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1.
Waste Manag ; 113: 469-477, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32604008

RESUMO

A process for the valorization of citrus peel waste (CPW) has been developed aiming to produce succinic acid and a series of added-value products through the biorefinery platform. CPW was subject to physicochemical and biological treatment to isolate essential oils (0.43%) and pectin (30.53%) as extractable products, pretreating the material for subsequent production of succinic acid that enabled application of remaining biorefinery residues (BR) as fertilizer substitute. Cellulose, hemicellulose and lignin contents of CPW accounted for 22.45%, 8.05% and 0.66% respectively, while acid hydrolysis reduced hemicellulose by 3.42% in BR. Moreover, essential oils extracted from CPW included 17 compounds, among which D-limonene reached 96.7%. The hydrolyzate generated was fermented for succinic acid production using Actinobacillus succinogenes. Different batch experiments demonstrated that the combined use of corn steep liquor (CSL) and vitamins in a lab-scale bioreactor resulted in product concentration and yield that reached 18.5 g L-1 and 0.62 g g-1 respectively. Although simultaneous saccharification and fermentation (SSF) could not enhance succinic acid production, a fed-batch fermentation strategy increased succinic acid concentration and yield generating 22.4 g L-1 and 0.73 g g-1 respectively, while the mass of the platform chemical formed was enhanced by 27% as compared to the batch process. BR was explored as fertilizer substitute aiming to close the loop in the management of CPW towards development of a zero-waste process demonstrating that although the material imposed stress on plant growth, the content of potassium, phosphorus and nitrogen in the mixture increased.


Assuntos
Citrus , Óleos Voláteis , Actinobacillus , Fermentação , Fertilizantes , Pectinas , Ácido Succínico
2.
Water Sci Technol ; 81(9): 1852-1862, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32666940

RESUMO

The kinetics of Se uptake and toxicity to Lemna were studied over a period of 14 days of exposure to Se(IV) or Se(VI). The growth of Lemna stopped immediately after exposure to 5.0 mg/L of Se(IV) or Se(VI). The content of chlorophyll and phaeopigments of Lemna exposed to 5.0 mg/L of Se(IV) was two to three times less than in the control after 3 d exposure. Lemna took up Se rapidly within the first 3 d. The Se content in Lemna along with the exposure time fitted well the two-compartment and the hyperbolic model, which demonstrates that the mechanism of Se(IV) and Se(VI) uptake in Lemna is not only through passive diffusion, but also through other processes such as ion channel proteins or transporters. The kinetic bioconcentration factors (BCFs) were 231 and 42 for 0.5 mg/L Se(IV) and Se(VI) exposure, respectively. The uptake rate of Lemna reached 263 mg/kg/d and 28 mg/kg/d in the Se(IV) and Se(VI) treatments, respectively. This study showed that Se(IV) has a faster accumulation rate than Se(VI), but a higher toxicity, indicating Lemna could be a good candidate to remove Se(IV) from water, producing Se-enriched biomass which may eventually also be considered for use as Se-enriched feed supplement or fertilizer.


Assuntos
Araceae , Selênio , Biomassa , Fertilizantes , Ácido Selênico , Ácido Selenioso
3.
Mar Pollut Bull ; 157: 111331, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32658695

RESUMO

Dissolved inorganic nitrogen (DIN) enrichment accompanied by silicate deficiency in seawater can promote dinoflagellate growth over diatom growth and induce further negative ecological consequences. Here, we propose an easily exercisable method for silicate fertilization as a remedy of eutrophication. In the laboratory, rice husk ash (RHA) released silicate and phosphate in an atomic ratio range of 38-113 without a significant influence on DIN. During incubations of silicate-limited waters, low-dose fertilization increased the diatom/dinoflagellate ratio by 1-5 times. With the high-dose fertilizer addition, DIN, with an initial concentration of 7.63 ±â€¯0.95 µmol l-1, was exhausted in three days, and the diatom abundance increased by 19 times on the 5th day. The silicate fertilization method presented here can be applied independently in eutrophicated waters for dinoflagellate suppression and dissolved nitrogen removal; this method could also work as a supplementary measure to existing nutrient (N, P) reduction and biomanipulation efforts.


