中国生态农业学报(中英文)

Research progress and future directions of arbuscular mycorrhizal fungi-plant-rhizosphere microbial interaction

CHU Wei, GUO Xinlai, ZHANG Chen, ZHOU Liuting, WU Zeyan, LIN Wenxiong

2022, 30(11): 1709-1721. doi: 10.12357/cjea.20220093

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Microecology of rhizosphere, a key area of soil ecology, affects plant growth and metabolism in many ways. Many scientists regard the root system as key to the second green revolution. Arbuscular mycorrhizal (AM) is one of the most common mycorrhizal symbiotic categories of plants and is closely related to the evolutionary history of terrestrial plants. Mycorrhizal symbionts formed by arbuscular mycorrhizal fungi (AMF) and host plant roots can change plant root morphology and improve nutritional status to promote the growth and development of host plants, improve stress resistance and disease resistance, participate in many physiological metabolic processes of plants, and indirectly affect plant growth through the regulation of soil structure and microbial community structure. This paper briefly describes the interaction between AMF and plants, rhizosphere microorganisms, and mycorrhizal helper bacteria (MHB); and discusses the important role of mycorrhizal symbiosis in plant establishment, competition, maintenance of biodiversity, and its role in the Earth’s ecology. Although the symbiosis between AMF and plants has shown good production benefits, most of the studies reported in the scientific literatures have been carried out under controlled conditions (growth chamber or greenhouse, sterile substrate). Because the response of AMF in the natural environment may differ significantly, it is also needed to evaluate the ability of AMF under field conditions. It is also very important to further explore the symbiotic gene network and key transcription factors in the molecular dialogue between plants and fungi, and decipher the key metabolic signaling pathway of MHB.

Temporal and spatial characteristics of nutrient flow and losses of the crop-livestock system in Baiyangdian Basin

YANG Wenbao, YANG Jing, ZHAO Zhanqing, ZHANG Jianjie, WEI Jing

2022, 30(11): 1722-1736. doi: 10.12357/cjea.20220181

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The crop-livestock system in Baiyangdian Basin has changed significantly owing to the implementation of related policies and establishment of the Xiong’an New Area. Based on the NUFER (Nutrient flows in Food chains, Environment and Resources use) model and data from statistical year books, surveys, and literatures, this study determined the nitrogen and phosphorus requirements for crop-livestock systems and analyzed the temporal and spatial characteristics of nutrient use and environmental losses in Baiyangdian Basin on a county scale in the years 2005, 2015, and 2018. The results showed that the inputs of nitrogen and phosphorus fertilizers in Baiyangdian Basin in 2018 were far less than those in 2005 and 2015. For example, the input of nitrogen fertilizer in 2018 was 8.0% and 11.6% lower than that in 2005 and 2015, respectively. The nitrogen use rate of the crop system remained at approximately 44% throughout the study period, whereas the phosphorus use rate increased from 27.1% to 30.7%. The total nutrient input and manure nutrient losses decreased significantly in the livestock system, especially for the directly discharge pathway, whose nitrogen and phosphorus losses reduced to 24.7 Gg and 10.3 Gg, respectively in 2018, which were only approximately 37% of that in 2015. Nitrogen and phosphorus use rates increased significantly for the whole livestock system, reaching 23.3% and 18.6%, respectively in 2018. In 2018, the nitrogen and phosphorus inputs in the crop-livestock system were significantly lower than those in the previous two study years. However, the nitrogen and phosphorus use rates of the whole crop-livestock system first increased and then decreased during 2005–2018. Spatial analysis revealed that the nutrient input, output, and loss of the crop-livestock system were relatively lower in the eastern and western Baiyangdian Basin but higher in the middle areas compared to those in other areas. In conclusion, the goal of “zero increase” in fertilizer and optimization of manure management was achieved in Baiyangdian Basin, but the nutrient use rates of the crop-livestock system were still at a low level. There was an unbalanced development pattern of crop-livestock systems; some counties were characterized by high input, high loss, and low efficiency. In the future, the Baiyangdian Basin should deepen the policy of zero increase in fertilizer, continue to implement the action of recycling livestock waste, and distribute animals rationally to ensure a synergistically optimized crop-livestock system.

