Frequency Versus Quantity: Phenotypic Response of Two Wheat Varieties to Water and Nitrogen Variability

AbstractDue to climate change, water availability will become increasingly variable, affecting nitrogen (N) availability. Therefore, we hypothesised watering frequency would have a greater impact on plant growth than quantity, affecting N availability, uptake and carbon allocation. We used a gravimetric platform, which measures the unit of volume per unit of time, to control soil moisture and precisely compare the impact of quantity and frequency of water under variable N levels. Two wheat genotypes (Kukri and Gladius) were used in a factorial glasshouse pot experiment, each with three N application rates (25, 75 and 150 mg N kg−1 soil) and five soil moisture regimes (changing water frequency or quantity). Previously documented drought tolerance, but high N use efficiency, of Gladius as compared to Kukri provides for potentially different responses to N and soil moisture content. Water use, biomass and soil N were measured. Both cultivars showed potential to adapt to variable watering, producing higher specific root lengths under low N coupled with reduced water and reduced watering frequency (48 h watering intervals), or wet/dry cycling. This affected mineral N uptake, with less soil N remaining under constant watering × high moisture, or 48 h watering intervals × high moisture. Soil N availability affected carbon allocation, demonstrated by both cultivars producing longer, deeper roots under low N. Reduced watering frequency decreased biomass more than reduced quantity for both cultivars. Less frequent watering had a more negative effect on plant growth compared to decreasing the quantity of water. Water variability resulted in differences in C allocation, with changes to root thickness even when root biomass remained the same across N treatments. The preferences identified in wheat for water consistency highlights an undeveloped opportunity for identifying root and shoot traits that may improve plant adaptability to moderate to extreme resource limitation, whilst potentially encouraging less water and nitrogen use.

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The Exudation of Surplus Products Links Plant Functional Traits and Plant-Microbial Stoichiometry

Land ◽

10.3390/land10080840 ◽

2021 ◽

Vol 10 (8) ◽

pp. 840

Author(s):

Julian Cardenas ◽

Fernando Santa ◽

Eva Kaštovská

Keyword(s):

Plant Growth ◽

Functional Traits ◽

Plant Functional Traits ◽

Ammonium Uptake ◽

Grass Species ◽

N Availability ◽

Soil N ◽

Mineral N ◽

C:N:P Stoichiometry ◽

Soil N Availability

The rhizosphere is a hot spot of soil microbial activity and is largely fed by root exudation. The carbon (C) exudation flux, coupled with plant growth, is considered a strategy of plants to facilitate nutrient uptake. C exudation is accompanied by a release of nutrients. Nitrogen (N) and phosphorus (P) co-limit the productivity of the plant-microbial system. Therefore, the C:N:P stoichiometry of exudates should be linked to plant nutrient economies, plant functional traits (PFT) and soil nutrient availability. We aimed to identify the strongest links in C:N:P stoichiometry among all rhizosphere components. A total of eight grass species (from conservative to exploitative) were grown in pots under two different soil C:nutrient conditions for a month. As a result, a wide gradient of plant–microbial–soil interactions were created. A total of 43 variables of plants, exudates, microbial and soil C:N:P stoichiometry, and PFTs were evaluated. The variables were merged into four groups in a network analysis, allowing us to identify the strongest connections among the variables and the biological meaning of these groups. The plant–soil interactions were shaped by soil N availability. Faster-growing plants were associated with lower amounts of mineral N (and P) in the soil solution, inducing a stronger competition for N with microorganisms in the rhizosphere compared to slower-growing plants. The plants responded by enhancing their N use efficiency and root:shoot ratio, and they reduced N losses via exudation. Root growth was supported either by reallocated foliar reserves or by enhanced ammonium uptake, which connected the specific leaf area (SLA) to the mineral N availability in the soil. Rapid plant growth enhanced the exudation flux. The exudates were rich in C and P relative to N compounds and served to release surplus metabolic products. The exudate C:N:P stoichiometry and soil N availability combined to shape the microbial stoichiometry, and N and P mining. In conclusion, the exudate flux and its C:N:P stoichiometry reflected the plant growth rate and nutrient constraints with a high degree of reliability. Furthermore, it mediated the plant–microbial interactions in the rhizosphere.

