中国生态农业学报(中英文)

Effects of agricultural landscape pattern on qualitative food web structure of corn pest-predatory natural enemies

BIAN Zhenxing, ZHANG Yufei, YANG Yibo, YU Miao

2020, 28(10): 1475-1487. doi: 10.13930/j.cnki.cjea.200021

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Abstract:
The homogenization of agricultural landscape caused by excessive agricultural intensification has been one of the main reasons for the reduction of farmland biodiversity. Research on the impact of the agricultural landscape pattern on the qualitative food web structure of pest-predatory natural enemies was conducted in Changtu County, Liaoning Province, where eight typical fields were sampled. Regression analysis and optimal model determined the relationship between food web parameters and landscape indexes. The results showed an insignificant correlation between food web interaction richness (IR) and landscape indexes. However, a significant positive multiple correlations between food web linkage density (LD) and contagion index (CONTAG, x₁) and aggregation index (AI, x₂) were observed. The corresponding optimal model was: LD=-64.621+0.780x₁+0.739x₂. The complexity of the qualitative food web structure of the corn pest-predatory natural enemies was dependent on the degree of concentration of the non-cultivated patches in the agricultural landscape. Furthermore, food web connectance (C) was significantly positively correlated with CONTAG, (x₁) and Shannon diversity index (SHDI, x₃), but was significantly negatively correlated with Shannon evenness index (SHEI, x₄). The corresponding optimal model was: C=-178.500+1.831x₁-106.808x₄; the more diverse the landscape types, the better the connectivity of the same patches; the more frequent the interaction between pests and predatory natural enemies, the more beneficial it is to maintain the complex food web structure. Food web generality (G) was significantly positively correlated with landscape shape index (LSI, x₅), cohesion index (COHESION, x₇), and AI (x₂); however, it was significantly negatively correlated with patch density (PD, x₆). The corresponding optimal model was: G=-2 994.798+26.891x₂+27.090x₅-0.491x₆+2.851x₇; the lower the degree of non-cultivated patch fragmentation, the stronger the search and aggregation behavior of natural enemies, which is beneficial and increases the stability of the food web structure. Food web vulnerability (V) was significantly positively correlated with the SHEI (x₄), but was significantly negatively correlated with CONTAG (x₁). The corresponding optimal model was: V=8.411+5.351x₄; the more evenly distributed patch types in the landscape, the higher the pest diversity and the increased complexity of the community structure. In general, the construction of the qualitative food web of corn pest-predatory natural enemies and the enhancement of anti-interference largely depends on the strength of the heterogeneity of the agricultural landscape. The use of field data in the construction of a food web matrix is a method that can be a powerful resource for studying ways to enhance the heterogeneity of agricultural landscapes.

Effects of agricultural landscape habitat types on spider community structure and the influencing factors in Taihang Mountain

CHEN Xi, ZHANG Xuzhu, JIN Chi, LI An, GAO Mengmeng, LU Tong, ZHANG Xiaohua, LI Liangtao

2020, 28(10): 1488-1498. doi: 10.13930/j.cnki.cjea.200173

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Abstract:
Ground-dwelling spiders were collected using pitfall traps from five different habitats (walnut grove, maize field, apple-peony intercropping orchard, secondary forest, and flower belt) to explore the effects of various habitats on the distribution of spiders in the agricultural landscape of Taihang, Wu'an City mountain area. The distribution of spider diversity and their correlation with the local habitat factors were analyzed. The results showed that walnut grove conserved significantly higher Shannon-Wiener diversity of spiders than the other four habitats. The spider richness was significantly higher in walnut grove, secondary forest, and flower belt than in apple-peony intercropping orchard and maize field; although, apple-peony intercropping orchard and flower belt significantly conserved spider abundance more than the other three habitats. A decrease in spider abundance was due to the field disturbance; however, the spider richness increased with increasing of vegetation complexity, while there was a negative correlation between spider abundance and the vegetation structure complexity. Moreover, the abundance of spiders increased with an increase in the understory litters. Understory litter was the most important factor which determined the spider composition; spider assemblage composition was homogeneous in maize fields, apple-peony intercropping orchard, and flower belts, whereas they were heterogeneous in walnut groves and natural forests. The results of this study indicated that walnut groves, apple-peony intercropping orchard, and intercropping flower with chestnut in the transition zone between agricultural landscape and natural landscape could contribute to spider conservation. Factors of different habitats had different relationships with different spider communities; for example, the Lycosidae prefers the apple-peony intercropping orchard and the flower belt with significant human interference. Therefore, the production management should combine the unique habitat conditions to conduct reasonable protection and efficient utilization of the corresponding spiders. Our results provide guidance for the management and biodiversity conservation of agricultural habitat in the study area.