Analysis of spatio-temporal dynamics and driving forces of vegetation cover in the Hutuo River Basin based on the geographic detector

DING Yongkang, YE Ting, CHEN Kang

2022, 30(11): 1737-1749. doi: 10.12357/cjea.20220309

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The Hutuo River Basin, located in the Shanxi and Hebei Provinces, plays an important role in regional ecological environment and urban development. Analysis of the spatio-temporal dynamics and driving forces of vegetation cover in the area provides an important scientific basis for sustainable social and economic development and ecological environmental protection. Based on the monthly scale MOD13Q1 (250 m) dataset for 21 years from 2000 to 2020, this study analyzed the spatio-temporal variation trend of vegetation using the unary linear regression method and discussed the correlation between temperature, precipitation, and NDVI using the Pearson correlation analysis method. Natural factors such as temperature, precipitation, vegetation type, soil type, and altitude, and human factors such as land use type, population density, and GDP were statistically divided using the geographic detector, and the degree of influence of each driving factor on NDVI was systematically discussed. Particularly in the case of the increasingly close relationship between vegetation cover and human activities, the driving force values of different human factors can be obtained quantitatively to provide a basis for future research and analysis of the influence mechanism of the main driving factors, ecological environment protection, and sustainable development of watershed. The results of this study were as follows: 1) In the past 21 years, vegetation cover in the area had been increasing, and the average NDVI and Slope index, which is used to indicate vegetation changing trend with the positive value meaning increase, from May to September every year were 0.71 and 0.0035, respectively. The vegetation restoration in the area improved slightly, with 81.00% of the area improving in NDVI and 10.08% of the area degrading. 2) There were positive correlations between NDVI and precipitation and temperature in the area, and the interannual variation in NDVI was more closely related to precipitation. The proportions of positive and negative correlation areas between precipitation and NDVI were 87.73% and 12.27%, respectively, among which 35.28% and 6.92% of the positive correlation area passed the significance test of P<0.05 and P<0.01, respectively. However, the NDVI in the surrounding areas of Yangquan and Shijiazhuang cities was negatively correlated with precipitation and temperature, which may be significantly affected by human activities. 3) The degree of influence of a single driving factor on NDVI in the area was ranked from high to low as follows: precipitation > temperature > land use type > vegetation type > soil type > population density > GDP > altitude. Among them, the q (showing impacting strength of factor) values of the first three factors were all greater than 0.3, and they were the main driving factors affecting the NDVI in the area. 4) The driving force of all the driving factors combined in pairs was significantly greater than that of a single driving factor, showing a two-factor enhancement effect. In addition, the interaction between land use type and precipitation, with a q value of 0.74, was the largest, and it was significantly greater than that of interactions between only human factors or only natural factors. In general, human activities have had a strong impact on the spatio-temporal pattern of vegetation cover, and comprehensive consideration of meteorological factors and rational planning of land use are key factors in improving vegetation cover in the area.

Research progress on photo-physiological mechanisms and characteristics of canopy microenvironment in the formation of intercropping advantages

FAN Hong, YIN Wen, CHAI Qiang

2022, 30(11): 1750-1761. doi: 10.12357/cjea.20220660

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Intercropping is a production approach that can address the issues faced by modern agriculture, such as lowering green gas emissions and fossil material input, while also ensuring yields and system sustainability. The benefits of intercropping are primarily derived from the efficient use of time and space through interspecific interactions, formation of a root and canopy structure that is conducive to crop growth and resource efficiency, creation of an appropriate rhizosphere environment, and optimization of the physiological indicators of crop growth and development. Clarifying the photo-physiological mechanism of intercropping and its relationship with the canopy microenvironment will serve as crucial theoretical support for improving intercropping management technology and fully utilizing the advantages of intercropping. This study reviews the literatures on intercropping photosynthetic physiology at various levels, including populations, individuals, organs, cells, and molecules. Intercropping promotes the maintenance of photosynthetic sources and optimizes dry matter accumulation, distribution, and transportation at the population level; it increases the photosynthetic rate, chlorophyll content, and radiation use efficiency of tall crops but weakens the photosynthetic performance of short crops at the individual and organ levels. Additionally, the activities of phosphoenolpyruvate carboxykinase (PEPC) and Rubisco enzyme in tall crops are increased, whereas they are decreased in short crops; and intercropping tends to upregulate the expression of pepc and ppdk photosynthase genes in tall crops (maize) and upregulate genes encoding photoreaction centers in short crops (soybean). In terms of the intercropping canopy microenvironment, tall crops benefit from greater light interception and minimal temperature fluctuation. However, short crops experience deterioration in both light quantity and quality, lower canopy temperature, and higher humidity, which are unfavorable for crop growth. Regulatory approaches to promote the photo-physiology of intercropped crops and improve the canopy microenvironment include matching tall light-loving varieties and short shade-tolerant crop varieties, moderately increasing the row ratio of dwarf crops, and moderately increasing nitrogen and phosphorus fertilizers. Future research should explore the mechanisms at the microscale of intercropping using molecular biology techniques, discover growth laws and interspecies relationships of intercropping crops via growth model methods, breed special varieties to enhance interspecific interaction, and coordinate the spatial layout and group optimization theory appropriate for mechanization and interspecific interaction.

