Rapid development of agriculture and fossil fuel combustion greatly increased US reactive nitrogen emissions to the atmosphere in the second half of the 20th century, resulting in excess nitrogen ...deposition to natural ecosystems. Recent efforts to lower nitrogen oxides emissions have substantially decreased nitrate wet deposition. Levels of wet ammonium deposition, by contrast, have increased in many regions. Together these changes have altered the balance between oxidized and reduced nitrogen deposition. Across most of the United States, wet deposition has transitioned from being nitrate-dominated in the 1980s to ammonium-dominated in recent years. Ammonia has historically not been routinely measured because there are no specific regulatory requirements for its measurement. Recent expansion in ammonia observations, however, along with ongoing measurements of nitric acid and fine particle ammonium and nitrate, permit new insight into the balance of oxidized and reduced nitrogen in the total (wet + dry) US nitrogen deposition budget. Observations from 37 sites reveal that reduced nitrogen contributes, on average, ∼65% of the total inorganic nitrogen deposition budget. Dry deposition of ammonia plays an especially key role in nitrogen deposition, contributing from 19% to 65% in different regions. Future progress toward reducing US nitrogen deposition will be increasingly difficult without a reduction in ammonia emissions.
The possibility of formation of chalcogen bonds through π-holes is examined by means of ab initio calculations at MP2/aug-cc-pVTZ level. We investigate the complexes of SO3 with a series of ...electron-donating nitrogen bases (ZN), including NH3, H2Chorizontal lineboxNH, NH2F, NP, NCH, NCF, NF3, and N2, and their phosphorous analogues (ZP). The ZN:SO3 complexes show shorter chalcogen bond distances than the ZP:SO3 counterparts, accompanied with the more negative interaction energy in the former than in the latter. To understand the nature of interactions, molecular electrostatic potential analysis is performed. In addition, the quantum theory of atoms in molecules and electron localisation function are employed to analyse the chalcogen bond properties in these complexes.
Humans continue to transform the global nitrogen cycle at a record pace, reflecting an increased combustion of fossil fuels, growing demand for nitrogen in agriculture and industry, and pervasive ...inefficiencies in its use. Much anthropogenic nitrogen is lost to air, water, and land to cause a cascade of environmental and human health problems. Simultaneously, food production in some parts of the world is nitrogen-deficient, highlighting inequities in the distribution of nitrogen-containing fertilizers. Optimizing the need for a key human resource while minimizing its negative consequences requires an integrated interdisciplinary approach and the development of strategies to decrease nitrogen-containing waste.
Nitrogen (N) is a key element for the production of potato. The N uptake efficiency, N use efficiency and increased N utilization efficiency can be decreased by N deficiency treatment. We performed ...this study to investigate the association between transcriptomic profiles and the efficiencies of N in potato. Potato cultivars "Yanshu 4" (short for Y), "Xiabodi" (cv. Shepody, short for X) and "Chunshu 4" (short for C) were treated with sufficient N fertilizer and deficient N fertilizer. Then, the growth parameters and tuber yield were recorded; the contents of soluble sugar and protein were measured; and the activities of enzymes were detected. Leaf and root transcriptomes were analyzed and differentially expressed genes (DEGs) in response to N deficiency were identified. The results showed that N deficiency decreased the nitrate reductase (NR), glutamine synthetase (GS) and root activity. Most of the DEGs between N-treated and N-deficiency participate the processes of transport, nitrate transport, nitrogen compound transport and N metabolism in C and Y, not in X, indicating the cultivar-dependent response to N deficiency. DEGs like glutamate dehydrogenase (StGDH), glutamine synthetase (StGS) and carbonic anhydrase (StCA) play key roles in these processes mentioned above. DEGs related to N metabolism showed a close relationship with the N utilization efficiency (UTE), but not with N use efficiency (NUE). The Major Facilitator Superfamily (MFS) members, like nitrate transporter 2.4 (StNRT2.4), 2.5 (StNRT2.5) and 2.7 (StNRT2.7), were mainly enriched in the processes associated with response to stresses and defense, indicating that N deficiency induced stresses in all cultivars.
