scholarly journals Defining the physiological determinants of low nitrogen requirement in wheat

2021 ◽  
Author(s):  
Nick S. Fradgley ◽  
Alison R. Bentley ◽  
Stéphanie M. Swarbreck
Keyword(s):  
Crop Production ◽  
Temporal Dynamics ◽  
Supply And Demand ◽  
Genetic Material ◽  
Triticum Aestivum L ◽  
N Losses ◽  
N Supply ◽  
Optimal Functioning ◽  
Plant Level ◽  
N Requirement

Nitrogen (N) is a major nutrient limiting productivity in many ecosystems. The large N demands associated with food crop production are met mainly through the provision of synthetic N fertiliser, leading to economic and ecological costs. Optimising the balance between N supply and demand is key to reducing N losses to the environment. Wheat (Triticum aestivum L.) production provides food for millions of people worldwide and is highly dependent on sufficient N supply. The size of the N sink, i.e. wheat grain (number, size, and protein content) is the main driver of high N requirement. Optimal functioning of temporary sinks, in particular the canopy, can also affect N requirement. N use efficiency (i.e. yield produced per unit of N available) tends to be lower under high N conditions, suggesting that wheat plants are more efficient under low N conditions and that there is an optimal functioning yet unattained under high N conditions. Understanding the determinants of low N requirement in wheat would provide the basis for the selection of genetic material suitable for sustainable cereal production. In this review, we dissect the drivers of N requirement at the plant level along with the temporal dynamics of supply and demand.

Film-mulched maize production: response to controlled-release urea fertilization

2017 ◽  
Vol 155 (8) ◽  
pp. 1299-1310 ◽  
Author(s):  
J. M. GUO ◽  
J. Q. XUE ◽  
A. D. BLAYLOCK ◽  
Z. L. CUI ◽  
X. P. CHEN
Keyword(s):  
Controlled Release ◽  
Production Systems ◽  
Supply And Demand ◽  
N Uptake ◽  
N Fertilization ◽  
N Recovery ◽  
N Losses ◽  
Maize Production ◽  
N Supply ◽  
Controlled Release Urea

SUMMARYOptimal nitrogen (N) management for maize in the film-mulched production systems that are widely used in dryland agriculture is difficult because top-dressing N is impractical. The current research determined how matching N supply and demand was achieved before and after silking stages, when single applications of controlled release urea (CRU) were combined with conventional urea in film-mulched maize production. The CRU: urea mixture was applied in a 1 : 2 or 2 : 1 ratio and all three fertilizer regimes (urea alone and CRU: urea at 1 : 2 or 2 : 1) were applied at N rates of 180 and 240 kg/ha over 2 years. The 1 : 2 CRU: urea mixture, applied once at 180 kg N/ha, was found to synchronize N supply with demand, thereby reducing N losses. The highest grain yields (11·8–12·0 t/ha), N uptake (232–239 kg/ha), N recovery (65·8–67·7%) and high net economic return were achieved with this regime. These results indicate that a single application of a mixture of CRU and urea can synchronize N supply with demand and provide higher yields and profits than conventional N fertilization in film-mulched maize systems.

scholarly journals The interaction of seasonal rainfall and nitrogen fertiliser rate on soil N2O emission, total N loss and crop yield of dryland sorghum and sunflower grown on sub-tropical Vertosols

Soil Research ◽  
2016 ◽  
Vol 54 (5) ◽  
pp. 604 ◽  
Author(s):  
G. D. Schwenke ◽  
B. M. Haigh
Keyword(s):  
Crop Yield ◽  
Crop Production ◽  
Field Experiments ◽  
N2o Emission ◽  
N2o Emissions ◽  
N Loss ◽  
N Losses ◽  
Total N ◽  
Tropical Regions ◽  
The Impact