Eco-physiological mechanisms of silicon in alleviating the biotic and abiotic stresses in plants

QIAN Cheng, LI Xin’e, ZHAO Xin, LIU Dalin, WANG Lin

2022, 30(11): 1762-1773. doi: 10.12357/cjea.20220112

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Owing to global climate change and human activity, abiotic and biotic stresses occur frequently, threatening crop yield and food safety. Reducing the effects of biotic and abiotic stresses is crucial for improving agricultural productivity. Silicon fertilizers are ecologically compatible and environmentally friendly. Silicon has been proven to alleviate plant stress under various conditions, indicating considerable application prospects. Systematic examination of the mitigation mechanisms of silicon on various abiotic and biotic stresses can provide guidance for future practice and research. In this review, we first introduced the absorption and deposition of silicon within plant organs, and the effect of silicon on the synthesis and metabolism of carbon-based substances (“Silicon-Carbon Trade-off Hypothesis”), and then summarized the eco-physiological alleviation mechanisms of abiotic stresses including osmotic stress, nutrient deficiency stress, heavy metal stress, extreme temperature, ultraviolet stress, and biotic stress. We concluded that the common mechanisms of silicon to improve plant stress resistance included improvement of anti-oxidation activities, enhancement of photosynthetic ability, and carbon-silicon trade-off; however, the mechanisms differed under different stresses. Furthermore, previous studies had mainly focused on the eco-physiological mechanisms of the effects of silicon, particularly on grass families such as rice, and the effects of silicon on carbon cycling in agricultural ecosystems had been largely ignored. Therefore, this paper concluded with an outlook on further studies on the molecular mechanisms of silicon, modifications of legume-rhizobia relationships, and significance of phytolith carbon sequestration in agricultural ecosystems. We aimed to provide help and references for broader and deeper investigations of silicon.

Effect of coated urea type and fertilization pattern on lodging resistance and yield of wheat following rice

MA Quan, QIAN Chencheng, JIA Wenxin, WU Yulei, LI Chunyan, DING Jinfeng, ZHU Min, GUO Wenshan, ZHU Xinkai

2022, 30(11): 1774-1783. doi: 10.12357/cjea.20220195

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The purpose of this study was to investigate the effects of coated urea on the lodging resistance of wheat following rice and evaluate the rational application of coated urea to coordinate the yield and lodging resistance of wheat following rice. Resin-coated urea (PCU) and sulfur-coated urea (SCU) were used as the experimental materials, and three fertilization patterns were designed: 100% coated urea applied before sowing (N1); 60% coated urea applied before sowing and 40% urea at jointing (N2); and 60% coated urea applied before sowing and 40% coated urea at regreening stage (N3). A control (CK), with 60% urea applied before sowing and 40% at regreening stage, was also included. The differences in stem morphological characteristics, lodging resistance, and grain yield of wheat following rice under different coated urea and fertilization patterns were analyzed. The results showed that, compared with CK, N1 significantly decreased the length of the basal second internode; increased the fullness, diameter, and wall thickness of the basal second internode; and enhanced snapping resistance and lodging resistance index. The actual field lodging coefficients in PCUN1 and SCUN1 were only 1.11 and 1.31, respectively. The yield in PCUN1 and SCUN1 was low but was not significantly different from that of CK. N2 significantly decreased the fullness of the basal second internode and lodging resistance index but significantly increased the field lodging rate and lodging coefficient compared with N1. N3 achieved the highest yield, which was significantly higher than that of N1, N2, and CK for PCU and SCU. The field lodging rate and lodging coefficient in N3 were not significantly different from those in N2 but were significantly lower than those in CK. In N3, the yield in PCU was the highest; it increased by 14.75% compared with that in CK. The length of the basal second internode in PCUN3 was significantly lower than that in SCUN3; and the fullness, diameter, and wall thickness of the basal second internode were significantly higher than those in SCUN3. Moreover, the field lodging rate and lodging coefficient of PCUN3 were lower than those of SCUN3. In conclusion, 60% PCU applied before sowing and 40% PCU topdressing at re-greening can limit the length of basal second internode, improve fullness and snapping resistance, decrease lodging coefficient, and increase yield, and this is beneficial for coordinating the high yield and lodging resistance of wheat following rice.

Effects of soil water restriction on root growth and root morphology of perennial ryegrass and pasture brome

ZHANG Yongmei, HU Haiying, BAI Xiaoming, Matthew CORY, García-Favre JAVIER, Ordóñez IVÁN P