Preliminary study on landscape design of ecological farms based on biodiversity and ecosystem service

GONG Cheng, LIU Yunhui, MAN Jiyong, QIAO Yuhui, LI Ji

2020, 28(10): 1499-1508. doi: 10.13930/j.cnki.cjea.200068

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With increasing demands for organic, environmentally friendly, and higher quality foods, ecological farms have flourished in China in recent years. Establishing ecological farms and meeting sustainable food production goals relies heavily on protecting biodiversity and harnessing biodiversity associated ecosystem services. We reviewed the demand and development of ecological farms, established the biodiversity implications, and assessed the relationships between landscape structure, biodiversity, and ecological services as well as the application of landscape design. We proposed general principles for ecological farms design and suggested three aspects to include relationship between farms and surrounding landscapes: designing planting system, protecting and reconstructing beneficial habitats. These principles were demonstrated as a case study on an ecological rice farm in southern China, where landscape ecology principles were applied to the design of off-farm habitats. Water purification and pest control were the primary ecosystem services. Therefore, a variety of plant strips were designed to support sustainable agriculture and enhance the biodiversity and ornamental value of the farm. To better integrate biodiversity and ecological farm construction, an in-depth understanding of the relationships between biodiversity and ecosystem services, agricultural production and income, and functional plants (that promote biodiversity) are required. Additionally, an ecological compensation policy to encourage biodiversity conservation in ecological farming should be considered. Our study provides general principles and empirical evidence for the integration of biodiversity and ecosystem services into ecological farm design, which promotes an ecological civilization.

Progress of research regarding the trade-offs of ecosystem services

DENG Chuxiong, ZHU Damei, NIE Xiaodong, LIU Changchang, LI Zhongwu, LIU Junyu, ZHANG Guangye, XIAO Linhui, ZHANG Yuting

2020, 28(10): 1509-1522. doi: 10.13930/j.cnki.cjea.200062

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The extreme intensification of human activities and global climate change have exerted immense pressure on the ecological environment. According to the Millennium Ecosystem Services Assessment, approximately 60% of ecosystem services are in decline globally. Therefore, to better maintain ecological health, promote human well-being, and achieve more sustainability in harmonizing environmental protection and socio-economic development, there remains an urgent need to summarize recent studies on the trade-offs of ecosystem services. In this study, based on the Web of Science Core Collection Database (WOS) and the Chinese Science Citation Database (CSCD), CiteSpace was used to determine the current situation and analyze the latest research on ecosystem services trade-offs by choosing different techniques to create a co-citation cluster view of the citations, a knowledge map of the co-occurrence of subject structure, and a key word emergence map. The results showed that: 1) the trade-offs between ecosystem services are affected by external risks and human needs at the ecosystem level, parameter selection and service providers at the landscape level, and regional differences and heterogeneity at the regional level. 2) Research methods mainly include three categories: trade-off analysis based on relationship recognition and concrete characterization, a module-based quantitative analysis of trade-off simulation and prediction, and multi-criterion analysis toward the optimization of ecosystem service trade-off management. 3) Urbanization, ecological engineering, and climate change are three key drivers of the trade-offs associated with ecosystem services. Most of the trade-offs between supply services, regulation, and support services are caused by urbanization. Ecological engineering improves ecosystem regulation and support services, but reduces supply services to some extent. Global climate change increases external risks while decreasing ecosystem service provision, regulation, and support functions. Based on this analysis, understanding the associated characteristics of ecosystem service trade-offs at various research levels, modifying and innovating study methods, identifying the major factors, and finally, integrating resources to build a data-sharing platform for ecosystem service trade-offs should be the focus of future research.

Climatic suitable area analysis and response to climate change of Actinidia arguta in China

ZHAO Jinpeng, WANG Yanli, LU Xingli, SHEN Zhanhong, WANG Mingtian, LI Qing, WANG Rulin