Assuntos
Diatomáceas , Proliferação de Células , Desnitrificação , Eutrofização , Fertilizantes , Nitrogênio , Fitoplâncton , Água do Mar , Silicatos
4.
Water Sci Technol ; 81(7): 1530-1540, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32616704

RESUMO

The lignite upgrading wastewater (LUW) produced in the drying and upgrading process of lignite cannot be discharged directly. Conventional wastewater treatment methods are usually costly and unable to achieve efficient utilization of water resources which are rich in activity components. In this study, the water quality analysis showed that LUW belonged to seriously polluted waters with low pH and very high total nitrogen content. Fifty-five compounds, mainly phenols and organic acids, were identified by gas chromatography-mass spectrometry (GC-MS) analysis. The study confirmed that the LUW, after being diluted to an appropriate concentration, could significantly promote the growth of wheat seedlings. The phenols and organic acids were the activity material basis of LUW, which promoted seed germination possibly through playing a role similar to plant hormones and simultaneously enhancing the utilization of nutrient elements. LUW had the natural advantages of directly developing high-end liquid fertilizers in terms of its physical form, chemical composition, biological activity, safety and economy. This study confirmed the feasibility of applying LUW to agricultural field as liquid fertilizer only through simple dilution without other treatments. Applying LUW as liquid fertilizer can not only supply a fertilizer product with low production cost and outstanding efficacy, but also provide an efficient and green way for the treatment of upgrading wastewater, which utilize the LUW as natural resources instead of purifying and discharging.


Assuntos
Eliminação de Resíduos Líquidos , Águas Residuárias/análise , Agricultura , Carvão Mineral , Fertilizantes
5.
J Environ Manage ; 270: 110755, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32721287

RESUMO

Nitrogen has a significant contribution to global warming and its reduction in agriculture is expected to reduce N2O emissions having however adverse effects on the productivity of agricultural ecosystems. Maintaining systems productivity with alternative N sources i.e manure and composts could be a strategy also to mitigate N2O emissions. In this paper, we present the effect of different N sources (organic and chemical) on field N2O emissions and how these emissions are associated with soil available N forms (NH4+ and NO3-) in three different rain-fed crops namely barley, pea and vetch grown in Cyprus for two growing seasons. The daily emissions ranged from -3.11 to 12.3 g N-N2O/ha/day, while cumulative emissions ranged from 119 g N-N2O/ha to 660 g N-N2O/ha depending on crop and nitrogen source type. The emissions showed a seasonal pattern and WFPS has been identified as a critical soil parameter controlling daily N2O emissions. The daily N2O fluxes in the current study derives mainly from nitrification irrespectively crop type or nitrogen source type. Specific emission factors for each crop cultivated under different N source type were calculated and ranged from 0.03% ± 0.02-0.34% ± 0.09. The application of manure and chemical fertilizers cause similar intensity of N2O emissions while compost exhibited the lower emission factors. These findings suggest that composts could be integrated in a nutrient management strategy of rain-fed crops with less N2O emissions. The high background emissions found suggest also that other factors than external inputs are associated with N2O emissions and further studies including the response of microbial community structure and their contribution and association with N2O emissions.


Assuntos
Ecossistema , Óxido Nitroso , Agricultura , Produtos Agrícolas , Chipre , Fertilizantes , Nitrogênio/análise , Chuva , Solo
6.
J Environ Manage ; 270: 110817, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32721295

RESUMO

We investigated the application of cheap but efficient sepiolite for the removal of phosphate and the use of phosphate-adsorbed sepiolite for rice cultivation. Sepiolite was calcined under different temperatures to improve its phosphate adsorption capacity; the sepiolite calcined at 950 °C (950-SPL) was found to have highest adsorption capacity. As the calcination temperature increased, the amount of Ca eluted from sepiolite also increased, resulting in the formation of Ca-P precipitates. Phosphate adsorption on 950-SPL reached equilibrium within 12 h. Both the Langmuir and Freudlich models were not well-fitted to the equilibrium adsorption model because phosphate at initial concentration was fully removed by 950-SPL. The maximum adsorption capacity of 950-SPL with respect to phosphate was 172.34 mg/g. The phosphate adsorption of 950-SPL was endothermic and spontaneous. Phosphate adsorption at pH 3 was two times higher than at pH 11. The presence of bicarbonate significantly influenced the decrease of phosphate by 950-SPL. A breakthrough of column packed with 950-SPL/sand was not observed during >200 h. The phosphate fraction in 950-SPL was mainly composed of apatite-P and residual fraction. A toxicity test using Daphnia magna showed that the toxic units of 950-SPL corresponded to no acute toxicity. Tiller number, shoot height, shoot dry weight and total dry weight were significantly higher in P-adsorbed 950-SPL application than control. It can be concluded that calcined sepiolite can be effective in the removal of phosphate and that the sepiolite after phosphate adsorption can be used as a P fertilizer in soil.


