Bio-organic substitution in tobacco (Nicotiana tabacum L) cultivation: Optimum strategy to lower carbon footprint and boost net ecosystem economic benefit.

The partial substitution of organic manure for chemical nitrogen fertilizers, known as organic substitution, is widely regarded as a cleaner and more sustainable production strategy. However, few studies have quantified greenhouse gas emissions, product income and net ecosystem economic benefit (NEEB) using a life cycle assessment (LCA) approach, particularly for typical tobacco (Nicotiana tabacum L.) production.

Bio-manure substitution declines soil NO and NO emissions and improves nitrogen use efficiency and vegetable quality index.

Substituting mineral fertilizer with manure or a combination of organic amendments plus beneficial soil microorganisms (bio-manure) in agriculture is a standard practice to mitigate NO and NO emissions while enhancing crop performance and nitrogen use efficiency (NUE). Here, we conducted a greenhouse trial for three consecutive vegetable growth seasons for Spinach, Coriander herb, and Baby bok choy to reveal the response of NO and NO emissions, NUE, and vegetable quality index (VQI) to fertilization strategies. Strategies included solely chemical nitrogen fertilizer (CN), 20 (M1N4) and 50% (M1N1) substitution with manure, 20 (BM1N4) and 50% (BM1N1) substitution with bio-manure, and no fertilization as a control and were organized in a completely randomized design (n = 3).

Biochar amendments and climate warming affected nitrification associated NO and NO production in a vegetable field.

Soil nitrification driven by ammonia-oxidizing microorganisms is the most important source of nitrous oxide (NO) and nitric oxide (NO). Biochar amendment has been proposed as the most promising measure for combating climate warming; both have the potential to regulate the soil nitrification process. However, the comprehensive impacts of different aged biochars and warming combinations on soil nitrification-related NO and NO production are not well understood.

Proper organic substitution attenuated both NO and NO emissions derived from AOB in vegetable soils by enhancing the proportion of Nitrosomonas.

The ammonia oxidation process driven by microorganisms is an essential source of nitrous oxide (NO) and nitric oxide (NO) emissions. However, few evaluations have been performed on the changes in the community structure and abundance of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) under substituting portion of chemical fertilizers with organic manure (organic substitution) and their relative contribution to the ammonia oxidation process. Here, five long-term fertilization strategies were applied in field (SN: synthetic fertilizer application; OM: organic manure; M1N1: substituting 50 % of chemical N fertilizer with organic manure; M1N4: substituting 20 % of chemical N fertilizer with organic manure; and CK: no fertilizer).

Contrasting effects of different field-aged biochars on potential methane oxidation between acidic and saline paddy soils.

There is recognition that biochar addition is an appropriate measure to mitigate methane (CH) emissions by promoting potential methane oxidation (PMO) in the field. However, the mechanism for different field-aged biochars and effective duration after field application are not well documented. Based on a long-term field experiment, biochar was field aged and separated from two contrasting acidic (Ba) and saline (Bs) paddy fields.

Soil organic carbon decomposition responding to warming under nitrogen addition across Chinese vegetable soils.

Chemical fertilization in excess and warming disrupt the soil microbes and alter resource stoichiometry, particularly in intensive vegetable soils, while the effects of these variables on the temperature sensitivity of soil organic carbon (SOC) decomposition (Q) and SOC stability remain elusive. Thus, we collected six long-term vegetable soils along a climatic gradient to examine the microbial mechanisms and resource stoichiometry effects on fluctuations in Q and SOC stability induced by warming and fertilization from vegetable soils. Our results showed that the SOC decomposition was dominated by microbes and regulated by stoichiometry.

NO and NO production and functional microbes responding to biochar aging process in an intensified vegetable soil.

Vegetable soils with high nitrogen input are hotspots of nitrous oxide (NO) and nitric oxide (NO), and biochar amended to soil has been documented to effectively decrease NO and NO emissions. However, the aging effects of biochar on soil NO and NO production and the relevant mechanisms are not thoroughly understood. AN tracing microcosm study was conducted to clarify the responses of NO and NO production pathways to the biochar aging process in vegetable soil.

Biochar addition stabilized soil carbon sequestration by reducing temperature sensitivity of mineralization and altering the microbial community in a greenhouse vegetable field.

Biochar is widely used for soil carbon sequestration and fertility improvement. However, the effects of biochar interacted with nitrogen (N) on the mineralization of soil organic carbon (SOC) and microbial community have not been thoroughly understood, particularly no reports have been published on the long term effects of biochar in vegetable field. Here, we examined soil properties, SOC mineralization and microbial community affecting by biochar (0, 20 and 40 t ha; C0, C1 and C2, respectively), N (0 or 240 t ha; N0 or N1, respectively) and their interaction in a greenhouse vegetable field.