2020, 28(10): 1523-1532. doi: 10.13930/j.cnki.cjea.200244

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Actinidia arguta is suitable for growing in a cool and humid environment. Compared with other species, A. arguta has higher nutritional and medicinal value and is also resistant to diseases, pests, drought, and cold. Determining a climactically suitable area for A. arguta may provide a reference for its investigation, protection, development, utilization, and cultivation in China. The MaxEnt (maximum entropy model) and ArcGIS (geographic information system) were used to study the key environmental factors and value range affecting the distribution of A. arguta. Predictions for suitable areas were performed under current and future climate scenarios. Environmental factors were tested for significance (via Jackknife), correlations were determined (via Pearson correlation coefficient), and six key environmental factors affecting the distribution of A. arguta were found (listed in order of significance): precipitation in July > mean temperature in April > temperature seasonality > mean temperature in March > precipitation during the warmest quarter > altitude. Presently, the total highly-suitable area is 9.287×10⁵ km² and is concentrated in the east of Southwest China, the west of Central China, the southeast of North China, the north and southeast of East China, and the southeast of Northeast China. The total moderately suitable area, distributed around the highly suitable area, is 1.786×10⁶ km². Representative concentration pathways (RCP) (i.e., future climate scenarios) predicted that the highly suitable areas will increase (RCP2.6=3.758×10⁵ km², RCP4.5=1.725×10⁵ km², and RCP8.5=6.300×10³ km²), the moderately suitable areas will decrease in the RCP2.6 by 1.902×10⁵ km², while it will increase in the RCP4.5 and RCP8.7 (RCP4.5=2.617×10⁵ km², and RCP8.5=9.760×10⁴ km²). In the RCP2.6 and RCP4.5 scenarios, the geometric center of the highly suitable areas and the total suitable areas will move to the northeast by the 2070s. In the RCP8.5 scenario, the geometric center of the highly suitable areas will move to the northeast, but the geometric center of the total suitable area will move to the southeast by the 2070s. The MaxEnt model was used to predict suitable cultivation areas for A. arguta in the present day and future climate scenarios. All of the 'area under the curve' (AUC) averages were higher than 0.98, indicating high reliability of the predicted model results.

Thermal resource change dynamics for single-season rice in China under RCP scenarios

ZHANG Lei, LI Sen, GUO Anhong, WANG Chunzhi

2020, 28(10): 1533-1542. doi: 10.13930/j.cnki.cjea.200211

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Rice production is affected by current climate change, but future changes are rarely mentioned. A better understanding of the thermal resource dynamics of rice production is important for future optimization. Changes in the spatial-temporal dynamics of the thermal resources for future single-season rice was analyzed under two representative concentration pathways (i.e., RCP4.5 and RCP8.5), using the mean air temperature, accumulated temperature above 10 ℃, and temperature suitability as indices. The analysis was based on daily reproduction data from 20 global climate models at a high resolution of 0.25°×0.25°, which was downscaled by Bias Correction Spatial Disaggregation. The results indicated that the mean air temperature, accumulated temperature above 10 ℃, and temperature suitability differed spatially. During the baseline period from 1986-2005, a higher mean air temperature and accumulated temperature above 10 ℃ were detected in the Sichuan Basin, as well as in the middle and lower reaches of the Yangtze River. Relative to the baseline, the mean air temperature and accumulated temperature above 10 ℃ during the future periods (i.e., 2021-2040, 2041-2060, 2061-2080, and 2081-2100) under RCP4.5 and RCP8.5 increased by varying magnitudes in different regions (increment magnitudes under RCP8.5 were larger than RCP4.5). Increasing mean air temperature and accumulated temperature suggest that more thermal resources will be available for rice in the future, making it appropriate to replace the early-mid rice variety with the mid-late variety. However, increasing temperature is not always beneficial to rice growing. Temperature suitability based on the temperature requirements were implemented for different rice-growing periods. During the baseline years, the temperature suitability was greater than 0.95 in the Sichuan Basin, as well as in the middle and lower reaches of the Yangtze River, which was higher than the other regions (i.e., Northeast China, Ningxia, and the southern and southeastern regions of Southwest China). No obvious (or negative) temperature suitability trends were observed in the Sichuan Basin or the middle and lower reaches of the Yangtze River, but positive trends were observed in other regions. Under future period predictions, there was a decreasing temperature suitability trend in the Sichuan Basin and in the middle and lower reaches of the Yangtze River, with a tendency of -0.03 - 0·(10a)^-1 and -0.11- -0.03· (10a)^-1 under RCP4.5 and RCP8.5, respectively. This was attributed to more days in the future with maximum temperatures greater than 35 ℃ and implies that a significant increase in heat stress would threaten rice growing. Comparatively, temperature suitability in Northeast China, Ningxia, the southern and southeastern regions of Southwest China increased at a rate of 0.00-0.03·(10a)^-1 under RCP4.5, which was smaller than under RCP8.5. This, combined with increasing mean air temperature and accumulated temperature above 10 ℃, would benefit rice growing in these regions. Understanding the thermal characteristics can help to optimize rice production among regions in response to climate change.

