Organic agriculture has developed rapidly in China since the 1990s, driven by the increasing domestic and international demand for organic products. Quantification of the environmental benefits and ...production performances of organic agriculture on a national scale helps to develop sustainable high yielding agricultural production systems with minimum impacts on the environment. Data of organic production for 2013 were obtained from a national survey organized by the Certification and Accreditation Administration of China. Farming performance and environmental impact indicators were screened and indicator values were defined based on an intensive literature review and were validated by national statistics. The economic (monetary) values of farming inputs, crop production and individual environmental benefits were then quantified and integrated to compare the overall performances of organic vs. conventional agriculture. In 2013, organically managed farmland accounted for approximately 0.97% of national arable land, covering 1.158 million ha. If organic crop yields were assumed to be 10%–15% lower than conventional yields, the environmental benefits of organic agriculture (i.e., a decrease in nitrate leaching, an increase in farmland biodiversity, an increase in carbon sequestration and a decrease in greenhouse gas emissions) were valued at 1921 million RMB (320.2 million USD), or 1659 RMB (276.5 USD) per ha. By reducing the farming inputs, the costs saved was 3110 million RMB (518.3 million USD), or 2686 RMB (447.7 USD) per ha. The economic loss associated with the decrease in crop yields from organic agriculture was valued at 6115 million RMB (1019.2 million USD), or 5280 RMB (880 USD) per ha. Although they were likely underestimated because of the complex relationships among farming operations, ecosystems and humans, the production costs saved and environmental benefits of organic agriculture that were quantified in our study compensated substantially for the economic losses associated with the decrease in crop production. This suggests that payment for the environmental benefits of organic agriculture should be incorporated into public policies. Most of the environmental impacts of organic farming were related to N fluxes within agroecosystems, which is a call for the better management of N fertilizer in regions or countries with low levels of N-use efficiency. Issues such as higher external inputs and lack of integration cropping with animal husbandry should be addressed during the quantification of change of conventional to organic agriculture, and the quantification of this change is challenging.
•1.158 million ha of farmland in China in 2013 was organically managed.•Environmental benefits can substantially, but not totally, offset yield decrease.•Main environmental impacts were related to N fluxes.•Payment for environmental benefits should be incorporated into public policies.
•Integrated effects of tillage, N fertilization and straw management were studied.•Straw incorporation lowers N2O emission only at optimal N fertilization.•No impacts on CH4 were observed for single ...or integrated farming practices.•No-till, straw addition and optimal N fertilization = high yields & reduced GHG.
No-till (NT), straw incorporation (SI) and optimized N fertilization are important mitigation options for reducing greenhouse gas (GHG) emissions from agroecosystems. These measures may also help to maintain high crop production and are frequently recommended for use in northern China. Few studies, however, have addressed the interactive effects of these conservation and fertilization practices with respect to GHG emissions and crop yields. We report on a field experiment conducted in two consecutive dry years (2013–2015) when precipitation was much lower than the long-term average. We examined the effects of three different N fertilizer application rates, tillage practice and straw management on crop yields, GHG, area-scaled GHG (in global warming potential) and net ecosystem economic budget (NEEB) of a winter wheat-summer maize rotation system in northern China. Results showed that reducing N fertilizer significantly decreased soil N2O emissions without affecting annual crop yields. Compared with the average of all other fertilization treatments, the no-till × straw incorporation (NT × SI) practice increased both wheat and maize yields. However, in the maize season, NT also increased cumulative N2O emissions compared with conventional tillage (CT). The practices of combining N fertilization with straw management conferred an additional effect on N2O emissions when compared with single practices (i.e. fertilization or straw management). Compared with straw removal (SR) treatments, SI increased annual cumulative N2O emissions by 37% for the conventional N fertilization, but decreased them by 13% at the optimized N fertilization. Neither single practice nor integrated practices had a significant effect on cumulative CH4 uptake. The highest NEEB values were obtained in NT × SI × optimal N fertilization (OPT) and NT × SR × OPT in the 1st and 2nd cropping years, respectively. We conclude that, when considering the additional benefits of SI for improving soil fertility and C sequestration, the NT × SI × OPT practice would be a viable strategy to achieve high crop yields, while simultaneously reducing GHG emissions.