Assuntos
Fósforo , Poluentes Químicos da Água , Adsorção , Fertilizantes , Concentração de Íons de Hidrogênio , Cinética , Silicatos de Magnésio , Fosfatos , Solo , Água
7.
J Environ Manage ; 270: 110888, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32721326

RESUMO

Nitrogen (N) fertilizer-induced soil acidification in Chinese croplands is well-known, but insight in the impacts of different N fertilizer management approaches (fertilizer type and rate) on soil acidification rates is very limited. Here, we conducted a field experiment on a moderate acid soil to quantify soil acidification rates in response to N fertilization by different fertilizer types and N rates through monitoring the fate of elements (mainly nutrients) related to H+ production and consumption. Two N fertilizer types (urea and NH4Cl) and three N rates (control, optimized and conventional, 0/120/240 kg N ha-1 for wheat, 0/160/320 kg N ha-1 for maize) were included. Nitrogen addition led to an average H+ production of 4.0, 8.7, 11.4, 29.7 and 52.6 keq ha-1 yr-1, respectively, for the control, optimized urea, conventional urea, optimized NH4Cl and conventional NH4Cl plots. This was accompanied with a decline in soil base saturation of 1-10% and in soil pH of 0.1-0.7 units in the topsoil (0-20 cm). Removal of base cations by crop harvesting and N transformations contributed ~70% and ~20% to the H+ production in the urea treated plots, being ~20% and ~75% in the NH4Cl treated plots, respectively. The large NH4+ input via fertilization in the NH4Cl treated plots strongly enhanced the H+ production induced by N transformations. The low contribution of N transformations to the H+ production in the urea treated plots was due to the limited NO3- leaching, induced by the high N losses to air caused by denitrification. Increased N addition by urea, however, strongly increased H+ production by enhanced plant uptake of base cations, mainly due to a large potassium uptake in straw. Our results highlight the important role of optimizing fertilizer form and N rate as well as straw return to the field in alleviating soil acidification.


Assuntos
Fertilizantes , Triticum , Agricultura , China , Concentração de Íons de Hidrogênio , Nitrogênio , Solo , Zea mays
8.
J Environ Manage ; 270: 110894, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32721331

RESUMO

Soil aggregation plays a critical role in the maintenance of soil structure, as well as in its productivity. Fertilization influences soil aggregation, especially by regulating soil organic carbon (SOC) and total nitrogen (TN) contents in aggregate fractions. The present study evaluated the influence of three contrasting fertilizer regimes (unfertilized control -CK-, mineral fertilization -NPK- and manure combined with NPK -NPKM) on soil aggregate stability, aggregate-associated organic carbon and total nitrogen sequestration and mineralization of SOC. Soil samples from (20 cm) depth were collected from a long-term fertilization experiment and analysed for size distribution ranging (>250 µm, 250-53 µm and <53 µm sizes), SOC and TN contents, as well as for mineralization of bulk and aggregate associated-SOC. Both NPK and NPKM fertilizations significantly enhanced SOC and TN contents in bulk soil and its constituent aggregates of >250 µm, 250-53 µm and <53 µm sizes, as compared to CK. Long-term NPK and NPKM increased SOC and TN stock in bulk soil by 45 and 98%, and by 70 and 144%, respectively, as compared to CK. Similarly, higher values of SOC and TN stock in all aggregate fractions was observed with the application of NPKM. Application of NPK and NPKM for 26 years significantly increased aggregate stability, which was positively correlated with total SOC contents in terms of mean weight diameter (MWD) (Adj. R2 = 0.689, p < 0.03) and geometric mean diameter (GMD) (Adj. R2 = 0.471, p < 0.24). Moreover, higher scores regarding cumulative mineralization for bulk soil and aggregate associated OC were observed with the application of NPK and NPKM. Irrespective of treatments, higher cumulative C-mineralization was observed for macro-aggregates (>250 µm size) followed by 250-53 µm and <53 µm size aggregates. Interestingly, a highly positive correlation was observed between aggregate stability and the cumulative amount of mineralization for bulk soil and aggregate fractions, with R2 ranging from 0.84 to 0.99. This study evidenced that long-term fertilization of NPK and NPKM can improve soil aggregation, stability and associated OC and TN stock in aggregates, as well as aggregate-associated OC mineralization, which was further governed by aggregate size.