Research progress on soil nitrogen internal cycling response to ecological cover change

YANG Lilin, YAO Qifu, LIANG Li, LU Xiaoming

2020, 28(10): 1543-1550. doi: 10.13930/j.cnki.cjea.190908

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Soil nitrogen (N) pool and its' cycles is directly related to crop growth, ecological environment security, and sustainable development. Soil N and carbon storage in natural ecosystems is relatively stable, with a low net mineralization and a closed or accumulative cycle. In order to meet the demand from the growing population for food production and living space, humans frequently modify natural ecosystems, resulting in changes to land use and ecological cover, which significantly change the soil active N content and N cycles, thereby affecting global climate change and the natural environment. In the face of threats from global warming, reduction of biodiversity, and ecological degradation, this paper reviewed the impact of soil active N on the environment, N storage, and N cycling process, including mineralization, nitrification, and fixation, caused by land use change. We considered the transformation, deforestation, afforestation, or reconstruction of ecosystems, as well as progress in research methods on microorganisms in the N cycle. Our review showed that agricultural reclamation or disturbance — the conversion of natural ecosystems into farmland or the abandonment of farmland that was originally forest or grassland — would lead to a significant decrease in total N, but an increase in the nitrate (NO₃^--N) content, which increases the risk of active N in the environment. Reforestation provides an alternative approach for the reconstruction of ecological cover, but full restoration of the N pool will take decades. It seems that the application of modern microbial molecular ecology is the key to research the response mechanism of the soil N cycle to ecological cover/land use change. The aim of this review was to provide a scientific basis for the protection and use of native ecosystems, the restoration and reconstruction of degraded ecosystems, scientific planning and policy-making for artificially disturbed ecosystems by understanding the effects of land use change on the soil N pool, coupled N cycling, and the soil microbial community structure.

Advances in research regarding the yield gap and resource use efficiency of winter wheat cultivation and the related regulatory approaches

WU Fen, XU Ping, GUO Haiqian, ZHANG Zhengbin

2020, 28(10): 1551-1567. doi: 10.13930/j.cnki.cjea.200180

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Reducing the gaps between actual yield and potential yield of crops is one of the current topics in crop science research, and is of great significance in ensuring food security. It is essential to explore the mechanisms underlying the gaps in grain yield and differences in resource utilization efficiency of winter wheat cultivation, to establish the strategies to reduce these gaps, and sustainably meet the requirements of increased total productivity of winter wheat worldwide. In this paper, the overall progress of research regarding the gaps in crop yield, differences in resource use efficiency, and the regulatory technology approaches at home and abroad are summarized first, and then placed in the context of winter wheat cultivation. The five major factors that lead to large gaps in yield and resource use efficiency differences in winter wheat are variety, climate, soil, human management technical factors, and farmers' decision-making. Finally, the following development directions to address these issues in China are proposed: a region-wise control approach based on cloud data analysis should be established; and research on yield gaps, resource use efficiency, and the regulatory approaches under various winter wheat rotation systems should be expanded. Technology approaches involving simplified models for different winter wheat production regions should be developed. Designing technological solutions to bridge the gaps in grain yield and resource use efficiency in winter wheat is inevitable means by which China can lead in the fields of precision agriculture, green agriculture, balanced agriculture, and high-yield and high-efficiency agriculture. The research progress discussed herein provides a theoretical basis and technical support for reducing these differences and enhancing the yield and efficiency of winter wheat in China.

Effect of sowing date and density on matter accumulation and translocation and on yield of chickpeas

HAO Xiyu, LIANG Jie, XIAO Huanyu, WANG Yingjie, GUO Wenyun, LIU Tingting, MA Xinfei

2020, 28(10): 1568-1580. doi: 10.13930/j.cnki.cjea.200115

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This study explores the effect of sowing date and density on matter accumulation and translocation and the yield formation of chickpeas. Determining the optimum sowing date and density for chickpeas planted in Northeast China will lay a foundation for promoting the cultivation of chickpeas and the development of the chickpea industry. Four sowing dates (March 29th, April 7th, April 16th and April 25th) and four sowing densities (16.7×10⁴ plants·hm^-2, 11.1×10⁴ plants·hm^-2, 8.3×10⁴ plants·hm^-2 and 6.7×10⁴ plants·hm^-2) were set during 2018 and 2019. 'Baiying 1' chickpea was as material, and the growth process, photosynthetic characteristics, population quality, carbon and nitrogen translocation, and yield formation of 'Baiying 1' chickpeas during different growth periods were determined through by measuring dry matter content, leaf area index, yield components, and the content of chlorophyll, soluble sugar, starch, and total nitrogen. The date of seedling, flowering, and maturity were delayed as the sowing date was delayed, the growth period was shortened, and pods per plant initially increased, and then decreased. With the growth of chickpeas, the chlorophyll content and leaf area index of different treatments first increased and then decreased. The dry matter accumulation in the vegetative organs of chickpeas planted early was lower than in those planted late. Therefore, later sowing increased the contribution of nitrogen amount accumulated post-anthesis to the grain nitrogen. Further, the dry matter accumulation of chickpeas planted with high density was lower than those planted with low density. Decreased density promoted increased translocation, rate of pre-anthesis assimilation, and nitrogen accumulated post-anthesis. The regression equation of sowing date (X₁), density (X₂), and yield (Y) was Y=-150.288 9+47.169 3X₁+ 464.092 5X₂-1.499 9X₁²-11.376 4X₂²+ 1.292 2X₁X₂. In summary, the dry matter accumulation of chickpeas planted with intermediate and late sowing dates was higher than those with intermediate and early sowing dates. With delayed sowing date, the soluble sugar accumulation and starch content in seeds decreased, and the redistribution amount and efficiency of nitrogen accumulated pre-anthesis stored in stems and leaves first increased and then decreased; however, the contribution of nitrogen accumulated post-anthesis to the grain nitrogent of chickpea increased. The effect of translocation on the yield of pre-anthesis of chickpeas planted with medium and low density was large, and the amount of nitrogen accumulated post-anthesis was high. Moreover, the effect of post-anthesis assimilate accumulation of chickpeas planted with medium and high density on yield was significant. The contribution of redistribution of nitrogen accumulated pre-anthesis to grain nitrogen of chickpeas planted with intermediate and early sowing dates with medium density or intermediate and late sowing dates with high density increased. Under the conditions of this experiment, the optimal cultivation of 'Baiying 1' occurred when sown on April 23th, with a density of 7.64×10⁴ plants·hm^-2. However, this could vary with differing local geographical, climatic, and other environmental factors.