AIMS: Pulse labeling of crops using ¹³C is often employed to trace photosynthesized carbon (C) within crop-soil systems. However, few studies have compared the C distribution for different labeling ...periods. The overall aim of this study was to determine the length of the monitoring interval required after ¹³C-pulse labeling to quantify photosynthate C allocation into plant, soil and rhizosphere respiration pools for the entire growing season of maize (Zea mays L.). METHODS: Pot grown maize was pulse-labeled with ¹³CO₂ (98 at. %) at the beginning of emergence, elongation, heading and grainfilling growth stages. The routing of ¹³C into shoot and root biomass, soil CO₂ flux and soil organic carbon (SOC) pools was monitored for 27 days after ¹³C-pulse labeling at the beginning of each growth stage. RESULTS: The majority of the ¹³C was recovered after 27 d in the maize shoots, i.e., 57 %, 53 %, 70 % and 80 %, at the emergence, elongation, heading, and grainfilling stages, respectively. More ¹³C was recovered in the root biomass at elongation (27 %) compared to the least at the grainfilling stage (3 %). The amount recovered in the soil was the smallest pool of ¹³C at emergence (2.3 %), elongation (3.8 %), heading and grainfilling (less than 2 %). The amount of ¹³C recovered in rhizosphere respiration, i.e. ¹³CO₂, was greatest at emergence (26 %), and similar at the elongation, heading and grainfilling stages (~16 %). CONCLUSIONS: At least 24 days is required to effectively monitor the recovery of ¹³C after pulse labeling with ¹³CO₂ for maize in plant and soil pools. The recovery of ¹³C differed between growth stages and corresponded to the changing metabolic requirements of the plant, which indicated labeling for the entire growth season would more accurately quantify the C budget in plant-soil system.
•Optimized fertilization and irrigation increase N and water utilization rate.•Lower N application and soil moisture reduce the N2O emission.•WFA and LCA method can be used to evaluate water ...consumption in northern China.
Excessive nitrogen (N) application and shortage of water are the major obstacles to sustainable agricultural development in the high-yielding regions of the North China Plain. New cropping systems need to be created that use integrated management practices to improve the utilization of nitrogen and water and to reduce the emissions of greenhouse gases. We conducted a 4-year (2011–2015) field experiment in Huantai county using three cropping treatments: local farmers’ conventional practices (FP), recommended farming management (REC), and no N fertilization (CK). The study revealed that, the mean annual grain yield of FP and REC was both 16.5 Mg ha−1 which was higher than CK (7.9 Mg ha−1). In comparison with FP, the REC treatment showed N fertilizer and groundwater input reduced by 43% and 28% with increasing of 79.3% and 61.7% of N use efficiency (NUE) and irrigation water use efficiency (IWUE), respectively. The REC treatment demonstrated consistently lower N2O emissions (36% on average) compared with the FP treatment. The annual net global warming potentials of the REC and CK treatments were 37% and 73% lower, respectively, than that of the FP treatment. The water footprint of the REC treatment was 30% (the Water Footprint Assessment method) to 37% (the Life Cycle Assessment method) less than that of the FP treatment. These results indicate that REC is a promising and feasible treatment for ensuring environmentally friendly, and energy-efficient sustainable agriculture in the high-yielding regions of the North China Plain.
Straw incorporation is typically employed to enhance the nutrient content of soil and promote crop growth in intensive agricultural systems. Despite studies regarding the effects of straw ...incorporation on soil microbial communities, the underlying mechanisms of its effect on community co-occurrence interactions and assembly processes remain poorly understood. Herein, soil samples with or without straw incorporation were collected across a latitudinal gradient from north to central China. We found that straw incorporation considerably altered the structure of soil microbial community. The relative abundance of bacterial Latescibacterota and fungal Mortierellomycota were higher in straw-amended soils owing to their ability to decompose straw residues. The co-occurrence network in straw-amended soil exhibited greater complexity, including more network connectivity and keystone species, and higher average degrees and clustering coefficients compared with the control sample network. The network robustness and vulnerability indices suggested that straw incorporation increased the microbial network stability. Normalized stochastic ratios demonstrated that the stochastic process was the dominant mechanisms shaping the assembly of microbial communities in straw-amended soils. Concurrently, null model analysis revealed that straw increased the contribution of dispersal limitation to the assembly of bacterial and fungal communities. The migration rate of the microbial community, obtained from Sloan neutral community model, was relatively low in straw-amended soil at all the sample sites, potentially indicating the great importance of dispersal limitation. These findings would enhance our understanding of the ecological patterns and interactions of soil microbial communities in response to straw incorporation.
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•Three experimental fields across a latitudinal gradient in China were investigated.•Straw incorporation increased the complexity of microbial interaction network.•Microbial network showed greater stability under straw incorporation.•Straw incorporation elevated the importance of stochastic processes.•Straw incorporation may mitigate the stress caused by agricultural intensification.
