中国生态农业学报(中英文)

Ecological network characteristics of the functional groups of epigaeic arthropod in arable land with different field margin types

BIAN Zhenxing, WANG Chuqiao, LIU Yao, SUN Zhiquan, WANG Shuang, LIU Shuang, ZHU Su, YU Miao

2022, 30(9): 1381-1392. doi: 10.12357/cjea.20210917

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Abstract:
Species diversity and functional group characteristic of epigaeic arthropod community is key to maintaining the diversity and stability of farmland ecosystems. Exploring the effects of semi-natural habitats, such as field margins, on the diversity of natural enemies and utilizing the spillover effects of natural enemies in semi-natural habitats and farmland is beneficial for strengthening the protection of natural enemies, which is of great significance in formulating sustainable pest control strategies and optimizing the allocation of agricultural landscape. However, the ecological network characteristics of epigaeic arthropod functional groups in arable land with different field margin types are currently unclear. A systematic understanding of species distribution patterns and interactions among species in arable land with different field margin types is the basis for determining the population occurrence of insect herbivores and natural enemies. To optimize the structure of non-tillage habitats and rationally distribute agricultural landscape, we used the trap method to investigate the community compositon and the functional groups (natural enemies, herbivores, and neutral) of epigaeic arthropods in the adjacent arable lands of five field margin types (paved road, irrigation canal and ditch, woodland, dirt road, and grassland) in Changtu County, Liaoning Province. Variance analysis, community ordination, and ecological networks were used to analyze the differences in arthropod community distribution, functional group diversity, and ecological network symbiosis in adjacent arable land with the margins of different vegetation characteristics, margin width, and human disturbance intensity. The results showed that the species diversity of epigaeic arthropods decreased from the margin to the interior of arable land, and there were significant differences in species diversity between 0 m and 15 m, 30 m in arable land with margin of paved road and significant differences in species diversity between 0 m and 30 m in arable land with margin of woodland, dirt road, and grassland. The diversity of natural enemy groups was higher in woodland and grassland. The epigaeic arthropod community structure was more complex in margins with higher plant diversity. The ecological network of the epigaeic arthropod community showed a positive correlation, the network structure of the epigaeic arthropod community with woodland and grassland margins was more stable, and the entire network system was more resistant to external changes. The internal network connectivity of grasslands, ditches, and woodlands was strong and robust. The internal ecological network of arable land with paved roads and dirt roads was unstable. In general, the more complex the community structure of the field margin vegetation is, the more stable are the margin habitat conditions. In addition, the more complex the ecological network structure between natural enemies and herbivores in adjacent arable land is, the more beneficial it is to maintain the high diversity of natural enemies and improve the biological control function. Therefore, strengthening the vegetation community structure of field margins, such as the construction of an appropriate vegetation community structure and margin width, can improve the ecological network relationship between epigaeic arthropod communities, which is important for pest control and ecosystem stability. For future agricultural landscape construction, we should not only enhance biodiversity but also explore the ecological network relationship and co-occurrence law among species.

Decomposition processes of organic materials and their mechanisms of improving soil fertility in cropland ecosystems