Effects of straw returning and nitrogen application on yield and quality of hybrid indica rice under different rotation patterns

LIN Dan, LI Yu, SUN Yongjian, SHEN Jie, LYU Tengfei, SUN Zhibai, LYU Xu, LIU Fangyan, GUO Changchun, SUN Yuanyuan, YANG Zhiyuan, MA Jun

2020, 28(10): 1581-1590. doi: 10.13930/j.cnki.cjea.200236

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The effects of straw return and nitrogen fertilizer application on the quality and yield of indica rice were studied using the hybrid strain 'F you 498'. The multiple-straw rotation method was investigated using the straw return of three previous crops [vegetable-rice (G), rape-rice (R), and wheat-rice (W)]. Nitrogen fertilizer was optimized by testing different ratios [conventional application of pure nitrogen = 150 kg·hm^-2; base to tiller to panicle fertilizer ratios tested = 4:4:2 (N₁) and 3:3:4 (N₂)]. The results showed significant effects on the rice quality and yield in all of the straw return types and nitrogen fertilizer applications. Two factors had a large effect on the yield: the chalky grain rate and the grain protein content. The vegetable-straw yield (g) increased by 1.1%-7.8% compared to rape-straw (R), and by 10.5%-19.8% compared to wheat-straw (W). The vegetable-rice straw also improved the whole rice rate, reduced the chalky grain rate, and improved the food quality. Regardless of straw type, the yield increased after nitrogen fertilizer application, and the highest yield was obtained using the N₂ treatment. All straw types reduced the amount of nitrogen applied: N-G treatment by 16.7%, N-R treatment by 30.0%, and N-W treatment by 16.7%. Compared to the N₂ treatment, the yield decreased by 2.6% (N-G), 1.7% (N-R), and 5.8% (N-W). The rice yield was not significantly reduced when the N-G and N-R rotations were used, but the rice chalkiness rate and chalkiness degree were significantly reduced, and the quality improved. Therefore, rice quality was improved and yields were maintained, but nitrogen was saved. Based on the rice quality and yield when using the vegetable-rice straw rotation, the nitrogen fertilizer amount should be reduced to 125 kg·hm^-2, and a base to tiller to ear fertilizer ratio of 3:3:4 was the optimal combination in this study. When using the rape-rice and wheat-rice straw rotations, the nitrogen fertilizer amounts should be 105 kg·hm^-2 and 150 kg·hm^-2, respectively, and the fertilizer ratio remains 3:3:4. This study may provide a theoretical basis for improving the quality and yield of rice when using the straw return rotation method.

Effects of controlled-release and stable urea application on soil nitrogen transport and yields of winter wheat and summer maize