Summer crop production on slow-draining Vertosols in a sub-tropical climate has the potential for large emissions of soil nitrous oxide (N2O) from denitrification of applied nitrogen (N) fertiliser. While it is well established that applying N fertiliser will increase N2O emissions above background levels, previous research in temperate climates has shown that increasing N fertiliser rates can increase N2O emissions linearly, exponentially or not at all. Little such data exists for summer cropping in sub-tropical regions. In four field experiments at two locations across two summers, we assessed the impact of increasing N fertiliser rate on both soil N2O emissions and crop yield of grain sorghum (Sorghum bicolor L.) or sunflower (Helianthus annuus L.) in Vertosols of sub-tropical Australia. Rates of N fertiliser, applied as urea at sowing, included a nil application, an optimum N rate and a double-optimum rate. Daily N2O fluxes ranged from –3.8 to 2734g N2O-Nha–1day–1 and cumulative N2O emissions ranged from 96 to 6659g N2O-Nha–1 during crop growth. Emissions of N2O increased with increased N fertiliser rates at all experimental sites, but the rate of N loss was five times greater in wetter-than-average seasons than in drier conditions. For two of the four experiments, periods of intense rainfall resulted in N2O emission factors (EF, percent of applied N emitted) in the range of 1.2–3.2%. In contrast, the EFs for the two drier experiments were 0.41–0.56% with no effect of N fertiliser rate. Additional 15N mini-plots aimed to determine whether N fertiliser rate affected total N lost from the soil–plant system between sowing and harvest. Total 15N unaccounted was in the range of 28–45% of applied N and was presumed to be emitted as N2O+N2. At the drier site, the ratio of N2 (estimated by difference)to N2O (measured) lost was a constant 43%, whereas the ratio declined from 29% to 12% with increased N fertiliser rate for the wetter experiment. Choosing an N fertiliser rate aimed at optimum crop production mitigates potentially high environmental (N2O) and agronomic (N2+N2O) gaseous N losses from over-application, particularly in seasons with high intensity rainfall occurring soon after fertiliser application.

Participatory soil quality assessment: The case of smallholder farmers in Ethiopian highlands

Soil Research ◽  
2004 ◽  
Vol 42 (7) ◽  
pp. 793 ◽  
Author(s):  
Teklu Erkossa ◽  
Karl Stahr ◽  
Thomas Gaiser
Keyword(s):  
Quality Assessment ◽  
Soil Quality ◽  
Crop Production ◽  
Smallholder Farmers ◽  
Soil Management ◽  
Triticum Aestivum L ◽  
Soil Functions ◽  
Yield Data ◽  
Management Interventions ◽  
Soil Quality Assessment

The study was conducted at Caffee Doonsa (08°88′N, 39°08′E; 2400 m asl), a small watershed in the central highlands of Ethiopia, in order to identify farmers’ goals of soil management and the indicators they use in selecting soils for a certain function, and to categorise the soils in different quality groups with respect to the major functions. Thirty-six male farmers of different age and wealth groups participated in a Participatory Rural Appraisal technique. They listed and prioritised 12 soil functions in the area and itemised the soil quality indicators (characteristics). Based on the indicators, the soils in the watershed were classified into 3 soil quality (SQ) groups (Abolse, Kooticha, and Carii). The SQ groups have been evaluated and ranked for the major soil functions. For crop production, Abolse was graded best, followed by Kooticha and Carii, respectively. The grain and straw yield data of wheat (Triticum aestivum L.) taken from the SQ groups confirmed the farmers claim, in that Abolse gave the highest grain yield (4573 kg/ha), followed by 4411 and 3657 kg/ha for Kooticha and Carii, respectively. Local insights should be included in systematic soil quality assessment, and in planning and implementation of various soil management interventions.

scholarly journals Processes of ammonia air-surface exchange in a fertilized <i>Zea mays</i> canopy

