Vegetable Field In Southeastern China Research Articles

The combined effects of nitrogen fertilizer and biochar on soil aggregation, N2O emission, and yield from a vegetable field in southeastern China.

Biochar amendment is a recently promoted agricultural management strategy that can exert distinct impacts on reducing greenhouse gas (GHG) emissions and improving soil fertility and crop productivity. This study aims to evaluate the combined effects of biochar and nitrogen (N) fertilizer on soil aggregation, nitrous oxide (N2O) emission, global warming potential (GWP), vegetable yield, and greenhouse gas intensity (GHGI). The experiments were conducted in a vegetable field with two consecutive vegetable crops in 2019 and 2020 in southeastern China. There were four treatments: control (CK), conventional N fertilizer (U), biochar applied at 15 t ha-1 with N fertilizer (UB1), and biochar applied at 30 t ha-1 with N fertilizer (UB2). The results indicate that while N application significantly increased N2O emission of the vegetable field, both UB1 and UB2 led to significant reductions of the total N2O emission, GWP, and yield-scaled GHGI as well as significant growth of the total vegetable crop yield compared with U. However, no significant differences have been found in N2O emission, GWP, crop yield, and yield-scaled GHGI between UB1 and UB2. Meanwhile, biochar application in addition to N fertilizer did not result in any significant change in the soil water-stable aggregate size distribution and stability compared with U. Soil water-stable aggregates smaller than 0.25 mm and those larger than 5 mm have been found to significantly impact N2O emission and vegetable yield.

The effects of biochar and nitrification inhibitors on reactive nitrogen gas (N2O, NO and NH3) emissions in intensive vegetable fields in southeastern China

ABSTRACT Application of biochar and nitrification inhibitors (NIs) to soil has been suggested as a strategy for mitigating climate change and promoting nitrogen use efficiency. However, few studies have focused on how N2O, NO and NH3 emissions and vegetable yield are affected by simultaneous biochar and NI application in vegetable fields. This study aims to investigate the effects of biochar and 3,4-dimethylpyrazole phosphate (DMPP, one type of NIs) amendment on reactive nitrogen gas emissions (GNrEs), vegetable yield, and reactive gaseous N intensity (GNrI) in an intensive vegetable field. There were three treatments: U: urea, UB: urea combined with biochar, UDMPP: urea combined with DMPP. The results show that biochar amendment increased NH3 volatilization by 92.8% (p < 0.05) compared to that under the U treatment. DMPP application abated significantly NO and GNrEs by 49.9% and 21.4%, respectively, compared to those of the U treatment. No significant differences were observed in GNrI among all three treatments; however, DMPP addition had more potential to reduce GNrI than biochar application, based on their results compared to those of the U treatment. Our findings suggest that DMPP application is a suitable practice to reduce GNrEs and maintain yields in intensive vegetable fields.

Organic fertilizer effects on greenhouse gas emissions and greenhouse gas intensity in a vegetable field in southeastern China

Organic fertilizer effects on greenhouse gas emissions and greenhouse gas intensity in a vegetable field in southeastern China

Organic fertilizer effects on greenhouse gas emissions and greenhouse gas intensity in a vegetable field in southeastern China

A field experiment was conducted to assess greenhouse gas emissions and global warming potential in response to organic fertilizer application. These experiments were conducted using the static chamber method and gas chromatography in an intensive vegetable field with 10 consecutive vegetable crops in 2011 and 2014 in south-eastern China. Three treatments were implemented as CONT (no fertilizer), CHEM (conventional chemical fertilizer), and ORGA (organic fertilizer). Results revealed that there was no significant difference in cumulative N2O emissions between CHEM and ORGA treatments though CHEM and ORGA treatments emitted significantly more N2O than CONT treatment. The highest cumulative CH4 emission (72.2 kg C ha-1) was observed in the ORGA treatment, followed by the CHEM treatment (56.3 kg C ha-1) and CONT treatment (39.8 kg C ha-1). The application of organic fertilizer significantly increased the yield by 30.3% and decreased the yield-scaled N2O emissions by 51.0% compared with those parameters in CHEM. Due to higher yield, ORGA decreased GHGI by 28.1% relative to CHEM although no significant difference in GWP was observed. The results enlighten us that the reasonable application of organic fertilizer can gain higher yield and higher environmental benefits at the same time in an intensively managed vegetable field.