XIAO Qiang, LI Hongyan, YI Wenping, ZOU Guoyuan, WEI Dan, SUN Shiyou, LI Lixia

2020, 28(10): 1591-1599. doi: 10.13930/j.cnki.cjea.200117

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The combined application of controlled-release and stable urea can enhance the efficiency of nitrogen management. In the present study, a combination of polyurethane-coated controlled-release urea and inhibitor-coated urea were used to study the effect of nitrogen transformation in winter wheat and summer maize. The results will provide new ideas and technical means for the development of high-efficiency fertilizer and limited non-point source pollution. The study included six treatments: no nitrogen application (control), traditional nitrogen application [CV, 285 and 225 kg(N)·hm^-2 in wheat and maize, respectively], optimized nitrogen application [OPT, 199.50 and 157.50 kg(N)·hm^-2 in wheat and maize, respectively], controlled-release urea + traditional urea application (CRF1, 40% and 30% controlled released nitrogen for wheat and maize, respectively), controlled-release urea + inhibitor-coated urea (CRF2, 30% and 20% controlled released nitrogen for wheat and maize, respectively), and controlled-release urea + inhibitor-coated urea (CRF3, 50% and 30% controlled released nitrogen for wheat and maize, respectively). CRF1, CRF2 and CRF3 were all the optimized nitrogen application, which significantly reduced cumulative ammonia volatilization during the summer maize and winter wheat seasons by 24.90%-57.00% and 10.20%-27.80%, respectively, compared with OPT treatment. At the same nitrogen application rate, the cumulative ammonia volatilization of CRF2 and CRF3 treatments were significantly lower than that of CRF1 treatment by 33.30%-42.80% and 12.20%-19.60% during the summer maize and winter wheat seasons, respectively. After fertilization, the rate of soil nitrate increase or decrease was greatest in CV treatment, followed by OPT, CRF1, CRF2, and CRF3 treatments. During the summer maize harvest period, the risk of residual nitrate leaching was highest in CV treatment, followed by OPT, CRF1, CRF2, and CRF3 treatments; whereas during the winter wheat season, leaching rate decreased as follows: CV, OPT, CRF2, CRF1, and CRF3. The yields of both winter wheat and summer maize under CRF1, CRF2, or CRF3 treatments were not significantly different from those of CV or OPT treatments. However, the net incomes of CRF2 and CRF3 treatments were 639 ￥·hm^-2 and 859 ￥·hm^-2 greater than that of CRF1 treatment during the summer maize season, whereas they were 1 196 ￥·hm^-2 less and 61 ￥·hm^-2 greater than that of CRF1 treatment during the winter wheat season. The favorable ratios of controlled-release nitrogen to stable nitrogen were 5:5 and 3:7 for winter wheat and summer maize, respectively, in the study area.

Effects of biochar and arbuscular mycorrhizal fungi on the growth of continuous cropping pepper and soil nutrient status

WANG Yan, ZHOU Peng, BAI Liwei, WU Kangyun, XING Dan, GUO Tao, ZHANG Chengming

2020, 28(10): 1600-1608. doi: 10.13930/j.cnki.cjea.200196

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In this study, a pot experiment was conducted to investigate the synergistic effects of biochar and arbuscular mycorrhizal (AM) fungi on the alleviation of the continuous cropping obstacles of pepper, improve soil nutrient status, and further provide theoretical foundations for continuous cropping soil improvement and new fertilizer development. A total of eight treatments were set as growth conditions of pepper consisting of four biochar addition levels (0, 1%, 2%, and 3%) with or without AM fungal inoculations (+AM and -AM), each treatment was replicated four times. Peppers were harvested after 60 days, and the physiological index, soil enzyme activity, and soil nutrient content were analyzed. Results showed that the biochar+AM treatments significantly promoted the growth of successive cropping pepper and increased the net photosynthetic rate (P_n), transpiration rate (T_r), stomata conductance (G_s), and chlorophyll content in pepper leaves. The treatments of only AM fungi inoculation also showed an increase in the growth and yield of peppers; however, biochar+AM had the best combined treatment effect. The effect of only AM fungal inoculation on P absorption in pepper plants and fruits showed a better result compared with that of only biochar, while the effect was opposite on K absorption. Moreover, the contents of N, P, and K in the root of pepper treated with 3% biochar+AM fungi increased by 74.04%, 106.42%, and 78.82%, compared with 0 biochar without AM fungi (control), respectively. The mycorrhizal infection rate under the treatment of 3% biochar+AM was 58.96%, which was 41.59% higher than that of the control. Soil pH and activities of urease and sucrase increased with an increase in biochar application; although, there was no significant difference in pH. AM inoculation showed not significant effects on soil enzyme activity. In addition, the available contents of K, P, and organic matter in the soil also increased with an increase in biochar application. The most significant improvement was achieved under the 3% biochar+AM treatment, while the treatment of only AM fungal inoculation showed no marked effect on these indexes. In conclusion, biochar, especially the treatment of 3% biochar+AM, had a significant synergistic effect on the growth and soil nutrient improvement of the continuous cropping pepper.

