at maturity. Overall, recovered clean root N represented 30–62% of estimated total below-ground N, so it was concluded that standard root recovery procedures might be likely to underestimate severely the total below-ground N accretion and N turnover by legumes. The implications of these results for field estimation of total legume N yield, biological N fixation, and the N benefit from legumes in rotations are discussed.

Estimates of lupin below-ground biomass nitrogen, dry matter, and nitrogen turnover to wheat

1996 ◽  
Vol 47 (7) ◽  
pp. 1047 ◽  
Author(s):  
CA Russell ◽  
IRP Fillery
Keyword(s):  
Dry Matter ◽  
Soil Columns ◽  
Soil System ◽  
Wheat Growth ◽  
Ground Biomass ◽  
Plant Soil ◽  
Below Ground ◽  
3.0 T ◽  
Net Mineralisation

The amount of lupin below-ground biomass (BGB), BGB nitrogen (N) content, and utilization of BGB-N by subsequent wheat was estimated from lupins grown in soil columns. Lupin plants were enriched in situ with 15N-labelled urea through a cotton wick inserted through the stem. Of the applied 15N. 92% was recovered in the lupin plant-soil system at maturity: 87% of this 15N was in lupin aboveground biomass and 13% in the soil columns. Total mature lupin dry matter (DM) approximated 11 t/ha, with 3.0 t/ha (27%) of this DM below ground. Total mature lupin N approximated 321 kg/ha, of which 91 kg/ha (28%) resided below ground. In terms of N and DM, BGB was the largest lupin residue component even though only 35% of this was recoverable as root material. About 13% of the BGB-N was in inorganic form at maturity. The net mineralisation of lupin BGB-N after 2 consecutive years of wheat growth was 27%. and wheat assimilated about 74% of this N (i.e. 20% of BGB-N), with equal quantities assimilated in each year. The contribution of lupin BGB-N to the N in wheat tops ranged from 40% for soil columns receiving no fertiliser N to 15-20% for soil columns fertilised with 30 kg N/ha. The net mineralisation of BGB-N and the assimilation of BGB-N by wheat were unaffected by the application of fertiliser N.

scholarly journals Changes in nitrogen pools in the maize-soil system after urea or straw application to a typical intensive agricultural soil: A 15N tracer study

2020 ◽  
Author(s):  
Jie Zhang ◽  
Ping He ◽  
Dan Wei ◽  
Liang Jin ◽  
Lijuan Zhang ◽  
...  
Keyword(s):  
Rhizosphere Soil ◽  
Bulk Soil ◽  
15N Tracer ◽  
Organic N ◽  
Microbial Biomass N ◽  
Soil System ◽  
Total N ◽  
Available N ◽  
Leaf Stage ◽  
Exogenous Substrate

AbstractA 15N maize pot experiment was conducted to compare the N value of fertilizer alone and fertilizer combined with straw at an equivalent N rate. The four treatments were control (CK), 15N-urea, 15N-urea plus straw, and 15N-straw plus urea. Soil N pools, maize N and their 15N abundance were determined during maize growth. At maturity 26.0% of straw N was assimilated by maize in the urea plus straw treatment. From the eighth leaf stage to maturity, urea plus straw had a significantly (P < 0.05) higher concentration and percentage of exogenous substrate N present as soil total N (TN), particulate organic N (PON), and mineral associated total N (MTN) in bulk and rhizosphere soils than the urea-only treatment. From silking to maturity in the urea plus straw treatment, rhizosphere soil significantly (P < 0.05) increased the percentage of exogenous substrate N present as inorganic N (Inorg-N) and MTN, and significantly (P < 0.05) decreased that present as PON and microbial biomass N (MBN) compared with the bulk soil. From the eighth leaf stage to maturity, rhizosphere soil significantly (P < 0.05) increased the percentage of straw N present as Inorg-N and MTN except for MTN at the silking stage, and significantly decreased (P < 0.05) that present as PON compared with the bulk soil. Overall, straw was an available N source to the crop, and the increase in straw N availability needs to be considered from the interaction of fertilization practices and the crop rhizosphere.