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Nitrate uptake and carbon exudation – do plant roots stimulate or inhibit denitrification?

Plant and Soil ◽

10.1007/s11104-020-04750-7 ◽

2020 ◽

Author(s):

Pauline Sophie Rummel ◽

Reinhard Well ◽

Birgit Pfeiffer ◽

Klaus Dittert ◽

Sebastian Floßmann ◽

...

Keyword(s):

Soil Moisture ◽

Plant Growth ◽

Nitrate Uptake ◽

N Uptake ◽

Root Exudation ◽

Mineral N ◽

Double Labeling ◽

Organic C ◽

C And N

Abstract Background and aims Plant growth affects soil moisture, mineral N and organic C availability in soil, all of which influence denitrification. With increasing plant growth, root exudation may stimulate denitrification, while N uptake restricts nitrate availability. Methods We conducted a double labeling pot experiment with either maize (Zea mays L.) or cup plant (Silphium perfoliatum L.) of the same age but differing in size of their shoot and root systems. The 15N gas flux method was applied to directly quantify N2O and N2 fluxes in situ. To link denitrification with available C in the rhizosphere, 13CO2 pulse labeling was used to trace C translocation from shoots to roots and its release by roots into the soil. Results Plant water and N uptake were the main factors controlling daily N2O + N2 fluxes, cumulative N emissions, and N2O production pathways. Accordingly, pool-derived N2O + N2 emissions were 30–40 times higher in the treatment with highest soil NO3− content and highest soil moisture. CO2 efflux from soil was positively correlated with root dry matter, but we could not detect any relationship between root-derived C and N2O + N2 emissions. Conclusions Root-derived C may stimulate denitrification under small plants, while N and water uptake become the controlling factors with increasing plant and root growth.

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Development of an Online Tool for Tracking Soil Nitrogen to Improve the Environmental Performance of Maize Production

Sustainability ◽

10.3390/su13105649 ◽

2021 ◽

Vol 13 (10) ◽

pp. 5649

Author(s):

Giovani Preza-Fontes ◽

Junming Wang ◽

Muhammad Umar ◽

Meilan Qi ◽

Kamaljit Banger ◽

...

Keyword(s):

Real Time ◽

N Uptake ◽

Growing Season ◽

Weather Data ◽

N Availability ◽

Soil N ◽

N Losses ◽

Online Tool ◽

Support Tool ◽

Soil N Availability

Freshwater nitrogen (N) pollution is a significant sustainability concern in agriculture. In the U.S. Midwest, large precipitation events during winter and spring are a major driver of N losses. Uncertainty about the fate of applied N early in the growing season can prompt farmers to make additional N applications, increasing the risk of environmental N losses. New tools are needed to provide real-time estimates of soil inorganic N status for corn (Zea mays L.) production, especially considering projected increases in precipitation and N losses due to climate change. In this study, we describe the initial stages of developing an online tool for tracking soil N, which included, (i) implementing a network of field trials to monitor changes in soil N concentration during the winter and early growing season, (ii) calibrating and validating a process-based model for soil and crop N cycling, and (iii) developing a user-friendly and publicly available online decision support tool that could potentially assist N fertilizer management. The online tool can estimate real-time soil N availability by simulating corn growth, crop N uptake, soil organic matter mineralization, and N losses from assimilated soil data (from USDA gSSURGO soil database), hourly weather data (from National Weather Service Real-Time Mesoscale Analysis), and user-entered crop management information that is readily available for farmers. The assimilated data have a resolution of 2.5 km. Given limitations in prediction accuracy, however, we acknowledge that further work is needed to improve model performance, which is also critical for enabling adoption by potential users, such as agricultural producers, fertilizer industry, and researchers. We discuss the strengths and limitations of attempting to provide rapid and cost-effective estimates of soil N availability to support in-season N management decisions, specifically related to the need for supplemental N application. If barriers to adoption are overcome to facilitate broader use by farmers, such tools could balance the need for ensuring sufficient soil N supply while decreasing the risk of N losses, and helping increase N use efficiency, reduce pollution, and increase profits.

