中国生态农业学报(中英文)

A high-resolution ammonia emission inventory for cropland and livestock production in China

WANG Chen, ZHANG Xiuming, DUAN Jiakun, ZHAO Zhanqing, TI Chaopu, WANG Guishi, ZHOU Feng, ZHANG Lin, LIU Hongbin, DONG Hongmin, ZHU Zhiping, GU Baojing

2021, 29(12): 1973-1980. doi: 10.12357/cjea.20210298

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Abstract:
Ammonia (NH₃) volatilization has negative impacts on ecosystem and human health and NH₃ emission from cropland and livestock accounts for approximately 90% of the total NH₃ emission, which also indicates nitrogen fertilizer loss and brings economic burden to farmers. We presented the main contents of topic 4 ‘Research on Ammonia Emission Inventory Compilation and Reduction Assessment for Cropland and Livestock Production’ in National Key Research and Development Program ‘High Efficiency Control Technology for Ammonia Emission Pollution from Cropland and Livestock Production’ and mainly focused on the latest progress of dynamic high-resolution ammonia emission inventory for cropland and livestock. This project developed the basic characteristic parameters and agricultural activity data set of both cropland and livestock production, then compiled the 1 km-resolution cropland nitrogen fertilizer and livestock NH₃ emission inventory of 2853 cities at county level in 2017. The NH₃ emission of cropland nitrogen fertilizer in China was 3.6 Tg of which the emission intensity in South China was higher than that in the North China. The total NH₃ emission inventory of livestock was 5.0 Tg of which the NH₃ emission in housing and manure spreading stage was higher. The North China Plain and Guangdong are the main emission hotspots and the emission peak was concentrated in spring and early summer. The GEOS-Chem atmospheric chemistry model was used to evaluate the air quality changes caused by various emission reduction scenarios, to guide the emission reduction strategies in demonstration area as well as provide information to localized emission characteristics and the fine management of agriculture in different regions.

Ammonia emission patterns of typical planting systems in the middle and lower reaches of the Yangtze River and key technologies for ammonia emission reduction

XIA Yongqiu, WANG Shenqiang, SUN Pengfei, CHEN Xiaoqin, SHEN Jianlin, WANG Hua, XIAO Zhihua, LI Xiaoming, YANG Guang, YAN Xiaoyuan

2021, 29(12): 1981-1989. doi: 10.12357/cjea.20210247

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Abstract:
Rice, vegetables, and fruit fields in the middle and lower reaches of the Yangtze River are the main sites of ammonia volatilization in the planting system of China. Therefore, there is an urgent need to understand the characteristics and key control technologies of ammonia emissions in the middle and lower reaches of the Yangtze River. This paper systematically reviewed the major progresses of the National Key Research and Development Project of the National 13^th Five-Year Plan: “Research and Development of Key Technologies for Efficient Ammonia Control and Emission Reduction in Planting System in the Middle and Lower Reaches of the Yangtze River,” and foreseen the research focus during the 14^th Five-Year period. The main research results included the followings: 1) The ammonia emission coefficient and characteristics of typical rice, and vegetables and fruit trees fields were identified, indicating that the paddy field had the largest ammonia emission coefficient and variation, averaging 14.2%, followed by open-air vegetables (averaging 11.2%), and fruit fields (averaging 4.76%). 2) After verifying the whole process of ammonia emission reduction, “reduction, retrain, control, and immobilization”, we put forward technologies such as optimized nitrogen reduction technology in paddy fields, deep fertilizer applications for ammonia emission control technology in paddy fields, ammonia emission immobilization by periphyton technology in paddy fields, deep application of large-size granular fertilizer for fruit trees, and slow-release fertilizer for open-air vegetables. With these technologies, we achieved the goals of reducing ammonia volatilization. During the 14^th Five-Year Plan period, the long-term in-situ monitoring and simulation of ammonia volatilization should be strengthened, ammonia emission reduction technologies should be evaluated environmentally and economically, and simple and low-cost ammonia volatilization emission reduction technology should be developed.

Comparison of two monitoring methods for ammonia volatilization based on rice-wheat rotation system

