中国生态农业学报(中英文)

Yields and interspecific relationship of the maize-soybean intercropping system in the upland red soil of Jiangxi Province

FENG Liang, HUANG Guoqin, YANG Wenting, HUANG Tianbao, TANG Haiying, MA Qiaoying, WANG Shubin

2021, 29(7): 1127-1137. doi: 10.13930/j.cnki.cjea.200882

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Abstract:
The upland red soil in Jiangxi Province is rich in light, heat, and water resources and provides superior natural conditions for agricultural development. To screen the maize-soybean intercropping system with obvious advantages, better group yield, and economic benefits in the upland red soil of Jiangxi Province, seven treatments were set up in 2018 and 2019, of which five were maize-soybean intercropping systems with 1) 2 m bandwidth and 2-2 rows ratio, 2) 2.4 m bandwidth and 2-3 rows ratio, 2.4 m bandwidth and 2-4 rows ratio, 2.8 m bandwidth and 2-3 rows ratio, and 2.8 m bandwidth and 2-4 rows ratio; other two were sole maize and sole soybean. The effects of different intercropping patterns of maize and soybean were analyzed for crop yield and the interspecific relationships. The results showed that 1) the yield of sole maize and soybean was significantly higher than that of the intercropped ones. In the 2-year experiment, the average yield was 6801.88 kg·hm^-2 under the intercropping treatment of 2.4 m bandwidth and 2-4 rows ratio, which was 7.56% higher than that under the intercropping treatment of 2.4 m bandwidth and 2-3 rows ratio, indicating that increasing one row soybean of the intercropping system with suitable bandwidth benefited yield increase. The average economic benefit of intercropping system with a 2.4 m bandwidth and 2-4 rows ratio was 15 822.96 ￥·hm^-2 for the 2 years, 9.90% and 209.48% higher than that of sole maize and sole soybean, respectively. This indicated that intercropping improved the farmers' economic benefit. 2) In 2019, the land equivalent ratio (LER) of the intercropping treatment with 2.4 m bandwidth and 2-4 rows ratio was 1.77, significantly higher than the other intercropping treatments. The 2-year average LER in this intercropping system was 1.59, compared with 1.55 for the 2.0 m bandwidth and 2-2 rows ratio, 1.44 for the 2.4 m bandwidth and 2-3 rows ratio, 1.35 for the 2.8 m bandwidth and 2-3 rows ratio, and 1.44 for the 2.8 m bandwidth and 2-4 row ratio, which showed better land productivity. 3) When the bandwidth was 2.4 m or 2.8 m, adding one more row of soybean increased the LER by 10.42% and 7.41%, the maize actual yield loss (AYL_M) by 77.01% and 59.02%, the maize invasion (A_M) by 91.89% and 82.22%, the maize competition ratio (CR_M) by 38.69% and 24.11%, the economic benefit (EB) by 8.38% and 4.80%, and the maize harvest index (HI) by 6.12% and 6.25%, respectively. These results showed that increasing the row ratio of soybean could enhance the competitive advantage of intercropped maize with a suitable bandwidth, which improved crop yield and economic benefits. When the bandwidth increased from 2.4 m to 2.8 m with the rows ratios of 2-3 and 2-4, LER decreased by 6.67% and 9.66%, AYL_M decreased by 42.62% and 59.79%, A_M decreased by 64.44% and 73.17%, CR_M decreased by 19.15% and 33.14%, EB decreased by 10.23% and 13.99%, and HI decreased by 2.08% and 0.51%, respectively. These results showed that increased bandwidth weakens the competitive advantage of intercropped maize with different rows ratios and reduced the group yield and economic benefit. In conclusion, the maize-soybean intercropping system of 2.4 m bandwidth with a 2-4 rows ratio better coordinated the crop interspecific relationships and resulted in higher crop yield and better economic benefits. This study provides a reference for the maize-soybean intercropping system in the upland red soil of Jiangxi Province.

Effects of planting density and film mulching on the integrated productivity of soybean in young apple orchard of the Loess Plateau