2022, 30(11): 1784-1794. doi: 10.12357/cjea.20220336

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To study the adaptability of herb roots to drought environments, perennial ryegrass (Lolium perenne) and pasture brome (Bromus valdivianus) were supplied 80%–85% plant available water (PAW) and 20%–25% PAW in a pot experiment. By analyzing of root appearance, biomass accumulation, and root morphology of perennial ryegrass and pasture brome, an effective production strategy for the two forage grasses under extreme drought stress was explored. The results showed that the appearance of the root tips differed slightly between the two forage grasses. Pasture brome had long and dense root hair and a long elongation area in the root tips, whereas perennial ryegrass had sparse root hair and a short elongation area. Extreme drought stress (20%–25% PAW) resulted in uneven root thickness and malformation in perennial ryegrass. No obvious damage was observed in pasture brome roots. There was no significant difference between species and soil water content in terms of biomass accumulation and distribution in the shoots and roots of the two forage grasses. However, there were significant differences in root length, root area, root diameter, root tips, and root forks between the perennial ryegrass and pasture brome. The root quantity of perennial ryegrass was significantly higher than that of brome (P≤0.01); the root length and root area were approximately 1.5 times those of pasture brome; and the root tips and forks were more than twice those of pasture brome. Pasture brome roots were significantly thicker than perennial ryegrass roots, with root diameters of 0.315 mm and 0.259 mm, respectively. The lateral root branches of the pasture brome root were short, thick, and dense, whereas the lateral roots of the perennial ryegrass were long and thin. Drought stress significantly reduced the total root length of the two forage species and promoted the radial growth of roots in the pasture brome. In conclusion, pasture brome had a more developed root-hair-area, and perennial ryegrass had more root quantity. Therefore, perennial ryegrass is distinguished mainly by its root quantity and adopts an adaptive strategy of extensive water absorption, whereas pasture brome is distinguished by well-developed root hair, high lateral root branch density (quality), and adaptive strategies to ensure effective water absorption.

Interactive effects of drought and salt stresses on the growth and physiological characteristics of Thinopyrum ponticum

ZHANG Rui, FENG Xiaohui, WU Yujie, SUN Qi, LI Jing, LI Jingsong, LIU Xiaojing

2022, 30(11): 1795-1806. doi: 10.12357/cjea.20220185

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Saline soils are mainly distributed in arid and semi-arid regions where both soil salt content and drought affect plant growth at the same time. Therefore, soil pot experiments were conducted to study the effects of soil salt content, drought, and their interactions on the growth and physiological characteristics of Thyropyrum ponticum seedlings to understand the adaptability of T. ponticum seedlings in saline soil areas and to provide a theoretical basis for the population establishment of T. ponticum in such areas. Twelve treatments, including four soil salinity levels (0, 4, 8, and 12 g∙kg⁻¹ NaCl) and three soil moisture levels (75%–85%, 55%–65%, and 35%–45% of field capacity) were used. Shoot and root dry weights, leaf chlorophyll contents (SPAD values), leaf photosynthetic parameters, leaf antioxidant enzymes activities, and Na⁺ and K⁺ contents in shoots and roots were measured. The results showed that the growth of T. ponticum was significantly inhibited under drought stress or salt stress, whereas root/shoot ratios increased under the interactions of soil salt and drought stress, and the plants could still survive under 35%–45% field capacity with 12 g∙kg⁻¹ NaCl. Drought and salt stress significantly reduced leaf chlorophyll content, net photosynthetic rate, stomatal conductance, and transpiration rate, whereas these parameters were increased under high salinity levels under moderate drought stress (55%–65% of field capacity) compared with those under normal irrigation. Moderate drought or salt stress increased the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), but these activities were decreased under 12 g∙kg⁻¹ NaCl. The leaf malondialdehyde (MDA) content increased under extreme drought or salt stress. In terms of ion accumulation, Na⁺ and K⁺contents, and K⁺/Na⁺ ratio were higher in shoots than in roots. Roots and shoots Na⁺ contents were increased with decreasing soil water content or increasing soil salinity, whereas K⁺ contents decreased but remained relatively high. Regarding salt-drought interactions, drought treatment could reduce salt stress in plants by promoting the accumulation of Na⁺ in roots. Under drought stress, root Na⁺ content was further increased by increasing soil salinity, while root K⁺/Na⁺ ratio remained stable and shoot K⁺/Na⁺ ratio was significantly decreased. The above results indicate that T. ponticum can survive under high drought and salt conditions, possibly due to its strong root system, higher root/shoot ratio, relatively complete antioxidant enzyme system, Na⁺ accumulation, and stable K⁺/Na⁺ ratio in roots. Although T. ponticum can survive under high drought and salt conditions, the high production of biomass still requires lower soil salinity and moderate drought conditions because the shoot biomass significantly decreases with the increase in soil salinity or decrease in soil moisture.

Community characteristics of nitrite-oxidizing bacteria in the rhizosphere of Fusarium wilt-diseased cucumber caused by continuous greenhouse cultivation

ZHENG Chenmeng, LIU Xing, ZHANG Ying, REN Xiujuan, CHEN Bihua, WANG Fei, SHEN Changwei, WU Dafu