Assuntos
Nitrogênio/análise , Solo , Agricultura , Carbono/análise , China , Fertilizantes/análise , Esterco
9.
J Environ Manage ; 270: 110929, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32721354

RESUMO

Excessive synthetic nitrogen (N) applications, high mineral N accumulation and low N use efficiency (NUE) are current issues in intensively cultivated winter wheat production system impeding the sustainable development of agriculture in China. To solve these problems, soil accumulated N in the top 1 m of the soil profile before sowing (Nsoil), returned straw-N from the previous maize crop (Nstraw) and fertilizer N application (Nfertilizer) should be comprehensively considered N supply sources in N management. As such, the objective of this research was to determine the optimal total N supply (TNsupply) level needed to meet crop requirements while minimizing environmental impacts. A 9-year on-farm experiment was conducted in accordance with a split-plot design involving two different fertilizer management systems (main treatments) and three N application strategies (sub treatments). Extensive TNsupply levels (ranging from 61 kg ha-1 to 813 kg ha-1) were detected, and relative yield (RY), N input and N output in response to the TNsupply were measured. The relationships between TNsupply and RY, N input, and N output strongly fit linear-plateau, linear, and linear-plateau models, respectively. The minimum TNsupply levels needed to achieve the maximum RY and N output were 325 and 392 kg ha-1, respectively. On the basis of N supply capacity, the TNsupply was removed from the growing system by 61% (N input). As the N input increased past 209 kg ha-1, the NUE declined, at which point the TNsupply reached 433 kg ha-1. Therefore, the suitable TNsupply should range from 325 kg ha-1 (ensuring a total N supply for high yield and N uptake) to 433 kg ha-1 (obtaining a relatively higher NUE and less N loss to the environment). The TNsupply was highlighted to be an indicator for use in N management recommendations. Considering the average high N accumulation in winter wheat production systems, N management should essentially take into account the consumption of Nsoil, the levels of Nstraw and the minimum application of Nfertilizer to obtain high yields while minimizing environmental impacts under suitable TNsupply levels.


Assuntos
Nitrogênio/análise , Triticum , Agricultura , China , Fertilizantes , Solo
10.
Ying Yong Sheng Tai Xue Bao ; 31(7): 2314-2322, 2020 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-32715697

RESUMO

We explored the coupling effects of water and nitrogen in furrow irrigation on the growth and absorption and utilization of water and nitrogen in young poplar trees (triploid Populus tomentosa), under three irrigation levels (W20, W33, W45; when the soil water potential of 40 cm under the ditch reaches -20, -33 and -45 kPa respectively, irrigate), four N application levels (N120, N190, N260 and N0; the fertilization amount was 120, 190, 260 and 0 kg·hm-2·a-1), and natural conditions (CK). Based on the growth status of trees, the optimal combination of irrigation level and nitrogen application rate under furrow irrigation conditions was determined. The results showed that W20N120 (high water and low fertilizer; soil water potential threshold for initiating irrigation was -20 kPa and N application rate was 120 kg·hm-2·a-1) had the strongest effect on the stand productivity, with a value of 33.37 m3·hm-2·a-1. The significant coupling effect of water and N was detected only for tree height and total individual biomass. The increase of both irrigation amount and N application rate could increase the amount of N uptake, being mainly affected by the latter. The total amount of N uptake was the highest in the W20N260 treatment and reached 112.17 kg·hm-2·a-1, being 74.0% higher than that in CK. Among all the treatments, N uptake efficiency and N fertilizer partial productivity of W20N120 were the highest and significantly higher than those of the other treatments. The N uptake efficiency of the whole plant, aboveground part, and belowground part reached 36.8%, 28.5% and 6.4% in the W20N120 treatment, and its total N partial productivity reached 221.4 kg·kg-1. The effect of irrigation amount under different water-nitrogen coupling treatments on the irrigation water use efficiency was significant. Among them, irrigation water use efficiency in W45N260 was the highest and reached 13.66 g·kg-1. W20N120 had the highest water uptake amount and efficiency, which were 13268.28 t·hm-2 and 129.4%, respectively. To achieve great benefits, adequate irrigation (-20 kPa) and relatively low N application rate (120 kg·hm-2·a-1) should be selected during the young growth of the triploid P. tomentosa.