Agricultural Wastes and Its Applications in Plant-Soil Systems

2021 ◽  
pp. 15-34
Author(s):  
Zia Ur Rahman Farooqi ◽  
Umair Mubarak ◽  
Nukshab Zeeshan ◽  
Muhammad Mahroz Hussain ◽  
Muhammad Ashar Ayub
Keyword(s):  
Agricultural Wastes ◽  
Plant Soil ◽  
Soil Systems

scholarly journals   Distribution of recently fixed photosynthate in a switchgrass plant-soil system

2012 ◽  
Vol 58 (No. 6) ◽  
pp. 249-255 ◽  
Author(s):  
D.R. Chaudhary ◽  
J. Saxena ◽  
N. Lorenz ◽  
R.P. Dick
Keyword(s):  
Panicum Virgatum ◽  
Rhizosphere Soil ◽  
Microbial Biomass Carbon ◽  
Bulk Soil ◽  
Energy Crop ◽  
Marginal Lands ◽  
Soil System ◽  
Plant Soil ◽  
Panicum Virgatum L ◽  
Maintenance Requirements

The use of switchgrass (Panicum virgatum L.) as an energy crop has gained great importance in past two decades due to its high biomass yields on marginal lands with low agricultural inputs and low maintenance requirements. Information on the allocation of photosynthetically fixed C in the switchgrass-soil system is important to understand the C flow and to quantify the sequestration of C in soils. The allocation of <sup>13</sup>C labeled photosynthates in shoot, root, soil, and in microbial biomass carbon (MBC) of rhizosphere and bulk soil of 45 days old, greenhouse grown-switchgrass was examined during 20 days <sup>13</sup>C-CO<sub>2</sub> pulse labeling period. The total <sup>13</sup>C recovered in the plant-soil system varied from 79% after 1 day to 42% after 20 days of labeling. After labeling, 54%, 40%, and 6% excess <sup>13</sup>C resided in shoot, root and soil, respectively on day 1; 27%, 61% and 11%, respectively on day 5 and 20%, 63% and 17%, respectively day 20 after labeling. The maximum incorporation of <sup>13</sup>C from roots into the MB of rhizosphere soil occurred within the first 24 h of labeling. The excess <sup>13</sup>C values of rhizosphere soil and rhizosphere MBC were significantly higher than excess <sup>13</sup>C values of bulk soil and the bulk soil MBC, respectively. The proportion of excess <sup>13</sup>C in soil as MBC declined from 92 to 15% in rhizosphere soil and from 79 to 18% in bulk soil, for 1 day and 20 days after labeling, respectively. The present study showed the effectiveness of <sup>13</sup>C labeling to examine the fate of recently photosynthesized C in soil-plant (switchgrass) system and dynamics of MBC. &nbsp;

scholarly journals Carbon and nitrogen accumulation within four black walnut alley cropping sites across Missouri and Arkansas, USA

2020 ◽  
Vol 94 (5) ◽  
pp. 1625-1638
Author(s):  
Andrew L. Thomas ◽  
Robert Kallenbach ◽  
Thomas J. Sauer ◽  
David K. Brauer ◽  
David M. Burner ◽  
...  
Keyword(s):  
Alley Cropping ◽  
Cropping Systems ◽  
Agroforestry Systems ◽  
Black Walnut ◽  
Allometric Equations ◽  
Nitrogen Accumulation ◽  
Total N ◽  
Organic C ◽  
Below Ground ◽  
Woody Tissues

Abstract Agroforestry systems that integrate useful long-lived trees have been recognized for their potential in mitigating the accumulation of atmospheric fossil fuel-derived carbon (C). Black walnut (Juglans nigra) is frequently planted and cultivated in North America for its valuable lumber and edible nuts, and is highly amenable to the integration of understory crops or livestock in agroforestry systems. However, little is known about C content in black walnut trees, including the amounts of C assimilated into lignocellulosic tissues within different tree compartments. Therefore, allometric equations for above- and below-ground compartments of 10-year-old black walnut trees across diverse locations were developed. Ten grafted black walnut trees from each of four sites across the midwestern USA were destructively harvested for above- and below-ground biomass, and dry biomass weight (DWw), C (Cw) and nitrogen (N; Nw) stocks were quantified. Soils surrounding the harvested trees were sampled and analyzed for soil organic C (SOC) and total N (TN). Total DWw ranged from 27 to 54 kg tree−1, with woody tissues containing an average of 467 g kg−1 C and 3.5 g kg−1 N. Woody tissues differed in Cw and Nw across location, and above-ground sections contained more C and less N compared with most root tissues. The slopes of the allometric equations did not differ significantly among locations, while intercepts did, indicating that trees only differed in initial size across locations. SOC and TN did not vary in distance from the trees, likely because the trees were not yet old enough to have impacted the surrounding soils. Our results establish a foundation for quantifying C and N stocks in newly established black walnut alley cropping systems across diverse environments.