WANG Yuan, MIN Ju, SHI Peihua, MA Mingkun, HAO Yaqiong, SHI Weiming

2021, 29(12): 1990-2001. doi: 10.13930/j.cnki.cjea.210210

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Abstract:
Ammonia volatilization is an important pathway of active nitrogen (N) loss from farmlands. The accurate and effective measurement of farmland ammonia emissions is the basis for environmental assessments and policymaking. Soil ammonia volatilization is controlled by fertilizer application rates, fertilizer application methods, soil properties, and meteorological conditions, so there is a wide variability in the cumulative ammonia emissions and emission factors in different studies. There are also different methods for ammonia volatilization measurements, which further reduce the comparability of data across studies. The most widely used methods for soil ammonia volatilization measurements in China are the ventilated sponge absorption method and the intermittent airflow enclosure method. However, consistency between measurements is unclear because of substantial differences in the ventilation rates between methods, and only a few studies have compared the two methods. Based on a typical rice-wheat rotation system in the Lower Reaches of the Yangtze River, this study set up treatments with different N fertilizer application rates (N0: no N fertilizer; N1: 200 kg(N)·hm⁻² for rice and 180 kg(N)·hm⁻² for wheat; N2: 300 kg(N)·hm⁻² for rice and 270 kg(N)·hm⁻² for wheat; and N3: 400 kg(N)·hm⁻² for rice and 360 kg(N)·hm⁻² for wheat). Soil ammonia volatilization was measured continuously after fertilization during rice and wheat growth using the ventilated sponge absorption and intermittent airflow enclosure methods, and the ammonia emission factors in the study area were analyzed using literature analysis. The results showed that the cumulative ammonia emission measured by the ventilated sponge absorption method was 25%–35% lower than that measured by the intermittent airflow enclosure method under the three N application treatments (except for the N0 treatment), and the results were consistent for both rice and wheat seasons. Under fertilization treatments (N1, N2 and N3), the cumulative ammonia emissions measured by the ventilated sponge absorption method ranged from 17.36 to 43.90 kg·hm⁻² in the rice season and from 5.90 to 20.43 kg·hm⁻² in the wheat season, with emission factors ranging from 2.56% to 10.39%. The cumulative ammonia emissions measured by the intermittent airflow enclosure method ranged from 23.28 to 61.05 kg·hm⁻² in the rice season and from 14.63 to 27.73 kg·hm⁻² in the wheat season, with emission factors ranging from 7.09% to 15.01%. The cumulative ammonia emissions under the N0 treatment were higher for the ventilated sponge absorption method than for the intermittent airflow enclosure method, and the measurements of the two methods were significantly different in the rice season but not in the wheat season. The results of the literatures analysis in the study area were consistent with the monitoring results. The cumulative ammonia emissions measured by the ventilated sponge absorption method were higher than those measured by the intermittent airflow enclosure method when the N application rate was between 0 and 100 kg·hm⁻², with average emission factors of 6.18% and 12.31%, respectively. When the N application rate was between 101 and 200 kg·hm⁻², the ventilation sponge absorption method led to 25% lower emissions than the intermittent airflow enclosure method, with average emission factors of 9.46% and 12.61%, respectively. When the N application rate was between 201 and 300 kg·hm⁻², the ventilation sponge absorption method led to 5% lower emissions than the intermittent airflow enclosure method, and the average emission factors were 12.71% and 13.43%, respectively. In general, the cumulative ammonia emissions measured by the two methods were consistent; the ventilated sponge absorption method led to higher measured values than the intermittent airflow enclosure method in fields without N application or with low ammonia volatilization rates, and the ventilated sponge absorption method led to lower measurements than the intermittent airflow enclosure method in fields with N application. The measurements of the two methods can be converted using a ratio. The results of this study provide support for the estimation of regional ammonia emissions using the ventilated sponge absorption and intermittent airflow enclosure methods.

The effects of nitrogen fertilizer deep placement on the ammonia volatilization from paddy fields in the Taihu Lake region of China

WANG Shuwei, LIN Jinghui, WU Zhenggui, CHEN Ji, PAN Yunjun, SHENG Xuewen

2021, 29(12): 2002-2012. doi: 10.13930/j.cnki.cjea.210119

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Abstract:
.Ammonia (NH₃) volatilization is an important nitrogen (N) loss pathway in paddy fields. However, the effects of N fertilizer deep placement, slow-release N fertilizers, and urea inhibitors on NH₃ volatilization reduction during the entire rice-growing season remain uncertain. To fill this knowledge gap, we conducted a field experiment with seven treatments: (1) no N application, (2) local broadcasting application of urea at a rate of 300 kg(N)∙hm⁻² (SN300), (3) 10% reduction of N from SN300 (SN270), (4) deep placement of basal urea together with the broadcasting of topdressing of urea at tiller and panicle stages of rice, at a total a rate of 270 kg(N)∙hm⁻² (DN270), (5) application of urea inhibitor for DN270 (DN270+UI), (6) 10% nitrogen reduction, deep application of basal urea together with the surface application of slow-release N fertilizer (DN270+SR), and (7) application of urease inhibitors for DN270+SR (DN270+SR+UI). Compared with the SN300 treatment, deep placement of basal N fertilizer reduced the cumulative NH₃ emissions by 78.2%−85.2% in the basal fertilization period. The combined application of the urease inhibitors in the rice topdressing periods (DN270+UI treatment) reduced the NH₃ emissions by 30.4% at the tillering stage and 25.3% at the panicle stage in comparison with the SN300 treatment. Replacing urea with a slow-release N fertilizer (DN270+SR treatment) in the rice topdressing periods reduced NH₃ volatilization by 36.4% at the tillering stage and 28.1% at the panicle stage. The cumulative NH₃ volatilization changed in the following order: SN300 > SN270 > DN270 > DN270+UI > DN270+SR > DN270+SR+UI. Compared to the local treatment (SN300), DN270+SR+UI significantly reduced NH₃ volatilization by 50.9%. There was no significant difference in rice yield among the N fertilizer treatments. NH₃ emission intensity per unit rice yield was lowest for the DN270+SR+UI treatment, 52.5% lower than the SN300 treatment. Overall, simultaneous N fertilizer deep placement with slow-release N and urease inhibitors produced more grains with lower environmental costs associated with NH₃ emissions. This represents a promising and sustainable management strategy for paddy fields in the Taihu Lake region of China.