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Morphological and Physiological Root Traits and Their Relationship with Nitrogen Uptake in Wheat Varieties Released from 1915 to 2013

Agronomy ◽

10.3390/agronomy11061149 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1149

Author(s):

Guglielmo Puccio ◽

Rosolino Ingraffia ◽

Dario Giambalvo ◽

Gaetano Amato ◽

Alfonso S. Frenda

Keyword(s):

Durum Wheat ◽

Root System ◽

N Uptake ◽

Specific Root Length ◽

Root Traits ◽

Wheat Breeding ◽

N Availability ◽

Wheat Varieties ◽

Uptake Efficiency ◽

Positive Effects

Identifying genotypes with a greater ability to absorb nitrogen (N) may be important to reducing N loss in the environment and improving the sustainability of agricultural systems. This study extends the knowledge of variability among wheat genotypes in terms of morphological or physiological root traits, N uptake under conditions of low soil N availability, and in the amount and rapidity of the use of N supplied with fertilizer. Nine genotypes of durum wheat were chosen for their different morpho-phenological characteristics and year of their release. The isotopic tracer 15N was used to measure the fertilizer N uptake efficiency. The results show that durum wheat breeding did not have univocal effects on the characteristics of the root system (weight, length, specific root length, etc.) or N uptake capacity. The differences in N uptake among the studied genotypes when grown in conditions of low N availability appear to be related more to differences in uptake efficiency per unit of weight and length of the root system than to differences in the morphological root traits. The differences among the genotypes in the speed and the ability to take advantage of the greater N availability, determined by N fertilization, appear to a certain extent to be related to the development of the root system and the photosynthesizing area. This study highlights some variability within the species in terms of the development, distribution, and efficiency of the root system, which suggests that there may be sufficient grounds for improving these traits with positive effects in terms of adaptability to difficult environments and resilience to climate change.

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Nitrogen Availability in Biochar-Amended Soils with Excessive Compost Application

Agronomy ◽

10.3390/agronomy10030444 ◽

2020 ◽

Vol 10 (3) ◽

pp. 444 ◽

Cited By ~ 3

Author(s):

Chen-Chi Tsai ◽

Yu-Fang Chang

Keyword(s):

N Mineralization ◽

Nitrogen Availability ◽

Agricultural Soils ◽

Inorganic Nitrogen ◽

Clay Content ◽

N Availability ◽

Net N Mineralization ◽

Mineral N ◽

Mineralization Potential ◽

The Impact

Adding biochar to excessive compost amendments may affect compost mineralization rate and nitrogen (N) availability. The objective of this 371-day incubation study was to evaluate the effects of four proportions of woody biochar (0%, 0.5%, 1.0%, and 2.0%) from lead tree (Leucaena leucocephala (Lam.) de. Wit) biochar produced at 750 °C through dynamic mineral N and N mineralization rates in three rural soils (one Oxisol and two Inceptisols). In each treatment, 5% poultry–livestock manure compost was added to serve as an excessive application. The results indicated that the biochar decreased available total inorganic nitrogen (TIN) (NO3−-N+NH4+-N) by on average 6%, 9% and 19% for 0.5%, 1.0% and 2.0% treatments, respectively. The soil type strongly influenced the impact of the biochar addition on the soil nitrogen mineralization potential, especially the soil pH and clay content. This study showed that the co-application of biochar and excessive compost benefited the agricultural soils by improving NO3−-N retention in agroecosystems. The application of biochar to these soils to combine it with excessive compost appeared to be an effective method of utilizing these soil amendments, as it diminished the net N mineralization potential and reduced the nitrate loss of the excessive added compost.

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EFFECT OF SOIL MOISTURE STRESS ON UPTAKE AND RECOVERY OF TAGGED NITROGEN BY WHEAT

Canadian Journal of Soil Science ◽

10.4141/cjss71-005 ◽

1971 ◽

Vol 51 (1) ◽

pp. 37-43 ◽

Cited By ~ 11

Author(s):

E. A. PAUL ◽

R. J. K. MYERS

Keyword(s):