Seed-setting in subterranean clover (Trifolium subterranean L.). III. The effect of plant density

1961 ◽  
Vol 12 (1) ◽  
pp. 10 ◽  
Author(s):  
JJ Yates
Keyword(s):  
Seed Production ◽  
Seed Weight ◽  
Plant Density ◽  
Plant Cover ◽  
General Pattern ◽  
Strain Differences ◽  
Subterranean Clover ◽  
Seed Setting ◽  
Below Ground ◽  
Australian Wheat

Various aspects of seed production in a number of strains of subterranean clover sown at fire seeding rates at two sites in the Western Australian wheat-belt were investigated. Dry matter yields and percentage leaf in the foliage were also recorded. Percentage leaf increased with plant density in the earlier-maturing, stemmy strains, so that differences amongst strains diminished as density increased. The differences amongst strains in number of inflorescences when grown as single plants were largely eliminated under dense sward conditions, so that the two main factors in seed production were number of seeds per inflorescence and mean seed weight. The proportion of burrs above and below ground varied widely amongst strains, and was influenced by plant density in some strains. It is postulated that the extent of burr burial depends on the interaction between strain, environment, and condition of the surface soil. Burr burial improved the efficiency of seed-setting, particularly in the more severe environment. Strain differences in seeds per inflorescence below ground were relatively small, but within each strain, values were higher in the more favorable environment. The efficiency of seed-setting above ground differed considerably amongst strains and between the two environments, and tended to increase with plant density particularly in the earlier-maturing strains. Correlations were established between seeds per inflorescence above ground and the amount of plant cover in these strains. An artificial covering of wood-wool also improved seed-setting above ground. Mean seed weight followed the same general pattern as seeds per inflorescence.

TDR estimation of the resident concentration of electrolyte in the soil solution

Soil Research ◽  
1997 ◽  
Vol 35 (3) ◽  
pp. 515 ◽  
Author(s):  
I. Vogeler ◽  
B. E. Clothier ◽  
S. R. Green
Keyword(s):  
Electrical Conductivity ◽  
Soil Solution ◽  
Electrolyte Concentration ◽  
Time Domain Reflectometry ◽  
The Other ◽  
Bulk Soil ◽  
Small Scale ◽  
Soil Electrical Conductivity ◽  
Soil Columns ◽  
Leaching Experiments

In order to examine whether the electrolyte concentration in the soil solution can be estimated by time domain reflectometry (TDR) measured bulk soil electrical conductivity, column leaching experiments were performed using undisturbed soil columns during unsaturated steady-state water flow. The leaching experiments were carried out on 2 soils with contrasting pedological structure. One was the strongly structured Ramiha silt loam, and the other the weakly structured Manawatu fine sandy loam. Transport parameters obtained from the effluent data were used to predict the transient pattern in the resident electrolyte concentration measured by TDR. The electrolyte concentration was inferred from the TDR-measured bulk soil electrical conductivity using 2 different calibration approaches: one resulting from continuous solute application, and the other by direct calibration. Prior to these, calibration on repacked soil columns related TDR measurements to both the volumetric water content and the electrolyte concentration that is resident in the soil solution. The former calibration technique could be used successfully to describe solute transport in both soils, but without predicting the absolute levels of solute. The direct calibration method only provided good estimates of the resident concentration, or electrolyte concentration, in the strongly structured top layer of the Ramiha soil. This soil possessed no immobile water. For the less-structured layer of the Ramiha, and the weakly structured Manawatu soil, only crude approximations of the solute concentration in the soil were found, with measurement errors of up to 50%. The small-scale pattern of electrolyte movement of these weakly structured soils appears to be quite complex.

scholarly journals Management Intensity Controls Nitrogen-Use-Efficiency and Flows in Grasslands—A 15N Tracing Experiment

Agronomy ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 606
Author(s):  
Marcus Zistl-Schlingmann ◽  
Steve Kwatcho Kengdo ◽  
Ralf Kiese ◽  
Michael Dannenmann
Keyword(s):  
Land Use ◽  
N Balance ◽  
15N Tracer ◽  
15N Recovery ◽  
Soil N ◽  
N Losses ◽  
Soil System ◽  
Land Use Intensification ◽  
Plant Soil ◽  
Montane Grasslands

The consequences of land use intensification and climate warming on productivity, fates of fertilizer nitrogen (N) and the overall soil N balance of montane grasslands remain poorly understood. Here, we report findings of a 15N slurry-tracing experiment on large grassland plant–soil lysimeters exposed to different management intensities (extensive vs. intensive) and climates (control; translocation: +2 °C, reduced precipitation). Surface-applied cattle slurry was enriched with both 15NH4+ and 15N-urea in order to trace its fate in the plant–soil system. Recovery of 15N tracer in plants was low (7–17%), while it was considerably higher in the soil N pool (32–42%), indicating N stabilization in soil organic nitrogen (SON). Total 15N recovery was only 49% ± 7% indicating substantial fertilizer N losses to the environment. With harvest N exports exceeding N fertilization rates, the N balance was negative for all climate and management treatments. Intensive management had an increased deficit relative to extensive management. In contrast, simulated climate change had no significant effects on the grassland N balance. These results suggest a risk of soil N mining in montane grasslands under land use intensification based on broadcast liquid slurry application.

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