Effects of organic fertilizer on net global warming potential under an intensively managed vegetable field in southeastern China: A three-year field study

Organic fertilizer may not only improve soil quality but may also contribute to climate protection by increasing carbon sequestration in agricultural ecosystems. A 3-yr study was conducted with ten consecutive vegetable crops in intensively managed vegetable cropping systems in southeastern China to examine the effects of organic fertilizer application (ORGA) on net global warming potential (net GWP) after accounting for carbon dioxide equivalent emissions from all sources including methane (CH4) and nitrous oxide (N2O) emissions, agrochemical inputs and farm operations and sinks (i.e., soil organic carbon (SOC) sequestration derived from the net ecosystem carbon budget). Results indicated that ORGA significantly increased ecosystem respiration by 13.9% without obvious effects on CH4 and N2O emissions as compared to local conventional chemical fertilization (CHEM). The SOC sequestration rates during the 3-year observation period were estimated at −0.52 t C ha−1 for the control, −0.42 t C ha−1 for the CHEM plot and 0.27 t C ha−1 for the ORGA plot, respectively, and thus contributed significantly to the net GWP. Overall, compared with CHEM, the ORGA significantly decreased net GWP and greenhouse gas intensity by 15.3% and 27.4%, respectively. Our findings suggest that higher yields and lower greenhouse gas intensities and carbon costs can be achieved by substituting chemical nitrogen fertilizers with organic fertilization strategies.

Dynamic responses of nitrous oxide emission and nitrogen use efficiency to nitrogen and biochar amendment in an intensified vegetable field in southeastern China

AbstractIntensive vegetable production exhibits contrasting characteristics of high nitrous oxide (N2O) emissions and low nitrogen use efficiency (NUE). In an effort to mitigate N2O emissions and improve NUE, a field experiment with nine consecutive vegetable crops was designed to study the combined effects of nitrogen (N) and biochar amendment and their interaction on soil properties, N2O emission and NUE in an intensified vegetable field in southeastern China. We found that N application significantly increased N2O emissions, N2O–N emission factors and yield‐scaled N2O emissions by 51–159%, 9–125% and 14–131%, respectively. Moreover, high N input significantly decreased N partial factor productivity (PFPN) and even yield during the seventh to ninth vegetable crops along with obvious soil degradation and mineral N accumulation. To the contrary, biochar amendment resulted in significant decreases in cumulative N2O emissions, N2O–N emission factor and yield‐scaled N2O emissions by 5–39%, 16–67% and 14–53%, respectively. In addition, biochar significantly increased yield, PFPN and apparent recovery of N (ARN). Although without obvious influence during the first to fourth vegetable crops, biochar amendment mitigated N2O emissions during the fifth to ninth vegetable crops. The relative effects of biochar amendments were reduced with increasing N application rate. Hence, while high N input produced adverse consequences such as mineral N accumulation and soil degradation in the vegetable field, biochar amendment can be a beneficial agricultural strategy to mitigate N2O emissions and improve NUE and soil quality in vegetable field.

The combined effects of nitrification inhibitor and biochar incorporation on yield-scaled N&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;O emissions from an intensively managed vegetable field in southeastern China

Abstract. An experiment was conducted to study the influences of nitrification inhibitor (NI) and biochar incorporation on yield-scaled N2O using the static chamber method and gas chromatography in an intensively managed vegetable field with seven consecutive vegetable crops from 2012 to 2014 in southeastern China. With an equal annual nitrogen (N) application rate (1217 kg N ha-1 yr-1), six treatments under three biochar amendment rates – namely, 0 t ha-1 (C0), 20 t ha-1 (C1) and 40 t ha-1 (C2) – with compound fertilizer (CF) or urea mixed with NI of nitrapyrin as chlorinated pyridine (CP) were studied in these field experiments. The results showed that, although there was no significant influence on soil organic carbon (SOC) content or total nitrogen (TN), nitrapyrin could result in a significant increase in soil pH during the experimental period. Nitrapyrin significantly decreased cumulative N2O emissions by 15.9–32.1% while increasing vegetable yield by 9.8–41.9%. Thus, it also decreased yield-scaled N2O emissions significantly. In addition to the differential responses of the soil pH, biochar amendment significantly increased SOC and TN. Compared with the treatments without biochar addition, the cumulative N2O emissions showed no significant difference in the CF or the CP group treatments but increased slightly (not significantly) by 7.9–18.3% in the CP group treatments. Vegetable yield was enhanced by 7.1–49.5% in the CF group treatments compared with the treatments without biochar amendment, while there was no significant difference in the CP group treatments, and the yield-scaled N2O emissions were thus decreased significantly. Furthermore, treatments involving with nitrapyrin and biochar incorporation slightly increased yield-scaled N2O emissions by 9.4%, on average, compared with CP-C0. Therefore, the application of nitrapyrin could serve as an appropriate practice for increasing vegetable yield and mitigating N2O emissions in intensively managed vegetable fields and should be further examined in various agroecosystems.