Effects of different water and nitrogen management on ammonia volatilization in pear orchard soil

XING Hanbing, DONG Wenxu, PANG Guibin, HU Chunsheng

2021, 29(12): 2013-2023. doi: 10.13930/j.cnki.cjea.210133

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Abstract:
Conventional pear tree fertilization and management results in fertilizer waste, environmental contamination and other problems. The long-term goal of farmland managers is to use soil water and fertilizers efficiently to improve crop yield. In this study, the dynamic box method was used to analyze changes in the soil ammonia volatilization rate, loss, and the physical and chemical properties under different water and nitrogen management regimes in the pear topdressing period in the orchard demonstration base of Jinzhou City, Hebei Province, from March to September 2019. The experiment had five treatments: blank (CK, no fertilization with conventional irrigation), compound fertilizer broadcasting and conventional irrigation (BW1), rhizosphere injection (20 cm deep) of liquid fertilizer and conventional irrigation (IW1), compound fertilzer broadcasting and 70% conventional irrigation (BW2), rhizosphere (20 cm deep) injection of liquid fertilizer and 70% conventional irrigation (IW2). The volatilization of ammonia in each treatment was the most severe in the first four days after fertilization. Two treatments of compound fertilizer broadcasting (BW1 and BW2) were especially severe, the peak variation range was 1.5−7.5 kg·hm⁻²·d⁻¹. Two treatments of rhizosphere injection of liquid fertilizer (IW1 and IW2) steadily changed with time, the peak range was 0.1−5.0 kg·hm⁻²·d⁻¹. The volatile loss of ammonia in the BW1, IW1, BW2, and IW2 treatments was 24.05 kg·hm⁻², 8.43 kg·hm⁻², 31.94 kg·hm⁻², and 14.06 kg·hm⁻², respectively; compared with BW1 (traditional management), the emission reduction rates of rhizosphere injection of liquid fertilizer (IW1 and IW2) was 64.95% and 41.54%, respectively. Ammonia volatilization was significantly affected by the irrigation amount, and rhizosphere injection fertilization significantly reduced ammonia volatilization emission and was less affected by the irrigation amount. Correlation analysis showed that ammonia volatilization was positively correlated with the soil ammonium nitrogen content and pH, but negatively correlated with the soil nitrate nitrogen content. The correlation between ammonium nitrogen and nitrate nitrogen was highly significant (P<0.01). Soil moisture was positively correlated with ammonium nitrogen content (P<0.01). Compared with traditional management methods, the combination of rhizosphere injection fertilization and water-saving irrigation is an effective way to reduce nitrogen loss in orchards.

Combined return of rice straw and organic fertilizer to yellow-mud paddy soil to improve the rice productivity and substitute chemical fertilizers