Linkages of nitrogen-cycling microbial resistance and resilience to soil nutrient stoichiometry under dry-rewetting cycles with different fertilizations and temperatures in a vegetable field.

Multiple dry-rewetting (DRW) cycles occur in intensively managed vegetable fields due to frequent tillage and irrigation. Soil nitrogen (N) cycling depends on the resistance and resilience of related microbial populations to DRW cycles, which could be closely related to soil nutrient status. However, the linkage of N-cycling microbial resistance and resilience and soil nutrient stoichiometry remains unknown in vegetable field.

Biochar amendment mitigated NO emissions from paddy field during the wheat growing season.

Biochar may variably impact nitrogen (N) transformation and N-cycle-related microbial activities. Yet the mechanism of biochar amendment on nitrous oxide (NO) emissions from agricultural ecosystems remains unclear. Based on a 6-year long-term biochar amendment experiment, we applied a dual isotope (N-O) labeling technique with tracing transcriptional genes to differentiate the contribution of nitrifier nitrification (NN), nitrifier denitrification (ND), nitrification-coupled denitrification (NCD) and heterotrophic denitrification (HD) pathway to NO production.

Organic substitutions aggravated microbial nitrogen limitation and decreased nitrogen-cycling gene abundances in a three-year greenhouse vegetable field.

Partially substituting chemical fertilizer with organic fertilizer has substantially changed the stoichiometric imbalances of carbon (C), nitrogen (N) and phosphorus (P) between microbial communities and their available resources in agroecosystems. However, how organic substitution alters microbial nutrient limitation and then affects soil N cycle in intensive greenhouse vegetable ecosystem, remain unknown. Thus, we performed a three-year greenhouse vegetable field experiment in China with different fertilization strategies: no N fertilization, chemical N fertilization, and substituting 20% (1M4N) or 50% (1M1N) of chemical N with organic fertilizer (organic substitutions).

The effect of long-term biochar amendment on NO emissions: Experiments with N-O isotopes combined with specific inhibition approaches.

Numerous studies reporting a transient decrease in soil nitrous oxide (NO) emissions after biochar amendment have mainly used short-term experiments. Thus, long-term field trials are needed to clarify the actual impact of biochar on NO emissions and the underlying mechanisms. To address this, both a NO labeling technique and gene analyses were applied to investigate how NO production pathways and microbial mediation were affected by long term biochar amendment in field.

Temperature decouples ammonia and nitrite oxidation in greenhouse vegetable soils.

The influence of temperature on soil ammonia (NH) and nitrite (NO) oxidation and related NO accumulation in soils remain unclear. The soil potential NH oxidation (PAO) and NO oxidation (PNO) rates were evaluated over a temperature gradient of 5-45 °C in six greenhouse vegetable soils using inhibitors. The values of temperature sensitivity traits such as temperature minimum (T), temperature optimum (T), and maximum absolute temperature sensitivity (T) were also fitted to the square root growth (SQRT) and macromolecular rate theory (MMRT) models.

Biochar-enriched soil mitigated NO and NO emissions similarly as fresh biochar for wheat production.

Biochar amendment has been recommended as a potential strategy to mitigate nitrous oxide (NO) and nitric oxide (NO) emissions for wheat production, but its mechanism and effective duration are not well understood. The 1-octyne and 2-pheny l-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) in combination with potassium chlorate were used to evaluate the relative contribution of ammonia-oxidizing bacteria (AOB) and archaea (AOA) to potential ammonia oxidation (PAO) and NO and NO production as affected by biochar. Acidic and alkaline soils were collected during wheat-growing season, and four treatments were installed in each soil type: CK, urea alone; BE, biochar-enriched soil for 2-6 years; FB, fresh biochar added to CK; and AB, aged biochar added to CK.

Biochar can mitigate methane emissions by improving methanotrophs for prolonged period in fertilized paddy soils.

Biochar application to fertilized paddy soils has been recommended as an effective countermeasure to mitigate methane (CH) emissions, but its mechanism and effective duration has not yet been adequately elucidated. A laboratory incubation experiment was performed to gain insight into the combined effects of fresh and six-year aged biochar on potential methane oxidation (PMO) in paddy soils with ammonium or nitrate-amendment. Results showed that both ammonium and nitrate were essential for CH oxidation though high ammonium (4 mM) inhibited PMO as compared to low ammonium (1 mM and 2 mM), and that nitrate was better in promoting PMO than ammonium.