2012 ◽  
Vol 9 (6) ◽  
pp. 7893-7941 ◽  
Author(s):  
J. T. Walker ◽  
M. R. Jones ◽  
J. O. Bash ◽  
L. Myles ◽  
T. Meyers ◽  
...  
Keyword(s):  
Zea Mays ◽  
Temporal Dynamics ◽  
Daily Maximum ◽  
N Losses ◽  
Surface Exchange ◽  
Total N ◽  
Soil Emissions ◽  
Source Sink ◽  
Resistance Modeling ◽  
Process Level

Abstract. Recent incorporation of coupled soil biogeochemical and bi-directional NH3 air-surface exchange algorithms into regional air quality models holds promise for further reducing uncertainty in estimates of NH3 emissions from fertilized soils. While this represents a significant advancement over previous approaches, the evaluation and improvement of such modeling systems for fertilized crops requires process level field measurements over extended periods of time that capture the range of soil, vegetation, and atmospheric conditions that drive short term (i.e., post fertilization) and total growing seasonNH3 fluxes. This study examines the processes of NH3 air-surface exchange in a fertilized corn (Zea mays) canopy over the majority of a growing season to characterize soil emissions after fertilization and investigate soil-canopy interactions. Micrometeorological flux measurements above the canopy, measurements of soil, leaf apoplast and dew/guttation chemistry, and a combination of in-canopy measurements, inverse source/sink, and resistance modeling were employed. Over a period of approximately 10 weeks following fertilization, daily mean and median net canopy-scale fluxes yielded cumulative total N losses of 8.4% and 6.1%, respectively, of the 134 kg N ha−1 surface applied to the soil as urea ammonium nitrate (UAN). During the first month after fertilization, daily mean emission fluxes were positively correlated with soil temperature and soil volumetric water. Diurnally, maximum hourly average fluxes of ≈700 ng N m−2 s−1 occurred near mid-day, coincident with the daily maximum in friction velocity. Net emission was still observed 5 to 10 weeks after fertilization, although mid-day peak fluxes had declined to ≈125 ng N m−2 s−1 A key finding of the surface chemistry measurements was the observation of high pH (7.0 – 8.5) in leaf dew/guttation, which reduced the ability of the canopy to recapture soil emissions during wet periods. In-canopy measurements near peak LAI indicated that the concentration of NH3 just above the soil surface was highly positively correlated with soil volumetric water, which likely reflects the influence of soil moisture on resistance to gaseous diffusion through the soil profile and hydrolysis of remaining urea. Inverse source/sink and resistance modeling indicated that the canopy recaptured ≈73% of soil emissions near peak LAI. Stomatal uptake may account for 12–34% of total uptake by foliage during the day compared to 66–88% deposited to the cuticle. Future process-level \\NH3 studies in fertilized cropping systems should focus on the temporal dynamics of net emission to the atmosphere from fertilization to peak LAI and improvement of soil and cuticular resistance parameterizations.

Assessing climate change impacts on greenhouse gas emissions, N losses in drainage and crop production in a subsurface drained field

2020 ◽  
Vol 705 ◽  
pp. 135969 ◽  
Author(s):  
Qianjing Jiang ◽  
Zhiming Qi ◽  
Lulin Xue ◽  
Melissa Bukovsky ◽  
Chandra A. Madramootoo ◽  
...  
Keyword(s):  
Climate Change ◽  
Greenhouse Gas Emissions ◽  
Greenhouse Gas ◽  
Crop Production ◽  
Climate Change Impacts ◽  
N Losses ◽  
Gas Emissions

Relative cost to soil fertility of long-term crop production without fertilization

1996 ◽  
Vol 76 (3) ◽  
pp. 401-406 ◽  
Author(s):  
C. A. Campbell ◽  
F. Selles ◽  
J. T. Harapiak ◽  
G. P. Lafond
Keyword(s):  
Soil Moisture ◽  
Soil Fertility ◽  
Green Manure ◽  
Soil Degradation ◽  
Crop Production ◽  
Cropping Systems ◽  
Triticum Aestivum L ◽  
Growth Chamber ◽  
Rotation Phase ◽  
N Fertility