LEI Wanying, LI Na, TENG Peiji, YU Jinchao, LONG Jinghong

2022, 30(9): 1393-1408. doi: 10.12357/cjea.20210878

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Abstract:
Cropland ecosystems are terrestrial ecosystems that are highly disturbed by human activity. Fertile soil, organic matter, and balanced nutrients play fundamental roles in ensuring crop growth, harmonious symbiosis of soil organisms, and stability of ecosystem productivity. In cropland ecosystems, crop straw and livestock manure are two main exogenous organic materials that are incorporated into soils; and are the main sources of soil organic matter. The incorporation of organic materials into soils can increase soil organic carbon accumulation, improve soil fertility, and enhance crop yield. Organic materials are ultimately transformed into soil organic matter (SOM) after undergoing a series of complex physical, chemical, and biological decomposition processes. These complex decomposition processes are controlled by many factors, such as organic materials properties, soil types and their inherent characteristics, environmental conditions, and agricultural management practices. Therefore, these processes and their driving factors are receiving increasing attention worldwide. This article comprehensively reviewed the main research progress in the decomposition characteristics of organic materials and their main influencing factors. The effects of organic amendments on soil nutrient pools and soil quality and the underlying mechanisms regulating the transformation of organic materials to soil organic matter were also discussed. This study first outlined the main methods and indicators for characterizing the decomposition processes of organic materials, analyzed the characteristics of the chemical structure of organic materials and soil during decomposition, and revealed the main factors regulating the decomposition processes of organic materials (environmental factors; the quality, composition, and chemical structure of organic materials). Second, the contributions of organic material incorporation to the soil organic carbon pool, active organic carbon, humus composition, nutrient pools, and soil quality were evaluated. Effects of incorporating organic materials on soil fertility were discussed in terms of crop yield and soil physical, chemical, and biological properties. Third, the underlying physical, chemical, and biological mechanisms regulating the transformation of organic materials to soil organic matter were illustrated. Finally, prospects for future research on the processes and mechanisms of organic material decomposition in the cropland ecosystems were presented, as listed in the following points: to optimize scientific and reasonable measures for organic materials returning to the field by considering local conditions, long-term positioning field experiments and cross-regional network experiments. The optimal ratio between the labile and recalcitrant components of organic materials must be quantified to achieve a highly efficient decomposition degree of the organic materials. More advanced and elaborate techniques are advocated to be applied together to characterize the decomposition products more comprehensively and accurately. This review is expected to provide a theoretical basis and data support for interpreting the decomposition and transformation processes of organic materials and optimizing cropland management practices in cropland ecosystems.

Effect of peanut||sesame intercropping on iron nutrient absorption and utilization of peanut

SUN Zengguang, WANG Jiangtao, NIE Liangpeng, WU Yanyan, LIU Juan, JIAO Nianyuan

2022, 30(9): 1409-1416. doi: 10.12357/cjea.20220056

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Peanut and sesame are important oil crops in China, and they play an important role in national production. In alkaline soils, iron deficiency and chlorosis often occur in single-cropped peanut; however, iron deficiency rarely occurs in single-cropped sesame. Iron deficiency symptoms in peanut are significantly improved when intercropped with sesame and have significant yield advantages and economic benefits. To explore the mechanism of improvement in iron nutrition of peanut in peanut/sesame intercropping system (peanut||sesame), a field experiment was conducted to investigate the effects of two intercropping modes of peanut and sesame with rows ratios of 4∶2 (P||S 4:2) and 6∶3 (P||S 6:3) on the leaves SPAD value, pH of rhizosphere soil, active iron contents and total iron contents of different parts, and iron accumulation and distribution per plant of peanut. In this experiment, peanut cultivar ‘Keda Heihua 001’ and sesame cultivar ‘Yuzhi No. 8’ were used as the materials, and peanut single cropping (SP) was used as the control. Furthermore, the yield advantages of two planting patterns of peanut||sesame were analyzed. The following results were obtained when intercropping was compared with SP: the leaf SPAD values of peanut in P||S 4:2 and P||S 6:3 treatments increased by 13.60%−30.10% and 22.15%−33.31% (P<0.05), respectively. The pH of the rhizosphere soil decreased significantly at the flowering and needling, pod setting, and pod expansion stages. Compared with those of SP, the contents of active iron in peanut stems and leaves were enhanced by 31.80%−72.78% and 24.41%−72.49% (P<0.05), respectively; and the total iron contents were enhanced by 16.80%−22.86% and 15.91%−27.88% (P<0.05), respectively, in P||S 4:2 and P||S 6:3 treatments. In addition, the iron accumulation per plant was increased by 7.91%−22.42% and 5.77%−15.58% in P||S 4:2 and P||S 6:3 treatments, respectively, at flowering and needling, pod expansion, and harvest stage; and, especially at harvest stage, the difference reached significant level (P<0.05). Compared with those of SP at the harvest stage, the total iron contents of peanut seeds in P||S 4:2 and P||S 6:3 treatments increased by 21.97% and 17.42%, respectively (P<0.05), and the yield advantage of peanut||sesame was P||S 6:3 > P||S 4:2. In conclusion, peanut||sesame can significantly increase the active iron contents in different parts of peanut, promote iron absorption and utilization, and improve the iron content and accumulation in seeds, and this is closely related to the fact that intercropping can significantly reduce the rhizosphere pH of peanut. The best intercropping pattern for iron nutrition improvement in peanut seeds was P||S 4:2; however, P||S 6:3 produced the highest yield.