ZHANG Wei, ZHAN Ai, LI Shiqing

2021, 29(7): 1138-1150. doi: 10.13930/j.cnki.cjea.200918

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Abstract:
Young apple tree and soybean intercropping is an important approach to the mutual benefits winnings between ecology and economic for apple production in Loess Plateau of Northwest China. The intercropped soybean is not only the drive force for ecological benefit, but also the dominant component for economical benefit under the intercropping system in young apple orchard. Few studies focused on productivity of intercropped-soybean under the soil condition in orchard, and evaluated its integrated productivity from the perspective of grain yield, protein quality, biological nitrogen fixation (BNF) and nitrogen byproduct, nitrogen in straw and straws included. The present study aimed to determine the integrated practices for the optimally integrated productivity of soybean by planting density and film mulching. Soybean crops with three densities (high density: 24×10⁴ plant·hm^-2; medium density: 16×10⁴ plant·hm^-2; low density: 10×10⁴ plant·hm^-2) and two mulching practices (film mulching, without film mulching) were planted in the young apple orchard of the Loess Plateau in 2018 and 2019. Indicators of grain yield, grain protein content, BNF rate, biomass and nitrogen distribution in organs, etc. were investigated under different treatments. The results showed that planting density was dominant for soybean grain yield and protein yield. The similar superiority over the high density was found both for grain yield and protein yield under the medium density and low density. Relative to high density, soybean grain yield and protein yield was increased by 23.8% and 24.5% on average of medium and low density, respectively. Under medium and low density, film mulching was beneficial to synergistic interaction between root nodules biological nitrogen fixation (BNF) and shoot development, and then greatly boosted accumulation of straw dry matter and nitrogen in straws while without decreasing soybean grain yield significantly. In detail, under film mulching for soybean crops with medium density, straw dry matter, nitrogen accumulation in straws and BNF from straws was increased by 1.76 t·hm^-2, 39.50 kg·hm^-2 and 32.42 kg·hm^-2 respectively, and contributed 98%, 79% and 67% to the improvement of soybean total dry matter, total nitrogen accumulation and total BNF in corresponding. Under film mulching for soybean crops with low density, straw dry matter, nitrogen accumulation in straws and BNF from straws was increased by 1.81 t·hm^-2, 33.70 kg·hm^-2 and 25.41 kg·hm^-2 respectively, and contributed 102%, 58% and 59% to the improvement of soybean total dry matter, total nitrogen accumulation and total BNF in corresponding. In addition, film mulching boosted protein content in grain by 9.6% on average of three densities, mainly due to the coaction from a slight decline in grain yield and increase of nitrogen absorption by soybean plant. Finally, soybean crops with medium density and film mulching achieved the optimally integrated productivity that comprised of grain yield of 3.55 t·hm^-2, protein yield of 1.27 t·hm^-2, BNF of 256.80 kg·hm^-2, nitrogen accumulation in straws of 134.87 kg·hm^-2, straw dry matter of 6.84 t·hm^-2 and the better grain protein quality in relative to its no mulching. This result indicates that the integrated practice by higher (medium) density with plastic film mulching for soybean can not only ensure plentiful grains with better protein quality, but more importantly, it is conducive to harvest more straws and nitrogen accumulation in straws that can be returned to local farmland for sustainable intensive production.

Effect of temperature increase on dryland spring wheat yield in different precipitation years

NIE Zhigang, FENG Yangqiang, DONG Lixia, WANG Jun, LI Guang

2021, 29(7): 1151-1158. doi: 10.13930/j.cnki.cjea.201018

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Abstract:
Climate change significantly affects crop production. To explore the effects of temperature increase on dryland spring wheat yield in different precipitation years in the hilly regions of the Loess Plateau, this study incorporated the meteorological data of Dingxi City, Gansu Province, from 1979 to 2018. Dryland spring wheat yield was simulated with the Agricultural Production Systems Simulator (APSIM) model when the daily maximum and minimum temperatures changed in the range of 0-2℃ in different precipitation years. Quadratic polynomial regression, single-factor analysis, and path analysis were used to study the influence mechanisms of temperature increase on dryland spring wheat yield. The results showed that the relationships between dryland spring wheat yield and daily minimum temperature, and between dryland spring wheat yield and daily maximum temperature were quadratic parabolas with an upward opening in different precipitation years, without a threshold value. When the daily maximum temperature was constant, an increase in the daily minimum temperature had a positive effect on the yield. The effect of increasing production was as follows: drought year > normal year > wet year. For every 0.5℃ increase in the daily minimum temperature, the average dryland spring wheat yield increased by 1.32% in wet years, 3.06% in normal years, and 3.99% in drought years. When the daily minimum temperature was constant, an increase in the daily maximum temperature had a negative effect on yield. The effect of production reduction was as follows: drought year > wet year > normal year. For every 0.5℃ increase in the daily maximum temperature, the average dryland spring wheat yield decreased by 9.08% in wet years, 7.98% in normal years, and 9.18% in drought years. The yield thresholds reached 798.61 kg·hm^-2 in wet years when the daily maximum temperature increased by 7.1℃, 1118.21 kg·hm^-2 in normal years when the daily maximum temperature increased by 3.9℃, and 1026.88 kg·hm^-2 in drought years when the daily maximum temperature increased by 3.1℃. Increased temperature led to a decrease in dryland spring wheat yield in different precipitation years. There was a negative interaction between the daily maximum temperature and daily minimum temperature. The effect of reduced production caused by increased daily maximum temperature was much greater than the effect of increased production caused by increased daily minimum temperature.