WANG Fei, LI Qinghua, HE Chunmei, LIU Cailing, YOU Yanling, HUANG Yibin

2021, 29(12): 2024-2033. doi: 10.12357/cjea.20210267

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Abstract:
Crop straw and livestock manure, the main components of organic fertilizer resources, play important roles in the improvement of soil fertility and reduction of chemical fertilizer. To provide a basis for improving the soil fertility, crop yield and benefits of rice in a southern hilly area, various amounts of combined rice straw and organic fertilizer were returned to yellow-mud paddy soils under uniform total N input conditions and the effects on the rice production capacity, chemical fertilizer substitution, and plant nutrient uptake were studied. The field experiment was conducted in a yellow-mud paddy field in Minqin County, Fujian Province over four consecutive years. The experiment involved six treatments with uniform total N input but varying percentages of replacing N from a mix of rice straw and organic fertilizer (RO); that was, 0 (RO0, CK), 20% (RO20), 40% (RO40), 60% (RO60), 80% (RO80), and 100% (RO100) of N input. The dry amounts of rice straw applied in treatments of RO20, RO40, RO60, RO80, and RO100 were 750 kg∙hm⁻², 1500 kg∙hm⁻², 2250 kg∙hm⁻², 3000 kg∙hm⁻², and 3750 kg∙hm⁻², respectively; and the shortage of N was supplied by organic ferilizer. The variations in rice yield, nutrient uptake, and soil fertility factors were analyzed. As a result, the 4-year average yield of rice grains of RO20, RO40, RO60, and RO80 treatments significantly increased by 8.4%–13.9% relative to the yield of CK (P<0.05). However, the increasement of yield tended to decline with the increased application rates of organic materials, as the rice yield of RO100 was comparable to that of CK. Among the yield components, the effective spike significantincreased by RO treatments. The benefits of rice of RO20 and RO40 treatments were 2204 ¥∙hm⁻² and 527 ¥∙hm⁻² higher than that of CK, respectively. The uptake of N, P and K by rice plants under various RO treatments significantly increased by 8.5%−14.9%, 8.5%−14.8% and 8.6%−16.9%, respectively, compared with CK, except for RO100 treatment. The recovery rate change of N in all RO treatments increased by 6.5−11.4 percentage points, with the differences between RO20 and RO80 or RO100 were statistically significant (P<0.05). Although the contents of Ca, Mg and Zn in rice grains increased, the content of Fe decreased following the return of organic materials. The RO treatments increased soil pH and the contents of organic matter, total N, available P, available K, microbial biomass C, microbial biomass N and urease activity; but decreased the soil bulk density. In conclusion, the combined return of rice straw and organic fertilizer to yellow-mud paddy soil for 4 consecutive years improved rice productivity and fertilizer uptake. In this study, the combination of organic materials can completely replace the chemical fertilizers. Based on the rice yield, reduction of chemical fertilizer use, and improvement of farmer earnings and soil fertility, RO20 treatment was considered as the best fertilization regime, followed by RO40 treatment.

The effects and mechanism of climate change on vegetables quality: a review

ZHANG Lu, ZHANG Wei, CHEN Xinping

2021, 29(12): 2034-2045. doi: 10.12357/cjea.20210327

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Vegetables are an important source of essential vitamins and mineral elements and provide phytochemicals that play an important role in human health. Increases in global carbon dioxide (CO₂) concentrations and temperature have changed the growth conditions of vegetables. However, the mechanism by which climate change affects vegetable quality is not fully understood. In this paper, the effects of climate change factors, such as CO₂, temperature, and their interactions, as well as their interaction with water and nitrogen (non-climatic factors) on vegetable quality, are briefly reviewed. At present, researches in this field mainly use artificial simulation experiments and crop growth simulation models. Under elevated CO₂ concentrations, the contents of proteins, nitrate, magnesium, iron, and zinc in vegetables decrease, and the antioxidant capacity increases for leafy vegetables and decreases for fruit vegetables. The contents of carbohydrates, vitamins, and phytochemicals (e.g., total glucosinolates, lycopene, and beta-carotene) increase with elevated CO₂. The physiological process may explain why elevated CO₂ levels affect vegetable quality. 1) Elevated CO₂ concentrations promote photosynthesis and thus provide more carbon, increasing the soluble sugar content. 2) Elevated CO₂ enhances the activity of nitrate reductase (NR) and related gene expression, and the increase in carbohydrate content can further promote the transcription and post-translational regulation of NR, which increases nitrate assimilation and reduces nitrate content. 3) Elevated CO₂ also induces the expression of genes involved in ascorbic acid biosynthesis and regeneration, leading to the accumulation of ascorbic acid. 4) The dilution effect, change in nitrogen distribution, decrease in stomatal conductance, respiration, and Rubisco synthesis, and increase in nutrient utilization and root exudates may lead to decreased mineral elements in vegetables under elevated CO₂. Global warming generally decreases vegetable quality. Heat stress restricts photosynthesis by affecting electron transport in photosystem Ⅱ during photosynthesis and the activity of Rubisco in the Calvin cycle dark reaction, affecting vegetable quality. The interaction between elevated CO₂ concentration and increased temperature results in an overall decline in vegetable quality. Reducing irrigation and using a moderate nitrogen supply could improve vegetable quality under elevated CO₂ concentrations. Future vegetable production requires the application of an interdisciplinary and integrated approach that combines physiology and genomics to study the responses of vegetables to climate change.

Quantification planting density based on heat resource for enhancing grain yield and heat utilization efficiency of grain mechanical harvesting maize

YU Shengnan, GAO Julin, MING Bo, WANG Zhen, ZHANG Baolin, YU Xiaofang, SUN Jiying, LIANG Hongwei, WANG Zhigang