Excess of water irrigation and fertilizer consumption by crops has resulted in high soil nitrogen (N) losses and underground water contamination not only in China but worldwide. This study explored ...the effects of soil N input, soil N output, as well as the effect of different irrigation and N- fertilizer managements on residual N. For this, two consecutive years of winter wheat (Triticum aestivum L.) –summer maize (Zea mays L.) rotation was conducted with: N applied at 0 kg N ha−1 yr−1, 420 kg N ha−1 yr−1 and 600 kg N ha−1 yr−1 under fertigation (DN0, DN420, DN600), and N applied at 0 kg N ha−1 yr−1 and 600 kg N ha−1 yr−1 under flood irrigation (FN0, FN600). The results demonstrated that low irrigation water consumption resulted in a 57.2% lower of irrigation-N input (p < 0.05) in DN600 when compared to FN600, especially in a rainy year like 2015–2016. For N output, no significant difference was found with all N treatments. Soil gaseous N losses were highly correlated with fertilization (p < 0.001) and were reduced by 23.6%–41.7% when fertilizer N was decreased by 30%. Soil N leaching was highly affected by irrigation and a higher reduction was observed under saving irrigation (reduced by 33.9%–57.3%) than under optimized fertilization (reduced by 23.6%–50.7%). The net N surplus was significantly increased with N application rate but was not affected by irrigation treatments. Under the same N level (600 kg N ha−1 yr−1), fertigation increased the Total Nitrogen (TN) stock by 17.5% (0–100 cm) as compared to flood irrigation. These results highlighted the importance to further reduction of soil N losses under optimized fertilization and irrigation combined with N stabilizers or balanced- N fertilization for future agriculture development.
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•Soil N residual was accumulated in top soil under fertigation.•Gaseous N emissions were highly stimulated by N fertilization.•N leaching was mainly affected by irrigation but not N fertilization measurement.•Optimal fertigation significantly decreased soil N losses and achieved a higher crop N uptake.
To investigate the possibility of identifying commercial organic teas from conventional teas based on their isotopic signatures, we sampled tea leaves and soil samples from three tea gardens in ...Pu'er, China, that underwent decades of certified organic cultivation and compared them with adjacent conventional gardens. We found that long-term organic tea cultivation increased the soil organic carbon and soil pH but significantly decreased the total N content of tea. Higher δ15N values were observed in the organic teas, but significant overlap existed with non-organic teas. The lower N content of the organic tea and contrasting pattern between the organic tea δ15N and soil δ15N suggested that the decline of the N availability could potentially act as a robust characteristic for discriminating between organic and non-organic tea cultivation systems. Further analysis implies that combining tea and soil N content with δ15N value is a promising approach to organic tea identification.
Correlation between tea δ15N and soil δ15N in organic tea gardens and conventional tea gardens Display omitted
•Changed N availability masked the δ15N difference between organic and nonorganic tea.•Using δ15N and δ13C values are not enough for identifying organic tea.•The relation between soil δ15N and tea δ15N in organic and conventional tea gardens was opposite.•Declining N availability is a robust characteristic for organic tea farming.
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•Optimized fertigation significantly increased water and fertilizer N efficiencies.•Optimized fertigation significantly reduced N2O and NO emissions at a higher yield.•Nitrifier ...denitrification was higher in flood fertigation and in summer season.
Agricultural soil is a major source of N2O and NO. In this study, we tested whether optimized N fertigation and water-saving irrigation methods could improve nutrient and water use efficiency while maintaining productivity in the intensified farmed winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) cropping system of northern China. A field experiment was conducted to test different flood irrigation (FN600, conventional N fertilization of 600 kg N ha−1 yr−1 and flood irrigation; FN0, no N input and flood irrigation) and drip fertigation (N0, no N input and drip irrigation; N420, optimized N fertilization of 420 kg N ha−1 yr−1 and drip irrigation; N600, conventional N fertilization of 600 kg N ha−1 yr−1 and drip irrigation) treatments. Compared with the FN600 treatment, the N600 treatment reduced water use by 62.5% (wheat season) and 36.4% (maize season). The N600 treatment significantly reduced N2O emissions (by 19.9%) during the maize season, but not during the wheat season. The N600 treatment increased NO emissions by 20.9% and 11.0% during the wheat and maize seasons, respectively. Compared with the N600 treatment, the N420 treatment significantly decreased N2O and NO emissions by 21.8% and 29.8%, respectively, during the wheat season, and by 31.5% and 41.6%, respectively, during the maize season, while achieving higher crop yield. The direct emission factors (ratio of the cumulative N2O or NO emissions of fertilized treatment minus CK to N rate) of N2O and NO were 0.19%–0.25% and 0.21%–0.27% for the wheat season and 0.38%–0.63% and 0.34%–0.42% for the maize season, respectively. Optimal fertilization (N420) significantly increased the water use efficiency, intrinsic water use efficiency, partial factor productivity, and apparent nitrogen use efficiency in both the wheat and the maize seasons. In addition to nitrification, nitrifier denitrification contributed to the generation and diffusion of N2O and NO, especially during the summer maize season. Considering the higher productivity, more efficient use of irrigation water and nitrogen, and lower N2O and NO emissions, drip irrigation combined with optimized N fertilization is recommended in northern China.
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