Soil Moisture ◽

Moisture Stress ◽

Organic Soil ◽

Soil Mineral ◽

High Moisture ◽

Soil Moisture Stress ◽

Mineral N ◽

Growing Period ◽

Stress Effects ◽

N Utilization

Labelled 15NH4NO3 was used in a growth chamber to study the effect of moisture stress on the utilization of nitrogen by wheat. This made it possible to determine the recovery of nitrogen (N) in the soil-plant system of two Chernozemic soils. Moisture stress effects were less evident in a clay soil than in a loam. Approximately 55% of the N utilized by the growing plants came from organic soil-N mineralized during the growing period. From 59 to 71% of the initial fertilizer plus soil mineral-N was utilized by the plants. Twenty to 36% remained in the soil, and 1 to 17% was lost. Losses were greatest in soils exposed to high moisture stress and were related to the residual NO3-N levels in the soil. They were attributed to denitrification. Immobilization of N was highest at low moisture stress where plant growth was the greatest, but mineralization was unaffected by the moisture stress applied. It was estimated that 5.0 to 6.2 kg N were required to produce 100 kg of wheat, the highest efficiency of N utilization being obtained at low soil moisture stress.

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Carbon allocation in Larrea tridentata plant-soil systems as affected by elevated soil moisture and N availability

Plant and Soil ◽

10.1007/s11104-013-2017-1 ◽

2014 ◽

Vol 378 (1-2) ◽

pp. 227-238 ◽

Cited By ~ 5

Author(s):

Paul S. J. Verburg ◽

Sheila E. Kapitzke ◽

Bryan A. Stevenson ◽

Marion Bisiaux

Keyword(s):

Soil Moisture ◽

Carbon Allocation ◽

Larrea Tridentata ◽

N Availability ◽

Plant Soil ◽

Soil Systems

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Organic amendment effects on tuber yield, plant N uptake and soil mineral N under organic potato production

Renewable Agriculture and Food Systems ◽

10.1017/s1742170508002330 ◽

2008 ◽

Vol 23 (03) ◽

pp. 250-259 ◽

Cited By ~ 24

Author(s):

Derek H. Lynch ◽

Zhiming Zheng ◽

Bernie J. Zebarth ◽

Ralph C. Martin

Keyword(s):

N Uptake ◽

N Availability ◽

Residual Soil ◽

Soil Mineral ◽

Soil Mineral Nitrogen ◽

Mineral N ◽

Total N ◽

Available N ◽

Organic Potato ◽

Certified Organic

AbstractThe market for certified organic potatoes in Canada is growing rapidly, but the productivity and dynamics of soil N under commercial organic potato systems remain largely unknown. This study examined, at two sites in Atlantic Canada (Winslow, PEI, and Brookside, NS), the impacts of organic amendments on Shepody potato yield, quality and soil mineral nitrogen dynamics under organic management. Treatments included a commercial hog manure–sawdust compost (CP) and pelletized poultry manure (NW) applied at 300 and 600 kg total N ha−1, plus an un-amended control (CT). Wireworm damage reduced plant stands at Brookside in 2003 and those results are not presented. Relatively high tuber yields (~30 Mg ha−1) and crop N uptake (112 kg N ha−1) were achieved for un-amended soil in those site-years (Winslow 2003 and 2004) when soil moisture was non-limiting. Compost resulted in higher total yields than CT in one of three site-years. Apparent recovery of N from CP was negligible; therefore CP yield benefits were attributed to factors other than N availability. At Winslow, NW300, but not NW600, significantly increased total and marketable yields by an average of 5.8 and 7.0 Mg ha−1. Plant available N averaged 39 and 33% for NW300 and NW600, respectively. Soil (0–30 cm) NO3−-N at harvest was low (<25 kg N ha−1) for CT and CP, but increased substantially both in season and at harvest (61–141 kg N ha−1) when NW was applied. Most leaching losses of NO3−-N occur between seasons and excessive levels of residual soil NO3-N at harvest, as obtained for NW600, must be avoided. Given current premiums for certified organic potatoes, improving yields through application of amendments supplying moderate rates of N or organic matter appears warranted.