An earlier analysis of yield trends of stubble-wheat in six cropping systems, over 35 yr, in a thin Black Chernozemic soil at Indian Head, Saskatchewan, showed that fertilizer improved soil quality, while absence of fertilizer, combined with frequent fallowing, led to soil degradation. The inclusion of a legume green manure crop in the rotation failed to maintain soil fertility, apparently because legumes do not supply P. Because the fertility and stored moisture effects were confounded, we conducted a growth chamber experiment to quantify soil responses to N and P in these six cropping systems. Soil from the top 15-cm of the rotation phase that had just grown two successive wheat (Triticum aestivum L.) crops was used. Various factorial combinations of ammonium nitrate-N and triple superphosphate-P were applied at N/P2O5 rates up to 200/200 kg ha−1. Soil moisture was maintained in the available range. Regression analysis showed that the fallow-wheat-wheat (F-W-W) and continuous wheat (Cont W) systems that had not been fertilized in 35 yr, and which had moderate amounts of NaHCO3-P, only responded to N. In contrast, the green manure (GM)- and hay (H)- containing systems, which had also not been fertilized before had low levels of NaHCO3-P and responded to both N and P. In the field, the yields of wheat grown on stubble in 1991 rated: Cont W (N + P) > F-W-W (N + P) > F-W-W-H-H-H > Cont W > GM-W-W > F-W-W. However, in the growth chamber the rating was: Cont W (N + P) > F-W-W-H-H-H > GM-W-W > Cont W > F-W-W (N + P) > F-W-W. We suggest that the growth chamber results more accurately reflect the present fertility status of these soils, because fertility is no longer confounded with soil moisture. Grain yields in the growth chamber were directly proportional to the previously measured initial potential rate of N mineralization, indicating the value of the latter parameter as a useful index of soil N fertility. Key words: Nitrogen, phosphorus, soil degradation, legumes, fertilizers

scholarly journals The impact of source or sink limitations on yield formation of winter wheat (Triticum aestivum L.) due to post-anthesis water and nitrogen deficiencies

2010 ◽  
Vol 56 (No. 5) ◽  
pp. 218-227 ◽  
Author(s):  
A. Madani ◽  
A. Shirani-Rad ◽  
A. Pazoki ◽  
G. Nourmohammadi ◽  
R. Zarghami ◽  
...  
Keyword(s):  
Grain Yield ◽  
Triticum Aestivum L ◽  
Grain Weight ◽  
Grain Number ◽  
Water Regimes ◽  
N Supply ◽  
Nitrogen Deficiencies ◽  
Rainfed Wheat ◽  
Source Sink ◽  
The Impact

The experiments were laid out to understand the mechanisms causing yield limitations imposed by post-anthesis water and nitrogen deficiencies in plants with modified source-sink ratios. Two soil-water regimes were allotted to the main plots. At anthesis, three levels of N were applied: none, 25% and 50% of total the N supply. Spike-halving caused reduction in grain yield at both water regimes and all N supply levels, showing that the reduction in grain number can not be compensated by a higher individual grain weight. Sink reduction by trimming 50% of the spikelets reduced grain number per ear by 38.5% and increased individual grain weight by 12.0%, which shows the plasticity in grain weight and grain set of wheat if sufficient assimilates are available. Additional nitrogen supply at anthesis had no significant effect on the total aboveground biomass, but increased grain yield through more allocation of dry matter to grains. Our findings suggest that for rainfed wheat with optimum N supply and supplemental irrigation, wheat growers should choose cultivars with a high grain number per ear and manage the crop to increase grain number per unit of land (sink capacity).

scholarly journals Nitrogen Utilization in a Cereal-Legume Rotation Managed with Sustainable Agricultural Practices