Aged biochar stimulated ammonia-oxidizing archaea and bacteria-derived NO and NO production in an acidic vegetable soil.

Both nitrous oxide (NO) and nitric oxide (NO) emissions are typically high in greenhouse-based high N input vegetable soils. Biochar amendment has been widely recommended for mitigating soil NO emissions in agriculture. However, knowledge of the regulatory mechanisms of fresh and aged biochar for both NO and NO production during ammonia oxidation is lacking.

Field-aged biochar reduces the greenhouse gas balance in a degraded vegetable field treated by reductive soil disinfestation.

Reductive soil disinfestation (RSD) is proposed as a pre-plant, non-chemical soil disinfestation technique to control several soilborne phytosanitary issues. However, limited information is available on the evaluation of greenhouse gas (GHG) balance and soil quality during the soil remediation process as affected by RSD method. A 44-day field experiment including four different treatments was conducted to investigate the effects of conventional RSD and field-aged biochar-amended RSD on GHG balance and soil quality in a degraded vegetable field.

Effects of different composting strategies on methane, nitrous oxide, and carbon dioxide emissions and nutrient loss during small-scale anaerobic composting.

Composting is considered as one of the main sustainable methods for the treatment of livestock manure. In this study we investigated the effects of additives (urea and rice straw) on methane (CH), nitrous oxide (NO), and carbon dioxide (CO) emissions using a traditional Chinese pig slurry composting method over an 81-day period, as well as examining total organic carbon and total nitrogen loss. Four common treatment strategies were examined in this study: a control (MC), urea nitrogen addition (MN), composting using rice straw cover (MS), and compost mixed with rice straw (MS).

Overdose fertilization induced ammonia-oxidizing archaea producing nitrous oxide in intensive vegetable fields.

Little is known about the effects of nitrogen (N) fertilization rates on ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) and their differential contribution to nitrous oxide (NO) production, particularly in greenhouse based high N input vegetable soils. Six N treatments (N1, N2, N3, N4, N5 and N6 representing 0, 293, 587, 880, 1173 and 1760 kg N ha yr, respectively) were continuously managed for three years in a typically intensified vegetable field in China. The aerobic incubation experiment involving these field-treated soils was designed to evaluate the relative contributions of AOA and AOB to NO production by using acetylene or 1-octyne as inhibitors.

Microbial explanations for field-aged biochar mitigating greenhouse gas emissions during a rice-growing season.

Knowledge about the impacts of fresh and field-aged biochar amendments on greenhouse gas (CH, NO) emissions is limited. A field experiment was initiated in 2012 to study the effects of fresh and field-aged biochar additions on CH and NO emissions and the associated microbial activity during the entire rice-growing season in typical rice-wheat rotation system in Southeast China. CH and NO fluxes were monitored, and the abundance of methanogen (mcrA), methanotrophy (pmoA), ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), nitrite reductase (nirS, nirK), NO reductase (nosZ), and potential soil enzyme activities related to CH and NO were simultaneously measured throughout different rice developmental stages.

Field-aged biochar stimulated NO production from greenhouse vegetable production soils by nitrification and denitrification.

Evidence suggests that biochar is among ideal strategies for climate change mitigation and sustainable agriculture. However, the effects of soil aging on the physicochemical characteristics of biochar and nitrous oxide (NO) production remain elusive. We set up a microcosm experiment with two greenhouse vegetable production (GVP) (alkaline and acid) soils by using the N tracing technique and quantitative polymerase chain reaction (qPCR) to investigate the mechanisms of NO production as affected by fresh (FB) and aged biochar (AB) amendment.

Nitrogen fertilizer in combination with an ameliorant mitigated yield-scaled greenhouse gas emissions from a coastal saline rice field in southeastern China.

Coastal saline rice fields play an increasingly important role in rice production and associated greenhouse gas (GHG) emissions. However, few studies investigated the influences of nitrogen (N) fertilizer and soil ameliorant on GHG emissions simultaneously in this region. Thus, a field experiment was established to study the effects of different N fertilizers and soil ameliorant on global warming potential (GWP) and yield-scaled GHG intensity (GHGI) after accounting for carbon dioxide (CO) equivalent emissions of methane (CH) and nitrous oxide (NO), agrochemical inputs, and farm operations along with agronomic nitrogen use efficiency (NUE) during the rice season of 2016 in a coastal saline paddy in Lianyungang, China.