Modeling impacts of fertilization alternatives on nitrous oxide and nitric oxide emissions from conventional vegetable fields in southeastern China

Intensive nitrogen (N) fertilizer application in the vegetable fields of China has commonly occurred during recent decades and may substantially increase both nitrous oxide (N2O) and nitric oxide (NO) emissions. However, the quantification of N2O and NO emissions from vegetable fields has been rare due to both the lack of long-term field measurements and reliable methods for extrapolating these measurements. Using a unique dataset from a four-year measurement study of an intensively managed conventional vegetable field in southeastern China, we tested a process-based biogeochemical model, denitrification-decomposition (DNDC), for its applicability for quantifying the impact of fertilizer management practices on emissions of N trace gases from vegetable production. The results from the model validation indicate that the simulations of vegetable yields and seasonal cumulative N2O and NO emissions are consistent with the observations. In addition, DNDC can generally capture the measured temporal pattern of daily N2O and NO fluxes. The modeled impacts of fertilization alternatives can be summarized as follows: (a) both the type and application rate of N fertilizers play important roles in regulating N2O and NO emissions as well as vegetable growth; (b) reducing the N application rate to 75% of the conventional amount decreased N2O and NO emissions by 31% and showed little impact on vegetable biomasses, suggesting that reducing the N dose to a reasonable level would be advisable for both the mitigation of N gases emissions and the maintenance of vegetable production; and (c) replacing synthetic fertilizer under the conventional management practices with organic manure may significantly stimulate N2O emission by 62% while decreasing vegetable yields. The results from this modeling study may provide useful information for the ongoing debate regarding the optimization of fertilizer use strategies in China. This study also demonstrates the potential of utilizing process-based models, such as DNDC, to quantify and mitigate N2O and NO emissions from intensive vegetable production through interpreting, integrating, and extrapolating field observations.

Nitrogen Balance and Loss in a Greenhouse Vegetable System in Southeastern China

High rates of fertilizer nitrogen (N) are applied in greenhouse vegetable fields in southeastern China to maximize production; however, the N budgets of such intensive vegetable production remain to be explored. The goal of this study was to determine the annual N balance and loss in a greenhouse vegetable system of annual rotation of tomato, cucumber, and celery at five N (urea) application rates (0, 348, 522, 696, and 870 kg N ha −1 year −1). Total N input to the 0–50 cm soil layer ranged from 531 to 1 053 kg ha −1, and N fertilizer was the main N source, accounting for 66%–83% of the total annual N input. In comparison, irrigation water, wet deposition, and seeds in total accounted for less than 1% of the total N input. The fertilizer N use efficiency was only 18% under the conventional application rate of 870 kg N ha −1 and decreased as the application rate increased from 522 to 870 kg N ha −1. Apparent N losses were 196–201 kg N ha −1, of which 71%–86% was lost by leaching at the application rates of 522–870 kg N ha −1. Thus, leaching was the primary N loss pathway at high N application rates and the amount of N leached was proportional to the N applied during the cucumber season. Moreover, dissolved organic N accounted for 10% of the leached N, whereas NH 3 volatilization only contributed 0.1%–0.6% of the apparent N losses under the five N application rates in this greenhouse vegetable system.