2021, 29(12): 2046-2060. doi: 10.12357/cjea.20210231

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The selection and promotion of mechanical grain harvesting maize varieties that shorten the maturity period in exchange for sufficient dehydration time pose new challenges for increase in the yield of spring maize in the north and the full utilization of heat. The use of a synergistic mechanism can provide a theoretical basis for the high-yield and high-efficiency cultivation and large-scale promotion of mechanically grain-harvested varieties of maize. In this study, different types of maize varieties were used as the tested materials, and the density network tests were conducted in four ecological regions of Inner Mongolia with different thermal conditions in eastern Inner Mongolia, which belonged to heat limit area (where medium-early- and early-maturing maize varieties are planted) and heat sufficient area (where the medium-later- or late-maturing varieties are planted), respectively. The effects of planting density on stage development, yield formation, and heat use efficiency (HUE) of different types of maize varieties were analyzed, and their responses to heat resources were analyzed. The results showed that the maximum yield of mechanical grain-harvesting varieties was obtained under the condition that the accumulated temperature utilization rate of ≥10 ℃ reached 86.0%−89.3%. The maximum yield and corresponding density of mechanical grain-harvesting varieties in different regions were higher than those of the current farmers’ variety, especially the differences were obvious in the regions with limited heat. The density of the maximum yield of mechanical grain-harvesting varieties decreased linearly with the increase of the total amount of heat resources. The density increased by 1700 plants·hm⁻² for every 100 ℃ decrease of accumulated temperature in the region ≥10 ℃. The areas with limited heat (ecological areas dominated by early-maturing and medium-early-maturing varieties, in this paper, it is east region of Xing’an Mountain and south region of Xing’an Mountain), the proportion of growing days per-silking and post-silking, the proportion of accumulated temperature ≥10 ℃, and the proportion of biomass of mechanical grain-harvesting varieties all approached 5∶5. To achieve the maximum yield, it was necessary to increase the densification from 60 000 plants·hm⁻² to 88 000−91 000 plants·hm⁻². Increases the density after increasing yield of 11.1−12.7 t·hm⁻², yield increase 20.1%−23.3%, and HUE can be increased by 20.6%−30.1%; In areas with abundant heat (ecological areas mainly planted with mid-late maturity or late maturity varieties, this paper refers is the north region of Yanshan Mountain and west Liao River Plain), the ratio of growing days and accumulated temperature per-silking and post silking tended to be 4.5∶5.5, the ratio of biomass at per-silking and post silking was 4∶6, and the yield ranged from 15.4 to 16.9 t·hm⁻². The maximum yield needed to be densified from 60000 plant ·hm⁻² to 81 000-83 000 plant ·hm⁻². After densification, the yield can be increased by 6.1%−11.5%, and the HUE can be increased by 8.6%−17.5%. The effective matching of heat demand of varieties and regional heat resources is the premise to obtain high yield and fully tap the potential of regional yield. Quantitative dense planting based on the matching of heat resources is an effective way to achieve increased yield and efficient utilization of heat resources for mechanical grain-harvesting varieties of spring maize. In the area with limited heat resources, the balance of pre-silking and post-silking at resources and the full accumulation of pre-silking biomass were the key factors, and the suitable density was 88 000 to 92 000 plants·hm⁻². In the area with abundant heat, the production of post-silking matter was explored, and the suitable density population was constructed. The maize was to delay post-silking leaf senescence, and the suitable density was 81 000−83 000 plants·hm⁻².

Spatiotemporal changes in the characteristics of the safe growth period and high temperature damage of ratoon rice in nine southern provinces of South China

DUAN Licheng, GUO Ruige, CAI Zhe, LIN Zhijian, WU Ziming, FANG Sheng, ZHANG Chonghua, LIU Dan

2021, 29(12): 2061-2073. doi: 10.12357/cjea.20210244

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Abstract:
In the context of global warming and with increasing cultivated area of ratoon rice, precise control of ratoon rice sowing is of particular importance to ensure safe maturation and for utilizing the optimal temperature and light resources, stabilizing the production of ratoon rice, and ensuring food security. This study aimed to clarify recent spatiotemporal changes in terms of safe sowing date, duration from safe sowing date to safe full heading date (i.e., safe growth period), and high-temperature damage, and provide insights into novel strategies to utilize optimal temperature and light resources, and ensure safe production under the pressure of global warming. After collecting daily average temperature data in the past 39 years (1981–2019) from 601 weather stations in nine southern provinces of China (namely Sichuan, Chongqing, Hubei, Hunan, Jiangxi, Anhui, Jiangsu, Zhejiang, and Fujian), we examined the changes in safe sowing date and safe growth period, as well as high-temperature damage of ratoon rice in these provinces by using methods of climate change trends calculation and abrupt changes analysis. The results showed that the safe sowing date had advanced 3.3 d·(10a)⁻¹, the safe full heading date was delayed by 1.5 d∙(10a)⁻¹, and the safe growth period had extended by 4.8 d∙(10a)⁻¹. The abrupt shift in the safe sowing date occurred in 2001, after then this date occurred 9 days earlier. The greatest change in the safe growth period occurred in 1996, after then this period was 12 days longer than before. The safe sowing date occurred earlier in the south part than in the north part, and the safe growth period was longer in the southeast than in the northwest. High-temperature damage in June to July and August to September tended to increase. Mild, moderate, and severe damage increased by 48.5 times∙(10a)⁻¹, 30.3 times∙(10a)⁻¹, and 37.4 times∙(10a)⁻¹, respectively, in June to July; and by 52.7 times∙(10a)⁻¹, 18.2 times∙(10a)⁻¹, and 34.6 times∙(10a)⁻¹, respectively, in August to September. Moreover, high-temperature damage in June to July was more serious than that in August to September. The annual average numbers of mild, moderate, and severe high-temperature damage in June to July were 83.9, 41.6, and 115.9 times more than those in August to September. The years characterized by abrupt changes in mild, moderate, and severe high-temperature damage were 1998, 1988, and 1986 in June to July, and 1992, 2002, and 2002 in August to September, respectively. In all cases, high-temperature damage increased significantly after the abrupt change years and their occurrence followed the order of mild > severe > moderate in both June to July, and August to September. In conclusion, the advancement of the safe sowing date and the extension of the safe growing period of ratoon rice were advantageous as they benefited full use of temperature and light resources and yield increasing of ratoon rice in nine provinces of South China. However, concurrent increases in high-temperature damage impeded the high yields of high-quality ratoon rice.