Effect of citric acid seed priming on the growth and physiological characteristics of tomato seedlings under low phosphorus stress

JIN Xiu, CHEN Haoting, SHI Yu, BAI Longqiang, HOU Leiping, ZHANG Yi

2021, 29(7): 1159-1170. doi: 10.13930/j.cnki.cjea.200953

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Abstract:
To explore the effects of seed priming with citric acid on tomato seed germination, seedling growth and physiological characteristics under low phosphorus stress, 'Zhongza 9' was cultured in sand at four phosphorus concentrations: control (0.66 mmol·L^-1), mild phosphorus deficiency (0.44 mmol·L^-1), severe phosphorus deficiency (0.22 mmol·L^-1), and non-phosphorus (0 mmol·L^-1). The tomato seeds were soaked in citric acid (7.5 mmol·L^-1), and the seed germination, seedlings growth and physiological characteristics were examined. This experiment aimed to clarify the physiological mechanisms of citric acid seed priming in alleviating low phosphorus stress in tomatoes. The results showed that, compared with seed soaking in distilled water, the different concentrations of citric acid seed soaking significantly increased the germination rate, germination potential, and germination index; the optimal concentration was 7.5 mmol·L^-1. Compared with the control, tomato seedling growth under low phosphorus stress was severely inhibited; the malondialdehyde (MDA) and reactive oxygen species ($ $\text{O}_2^{\bar \cdot }$$, H₂O₂) contents significantly increased; and the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities significantly decreased. The soluble protein, soluble sugar, and betaine contents significantly increased, and the osmotic potential was low. The seed priming with citric acid significantly promoted tomato seedling growth, increased biomass accumulation, increased the activities of antioxidant enzymes, reduced the accumulation of MDA and reactive oxygen species, and reduced the oxidative stress in tomato seedlings. It also significantly improved the organic acid and soluble sugar contents, alleviated osmotic potential decline, increased the phosphorus content, and lessened the symptoms of low phosphorus stress. In summary, priming tomato seeds with citric acid alleviated the oxidative damage caused by low phosphorus, improved the absorption efficiency of phosphorus, maintained normal growth and metabolism, and enhanced the resistance of tomato seedlings to low phosphorus stress.

Physiological response strategies of roots of different alkali-tolerant rice varieties to alkali stress

LU Xuping, LI Fanglan, MA Xiaojuan, JING Panpan, LUO Chengke, TIAN Lei, LI Peifu

2021, 29(7): 1171-1184. doi: 10.13930/j.cnki.cjea.200979

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Abstract:
This study aimed to investigate the physiological differences and coping strategies of the roots of rice varieties with different tolerances to alkali stress. In this experiment, alkali-sensitive rice variety 'Zhonghua 11' and alkali-tolerant rice variety 'Ninggeng 52' were subjected to nine alkali stress using two types of alkaline salts (sodium bicarbonate and sodium carbonate) in three alkali concentration levels (10 mmol·L^-1, 20 mmol·L^-1, and 30 mmol·L^-1) and three pH levels (8.65, 9.55, and 10.50). The effects of alkali stress on the root growth and stress resistance of rice seedlings were examined. Through stepwise regression analysis, the optimal regression equation was established, and the key indices of the response of different rice varieties to alkali stress were screened. The results showed that: 1) the decline of root growth characteristics (total root length, total root surface area, average root diameter, and root volume) and root activity of 'Zhonghua 11' were greater than those of 'Ninggeng 52' (P < 0.05). The lysyl oxidase (LOX), malondialdehyde (MDA), superoxide anion (O₂^·-) producing rate, and hydrogen peroxide (H₂O₂) content in the roots of 'Zhonghua 11' were significantly higher than those of 'Ninggeng 52' (P < 0.05). The content of osmotic adjustment substances[soluble sugar (SS), soluble protein (SP), free proline (Pro)], the activities of antioxidant enzymes[superoxide dismutase (SOD), peroxidase (POD), catalase (CAT)], reduced ascorbic acid (ASA), and reduced glutathione (GSH) in the roots of 'Zhonghua 11' were lower than those of 'Ninggeng 52'. 2) In 'Zhonghua 11', the average root diameter and root activity of the 20C treatment (20 mmol·L^-1, pH 10.50) were lower than those of the 30A treatment (30 mmol·L^-1, pH 8.65). The MDA content, LOX activity, O₂^·- production rate, and H₂O₂ content of the 20C treatment were significantly higher than those of the 30A treatment, and the damage caused by high pH and a low alkali concentration was greater than that of low pH and a high alkali concentration. 3) Redundancy analysis showed that the increase in sodium ions (Na⁺) and pH was negatively correlated with the increased growth indexes and positively correlated with increases in the physiological indexes for the tested rice varieties. 4) Stepwise regression analysis showed that the ASA, SS, and H₂O₂ contents were sensitive indicators of alkali stress in 'Zhonghua 11'. The average root diameter, total root surface area, root activity, Pro content, SS content, SOD activity, POD activity, and GSH content were the sensitive indexes of alkali stress for 'Ninggeng 52'. In summary, alkali and pH stress affected the growth and physiological characteristics of rice roots of rice. The effects of alkali composition and pH must be considered when cultivating rice in alkaline soil, as different rice varieties initiate different defense strategies against different alkali stresses.