Effect of brackish water irrigation on the resistibility of winter wheat leaf to dry-hot wind

ZHAO Fenghua, ZHU Kangying, LONG Buju, TIAN Zhenrong, LAI Jianbin, SUN Zhigang

2020, 28(10): 1609-1617. doi: 10.13930/j.cnki.cjea.200077

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Brackish water irrigation was carried out in the North China Plain to alleviate the shortage of irrigation water resources. Dry-hot wind is one of the main meteorological disasters for winter wheat in the region; the effect of brackish water irrigation on the ability of winter wheat to resist dry-hot wind is yet inconclusive. Therefore, we conducted field experiments on winter wheat at the Yucheng Comprehensive Experimental Station of the Chinese Academy of Sciences. Brackish water irrigation with three salinity levels of 1 g·L^-1, 3 g·L^-1, and 5 g·L^-1 was set up, and the dry-hot wind simulation was conducted in the filling period. In this study, physiological parameters of winter wheat, such as photosynthetic rate, transpiration rate, and stomatal conductance of winter wheat were observed. The analysis of the experimental data during four consecutive years (2016-2019), showed the following results: 1) the brackish water with the salinities of 3 g·L^-1 and 5 g·L^-1 could reduce the photosynthetic rate of winter wheat leaves by 32.2% and 59.3%, the transpiration rate by 29.2% and 51.9%, and the stomatal conductance by 30.7% and 54.8% (P < 0.05), respectively. 2) Dry-hot wind could reduce the photosynthetic rate by 35.4%-86.6%, the transpiration rate by 35.6%-67.5%, and the stomatal conductance by 36.4%-69.4%, respectively. The irrigation with the salinity levels of 1 g·L^-1, 3 g·L^-1, and 5 g·L^-1 decreased the four-year average dry-hot wind stress index of the photosynthetic rate of winter wheat leaves from 0.55 to 0.45 and then increased to 0.74, while the leaf transpiration rate (the difference in the saturation of water vapor pressure) decreased from 0.54 to 0.26, then increased to 0.41; the four-year average dry-hot wind stress index of the stomatal conductance decreased from 0.56 to 0.28, then increased to 0.43. The above results showed that the physiological stress of brackish water irrigation on photosynthesis, transpiration, and stomatal behavior was similar to that of dry-hot wind, and the brackish salinity water (3 g·L^-1) irrigation could improve the physiological adaptability of winter wheat leaves to dry-hot wind, reducing the damage caused by dry-hot wind.

The bacterial community structure and function of Suaeda salsa rhizosphere soil

SUN Jianping, LIU Yahui, ZUO Yongmei, HAN Minli, ZHANG Hongwei, LYU Jingjing

2020, 28(10): 1618-1629. doi: 10.13930/j.cnki.cjea.200160

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Abstract:
Suaeda salsa is an ideal agent for the biological enrichment of saline-alkali soil. Microorganisms in the rhizosphere of this plant play an essential role in soil improvement. The Illumina Misep high-throughput sequencing platform was used to explore the structural composition and function of the bacterial community in the rhizosphere soil of S. salsa and bare soil from coastal saline-alkali land in the Bohai Bay Rim area of Hebei, Shandong, and Tianjin, China. In total, 734 792 effective sequences were obtained from 16 samples, of which 4 285 OUTs belonged to 41 phyla, 100 classes, 282 orders, 400 families, 892 genera, and 1 577 species. The bacterial community in the rhizosphere soil of S. salsa contained Proteobacteria, Actinobacteria, Chloroflexi, Bacteroidetes, Gemmatimonadetes, Acidobacteria, Firmicutes, Cyanobacteria, Patescibacteria, and Planctomycetes. These results were consistent with the Alpha diversity analysis results, indicating that the community was highly diversified and significantly different from that of the bare soil. The LEfSe (LDA Effect Size) analysis showed that indicator species differentially occurred in S. salsa and bare soils. In S. salsa soil, Cyanobacteria, Acidobacteria, Alphaproteobacteria, Oxyphotobacteria, Chloroflexi, Rhizobiales, Nostocales, Sphingomonadales, Sphingomonadaceae, and Bacillus were the indicator species. Based on principal coordinates analyses and a correlation heatmap, the main factors affecting the soil bacterial community at order level were the presence of S. salsa, alkali-hydrolyzable nitrogen, available potassium, available phosphorus, and electrical conductivity. Also, Ectothiorhodospira and Balneolaceae could survive in bare soil with poor fertility, high salinity, and a viscous structure. PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) analysis showed that 304 metabolic pathways at pathway level 3 were active in both soil, of which 41 pathways, especially those involving in metabolism were different between S. salsa soil and bare land soil. These results indicated that S. salsa growth has a positive effect on the diversity and function of soil bacterial community by improving soil structure and increasing nutrients levels. These findings may be applied to improve saline-alkali land, optimize soil environment, and enhance its usefulness and sustainability.