Assuntos
Nitrogênio/análise , Populus , Irrigação Agrícola , Biomassa , Fertilizantes , Solo , Árvores , Água/análise
11.
Ying Yong Sheng Tai Xue Bao ; 31(7): 2373-2380, 2020 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-32715703

RESUMO

Application of organic amendments is an effective approach for improving soil organic carbon and soil fertility. To investigate the effects of different organic amendments on soil organic carbon and its labile fraction content, a batch of incubation experiments was conducted on the fluvo-aquic soil in Dongting Lake region, Hunan Province. There were six treatments, including soil amended with rice straw, soil amended with Chinese milk vetch, soil amended with bio-organic fertilizer, soil amended with pig manure, and soil amended with rice straw-derived biochar, with unamended soil as control. Each treatment had the same amount of carbon input. After 180 days of incubation, application of organic amendments increased soil labile organic carbon content. Application of bio-organic fertilizer, pig manure and rice straw-derived biochar significantly increased soil organic carbon content by 26.1%, 9.7% and 30.7%, respectively. There was no significant change in soil organic carbon content in rice straw and Chinese milk vetch treatments which were more favourable to the accumulation of soil dissolved organic carbon and microbial biomass carbon. Pig manure was more favourable to the accumulation of soil dissolved organic carbon. Bio-organic fertili-zer could benefit the accumulation of soil microbial biomass carbon and readily oxidizable organic carbon. Rice straw-derived biochar could promote the accumulation of soil microbial biomass carbon and light fraction organic carbon. Compared with rice straw, soil carbon pool management index was increased by 31.8%, 111.6%, 62.2% and 50.7% in Chinese milk vetch, bio-organic fertilizer, pig manure and rice straw-derived biochar treatments, respectively. The performance of bio-organic fertilizer, pig manure, and rice straw biochar was better than rice straw and Chinese milk vetch from the perspective of soil carbon sequestration and soil carbon pool management index.


Assuntos
Oryza , Solo , Agricultura , Animais , Carbono , Carvão Vegetal , Fertilizantes , Suínos
12.
Ying Yong Sheng Tai Xue Bao ; 31(7): 2381-2389, 2020 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-32715704

RESUMO

We explored the impacts of nitrogen (N) reduction and biochar application on soil fertility and nutrient uptake of rice in early and late seasons of 2018 with a field experiment. There were six treatments, including control (no N application, CK), conventional N application (N100), 20% N reduction (N80), 20% N reduction plus biochar application (N80+BC), 40% N reduction (N60), 40% N reduction plus biochar application (N60+BC). Our results showed that 20% and 40% N reduction and/or with biochar application did not affect soil pH, organic matter, total N, total phosphorous (P), total potassium (K), ammonium N, available P and K in comparison with N100 treatment. N80+BC and N60+BC substantially increased soil cation exchange capacity (CEC) at tillering stage and electrical conductivity (EC) at heading stage in late season, respectively. Compared with the treatment with single N reduction, N80+BC significantly increased soil available K in early and late seasons and soil pH and total N in late season, while N60+BC increased soil total K at mature stage in early season. Soil nitrate content was decreased along with the growth stages for all treatments in early season. Compared with tillering stage, soil nitrate N content in conventional N application at heading stage and mature stage was decreased by 50.0% and 71.6%, respectively. Soil nitrate content in biochar treatment only was decreased by 6.3%-45.5%. N application along with biochar application had no significant effects on plant N uptake and utilization in early season. However, N reduction with biochar application significantly increased plant N uptake and N utilization rate by 34.8%-52.4% in late season, compared to conventional N application and single N reduction. Our findings suggest that adequate N reduction along with biochar application could maintain soil health and improve plant N uptake and utilization efficiency.


Assuntos
Fertilizantes/análise , Oryza , Carvão Vegetal , Nitrogênio , Nutrientes , Solo
13.
Ying Yong Sheng Tai Xue Bao ; 31(7): 2390-2398, 2020 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-32715705