2022, 30(11): 1807-1818. doi: 10.12357/cjea.20220002

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Greenhouse cultivation is the most common method of vegetable production worldwide, and cucumber is one of the most important greenhouse vegetables. However, continuous cucumber cropping in intensive greenhouse production causes a high incidence of Fusarium wilt. It has been demonstrated that the occurrence of this disease was correlated with the alteration in plant rhizosphere microbiome. However, previous studies have focused on the overall microbial community (i.e., bacteria and fungi). The potential role of functional rhizosphere microorganisms in disease occurrence remains largely unclear. Nitrite oxidation (NO₂⁻ conversion to NO₃⁻), performed by nitrite-oxidizing bacteria (NOB), is a vital process in soil nitrification and therefore affects soil N availability and plant nitrogen uptake. In this study, we targeted greenhouse cucumbers subjected to continuous cropping by using rhizosphere soil samples from healthy plants (HPR) and Fusarium wilt-diseased plants (DPR), and assessed differences in their abundances and community diversities and structures of two major groups of NOB, Nitrobacter and Nitrospira, using real-time quantitative PCR and high-throughput amplicon sequencing. The results showed that there was no significant difference in the NO₂⁻-N content between DPR and HPR, whereas the potential nitrite oxidation rate (PNOR) in DPR was approximately twice as high as that of HPR (P<0.05). Nitrobacter abundance in the DPR was significantly higher than in the HPR (P<0.05), with no significant difference in Nitrospira abundance. Nitrobacter abundance was significantly and positively correlated with PNOR, suggesting that it dominated soil nitrite oxidation. For both Nitrobacter and Nitrospira, community diversity did not differ between the DPR and HPR, whereas significant differences in community structures were observed (P<0.05). Phylogenetic analyses revealed that the main members of the Nitrobacter community were Nitrobacter Cluster 3, Cluster 3-like, Cluster 2b, Cluster 4, Cluster 6, Cluster 1, and Cluster 5; in the Nitrospira community, Namibia soil Cluster 1, Cluster 2, Cluster 3, Nitrospira lineageⅠ, lineageⅡ, and lineageⅤ, respectively. In the Nitrobacter community, the average relative abundance of Nitrobacter Cluster 2b in HPR was significantly higher than that in DPR; and on the contrary for both Nitrobacter Cluster 6 and Nitrobacter Cluster 5. In the Nitrospira community, the average relative abundance of Namibia soil cluster 1 in the DPR significantly outnumbered that of the HPR by 92.19%, but the average relative abundance of Nitrospira lineageⅡ was far lower than that of the HPR. Redundancy analysis indicated that the NO₂⁻-N content was the most important soil physicochemical variable influencing the community structures of both Nitrobacter and Nitrospira. Among all the community members detected in this study, in terms of their average relative abundance, only Nitrobacter Cluster 6 was significantly positively linked with PNOR, suggesting that it may be an active member performing nitrite oxidation in continuously cropped greenhouse soil. Collectively, the present study confirmed that the occurrence of Fusarium wilt disease in greenhouse cucumbers in a continuous cropping system was accompanied by shifts in the community structure of NOB in the plant rhizosphere, which obviously affected nitrogen turnover in the diseased greenhouse soil.

Effects of chloroform fumigation on soil organic carbon mineralization in purple soil farmland

MA Han, WANG Xiaoguo

2022, 30(11): 1819-1826. doi: 10.12357/cjea.20220182

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In recent decades, mineralization of soil organic carbon has gradually become a focus due to greenhouse gas (GHG) emissions. The mineralization of soil organic carbon is mainly the decomposition of soil organic carbon under the action of microorganisms, which is an important pathway for soil organic carbon loss. Chloroform has strong sterilization power, and different microorganisms have different sensitivities to it. Furthermore, the soil microbial biomass and community composition can be changed by different fumigation durations. To explore the limiting factors of soil organic carbon mineralization in purple soil farmland, soils from plots with long-term application of pig manure treatment were selected for this laboratory incubation study. The effect of different soil microbial biomasses on soil organic carbon mineralization was investigated through varying the chloroform fumigation time and observing the changes in CO₂ emission rate under different treatments. The experiment included five treatments: fumigation for 24 h (C24), 2.5 h (C2.5), 1.5 h (C1.5), and 1 h (C1); and an unfumigated control (CK). The treatment not only changed the soil microbial biomass, but also greatly changed the soil microorganism community composition, which further verified the Regulation Gate hypothesis. The results showed that after fumigation, the soil microbial residues released microbial biomass carbon and the remaining microorganisms rapidly utilized this carbon source. Due to the availability of this new carbon source, the soil CO₂ emission rate increased rapidly. The variation trend in the soil CO₂ emission rate among different treatments was consistent. Due to the microbial residue carbon source, the CO₂ emission rate of fumigation treatment was higher than that of CK within 7 days of incubation, increasing rapidly to a maximum and then decreasing to a level comparable to the initial level. The order of the maximum values of the soil CO₂ emission rate among different treatments was C2.5>C24>C1.5>C1>CK. Compared with CK, the increases were 309.01%, 182.00%, 73.85%, and 30.45%, respectively. There were significant differences among the treatments (P<0.05). The soil CO₂ emission rate increased slowly and then decreased slowly during days 7–53 of the incubation. The average CO₂ emission rates of treatments C24, C2.5, C1.5, C1, and CK were 6.01±0.43, 5.94±0.29, 6.07±0.59, 5.78±0.49, and 6.23±0.13 μg∙g⁻¹∙h⁻¹, respectively. After 32 d, the rates of fumigation treatments were slightly lower than that of CK with no significant differences among different treatments. The variation in cumulative CO₂ emissions under different treatments conformed to the model y=at^b. The higher the maximum emission rate, the smaller the value of a and the larger the value of b. The b value of all treatments was less than 1, indicating that the cumulative emission increased with incubation time with a gradually slowing rate. The results of this study support the Regulatory Gate hypothesis of soil organic carbon mineralization, which states that the mineralization of soil organic carbon is unrelated to microbial biomass size, community composition, and activity in calcareous purple soil farmland treated with pig manure over a long period of time.