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Growth, Nitrogen and Phosphorus Uptake of Sorghum Plants as Affected by Green Manuring with Pea or Faba Bean Shell Pod Wastes Using 15N

The Open Agriculture Journal ◽

10.2174/1874331501913010133 ◽

2019 ◽

Vol 13 (1) ◽

pp. 133-145

Author(s):

Mohammed Al-Chammaa ◽

Farid Al-Ain ◽

Fawaz Kurdali

Keyword(s):

Faba Bean ◽

N Uptake ◽

Phosphorus Uptake ◽

P Uptake ◽

Isotopic Dilution ◽

Growth Enhancement ◽

N Availability ◽

Nitrogen And Phosphorus ◽

Nitrogen And Phosphorus Uptake ◽

The Impact

Background: During the freezing or canning preparation process of green grain leguminous, large amounts of shell pods are considered as agricultural organic wastes, which may be used as Green Manure (GM) for plant growth enhancement. Objective: Evaluation of the effectiveness of soil amended with shell pod wastes of pea (PGM) or faba bean (FGM) as GM on growth, nitrogen and phosphorus uptake in sorghum plants. Methods: Determination of the impact of adding four rates of nitrogen (0, 50, 100, and 150 kg N ha-1) in the form of pea (PGM) or faba bean (FGM) shell pod wastes as GM on the performance of sorghum using the indirect 15N isotopic dilution technique. Results: Sorghum plants responded positively and differently to the soil amendments with either GMs used, particularly, the PGM. In comparison with the control (N0), soil amendment with an equivalent rate of 3.5 t ha-1 of PGM (PGM100) or with 6.5 t ha-1 of FGM (FGM150) almost doubled dry weight, N and P uptake in different plant parts of sorghum. Regardless of the GM used, estimated values of %Ndfgm in sorghum plants ranged from 35% to 55% indicating that the use of pod shells as GM provided substantial portions and amounts of N requirements for sorghum. Moreover, nitrogen recoveries of added GM (%NUEgm) ranged from 29 to 45% indicating that N in both of GM forms were used effectively. Accordingly, equivalent amounts to 17 - 48 kg N ha-1 of inorganic fertilizer may be saved. The beneficial effect of incorporating pod shells in soil on sorghum N was mainly attributed to their N availability, besides to their effects on the improvement of soil N uptake, particularly when using PGM. Conclusion: The agricultural by-products of faba bean and pea pod shells could be used as GM for sorghum growth improvement by enhancing N and P uptake from soil and from the organic source.

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Evaluation of nitrogen availability indices and their relationship with plant response on acidic soils of India

Plant Soil and Environment ◽

10.17221/675/2012-pse ◽

2013 ◽

Vol 59 (No. 6) ◽

pp. 235-240 ◽

Cited By ~ 2

Author(s):

Bordoloi LJ ◽

Singh AK ◽

Manoj-Kumar ◽

Patiram ◽

S. Hazarika

Keyword(s):

Nitrogen Availability ◽

N Uptake ◽

Reliable Estimate ◽

Plant Responses ◽

N Availability ◽

Soil N ◽

Acidic Soils ◽

Total N ◽

Large Variability ◽

Available N

Plant’s nitrogen (N) requirement that is not fulfilled by available N in soil has to be supplied externally through chemical fertilizers. A reliable estimate of soil N-supplying capacity (NSC) is therefore essential for efficient fertilizer use. In this study involving a pot experiment with twenty acidic soils varying widely in properties, we evaluated six chemical indices of soil N-availability viz. organic carbon (Corg), total N (Ntot), acid and alkaline-KMnO4 extractable-N, hot KCl extractable-N (KCl-N) and phosphate-borate buffer extractable-N (PBB-N), based on their strength of correlation with available-N values obtained through aerobic incubation (AI-N) and anaerobic incubation (ANI-N), and also with the dry matter yield (DMY), N percentage and plant (maize) N uptake (PNU). In general, the soils showed large variability in NSC as indicated by variability in PNU which ranged from 598 to 1026 mg/pot. Correlations of the N-availability indices with AI-N and ANI-N decreased in the order: PBB-N (r = 0.784** and 0.901**) > KCl-N (r = 0.773** and 0.743**) > acid KMnO4-N (r = 0.575** and 0.651**) ≥ Corg (r = 0.591** and 0.531**) ≥ alkaline KMnO4-N (r = 0.394** and 0.548**) > Ntot (r = 0.297** and 0.273*). Of all the indices evaluated, PBB-N showed the best correlations with plant parameters as well (r = 0.790** and 0.793** for DMY and PNU, respectively). Based on the highest correlations of PBB-N with biological indices as well as plant responses, we propose PBB-N as an appropriate index of N-availability in the acidic soils of India and other regions with similar soils.

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