Nitrogen is an essential nutrient for plant growth. World-wide, large quantities of nitrogenous fertilizer are applied to ensure maximum crop productivity. However, nitrogen fertilizer application is ...expensive and negatively affects the environment, and subsequently human health. A strategy to address this problem is the development of crops that are efficient in acquiring and using nitrogen and that can achieve high seed yields with reduced nitrogen input. This review integrates the current knowledge regarding inorganic and organic nitrogen management at the whole-plant level, spanning from nitrogen uptake to remobilization and utilization in source and sink organs. Plant partitioning and transient storage of inorganic and organic nitrogen forms are evaluated, as is how they affect nitrogen availability, metabolism and mobilization. Essential functions of nitrogen transporters in source and sink organs and their importance in regulating nitrogen movement in support of metabolism, and vegetative and reproductive growth are assessed. Finally, we discuss recent advances in plant engineering, demonstrating that nitrogen transporters are effective targets to improve crop productivity and nitrogen use efficiency. While inorganic and organic nitrogen transporters were examined separately in these studies, they provide valuable clues about how to successfully combine approaches for future crop engineering.
Soil organic nitrogen (N) mineralization not only supports ecosystem productivity but also weakens carbon and N accumulation in soils. Recalcitrant (mainly mineral‐associated organic matter) and ...labile (mainly particulate organic matter) organic materials differ dramatically in nature. Yet, the patterns and drivers of recalcitrant (MNrec) and labile (MNlab) organic N mineralization rates and their consequences on ecosystem N retention are still unclear. By collecting MNrec (299 observations) and MNlab (299 observations) from 57 15N tracing studies, we found that soil pH and total N were the master factors controlling MNrec and MNlab, respectively. This was consistent with the significantly higher rates of MNrec in alkaline soils and of MNlab in natural ecosystems. Interestingly, our analysis revealed that MNrec directly stimulated microbial N immobilization and plant N uptake, while MNlab stimulated the soil gross autotrophic nitrification which discouraged ammonium immobilization and accelerated nitrate production. We also noted that MNrec was more efficient at lower precipitation and higher temperatures due to increased soil pH. In contrast, MNlab was more efficient at higher precipitation and lower temperatures due to increased soil total N. Overall, we suggest that increasing MNrec may lead to a conservative N cycle, improving the ecosystem services and functions, while increasing MNlab may stimulate the potential risk of soil N loss.
A systematic analysis reveals the driving patterns of different organic nitrogen fraction mineralization, and it highlights the importance of recalcitrant organic nitrogen mineralization for microbial nitrogen immobilization and plant nitrogen uptake.
The great challenge of reducing soil nutrient depletion and assuring agricultural system productivity in low-income countries caused by limited synthetic fertilizer use necessitates local and ...cost-effective nutrient sources. We estimated the changes of the nitrogen budget of agricultural systems in the East African Community from 1961 to 2018 to address the challenges of insufficient nitrogen inputs and serious soil nitrogen depletion in agricultural systems of the East African Community region. Results showed that total nitrogen input increased from 12.5 kg N ha
-1
yr
-1
in the 1960s to 21.8 kg N ha
-1
yr
-1
in the 2000s and 27 kg N ha
-1
yr
-1
in the 2010s. Total nitrogen crop uptake increased from 12.8 kg N ha
-1
yr
-1
in the 1960s to 18.2 kg N ha
-1
yr
-1
in the 2000s and 21.8 kg N ha
-1
yr
-1
in the 2010s. Soil nitrogen stock increased from -2.0 kg N ha
-1
yr
-1
in the 1960s to -0.5 kg N ha
-1
yr
-1
in the 2000s and 0.3 kg N ha
-1
yr
-1
in the 2010s. Our results allow us to substantiate for the first time that soil nitrogen depletion decreases with increasing input of nitrogen in agricultural systems of the East African Community region. This suggests that increases in nitrogen inputs through biological nitrogen fixation and animal manure are the critical nitrogen management practices to curb soil nitrogen depletion and sustain agricultural production systems in the East African Community region in order to meet food demand for a growing population.