Environmental risk and cost restraint mechanism for incorporating large quantities of vegetable residues into fields in semi-arid area of the Loess Plateau

ZHANG Guangquan, BA Yin, DU Yuming, LI Fengmin, XUE Wei

2022, 30(11): 1827-1841. doi: 10.12357/cjea.20220435

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The incorporation of vegetable residues can fertilize low-quality loess, but it is still unclear whether large quantity of vegetable residues incorporation will cause secondary environmental pollution and increase processing costs. In this study, a plot test was designed in the semi-arid area of the Loess Plateau in Yuzhong, which was randomly combined with three thicknesses of incorporated vegetable residues (20, 40, and 60 cm), three thicknesses of surface soil covering (10, 20, and 30 cm). Meantime, two medium-scale site tests were conducted, in which the thickness of incorporated vegetable residue was up to 350 cm, and the surface soil covering thickness was 30 cm. The degradation rate of vegetable residues, emission rate of NH₃ and H₂S on the soil surface, residue of heavy metals and pesticides in the soil, salt ions contents, and processing cost were investigated. The cumulative degradation rate of vegetable residues in all treatments showed a logarithmic growth curve, which was first fast and then slow. On the 20th and 35th days, the degradation rate of vegetable residues reached 70.0% in the plot and the medium-scale test sites, respectively, and subsequently slowed down. When the thickness of the incorporated vegetable residues was 60 cm and the depth of covering soil was 10–30 cm, the emission of NH₃ was reduced by 71.0%–86.0%, and the emission of H₂S was reduced by 84.9%−87.9%, compared with QC (vegetable residue thickness of 60 cm and no soil cover). The time series changes of the NH₃ emission rate on the soil surface showed a single narrow peak curve, and the peak value of emission rate and cumulative emission were significantly positively correlated with the thickness of incorporated vegetable residues, and significantly negatively correlated with the depth of the covering soil. There was no significant difference in H₂S emissions from the soil surface of the plot test and QT (no incorporation of vegetable residues), and the H₂S emissions from the medium-sized test increased significantly. The larger the amount of vegetable residues into the field, the smaller the emission intensity of pollutants was. There was no significant difference in the contents of heavy metals, pesticide residues, and Ca²⁺ in the vegetable residue layer and the upper and lower soil layers of the medium-sized test sites compared with those in QT (no incorporation of vegetable residues), whereas Na⁺ leached into the deep soil layer. There is a power-law negative correlation between the thickness of incorporated vegetable residues in the field and the processing cost in a medium-sized test field. The larger the incorporating capacity of vegetable residues, the lower the processing cost, and the lowest cost was 25.0 ¥∙t⁻¹ (fresh weight). Therefore, in the semi-arid area of the Loess Plateau, using the method of covering soil and burying pressure to incorporate vegetable residues into the field in high quantities is a low-cost, simple, eco-friendly, and efficient processing scheme for utilizing vegetable residues.

Research on influencing factors and prediction of agricultural carbon emission in Henan Province under the Carbon Peaking and Carbon Neutrality goal