Regulation and physiological mechanisms of flower bud differentiation in cotton seedlings under different soil water contents and planting densities

MI Yadi, LI Hui, FENG Haiping, ZHOU Ziyue, LIU Liantao, ZHANG Yongjiang, BAI Zhiying, SUN Hongchun

2021, 29(7): 1185-1193. doi: 10.13930/j.cnki.cjea.200864

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Improving the characteristics of cotton flower bud differentiation is important for coordinating the relationship between vegetative growth and reproductive growth in cotton plants, building a good cotton population structure, and increasing yield. To explore the regulatory effects and physiological mechanisms of the water supply and planting densities on cotton seedling flower bud differentiation, this study employed two split-plot designed experiments in 2019 on the Qingyuan Experimental Plot of Hebei Agricultural University. The main plot had two water treatments[full irrigation (CK) and drought (D)], and the sub-plot contained three density treatments[6×10⁴ plants·hm^-2 (low density), 9×10⁴ plants·hm^-2(medium density), and 12×10⁴ plants·hm^-2 (high density)]. By using 'Nongda 601' as the experiment material, the effects of different water supplies and planting densities on floral bud differentiation stage and progression, and the related physiological indexes (hormone, soluble sugar, and soluble protein contents) of cotton seedlings were studied. Before cotton sowing, different amounts of soil moisture were set: the control treatment was 900 m³·hm^-2, and the drought treatment was 450 m³·hm^-2. The results of microstructure showed that: 1) The differentiation speed of cotton shoot apical meristem accelerated under drought conditions. Under high-density conditions, the aspect ratio of cotton shoot apical meristem decreased, which slowed the differentiation rate. Under the same planting density, the position of the first fruit branch lowered down, but under the same water treatment, the position of the first fruit branch significantly raised with increased planting density (P < 0.05). Therefore, the interaction effect of the two factors is significant. 2) The drought and density treatments significantly impacted the soluble protein, soluble sugar, and endogenous hormone contents of the cotton shoot apical meristem. At the 2-leaf stage, the soluble protein and soluble sugar contents of the low-density treatment were significantly higher than those of the other two treatments, and the contents of endogenous hormone gibberellin (GA₃)was higher. The cytokinin (ZR) content was also lower. The ratios between endogenous hormones of indole-3-acetic acid/abscisic acid (IAA/ABA), ZR/ABA, and (IAA+ZR+GA₃)/ABA increased with increasing plant density. With flower bud differentiation, there was no significant difference in the contents of soluble protein and soluble sugar among the treatments. However, the ratios of IAA/ABA, ZR/ABA, and (IAA+ZR+GA₃)/ABA in the high-density treatment were significantly lower than those in other treatments (P < 0.05). The GA₃/ABA ratio was higher than that in other treatments. 3) Principal component analysis of the indexes of flower bud differentiation showed that the contents of soluble sugar and ZR at the shoot apical meristem had the greatest influence on initial flower bud differentiation at the 2-leaf and 3-leaf stages. Therefore, under drought conditions, the shoot apical meristem of cotton at a density of 6×10⁴ plants·hm^-2 differentiated faster, the nutrient substance and GA₃ content were higher, and the ZR content was lower, all of which was conducive to the initiation of cotton flower bud differentiation. However, the 12×10⁴ plants·hm^-2 treatment reduced the aspect ratio of the shoot apical meristem, increased the GA₃/ABA ratio, and slowed flower bud differentiation. The results provide a theoretical basis for the regulation of flower bud differentiation in cotton.

Composition and stability of soil aggregates in maize farmlands under different green manure utilization patterns in an oasis irrigation area