RESUMO

To develop high efficiency stabilized N fertilizer, a pot experiment was conducted to examine the effects of stabilized ammonium sulfate with different nitrification inhibitors on soil avai-lable nitrogen (N) contents, nitrification inhibition rate, apparent nitrification rate, yield, some agronomic parameters and N fertilizer utilization rate of corn in black soil of Jilin Provinve. In this study, blank (CK) and (NH4)2SO4 (N) were set as controls, and nitrification inhibitor 3,4-dimethyl-pyrazolate phosphate (DMPP), 2-chloro-6-trimethyl-pyridine (CP), ammonia protectant N-GD and nitrogen fertilizer synergist HFJ and their combination applied to ammonium sulfate to form nine treatments. The results showed that compared with the treatment of N, application of DMPP and its combinations in black soil significantly affected soil available N contents and the apparent nitrification rate. The contents of ammonium increased by 1.4-2.0 times, while the contents of nitrate and the apparent nitrification rate of soil decreased by 13.6%-17.9% and 55.3%-59.8%, respectively. DMPP, DMPP+HFJ, DMPP+N-GD had the highest nitrification inhibition rate, which reached higher than 16.5%. DMPP+HFJ+N-GD and HFJ increased the chlorophyll content in maize leaves by 4.5-5.3 times. The addition of nitrification inhibitors and fertilizer synergist to ammonium sulfate did not affect plant height. Compared with the treatment of N, HFJ increased corn biomass, grain yield, economic coefficient, harvest index, agronomic utilization rate of fertilizer, N uptake utilization rate, fertilizer contribution rate and N partial productivity of corn by 1.2, 2.5, 0.7, 0.6, 2.7, 2.1, 1.3 and 2.5 times, respectively. In general, HFJ, DMPP, DMPP+HFJ, DMPP+N-GD performed best in black soil. By considering both the cost and N utilization rate, N fertilizer synergist HFJ is the first choice for stable ammonium sulfate N fertilizer biochemical inhibitor, followed by DMPP+HFJ or DMPP+N-GD.


Assuntos
Fertilizantes/análise , Solo , Sulfato de Amônio , Nitrificação , Nitrogênio
14.
Ying Yong Sheng Tai Xue Bao ; 31(7): 2422-2430, 2020 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-32715709

RESUMO

A field experiment with five treatments, control (CK, no fertilizer), conventional fertilization (U), double-effect inhibitor synergistic urea (DU), coated urea (CU) and slow/controlled release urea mixture (CDU), was conducted to investigate the effects of conventional fertilization (240 kg N·hm-2) and one-off application of different slow/controlled release fertilizers (180 kg N·hm-2) on the yield and quality of fresh maize, soil inorganic nitrogen (N), and ammonia (NH3) emissions. The results showed that the total amount of ammonia volatilization was the highest in treatment of conventional fertilization (U), with N topdressing being an important source of NH3 emission. Compared with U treatment, the NH3 volatilization in the DU, CU, and CDU treatments was reduced by 78%-81%. At harvest stage, the soil layer of 80-100 cm in the U treatment had the highest nitrate concentration (51.6 mg·kg-1), resulting in a high risk of N leaching. In contrast, the nitrate concentrations in the same soil layer in the slow/controlled release fertilizer treatments were much lower, reducing the risk of leaching. In comparison with U, three slow/controlled release fertilizer treatments with 25% lower N application did not decrease yield but increased seed Vc, soluble sugar and protein contents. The agronomic efficiency and economic benefit of DU treatment were the highest among three slow/controlled release fertilizers treatments. In conclusion, the application of new type of slow/controlled release fertilizer could improve the yield and quality of fresh maize, and significantly reduce the risk of ammonia loss and N leaching. Considering the higher cost of the polymer coated urea, the double-effect inhibitor urea has lower cost and is more convenient to make. It is therefore a better choice to fresh maize planting.


Assuntos
Amônia/análise , Fertilizantes/análise , Agricultura , Preparações de Ação Retardada , Nitrogênio , Solo , Zea mays
15.
Sci Total Environ ; 735: 139393, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32492566

RESUMO

Biochar (BC) and nitrogen (N) fertilizers are frequently applied to improve soil properties and increase crop productivity. Nonetheless, our mechanistic understanding of plant-soil interactions under single or combined application of BC and N remains incomplete. For the first time, we applied a split-root system to evaluate how BC or N contributes to the changes in soil enzyme activities, N and phosphorus (P) cycling as well as root plasticity. Left and right parts of rhizoboxes were filled with silty-clay loamy soil amended with BC (15 g kg-1 soil, from wheat straw, 300 °C), N (0.05 g KNO3-N kg-1 soil) or a control (no amendments), resulting in the following combinations: BC/Control, N/Control, BC/N. Soil enzyme activities, available N and P, root morphology and plant biomass were analyzed after plant harvest. Plant biomass (shoot + root) ranged from 0.56 g pot-1 (BC/Control) to 0.91 g pot-1(BC/N). The decreased soil bulk density and increased P availability in the BC compartment (BC/Control and BC/N) stimulated root length by 1.4-1.8 times - an effect that was independent of N availability in the same rhizobox. Biochar stimulated activities of ß-glucosidase and leucine aminopeptidase (by 33-39%) compared to N due to the coupling of C, N and P cycles in BC/N treated soil. Nitrogen fertilization also increased ß-glucosidase activity compared to the unfertilized control, whereas root elongation remained unaffected. Thus, the combined application of BC/N had more efficient benefits for plant growth than BC or N alone. This is linked with i) the stimulation of enzyme activities at the BC locations to reduce N limitation for both microorganisms and plants, and ii) an increase of fine root production to improve N uptake efficiency. Thus, combined BC/N application is potentially especially sustainable to overcome nutrient limitation as well as to maintain crop productivity because it accelerates root-microbial interactions.