GAO Chenxi, LU Qiuping, OU Nianqing, HU Qingping, LIN Xue, BAO Lingxin

2022, 30(11): 1842-1851. doi: 10.12357/cjea.20220267

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Agricultural production is one of the main sources of carbon emissions, and agricultural carbon emission reduction is a key aspect for China to achieve Carbon Peaking and Carbon Neutrality goal. This study used the emission coefficient method to estimate agricultural carbon emissions in Henan Province from 2001 to 2020. The STIRPAT model was extended to qualitatively and quantitatively analyze the various factors influencing agricultural carbon emissions. Accounting for the defects of traditional prediction models, such as over-fitting, fuzzy nonlinear relationships, and insufficient generalization ability, an agricultural carbon emission prediction model based on the RBF (radial basis function) kernel ε-SVR (support vector regression) was established to predict agricultural carbon emissions and trends in Henan Province from 2021 to 2025 under different scenarios. Agricultural CO₂ emissions in Henan Province showed an overall “increasing-decreasing” trend from 2001 to 2020, with an annual growth rate of −1.18%, and reached peaks of 1.0257×10⁸ t in 2005. The main emission sources of agricultural CO₂ in Henan Province had changed from enteric fermentation and manure management in animal husbandry to land utilization and rice cultivation in planting industry. Every 1% increase in rural population, crop sown area, number of large livestock, agricultural GDP per capita, per capita rural disposable income, agricultural mechanization level, and urbanization rate caused changes in agricultural CO₂ emissions of 0.162%, 0.175%, 0.130%, −0.018%, −0.029%, 0.120%, and −0.071% in Henan Province, respectively. Among the seven factors affecting agricultural carbon emissions in Henan Province, the sown area of crops had the largest promoting effect, followed by the rural population and the number of large livestock, and the agricultural mechanization level had the smallest promoting effect. The urbanization rate had the strongest inhibitory effect, followed by the rural per capita disposable income, and per capita agricultural GDP had the least inhibitory effect. Under the baseline scenario, agricultural CO₂ emissions in Henan Province will continue to decline from 2021 to 2025, and the predicted value in 2025 will be 6.4838×10⁷ t, a decrease of 10.89% compared with 7.276×10⁷ t in 2020. The low carbon scenario I presents a faster decline rate than the baseline scenario, with a predicted value of 6.3692 ×10⁷ t in 2025, a decrease of 12.47% compared with 2020. Under low carbon scenario Ⅱ, the decrease rate of agricultural CO₂ emissions in Henan Province is the highest, and the predicted value in 2025 is 6.3383×10⁷ t, which is 12.89% less than that in 2020. This study showed that agricultural carbon peaking had been achieved in Henan Province. The further governance of agricultural carbon emissions should focuse on the land utilization of crops and manure management of large livestock, and the focus of promoting agricultural carbon emission reduction should be to steadily promote urbanization and rural economic development. Compared with the baseline scenario, the low-carbon scenario has greater carbon emission reduction potential and can realize the efficient development of the rural economy, urbanization process, and low-carbon agriculture, which will help accelerate the realization of the province’s Carbon Peaking and Carbon Neutrality goal.

Agricultural input-output efficiency and the potential reduction of emissions in Henan Province at the county scale

ZHU Yongbin, MA Xiaozhe, SHI Yajuan

2022, 30(11): 1852-1861. doi: 10.12357/cjea.20220219

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Abstract:
Agricultural modernization and technological progress have substantially improved the efficiency of production. However, the growing dependence on the inputs of agricultural materials has resulted in a series of deleterious issues, such as soil and water pollution, carbon emissions. Previous studies have always considered carbon emissions as an unexpected output when evaluating agricultural green total factor productivity. These studies failed to estimate the potential reduction in carbon emission, as well as the contribution of all sources. This study sought to improve commonly used approaches and enable them to calculate the potential reduction of carbon emissions. To do so, it utilized the variable returns to scale data envelopment analysis (VRS-DEA) two-stage model and the DEA-Malmquist method to evaluate the agricultural input-output efficiency and obtain the abundant input of each material. In this study, six agricultural materials were selected as inputs and five major crop products as outputs with 105 counties/cities in Henan Province, China, as decision-making units from 2000–2020. The results showed the following: 1) carbon emissions induced by agricultural inputs began to decline after reaching their peak in 2016. The counties/cities with higher emissions were primarily distributed in the eastern and southern plains. Those with higher intensities of emissions per unit of sown area were primarily concentrated in the northern plains, where have better terrain conditions. 2) High-agricultural-efficiency areas were primarily concentrated in southern and northern Henan. In contrast, low-agricultural-efficiency counties/cities were primarily concentrated near urbanized areas, indicating that urbanization has a negative effect on agricultural efficiency. Approximately 60% of the counties/cities improved their agricultural efficiency between 2000 and 2020. Those with decreased agricultural efficiency were primarily located in the central and western regions. They were adjacent to areas with a high urbanization rate and primarily included mountainous and hilly areas. 3) The comprehensive potential reduction of carbon emission was approximately 11% of gross agricultural emissions. Counties/cities with the highest potential rate of reduction were primarily distributed in the areas surrounding the developed urban agglomerations. The key areas of agricultural reduction were the three counties/cities of Ruzhou, Xinye, and Huixian, with an accumulated potential reduction of more than one million tons. Ten counties/cities, such as Huaibin and Weihui, had more than half a million tons of accumulated potential reductions. 4) Agricultural inputs with a high redundancy ratio were agriculture plastic films, pesticides, chemical fertilizers, agricultural machinery, and agricultural labor. Chemical fertilizers with immense usage was a major concern; its input had the potential reduction of carbon emission as much as 83.5%. In summary, it is the basic solution for reduction of agricultural carbon emission to increase agricultural input-output efficiency and reduce redundant agricultural inputs. uts.