LYU Yitong, YU Aizhong, LYU Hanqiang, WANG Yulong, SU Xiangxiang, CHAI Qiang

2021, 29(7): 1194-1204. doi: 10.13930/j.cnki.cjea.200913

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Long-term continuous cultivation of gramineous crops can lead to soil quality degradation, thereby decreasing crop productivity. Optimization of the agronomic measures is a powerful way to improve soil physical and chemical properties, increase soil fertility, and enhance the sustainable development of agricultural production. The effects of different green manure utilization on the composition and stability of soil aggregates and soil bulk density were studied in this study to provide a theoretical and practical basis for improving the quality of farmlands in oasis irrigation areas. A field experiment was conducted in the oasis irrigation area in Northwest China to determine the composition and stability of soil aggregates and soil bulk density at 0-30 cm soil depth in maize farmlands in response to different green manure returning patterns. The green manure utilization patterns included: no tillage with the full quantity of green manure mulched on the soil surface (NTG), conventional tillage with the full quantity of green manure incorporated into the soil (TG), no tillage with root returning of green manure after removing the above-ground part of green manure (NT), conventional tillage with root returning of green manure incorporated into the soil after removing the above-ground part of green manure (T), and conventional tillage without green manure (CT) as the control. The results showed that the four green manure utilization patterns increased the soil macro-aggregate content, mean weight diameter, geometric mean diameter, and mean weight-specific surface area (P < 0.05) at 0-30 cm soil depth, compared to CT. Among the four green manure treatments, NTG had the most significant effects. However, different green manure utilization patterns significantly decreased the fractal dimension of soil aggregates (P < 0.05). Among the four green manure treatments, NTG and NT significantly decreased the fractal dimension of soil aggregates at 0-30 cm soil depth in comparison to TG and T. There was no significant difference in the fractal dimension of soil aggregates at 0-20 cm soil depth between NTG and NT treatments; however, NTG had a lower fractal dimension of soil aggregates at 20-30 cm soil depth than that of NT (P < 0.05). Compared to CT, TG and T significantly reduced the soil bulk density at 0-30 cm soil depth, but NT significantly increased the soil bulk density at each soil depth in the 0-30 cm soil layer (P < 0.05). NTG had significantly lower soil bulk density than CT at 0-10 cm and 20-30 cm soil depth in 2019, but the difference was not significant in 2018. Compared to the other green manure utilization patterns (TG, NT, and T) and conventional tillage without green manure treatment (CT), no tillage with the full quantity of green manure mulched on the soil surface treatment (NTG) increased the macro-aggregate content and stability of soil aggregates and reduced the soil bulk density at 0-30 cm soil depth.

Effects of paddy field cropping patterns on soil organic carbon and carbon pool management index in the middle reaches of the Yangtze River

YUAN Jiaxin, YANG Binjuan, HU Qiliang, TANG Haiying, LI Shujuan, HUANG Guoqin

2021, 29(7): 1205-1214. doi: 10.13930/j.cnki.cjea.200972

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To explore the effects of paddy field planting patterns on soil organic carbon pools and to optimize cropping systems, in this study, we examined five typical paddy field cropping patterns in the middle reaches of the Yangtze River, including Chinese milk vetch-early rice-late rice (CRR, control), rape-early rice-late rice (RRR), potato-early rice-late rice (PRR), Chinese milk vetch-early rice-sweet potato||late soybean (CRI), and rape-early rice-sweet potato||late soybean (RRI). Soil organic carbon, active organic carbon and its components, carbon pool management index, and economic benefits were analyzed by measuring the content of soil organic carbon, the active organic carbon components in the paddy fields, and the crops yields. The results showed that after late rice harvest, compared to CRR, the CRI, RRI, and RRR treatments increased the soil organic carbon content by 12.06%-21.01% (P < 0.05); the CRI, RRI, and PRR treatments increased the active organic carbon content and microbial biomass carbon content by 16.80%-20.45% and 38.24%-50.00% (P < 0.05), respectively; while CRR, RRI, RRR and PRR increased the dissolved organic carbon content by 3.13%-15.64% (P>0.05). The CRI and RRI treatments significantly promoted the accumulation of soil total organic carbon and microbial biomass carbon, while the PRR treatment promoted the accumulation of soil active organic carbon. Compared to CRR, PRR increased the soil carbon pool activity and carbon pool activity index; RRI and CRI increased the soil carbon pool index; and CRI, RRI, and PRR significantly increased the soil carbon pool management index by 17.30%-33.49% (P < 0.05). The economic benefits of PRR and CRI increased by 12.05% and 9.86%, respectively (P < 0.05). There was an extremely significant positive correlation between rice yield and microbial biomass carbon (P < 0.01), and the correlation coefficient between the soil carbon bank management index and active organic carbon was the highest, with a significant positive correlation (P < 0.01). In summary, each cropping pattern is beneficial for increasing crop yield and changing the content of soil organic carbon and its components. Among them, Chinese milk vetch-early rice-sweet potato||late soybean and potato-early rice-late rice have better comprehensive effects, which can be popularized and applied in the middle reaches of the Yangtze River.