Assuntos
Carvão Vegetal , Nitrogênio/análise , Fertilizantes , Solo
16.
Environ Monit Assess ; 192(7): 436, 2020 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-32548706

RESUMO

Agricultural soils form the backbone of the country's economic development. The increased population has not only reduced this treasure but also has affected the global climate at an alarming rate. Among the GHGs, emission of N2O due to agricultural activities is nowadays a global concern. Agricultural industries have increased N2O and CH4 by 17% in the atmosphere since 1990, with an average emanation rate of around 60 MT CO2 equivalents per year. Crop production accounts for approximately 50% of N2O emissions stemming from the farming community and discharges of fertilizer-induced N2O, for the time being estimated by IPCC at 1.24% of the N used ranging from 0.76% (rice) to 2.77% (maize). The concentration of atmospheric N2O has increased (60 ppb) after the industrial revolution, at the pace of 0.73 ppb year-1. Besides, soil structure, temperature, moisture, denitrifying microbial population, pH, C:N ratio, and relief are the factors which significantly enhance the N2O levels into the atmosphere. N2O as a GHG has more potential towards global warming than CO2 and has a very long residence period (115 years) in the atmosphere. N2O emission is nowadays a core issue which needs to be mitigated so as to decline the levels of its production in agricultural soils. However, priority should be given to the organic farming, management of soil chemistry, and phytoremediation to reduce the addition of N2O into the ambient air. Furthermore, deployment of N2O reductase in agricultural soils increases the efficiency of converting N2O to inert N2 which is a valuable strategy to reduce N2O production.


Assuntos
Gases de Efeito Estufa , Óxido Nitroso/análise , Agricultura , Monitoramento Ambiental , Fertilizantes/análise , Metano/análise , Solo
17.
Environ Pollut ; 264: 114821, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32559859

RESUMO

Rice fields significantly contribute to the global N2O and NH3 emissions. Nitrification inhibitors (NIs) show promise in decreasing N2O emission, but they can increase NH3 volatilization under traditional broadcasting. Root zone fertilization (RZF) can mitigate NH3 volatilization, but it may pose a high risk to N2O emission. Additionally, most chemical NIs have limited availability and potential for environmental contamination, in contrast, biological NIs, such as methyl 3-(4-hydroxyphenyl) propionate (MHPP), are easily available and eco-friendly. However, the effects of RZF combined with MHPP on N2O and NH3 emissions are unknown. Therefore, a field experiment was conducted in a Chinese rice field with five treatments at 210 kg urea-N ha-1 (BC: 3-split surface broadcasting; BC + MHPP: BC with MHPP; RZ, root zone fertilization; RZ + MHPP, RZF with MHPP; RZ + MHPP + NBPT, RZF with MHPP and NBPT). The results showed that although RZ eliminated NH3 volatilization, it significantly increased total N2O emission by 761% compared with BC due to the stimulation of nitrification by mid-season aeration (MSA) and the trigger of denitrification by a large amount of NO3-. Nearly 90% N2O was emitted at MSA stage for RZF treatments, and their N2O fluxes were exponentially related to the soil NO3--N concentrations in the 7-20 cm deep soil layer. RZ + MHPP greatly reduced the peak values of N2O flux due to the suppression of nitrification by MHPP and then less production of NO3- for denitrification, its total N2O emission was 79% lower compared with that of RZ. However, RZ + MHPP + NBPT further increased the total N2O emission by 1044% compared with that of BC. Compared to BC, the RZF practice reduced total NH3 volatilization by 88-92% regardless use of NIs. RZF had no influence on CH4 emissions and enhanced the rice yields. In conclusion, RZF + MHPP is a promising strategy for simultaneously reducing N2O and NH3 emissions in rice fields.