Classification design of the meteorological index insurance for cold-frost damage on tea in Fujian Province

HUANG Chuanrong, CHEN Jiajin, SUN Chaofeng, WU Li, TAO Hongchao, LIN Huiyang

2021, 29(12): 2074-2083. doi: 10.12357/cjea.20210304

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Abstract:
To provide meteorological index products for tea insurance, the tea cold and frost damage insurance period and trigger meteorological indicators were analyzed to calculate the yield reduction rate, occurrence probability of cold-forest damage, and pure premium rate based on the meteorological data, and tea yield and disaster data of Fujian Province. Then, based on the risk assessment of cold-frost damage in tea plants, the regional premium rates under different trigger conditions and in different risk areas were improved. The insurance compensation ratio and compensation under different levels of cold-frost damage and in different periods were formulated and verified based on the intensity of cold-frost damage, the period of damage, and the average insurance compensation situation. Finally, a weather index insurance product for cold and frost damage to tea was provided. Results showed that the extreme minimum temperature of 4 °C, used as the initial trigger index of the tea cold-frost damage index insurance, as well as and seven grades with 1 °C interval, can fully reflect the historical disaster situation. Under the extremely low temperature of 4 °C, the average insurance premium rates in areas with altitudes below 200 m, 200−600 m, 600−900 m, and above 900 m in the northern region were 1.1%, 3.6%, 6.1%, and 8.4%, respectively; the average insurance premium rates in areas with altitudes below 300 m, 300−700 m, 700−1100 m, and above 1100 m in the southern region were 0.5%, 2.0%, 3.9%, and 5.5%, respectively. The average compensation rate of spring tea cold-forest damage in the northwest, northeast, southwest, and southeast regions was 78.4%, 90.5%, 72.7%, and 36.6%, respectively; the province’s average compensation rate was 69.5%, and the average basis ratio was −1.65%. The compensation rate and basis ratio met the basic requirements of insurance companies for the compensation ratio and basis ratio. The designed product can be applied to the weather index insurance of cold and frost damage of Fujian spring tea; therefore, this study could provide technical support for tea farmers to transfer and disperse the cold and frost damage risks.

Suitability analysis of remote sensing monitoring methods for grassland vegetation growth

RAO Xinyu, LI Hongjun, ZHANG Shengwei, LUO Meng, LIU Zhiqiang, ZHANG Jingwen

2021, 29(12): 2084-2092. doi: 10.12357/cjea.20210280

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The research and application of grassland vegetation growth monitoring methods have important scientific significance and application value for the sustainable use of grassland resources and the improvement of the ecological environment. Remote sensing monitoring has characteristics such as high timeliness and wide coverage, and several remote sensing monitoring methods have been increasingly used in crop growth monitoring. As the monitoring objects are all plants, these monitoring methods were tried to introduce to monitor grassland vegetation growth in this study. We applied four remote sensing monitoring methods for the crop growth: direct monitoring, vegetation growth process curve, same period comparison, and NDVI percentiles to the grassland vegetation growth monitoring of West Ujimqin County in Inner Mongolia; to clarify the suitability and limitation of these remote sensing monitoring methods for crop growth when monitoring grassland vegetation growth using MODIS Vegetation Index Products (NDVI). The monitoring results provided by the direct monitoring method and the NDVI percentile method were compared with the ground sampling data. The direct monitoring method could intuitively reflect the spatial heterogeneity of grassland vegetation growth by the grassland NDVI, and the NDVI value was significantly correlated with the dry weight of grassland yield per unit area (R²=0.5502). However, this method could not provide details on the growth of different types of grasslands owing to the limitation of the NDVI grade. The vegetation growth process curve method could only collectively reflect the changes in the overall growth of the grassland in the monitored area over time, showing that the growth was better or worse than that of the reference year. In this study, the NDVI peak values of the vegetation growth process curves for the meadow grassland and typical grassland were 0.73 and 0.55, respectively, significantly different from the whole regional lumped monitoring results (NDVI peak value was 0.60). This means that different grassland types should be monitored separately to reflect their respective growth processes. For the same period comparison method, if the selected reference year was different, the method would provide different monitoring results for grassland growth; the results from grassland growth monitoring were semi-quantitative comparative. Using the statistical analysis of NDVI data of different grassland types for 5 years, the NDVI percentile method could quantitatively evaluate the growth of corresponding grassland types, as shown in this study. The determination coefficient of the correlation between the growth score provided by the NDVI percentile method and the dry weight of grassland yield per unit area was 0.5047. To achieve a reasonable classification of these semi-quantitative monitoring results of grassland growth, the assistance of ground grassland monitoring information is required. There is an urgent need to establish a sky-air-ground integrated grassland growth monitoring platform to improve the efficiency and accuracy of grassland vegetation growth monitoring.