Response of soil fungal diversity to long-term conservation tillage in dryland wheat soils on the Loess Plateau, China

LYU Beibei, ZHANG Liping, ZHANG Guiyun, LIU Zhen, FAN Qiaolan, YAO Zhong, Chang Fangjuan

2021, 29(7): 1215-1223. doi: 10.13930/j.cnki.cjea.200818

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Different agricultural tillage practices create variable soil ecosystems that have different effects on soil microorganisms, especially those around the root system. Conservation tillage has numerous advantages and is used worldwide, but its sustainability has been challenged by the increase in soil pathogenic microorganisms caused by stubble mulching. To better understand the effects of long-term conservation tillage on the soil ecosystems in the dryland wheat regions of the Loess Plateau, this study used data from a 27-year conservation tillage experimental platform in Linfen, Shanxi Province, and high-throughput sequencing technology to investigate the response of the soil fungal community structure and diversity to different tillage treatments, including traditional tillage (TT1), no-tillage with stubble (NTS), and no-tillage with stubble after subsoiling (SNTS). The results showed that there were considerable differences in the composition and relative abundances of soil fungi among three treatments, and the NTS treatment included some unidentified or unknown fungi. Ascomycota, Basidiomycota, and Zygomycota were the dominant phyla of soil fungi in each treatment. Compared with TT1, the relative abundances of Ascomycota, Zygomycota, Chytridiomycota, and Glomeromycota increased under the two conservation tillage treatments, whereas the relative abundance of Basidiomycota significantly decreased. According to the heat map of species distribution at the genus level, the relative abundances of Gibberella and Fusarium increased compared to TT1 treatment, and Gibberella was the dominant genus under the two conservation tillage treatments. This indicated that long-term conservation tillage may increase the risk of wheat scab in this area. UPGMA (unweighted pair-group method with arithmetic means) showed that the soil fungal community composition was similar between the two conservation tillage treatments, which differed from the TT1 treatment. The key biomarker in the TT1 treatment belonged to Basidiomycota, whereas the key biomarkers belonged to Ascomycota for the NTS and SNTS treatments. The NTS treatment had the highest richness and PD_whole_tree of soil fungi, whereas the SNTS treatment had the highest diversity. However, there were no significant differences in the diversity and richness indices of soil fungi among three treatments. In conclusion, long-term conservation tillage significantly changed the structure and composition of soil fungal communities, and improved the richness and diversity of soil fungi with no significant differences among three treatments. Conservation tillage (for 27 years) may also increase the risk of wheat scab. Therefore, to minimize soil pathogens, appropriate stubble mulching frequency, no-tillage, conventional tillage or subsoiling rotation, and moderate shallow tillage should be examined in future soil management and conservation tillage studies. This study provides guidance for promoting conservation tillage and soil management in the dryland wheat regions of the Loess Plateau.

Timing sequence of permanent basic farmland reserve area delineation based on TOPSIS and the matrix grouping method at the county level

LIU Jing, TANG Feng, ZHANG Guijun, ZHANG Pengtao, WANG Li

2021, 29(7): 1224-1235. doi: 10.13930/j.cnki.cjea.200734

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The delineation of permanent basic farmland reserve areas is an important measure for consolidating permanent basic farmland demarcation and ensuring national food security. Reasonable planning of the reserve area and the delineated sequence can ensure that the permanent basic farmland is quickly replenished after being occupied. This study incorporated the land, space, engineering, and ecological environment qualities of cultivated land to evaluate the quality and spatial agglomeration of cultivated land in Huanghua City, Hebei Province, via the ranking method of the approximate ideal solution and the hot spot analysis method. The matrix method was then used to demarcate the permanent basic farmland reserve area. The results show that: 1) there are obvious differences in the quality of non-permanent basic farmland, and the overall soil fertility condition is good in the study area. The degree of salinization is higher in some areas, and the quality of agricultural engineering is poor. The irrigation guarantee rate is low. In the whole, the comprehensive quality is mainly high-or sub-high-value areas. The proportion of cultivated land area in the high-value and sub-high-value areas is larger, accounting for 44.22% of the non-permanent basic farmland. The comprehensive quality of cultivated land in the west is higher than that in the east, closer to the coast. 2) The permanent basic farmland reserve area is divided into three categories: priority area, suitable area, and regulation area. The comprehensive quality of cultivated land in the priority zone is high, with obvious agglomeration characteristics, accounting for 30.75% of the total area. Suitable areas have poor comprehensive quality or spatial aggregation, and it is necessary to invest manpower and material resources for quality construction. The regulation zone area is the largest, accounting for 41.19%, which should be committed to improving the long-term safety of agricultural ecology. Considering the delineated quality and ecological environment goals, this study has increased the scale limitation of space utilization that can effectively improve the efficiency of rapid supplementary planning for basic farmlands.

European Union organic fertilizer product standards, management mechanisms, and its enlightenment