Biological nitrogen fixation (BNF) is the largest natural source of exogenous nitrogen (N) to unmanaged ecosystems and also the primary baseline against which anthropogenic changes to the N cycle are ...measured. Rates of BNF in tropical rainforest are thought to be among the highest on Earth, but they are notoriously difficult to quantify and are based on little empirical data. We adapted a sampling strategy from community ecology to generate spatial estimates of symbiotic and free-living BNF in secondary and primary forest sites that span a typical range of tropical forest legume abundance. Although total BNF was higher in secondary than primary forest, overall rates were roughly five times lower than previous estimates for the tropical forest biome. We found strong correlations between symbiotic BNF and legume abundance, but we also show that spatially free-living BNF often exceeds symbiotic inputs. Our results suggest that BNF in tropical forest has been overestimated, and our data are consistent with a recent top-down estimate of global BNF that implied but did not measure low tropical BNF rates. Finally, comparing tropical BNF within the historical area of tropical rainforest with current anthropogenic N inputs indicates that humans have already at least doubled reactive N inputs to the tropical forest biome, a far greater change than previously thought. Because N inputs are increasing faster in the tropics than anywhere on Earth, both the proportion and the effects of human N enrichment are likely to grow in the future.
Nitrogen fixation is crucial for plants as it is utilized for the biosynthesis of almost all biomolecules. Most of our atmosphere consists of nitrogen, but plants cannot straightforwardly assimilate ...this from the air, and natural nitrogen fixation is inadequate to meet the extreme necessities of global nutrition. In this study, nitrogen fixation in water was achieved by an AC-driven non-thermal atmospheric pressure nitrogen plasma jet. In addition, Mg, Al, or Zn was immersed in the water, which neutralized the plasma-treated water and increased the rate of nitrogen reduction to ammonia due to the additional hydrogen generated by the reaction between the plasma-generated acid and metal. The effect of the plasma-activated water, with and without metal ions, on germination and growth in corn plants (
) was investigated. The germination rate was found to be higher with plasma-treated water and more efficient in the presence of metal ions. Stem lengths and germination rates were significantly increased with respect to those produced by DI water irrigation. The plants responded to the abundance of nitrogen by producing intensely green leaves because of their increased chlorophyll and protein contents. Based on this report, non-thermal plasma reactors could be used to substantially enhance seed germination and seedling growth.
Nitrogen use efficiency in rapeseed. A review Bouchet, Anne-Sophie; Anne Laperche; Christine Bissuel-Belaygue ...
Agronomy for sustainable development,
06/2016, Letnik:
36, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Mineral nitrogen fertilization has improved crop yield over the last century but has also caused air and water pollution. Reduction of nitrogen inputs and maintaining high yields are therefore ...essential to ensure a more sustainable agriculture. Improving the nitrogen use efficiency (NUE) of crops is therefore needed. Rapeseed, Brassica napus, depends on nitrogen fertilization due to its low NUE, with the ratio of plant nitrogen content to nitrogen supplied often not exceeding 60Â %. Here, we review the major phenotypic traits associated with NUE in B. napus, with special emphasis on winter oilseed rape. We discuss the genetic diversity available and potential breeding strategies. The major points are the following: (1) rapeseed seed yield elaboration is complex, with overlapping phases of nitrogen uptake and remobilization during the crop cycle; (2) traits related to nitrogen uptake, such as root length and the amount of nitrogen absorbed after flowering, and traits related to nitrogen remobilization, such as the âstay-greenâ phenotype, have been identified as possible levers to improve NUE in rapeseed; (3) a substantial body of studies investigating the genetic control of NUE traits have already published and potential candidate genes identified; and (4) rapeseed genetic diversity may be enriched by exploiting interpopulation genetic variation and the closely related gene pools of Brassica rapa and Brassica oleracea.
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