Agronomy ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 113 ◽  
Author(s):  
Mariangela Diacono ◽  
Paola Baldivieso-Freitas ◽  
Francisco Sans Serra
Keyword(s):  
Green Manure ◽  
Crop Production ◽  
Farmyard Manure ◽  
Agricultural Practices ◽  
Residual Effect ◽  
N Fertilization ◽  
Climatic Conditions ◽  
N Losses ◽  
Sustainable Agricultural Practices ◽  
N Use

Optimization of the nitrogen (N) inputs and minimization of nutrient losses strongly affect yields in crop rotations. The aim of this research was to evaluate the effect of agricultural practices on yield and N use in a 4-year cereal-legume rotation in organic farming and to identify the best combination of these practices. The following treatments were compared: conventional plough (P) vs. reduced chisel (RC) tillage; composted farmyard manure (F) vs. unfertilized control (NF); and green manure (GM) vs. no green manure (NoM). No significant differences were found for N use efficiency between P and RC in each crop. The results suggested that legumes in the tested rotation do not need supplemental N fertilization, particularly if combining GM and F. The use of composted farmyard manure should be considered in a long-term fertilization plan for cereals, to allow a higher efficiency in N use. The residual effect of fertilization over time, along with the site-specific pedo-climatic conditions, should also be considered. In both tested tillage approaches, soil N surplus was the highest in plots combining GM and F (i.e., more than 680 kg N ha−1 in combination with RC vs. about 140 kg N ha−1 for RC without fertilization), with a risk of N losses by leaching. The N deficit in NoM–NF both combined with P and RC would indicate that these treatment combinations are not sustainable for the utilized crops in the field experiment. Therefore, the combination of the tested practices should be carefully assessed to sustain soil fertility and crop production.

scholarly journals Assessment of Plant Growth Promoting and Abiotic Stress Tolerance Properties of Wheat Endophytic Fungi

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Farhana Alam Ripa ◽  
Wei-dong Cao ◽  
Shuai Tong ◽  
Jian-guang Sun
Keyword(s):  
Heavy Metals ◽  
Plant Growth ◽  
Endophytic Fungi ◽  
Crop Production ◽  
Abiotic Stress Tolerance ◽  
Antibiotic Sensitivity ◽  
Triticum Aestivum L ◽  
Pgp Traits ◽  
The North ◽  
Plant Growth Promoting

The aims of the present work were to isolate and characterize fungal endophytic communities associated with healthy wheat (Triticum aestivum L.) plants, collected from the North China. Segregated endophytes were screened for their PGP traits, abiotic stresses (heavy metals, salinity, drought, and temperature), and antibiotic sensitivity. A total of 16 endophytic fungi were isolated using the culture-dependent approach from different tissue parts of wheat plants. Based upon their internal transcribed spacer (ITS) rDNA gene sequencing, 15 out of 16 isolates were selected for further analysis. In the contemporary investigation, a number of the tested endophytes exhibited fairly good 1-aminocyclopropane-1-carboxylic acid deaminase (ACCD) (0.03±0.011 to 1.43±0.01µmolα-KB mg−1protein hr−1), indole acetic acid (IAA) (1.125±0.04 to36.12±0.004µgml−1), and phosphate solubilizing index (PSI) (2.08±0.03to5.16±0.36) activities. More than 30% isolates gave positive result for siderophore and ammonia tests, whereas all exhibited catalase activity but only 2 (582PDA1 and 582PDA11) produced hydrogen cyanide.Trichodermastrains showed salt, heavy metals, and drought tolerance at high levels and also exhibited resistance to all the tested antibiotics. Strain 582PDA4 was found to be the most temperature (55°C) tolerant isolate. The findings of this study indicated that the microbial endophytes isolated from wheat plants possessing a crucial function to improve plant growth could be utilized as biofertilizers or bioagents to establish a sustainable crop production system.

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