JIN Shuqin, TANG Jiali, YANG Xiaoming, YU Taize, LI Ying, MA Lin

2021, 29(7): 1236-1242. doi: 10.13930/j.cnki.cjea.210025

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The use of organic fertilizers is a beneficial measure for absorbing livestock manure, reducing chemical input, and improving soil health. European Union (EU) countries divide organic fertilizers into two types of mineral and non-mineral fertilizers, and solids and liquids in form. The organic fertilizer standards include the effective nutrients contents and the hazardous substances limits. Information ledgers, an obligation to disclose, and traceability has helped the EU to achieve strict market supervision and avoid environmental risks caused by excessive fertilizer application through the delineation of polluted areas. Such practices represent important references for China to vigorously promote the green development of agriculture. This study compared the standards of organic fertilizer products in China with the standards of organic fertilizer products from the EU and presents five recommendations. First, nitrate pollution areas should be delineated as soon as possible. Second, the product standards should be refined for the classification and designation of organic fertilizers. Third, the responsibilities of all parties should be considered, especially for the strict control of source addition and production specifications. Fourth, planting and breeding combinations should be vigorously promoted; we need to combine the promotion of organic fertilizer with fertilizer decrement and better resource utilization for livestock and poultry manure. Finally, we need broader publicity for organic fertilizer use. Therefore, it is recommended that China start delineating nitrate pollution areas as soon as possible, formulating organic fertilizer standards, strengthening supervision, and realizing the green development of combining planting and breeding.

Calculation of agricultural production efficiency based on a three-stage Data Envelopment Analysis model and analysis of the spatial-temporal characteristics: An example from the Yangtze River Economic Belt

CUI Haiyang, ZHUO Wenjun, YU Hu, LONG Jiao, LIU Yufang

2021, 29(7): 1243-1252. doi: 10.13930/j.cnki.cjea.200929

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In response to the strategic call for the "Great Protection" of the Yangtze River Economic Belt and to fulfill the important historical tasks assigned by the state to the provinces and cities of the area, the Yangtze River Economic Belt is adjusting the agricultural industry structure, optimizing the input-output ratio, and ensuring stable and sustainable agricultural production. Based on the combination of the three-stage Data Envelopment Analysis (DEA) model and cluster analysis, this study examined the Yangtze River Economic Belt from 2008 to 2018 to measure its agricultural production efficiency and to analyze its temporal and spatial characteristics. Studies shown that exogenous environmental factors significantly (P < 5%) impact agricultural production efficiency in the Yangtze River Economic Zone, and there were temporal and spatial differences. These include: 1) after excluding environmental factors, the overall agricultural production efficiency of the Yangtze River Economic Zone had improved. Sichuan and Jiangsu Provinces were at the forefront of efficiency, whereas the agricultural production efficiency of Shanghai had obviously declined. 2) The agricultural production efficiency of the Yangtze River Economic Belt varied year by year, with fluctuating development. The middle reaches of the Yangtze River had advanced agricultural production efficiency more than the upstream and downstream regions, and the agricultural production efficiency of the individual provinces did not match their economic and social development. 3) Increases in labor, land, irrigation, and other input factors increased agriculture production efficiency, there was no correlation between fiscal investment per capita gross domestic product (GDP) and agricultural production efficiency. The disaster-affected area had a significant negative impact on agricultural production efficiency.

Logic paths and driving forces of cultivated land quality improvement behavior of farmers: Research progress and prospects

SHANG Huifang, YI Xiaoyan, ZHANG Zongfang

2021, 29(7): 1253-1261. doi: 10.13930/j.cnki.cjea.210142

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Abstract:
The "three-in-one" approach of quantity, quality, and ecology has become the target of cultivated land protection in China; improving the quality of cultivated land is the resource basis for ensuring food security and effective supply of important agricultural products in China. It also helps to achieve high-quality agricultural development. To better understand the cultivated land quality improvement behavior of farmers, who represent a key demographic for achieving the strategic objectives of cultivated land protection, this study analyzed the logical paths and driving forces of cultivated land improvement behavior of farmers. We found that the logic of farmland quality improvement behavior of farmers generally followed the path of "cognition→will→behavior", but there was also the possibility of "cognition→behavior". This can be subdivided into four different logical paths based on the theory of planned behavior, the theory of stimulus and response, the theory of extended value-belief-norm, and the theory of rational individuals. The behavior response to cultivated land quality improvement was not optimistic, and the enthusiasm of farmers could be improved by adjusting the key driving factors. From the perspective of progress in behavior logic and response, the key driving forces of farmland quality improvement behavior of farmers were the business scale, stability of land management rights, awareness level, and policy support. There were linear and non-linear relationships between the scale of cultivated land and the cultivated land quality improvement behavior of farmer households, and the proportion of large-scale entities who implemented cultivated land quality improvement trended upward. The evaluation of farmland quality status of farmers hindered their farmland quality improvement behavior, whereas the awareness of farmers regarding environmental protection played a promoting role. The cognitive level of farmers was affected by the level of information acquisition. The stability of land management rights had a "guarantee effect" for improving the quality of cultivated land. Policy constraints primarily regulated farmland quality improvement behaviors of farmers by providing policy guidance or constraints, whereas preferential subsidies promoted quality improvement behavior by giving farmers preferential treatment or compensation. The existing literatures lacked quantitative researches on the obstacles to farmland quality improvement behavior, the stability of contract relationships, and the behavioral differences of different business entities. Therefore, future studies should use quantitative models and other methods to identify the key factors, analyze the obstacles, and examine policy support programs for farmland quality improvement behaviors of farmers.