Identification of key areas of territorial ecological restoration in Taihang Mountains — A case study of Tang County

WEN Xuejing, ZHOU Zhi, ZHANG Meili, ZHANG Pengtao, ZHANG Guijun, ZHANG Qinrui

2021, 29(12): 2093-2106. doi: 10.12357/cjea.20210387

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Abstract:
Diagnosing and restoring key areas of territorial space is fundamental to promote the construction of ecological civilization. From the perspective of “holistic perspective, system governance and global restoration”, the identification of key areas and suggestions for restoration can make up for some deficiencies existing in current research. In this paper, Tang County, a typical eco-poverty area in Taihang Mountain, is selected as the research area. The ecological quality was determined by integrating habitat quality and ecological service value, and then determine the ecological patch with the best stability as the ecological source, the ecological resistance surface is constructed by using the minimum cumulative resistance model, the ecological corridor is constructed based on the circuit theory. In addition to the ecological pinch points, ecological obstacle points and ecological break points included in the existing studies, the low ecological key areas are supplemented to identify, which are obtained from the lowest grade patches extracted during ecological quality evaluation. Some suggestions were put forward, such as priority protection in ecological pinch area, priority restoration in ecological obstacle area, strengthening maintenance in ecological break area, and improving habitat quality in low ecological quality area to prevent further damage. Aiming at the ecological patches with high habitat quality and ecological service value, it is recommended that these patches should be ecologically protected by prohibiting the encroachment of non-ecological construction projects. For the key ecological areas where the land use types are woodland, grassland and farmland, it is recommended to plant plants adapted to the native environment to increase vegetation abundance, return farmland to forests, and return to grassland for ecological restoration. It is recommended to build culverts and tunnels for the smooth movement of organisms in the area of obstacles caused by the cutting effect of traffic roads. The distribution of low ecological quality areas is relatively scattered, so the degraded landscape during ecological restoration can be combined with the surrounding landscape to achieve the effect of improving ecological quality. In addition, attention should be paid to the environmental protection of rural residential areas and construction land. The restoration of construction land should actively respond to the rural revitalization strategy. It can develop sightseeing agriculture in some areas, control the development intensity of the southeast of the research area, and speed up the greening construction of villages. In this way, ecological restoration of low ecological quality areas will be carried out. The research showed that: The remote sensing ecological index of Tang County in 2000, 2010 and 2018 were 0.57, 0.64 and 0.56, respectively. The ecological quality was all in good grade, and the ecological quality increased firstly and then declined. We identified 10 of ecological sources with good stability, with an area of 91.22 km², accounting for 6.4% of the total area, which mainly distributed in the north and southwest of the study area. The land use types were forest land and water area. We also identified 15 of ecological pinch points, 42 of ecological barrier points and 28 of ecological break points, and the area of low ecological quality was 178 km², accounting for about 1/10 of the total area. From the perspective of overall connectivity, this study systematically identified the key areas of territorial space restoration in Tang County of Taihang Mountain, and put forward protection and restoration measures, which could provide a realistic reference for ecological restoration in Taihang Mountain.

Forty years of China’s eco-agriculture: Looking back and looking forward—To commemorate the 30th anniversary of Professor MA Shijun’s death, the founder and promoter of eco-agriculture concept

HU Tao, QI Ye, SUN Hongliang

2021, 29(12): 2107-2115. doi: 10.12357/cjea.20210616

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Abstract:
This paper has reviewed the concept and background of Eco-agriculture proposed and promoted by Prof. Ma Shijun. Looking back the past 40 years’ development of China’s eco-agriculture, the authors think eco-agriculture has been widely accepted and has been integrated into the new era of ecological civilization; technical economic system has been established and ecological economic benefits have been increasing; the eco-agricultures’ critical role for carbon neutrality has been gradually evolved. And also the key challenges of eco-agriculture have been pointed out: engineering and systematical level are not high enough; the degree of connecting to the Carbon Market is not enough; eco-agriculture foods need to be recognized more by consumers in the market; policy supports to eco-agriculture development are not sufficient; international trade volume of eco-agriculture products are pretty small. Looking forward, the authors think eco-agriculture are to be more engineering, intelligent and lower carbon; market value of eco-agriculture products are to be enlarged; supporting policies for eco-agriculture are to be more acupunctured and coordinated; China’s eco-agriculture development model and credibility of eco-agriculture foods are to be more recognized internationally.