Assuntos
Nitrificação , Oryza , Agricultura , Amônia/análise , Fertilizantes/análise , Óxido Nitroso/análise , Solo
18.
J Environ Sci (China) ; 94: 179-185, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32563482

RESUMO

Microbial phosphorus (P) turnover is critical in C utilization efficiency in agroecosystems. It is therefore necessary to understand the P mobilization processes occurring during P fertilization in order to ensure both crop yield and environmental quality. Here, we established a controlled pot experiment containing soil amended with three different levels of starter P fertilizer and collected soil samples after 30, 60, and 90 days of incubation. Quantitative microbial element cycling (QMEC) smart chip technology and 16S rRNA gene sequencing were used to investigate functional gene structures involved in carbon, nitrogen and P cycling and the bacterial community composition of the collected samples. Although P fertilization did not significantly affect the structure of the soil microbial community, some rare microbiota were changed in particular phosphorus-solubilizing bacteria were enriched at the high P fertilization level, suggesting that the rare taxa make an important contribution to P turnover. P fertilization also altered the functional gene structure, and high P concentrations enhanced the functional gene diversity and abundance. Partial redundancy analysis further revealed that changes in rare taxa and functional genes of soil microorganisms drive the alteration of soil P pools. These findings extend our understanding of the microbial mechanisms of P turnover.


Assuntos
Fósforo , Solo , Agricultura , Fertilizantes/análise , RNA Ribossômico 16S , Microbiologia do Solo
19.
Sci Total Environ ; 727: 138197, 2020 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-32498200

RESUMO

Microbial communities in agricultural soils underpin many ecosystem services including the maintenance of soil structure, food production, water purification and carbon storage. However, the impact of fertilization on the health of microbial communities is not well understood. This study investigates the spatial and temporal dynamics of nitrogen (N) transport away from a fertilizer granule with pore scale resolution. Specifically, we examined how soil structure and moisture content influence fertilizer derived N movement through the soil pore network and the subsequent impact of on soil microbial communities. We develop a mathematical model to describe N transport and reactions in soil at the pore-scale. Using X-ray Computed Tomography scans, we reconstructed a microscale description of a soil-pore geometry as a computational mesh. Solving two-phase water/air model produced pore-scale water distributions at 15, 30 and 70% water-filled pore volume. The N-speciation model considered ammonium (NH4+), nitrate (NO3-) and dissolved organic N (DON), and included N immobilization, ammonification and nitrification processes, as well as diffusion in soil solution. We simulated the dissolution of a fertilizer pellet and a pore scale N cycle at three different water saturations. To aid interpretation of the model results, microbial activity at a range of N concentrations was measured. The model showed that the diffusion and concentration of N in water films is critically dependent upon soil moisture and N species. We predict that the maximum NH4+ and NO3- concentrations in soil solution around the pellet under dry conditions are in the order of 1 × 103 and 1 × 104 mol m-3 respectively, and under wet conditions 2 × 102 and 1 × 103 mol m-3, respectively. Supporting experimental evidence suggests that these concentrations would be sufficient to reduce microbial activity in the short-term in the zone immediately around the fertilizer pellet (ranging from 0.9 to 3.8 mm), causing a major loss of soil biological functioning. This model demonstrates the importance of pore-scale processes in regulating N movement and their interactions with the soil microbiome.


Assuntos
Solo , Ecossistema , Fertilizantes , Nitrogênio , Microbiologia do Solo
20.
J Environ Manage ; 269: 110767, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32560992

RESUMO

Anaerobic digestates from sewage sludge (SSADs) are a by-product of the wastewater treatment process that still preserves a certain agronomic interest for its richness in plant nutrients and organic matter. Fertilizing properties of two liquid and two dewatered SSADs were tested on tomato plants (Solanum lycopersicum L.). Pot experiments were performed on sandy soil and peat substrate under greenhouse conditions with a SSADs application rate of 170 kg N/ha over a period of three months. Beneficial effects of SSADs were reported on different growth parameters, revealing an increase in biomass and height up to 37.5 and 6-folds over untreated control. No phytotoxic effect occurred on SSAD-exposed plants. Chemical analysis of soils treated with SSADs showed enrichment of macro- and micro-nutrients as well as organic matter. In some cases, the chemical characterization of leaves revealed an enhancement of uptaken macronutrients. This study contributed in general to deepen the knowledge on the short-term growing season fertilizing effects of SSAD. Despite the treatment dosage was calculated only on nitrogen requirements, the study highlighted the importance of the other nutrients and organic matter on plant growth.


Assuntos
Fertilizantes , Lycopersicon esculentum , Anaerobiose , Areia , Esgotos , Solo
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