Impacts of agricultural infrastructure on ecology total factor productivity of grain from the perspective of environmental regulation

LI Ziqiang, YE Weijiao, MEI Dong, ZHENG Ciwen

2022, 30(11): 1862-1876. doi: 10.12357/cjea.20220214

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Abstract:
Increasing grain production while protecting the environment is an important prerequisite for ensuring sustainable development and food security of China. To explore effective strategies to improve the ecology total factor productivity of grain (ETFP) in China, this study used the Global-Malmquist-Luenberger (GML) index to measure the ETFP based on the ecological value of grain production. Based on the theory of public goods, we empirically explored the path to improve ETFP with agricultural infrastructure as the point of penetration. We found: (1) The ecological value of grain production per hectare in 30 provinces (cities, autonomous regions) of China increased from 1993 to 2019. The average ETFP during 1993–2019 generally showed a fluctuating upward trend. Among them, the ETFP of the Middle and Lower Reaches of the Yangtze River and the Northeast China were higher than the national average in most years. (2) Agricultural water conservancy facilities, agricultural electric power facilities, and agricultural transportation facilities can effectively improve ETFP, but there was a lag in time. Among these factors, the impact of agricultural water conservancy facilities on ETFP showed an “inverted U” shape. This finding suggests that there is an optimum value for the provision of agricultural field water conservancy facilities in the process of ecological food production. (3) In contrast to the full-sample regression results, the regression results of samples of northern and southern regions showed that the agricultural water conservancy facilities and their lag terms had no significant impact on ETFP, and the agricultural electric power facilities and their lag terms had a reducing effect on ETFP in southern region. The results of the sample regression showed that agricultural electric facilities and their lag items in main grain-producing areas had no significant impact on ETFP, while agricultural electric power facilities and their lag items in non-main grain-producing areas had no significant impact on ETFP. (4) The results of the moderating effect test indicated that environmental regulation had a positive moderating effect on ETFP. Further study found that, in the grouping regulation regression results, environmental regulation could play a stronger positive regulatory role in the region with a lower ETFP than in the region with a higher ETFP. Therefore, on the basis of this research, we recommend that the government should plan and invest in agricultural infrastructure construction in advance and formulate and publicize scientific, reasonable, and flexible environmental laws and regulations. This study innovatively incorporates the ecological value of grain production into the measurement of ETFP. While broadening the research boundary of agricultural infrastructure construction planning, it provides a basis for improving the ETFP in China.

Influence of consumption motivation and consumption habit on premium payment intention of ecological agricultural products using green manure-rice as an example

LI Fuduo, YIN Changbin

2022, 30(11): 1877-1890. doi: 10.12357/cjea.20220337

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Abstract:
Over the past few decades, the intensive use of chemicals in agricultural production in China has led to serious environmental and food safety problems, triggering a series of public health incidents and greatly undermining consumer confidence in traditional food. Due to food safety concerns, consumers in developed as well as developing countries such as China have been paying increasing attention to emerging ecological agricultural products (EEAPs) produced in environmentally conscious way. In the consumer market, guiding consumers to pay reasonable fees for EEAPs is not only conducive to promote the cultivation and development of the EEAPs market but also has important practical significance for improving the health of residents and ensuring environmental protection. Using green manure-rice (GMR) as an example, based on survey data from 974 consumers in Changsha, Wuhan, Nanchang, and Hefei in South China, this study first used the contingent valuation method (CVM) to evaluate consumers’ premium payment level for GMR. Then, the Heckman two-stage model was used to explore the mechanism of influence of consumer motivation and consumption habits on consumers’ willingness to pay (WTP) and to empirically test the moderating effect of external environmental cognition on the process by which consumer motivation affects WTP. The study showed that the average premium paid by consumers for GMR was 61.69%, the premium value calculated from premium ratio and conventional rice price was 3.27 ¥∙kg⁻¹, and the actual price consumers willing to pay for GMR was 8.57 ¥∙kg⁻¹. External environment cognition had the greatest influence on consumers’ WTP, and safety motivation and environmental motivation also had a significant positive influence on consumers’ WTP. Positive external environment cognition significantly improved consumers’ WTP by strengthening their safety and environmental motivation. In addition, young women with higher education level, children, and consumers with higher household income and pursuit of quality of life were more willing to pay a higher premium for GMR. Accordingly, this study had the following policy implications. First, a scientific pricing mechanism for green manure rice should be established as soon as possible to ensure improved returns for producers that are acceptable to consumers. Second, enhancing consumers’ cognition of the external environment is the key to encouraging them to pay a premium for GMR. The improvement of consumers’ comprehensive cognition of the external environment and the risks to the natural environment can enhance their perception of the value of GMR, thus increasing their WTP. Third, paying attention to consumers’ motivation contributes to a deeper understanding of the process and mechanism of premium payment behavior, which is conducive to shaping stable consumption preferences, thus improving the sustainability of consumers’ premium payments for GMR.

2022 Vol. 30, No. 11