Rural Ecology: An emerging discipline for the rural sustainable development

WANG Songliang, SHI Shengxu, WU Renye, DAI Yongwu

2021, 29(12): 2116-2125. doi: 10.12357/cjea.20210438

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Abstract:
The essential goal of rural revitalization is to promote the sustainable development of rural areas, which needs to integrate the theory of ecological hierarchy and scale. In this paper, the authors propose to construct a discipline of Rural Ecology (RE), together with Urban Ecology to form a completely geographical imagine of Ecology. The disciplinarities of RE are positioned as interdisciplinary approaches under a transdisciplinary model that integrates Agroecology, Landscape Ecology, Socio-ecology, and Political Ecology, aiming at building a sustainable rural ecosystem, i.e. addressing the ecological nexus between the peasants and their living & producing environment. The research scale of RE covers the vertical and horizontal scales of the rural ecosystem, and its core content is to study the material, energy, information, value and human resource flow of the rural ecosystem, the landscape at the urban-rural interface in particular to reveal the flow and loss of the peasants’ labor value. Finally, the authors put forward an analytical framework of RE for the sustainable development of rural areas, hotspots and four levels of transformation for the construction of sustainable rural ecosystems in China, i.e, reconstructing a sustainable rural ecosystem by revaluing the multi-functionalities of agriculture, reorganizing the agricultural industry, recycling the agricultural resources and innovating food production technology in sequence.

Linkage preference and heterogeneity of small farmers and the eco-agricultural industry chain: Based on the choice experiment method

SHANG Jie, LIU Shuang, CHEN Ximing

2021, 29(12): 2126-2138. doi: 10.12357/cjea.20210290

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Abstract:
The connection between small farmers and the ecological agriculture industry chain is an important way to establish an organic connection between small farmers and modern agricultural development, which is significant to the farmer’s prosperity and the development of ecological agriculture. However, the lack of pertinence in existing research restricts the development of related practices. This study aimed to understand the connection preferences of small farmers and the ecological agriculture industry chain and the source of their preference heterogeneity, further providing references for the design of related policies to promote the connetcion of small farmers with the ecological agriculture industry chain. Compared with existing researches, this research had expanded the concepts, research perspectives, and research methods, providing reference and support for small farmers in developing ecological agriculture-related policy design. In this article, based on the willingness of small farmers, we analyzed the related theories. First, we analyzed the organic connection between small farmers and the ecological agriculture industry chain; second, referring to the existing research results, we constructed a collection of choices for the connection of small farmers and the ecological agriculture industry chain. Among them, four types of attributes were set in the selection set design: linkage path, interest linkage mechanism, service type, and policy support type; finally, we conducted a household survey of 588 small farmers involved in ecological agriculture activities in Jiangxi Province. In this study, the random parameter Logit model was used to analyze and discuss the connection preferences of small farmers with the ecological agriculture industry chain, and the sources of heterogeneity. Research showed that there was a preference for the connection between small farmers and the ecological agriculture industrial chain: 1) In terms of linkage path selection, small farmers were more willing to connect with the ecological agriculture industry chain through the “small farmers + leading enterprises” path and the “small farmers + e-commerce platform” path, with coefficients of 4.60 and 2.10, respectively. 2) In terms of the choice of interest linkage mechanism, compared with the joint stock partnership, small farmers had a significant preference for contract cooperation and migrant work participation in employment and other interest linkage mechanisms, with coefficients of 7.47 and 5.41, respectively. 3) In terms of the provided service type, the preferences of smallholders for industry chain services were agricultural material supply, agricultural technical guidance services, capital and credit services, and processing and logistics services, with coefficients of 3.96, 2.94, 1.82, and 1.49, respectively. 4) In terms of the policy support type, small farmers preferred agricultural subsidies in policy support, with a coefficient of 2.10. 5) There was heterogeneity in the preference of small farmers to connect with the ecological agriculture industrial chain. The age, education level, and planting area of the ecological agricultural products of the interviewed farmers were the primary heterogeneity sources. Among them, the age of farmers and planting area of the ecological agricultural products positively impacted the connection of small farmers with the ecological agriculture industry chain. To a certain extent, the education level of small farmers restricted the connection effect. According to these research results, when designing policies, the accessibility to the ecological agriculture industrial chain should be improved, the standardization of the industrial chain benefit linkage mechanism be promoted, the construction of a socialized service system suitable for the development of small-scale ecological agriculture be accelerated, and the funds needed by small farmers to develop ecological agriculture be enriched.

2021 Vol. 29, No. 12