Farmers' behavior toward pesticide input based on the reduction target: Micro-data of grain farmers from seven provinces

XIONG Ying, LI Xiao, ZHONG Yu

2021, 29(7): 1262-1273. doi: 10.13930/j.cnki.cjea.200999

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Abstract:
Excessive pesticide input is a common problem of agricultural production in China. The reduction of pesticide input is important for promoting green and sustainable agricultural development. Farmers are the main micro-decision-making bodies for pesticide inputs; therefore, theoretical and empirical research was conducted on farmers' behavior regarding pesticide input. This study examined the important factors finely through analyzing internal mechanism of farmers' pesticide input behavior, such as production, operation, and the external environment, which were not considered in the prior researches. Based on the household survey data of 746 grain farmers from seven provinces of China, the generalized ordered Logit model was used to empirically analyze the effects of individual and family factors, production factors, and external environmental factors on farmers' behavior toward pesticide input. This study compensated for the shortcomings of the traditional ordinary least squares (OLS) model or the binomial Logit model estimation method and highlighted the impact direction and degree of each factor on farmers' pesticide input behavior. The results showed that 1) from the perspective of impact direction, education level, sown area of grain, land concentration, land tenure, pesticide input cost, agricultural technology training, and agricultural production insurance had significant negative effects on pesticide input intensity. Farmers' age, grain income proportion, and production motivation had significant positive effects on the pesticide input intensity. These results suggest that younger age, a higher education level, greater sown area of grain, higher land concentration, better land tenure, lower grain income proportion, production for self-sufficiency, lower pesticide input cost, participation in agricultural technology training, and agricultural production insurance were associated with a lower likelihood of pesticide input. 2) From the perspective of impact degree, agricultural technical training, agricultural production insurance, grain income proportion, education level, land concentration, land tenure, and production motivation had greater effects on pesticide input intensity, whereas the effects of sown area of grain, farmer's age, and pesticide input cost were weaker. To encourage farmers to reduce pesticide input, the government should introduce measures to stimulate the endogenous power of farmers' safe production and create supportive external conditions.

Relationship between policy incentives, ecological cognition, and organic fertilizer application by farmers: Based on a moderated mediation model

SANG Xiance, LUO Xiaofeng, HUANG Yanzhong, TANG Lin

2021, 29(7): 1274-1284. doi: 10.13930/j.cnki.cjea.200978

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Abstract:
When striving to promote the green and high-quality development of agriculture, can policy incentives effectively guide the formation of ecological values and promote the application of organic fertilizer by farmers? Existing studies have not provided corresponding evidence. This article explored the relationships between policy incentives, ecological cognition, and organic fertilizer application by farmers to provide a useful reference for understanding organic fertilizer application by farmers, promote the substitution of organic fertilizer for chemical fertilizer, and realize the green development of agriculture. This study had specifically developed two aspects. First, it analyzed the mechanisms of policy incentives on organic fertilizer application by farmers from the perspective of ecological cognition and examined the decision-making mechanism of the farmers. Second, it considered the differences in the economic level of farmers. Low-income farmers had a lower ability to pay and bear risks; therefore, even if they were willing to adopt organic fertilizers, they struggled to translate this willingness into action. Thus, household income should be included in the analysis framework. Based on the survey data of 758 rice farmers in Hubei Province, this study used the entropy method to measure the ecological cognition of farmers and verified the influence mechanisms of policy incentives, ecological cognition on organic fertilizer application by farmers by constructing a moderated mediation model. This study focused on the mediating effect of ecological cognition in the process of policy incentives affecting organic fertilizer application by farmers and the moderating effect of household income in the process of policy incentives affecting organic fertilizer application by farmers through ecological cognition. The results showed that: 1) policy incentives had a significant positive (P < 5%) impact on organic fertilizer application by farmers. Government propaganda, training, and subsidies encouraged organic fertilizer use. 2) Ecological cognition played a partial intermediary role between policy incentives and organic fertilizer application by farmers, suggesting that policy incentives positively impact organic fertilizer applications via improved ecological cognition. 3) The indirect effect of policy incentives on organic fertilizer application by farmers through ecological cognition was positively regulated by household income. Increased household income significantly enhanced the influence of policy incentives on organic fertilizer application through ecological cognition. Based on these results, this study proposed the following policy implications. It is necessary to implement organic fertilizer policy incentives and to strengthen the role of the government in organic fertilizer promotion. The government should also consider ecological cognition of farmers when promoting organic fertilizers application. In the early promotion stages of organic fertilizer technology, high-income farmers can serve as an entry point to rapidly expand the use of organic fertilizers. Conversely, low-income farmers may represent difficult targets for future organic fertilizer promotion. Increased subsidies for the application of organic fertilizers to low-income farmers may help to reduce their economic risks.

2021 Vol. 29, No. 7