Prediction model and threshold of soil cadmium contamination in cucumber greenhouses

XU Rui, CAO Shi, LIU Meng, ZHANG Hui, LIU Yuehan, LYU Shi, DUAN Yajun, ZHANG Yukun, YANG Zhixin

2020, 28(10): 1630-1636. doi: 10.13930/j.cnki.cjea.200178

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Abstract:
The accumulation of heavy metals in soil is difficult to reverse, and this threatens China's agricultural safety. Nevertheless, the current implementation of heavy metal standards involves determining the risk screening value based on the pollutant items and pH value. However, there is a risk of contamination in edible agricultural products, which cannot meet quality and safety standards. In order to guide the selection of suitable crops for different soil types to avoid the risk of cadmium (Cd) pollution and to fully utilize land under the premise of safe production, thresholds for Cd pollution of different crops in different soil types need to be developed urgently. A Cd pollution micro-plot experiment with cucumber as the research object was conducted for two consecutive years to establish a prediction model and threshold of Cd pollution in greenhouse soils. The results showed that the total Cd and available Cd in greenhouse cucumber soil exhibited significant linear, logarithmic, power functions, and exponential relationships with the Cd content in cucumbers. The total Cd content showed the highest correlation coefficient according to the exponential model, while the available Cd content had the highest correlation coefficient according to the linear model. On the basis of soil conditions with pH≥7.5 and loamy texture, the risk thresholds for total Cd and available Cd in facility cucumber soils were proposed to be 2.13 mg·kg^-1 and 0.26 mg·kg^-1, respectively, based on extremely significant correlation models and national food hygiene standards. The proposed threshold was further verified by the soil urease activity; thereby, it was concluded that soil Cd contents less than or equal to 2.13 mg·kg^-1 had no significant effect on soil urease. Hence, the determined thresholds are feasible after soil urease verification. When the Cd content in the soil is greater than 0.8 mg·kg^-1 and less than or equal to 2.13 mg·kg^-1 (soil pH≥7.5), cucumbers can be recommended to replace other risk crops to meet the quality and safety requirements of edible agricultural products. The results of this study provide a scientific and theoretical basis for cucumber planting in the Cd-contaminated soil area of northern China, and thus hold practical significance. In this study, referring to the large body of existing research on the threshold value of vegetable soil Cd, the threshold value of soil Cd obtained by the soil sensitive soil index of urease activity and by constructing a cucumber soil Cd mathematical model are mutually confirmed, and a safe and reasonable threshold value of soil Cd under the experimental conditions is obtained.

Land use change with topographic gradients in the Yuci District rapid urbanization area

CHEN Xuexiong, ZHANG Xiaojun, HAN Weihong

2020, 28(10): 1637-1648. doi: 10.13930/j.cnki.cjea.200224

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Abstract:
The influence of topographic factors on land use change is significant for land use and cover change research. In order to explore the characteristics of land use change with different topographic gradients, in this study, ASTER GDEM data and remote sensing data of Yuci District in 2000, 2008, and 2016 were used to analyze the spatio-temporal characteristics of land use change from 2000 to 2016. The distribution characteristics and varying development of each land use type with aspect gradient, slope change rate, landform relief, and terrain niche were analyzed. The results showed the following: 1) from 2000 to 2016, construction land expanded primarily to the northwest and was mainly distributed in areas with a landform relief less than 30 m, a slope change rate less than 2°, a sunny slope or semi-sunny slope, and a terrain niche grade area of 1-3. The land uses of Yuci District were mainly construction, crop land, and unused land, which accounted for more than 93% of the research area. The crop land area is the largest, accounting for an average 46.91% of total land area in 2000, 2008, and 2016. The land use change was characterized by a decrease in unused land area and an increase in crop and construction land areas. The construction land area increased by 43.07 km², while the unused land area decreased by 37.33 km² from 2000 to 2008. However, from 2008 to 2016, the unused land area decreased by 221.00 km², while the crop and construction land areas increased by 170.61 km² and 37.36 km², respectively. 2) Construction land, crop land, and water were mainly distributed on low gradients of landform relief, slope change rate, and terrain niche. Conversely, forest land and unused land were mainly distributed on middle and high gradients of the three topographic factors. The construction land and crop land was predominantly distributed on flat land, with sunny or semi-sunny slopes, while forest land was predominantly distributed along shady and semi-shady slopes. The distribution of unused land was predominantly along sunny and semi-sunny slopes. From 2000 to 2016, the main distribution area of crop land gradually expanded to areas with a landform relief greater than 30 m, a slope change rate of 2°-15°, and a terrain niche of 4-7 grade area. There were evident differences in the topographic gradient of land use change as a result of topographic factors, human activity, policy factors, transportation, and location. Therefore, this study provides a scientific basis for rational planning and utilization of land in the process of regional urbanization and decision support for ecological environment management.

2020 Vol. 28, No. 10