Characteristics of multiple-year nitrous oxide emissions from conventional vegetable fields in southeastern China

[1] The annual and interannual characteristics of nitrous oxide (N2O) emissions from conventional vegetable fields are poorly understood. We carried out 4 year measurements of N2O fluxes from a conventional vegetable cultivation area in the Yangtze River delta. Under fertilized conditions subject to farming practices, approximately 86% of the annual total N2O release occurred following fertilization events. The direct emission factors (EFd) of the 12 individual vegetable seasons investigated ranged from 0.06 to 14.20%, with a mean of 3.09% and a coefficient of variation (CV) of 142%. The annual EFd varied from 0.59 to 4.98%, with a mean of 2.88% and an interannual CV of 74%. The mean value is much larger than the latest default value (1.00%) of the Intergovernmental Panel on Climate Change. Occasional application of lagoon-stored manure slurry coupled with other nitrogen fertilizers, or basal nitrogen addition immediately followed by heavy rainfall, accounted for a substantial portion of the large EFds observed in warm seasons. The large CVs suggest that the emission factors obtained from short-term observations that poorly represent seasonality and/or interannual variability will inevitably yield large uncertainties in inventory estimation. The results of this study indicate that conventional vegetable fields associated with intensive nitrogen addition, as well as occasional applications of manure slurry, may substantially account for regional N2O emissions. However, this conclusion needs to be further confirmed through studies at multiple field sites. Moreover, further experimental studies are needed to test the mitigation options suggested by this study for N2O emissions from open vegetable fields.

Nitric oxide emissions from conventional vegetable fields in southeastern China

We conducted multi-year observations of nitric oxide (NO) fluxes from typical vegetable fields in the Yangtze River delta, which is located in southeastern China. Flux measurements were performed manually twice per week at intervals of 2–3 days, in both fertilized and unfertilized fields, over an investigation period of 1448 days (September 2004–August 2008). In total, twelve vegetable-growing periods and a short fallow period were investigated. On average, the NO fluxes from the fertilized plots were 21 times higher than fluxes from the unfertilized plots ( p < 0.001). Peak NO emissions usually occurred soon after the addition of nitrogenous fertilizer. Peak emissions took place during about 15% of the whole investigation time, but contributed to approximately 89% of the total NO release. The annual background NO emissions (from fields without nitrogen amendment) were observed at 0.290 ± 0.019 (standard deviation of 3 observations) kg N ha −1. The total amounts of NO emitted during the individual vegetable-growing periods correlated positively and exponentially with the products of seasonal mean soil temperatures and nitrogen addition rates ( R 2 = 0.87, p < 0.001). The mean direct NO emission factor (EF d, the loss rate of fertilizer nitrogen via NO emissions) for the four-year period was determined to be 0.51% ± 0.11% (standard error of 3 observations). The EF ds of individual vegetable-growing seasons ranged from 0.05% to 1.24%, varying linearly and positively with the products of seasonal mean soil temperatures and nitrogen addition rates ( R 2 = 0.58, p < 0.01). The observed interaction of soil temperature and nitrogen addition on NO emission in seasonal totals and EF ds occurred in soils with moisture contents ranging from 55% to 100% water-filled pore space (mean: 79%; standard deviation: 9%). The results of this study indicate that when other conditions remain relatively stable, the direct emission factor, a key parameter for compiling an inventory of NO emissions from vegetable fields, may vary with not only soil temperature but also nitrogen addition.

Vegetable cultivation under greenhouse conditions leads to rapid accumulation of nutrients, acidification and salinity of soils and groundwater contamination in South-Eastern China

Vegetable cultivation during winter season is economically profitable, but the impact of the intensive production on soil and water quality remains to be studied. The objectives of this study were to investigate the seasonal dynamics of soil nutrients, acidification and salt accumulation in vegetable fields in South-Eastern China. Various vegetables were grown either under open-field conditions or under two different alternating open-field and greenhouse conditions with three replications. Soil samples were collected periodically and analyzed for pH, plant available nitrogen (N), phosphorous (P), potassium (K), electrical conductivity (EC), and urease activity. Water samples from wells located in or near the plots were collected and analyzed for nitrate. Soil nitrate, available phosphate and salt concentrations declined in summer under open-field conditions and significantly increased from December to May under greenhouse conditions. Exchangeable K also decreased in summer season, but did not increase in the spring. Under alternating open-field and greenhouse conditions, nutrient accumulation, soil salinity and acidification were significantly higher for soil used for vegetable cultivation for 2 years (2-y-plot) than that for only half year (0.5-y-plot). The accumulation of nitrate significantly correlated with soil EC and soil acidification. Thirty-two percent of groundwater samples from the 2-y-plot showed a nitrate concentration higher than 50 mg NO3 l−1. Conversely, no groundwater sample of 0.5-y-plot showed such high nitrate concentration. It can be concluded that the nitrate accumulation in soil used for vegetable cultivation under alternating open-field and greenhouse conditions not only causes soil salinization and soil acidification but also presents a high pollution potential for groundwater.