Effect of elevated atmospheric CO₂ concentration on the metabolic function of microbe in rhizosphere of different soybean cultivars

GAO Zhiying, LI Yansheng, YU Zhenhua, JIN Jian, WANG Guanghua, LIU Xiaobing

2022, 30(9): 1417-1424. doi: 10.12357/cjea.20220018

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Climate change, characterized by increased concentrations of CO₂, can substantially stimulate plant photosynthesis and growth, and subsequently change the quantity and quality of below-ground rhizodeposition. From the perspective of soil microbiology, these alterations may indirectly induce changes in soil microbial biomass and function, and further influence the processes of soil organism evolution, such as nutrient transformation and the balance of soil carbon storage. In this study, four soybean cultivars, ‘Xiaohuangjin’ (XH), ‘Mufeng 5’ (MF), ‘Suinong 14’ (SN), and ‘Dongsheng 1’ (DS), which are released in 1951, 1972, 1996 and 2003, respectively, widely planted in Northeast China then, were selected. Soil samples were collected from the rhizosphere of soybeans grown in either ambient CO₂ (410 mol∙L⁻¹, CK) or elevated CO₂ (550 mol∙L⁻¹, EC) at the beginning of the seed stage. Each CO₂ treatment was performed in triplicate. Thus, there were 12 OTCs (open top chamber) in total. The effects of elevated CO₂ on microbial metabolic function were studied using the BIOLOG technique. The results showed that different soybean cultivars had different metabolic patterns and the order of average well color development (AWCD) ranked as: MF > SN > DS > XH. Biodiversity indices and PCA analysis revealed that the metabolic patterns of cultivars XH, MF, and DS were resistant to elevated CO₂, while elevated CO₂ significantly changed the metabolic patterns of SN. The contribution of each carbon source to the PCA indicated strong correlations between the variations of carbon sources in the EC treatment and CK of SN with the positive and negative carbon sources in PC1, respectively. In addition, some specific carbon sources in CK of SN, such as L-arginine and 2-hydroxy benzoic acid, are harmful for soybean growth, and whether elevated CO₂ may increase soybean diseases resistance merits further analysis. Meanwhile, there were interaction effects between soybean cultivars and elevated CO₂ on specific carbon sources. In summary, this study illustrates that different soybean cultivars have different metabolic functions and respond differently to increased CO₂.

Effects of aerated drip irrigation and degradable film mulching on growth and water use of maize

WU Mei, ZHANG Jinzhu, WANG Zhenhua, ZHU Yan, SONG Libing, ZONG Rui, HAN Yue

2022, 30(9): 1425-1438. doi: 10.12357/cjea.20220027

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Xinjiang is a typical arid area in China with scarce precipitation and intense water evaporation. Plastic film mulching increases temperature, preserves moisture, prevents weed growth, inhibits water evaporation, and improves crop yield. However, with the overuse of traditional plastic film, residual plastic film is constantly increasing in farmland, which has led to negative impacts, such as environmental pollution and decreased soil aeration. This study aimed to explore the effects of aerated drip irrigation and degradable film mulching on the growth and yield of maize and to reveal the compensation mechanism of aerated irrigation on maize yield reduction under degradable mulching film. Three kinds of films (oxidative biodegradable plastic films with induction periods of 60 and 100 days, and traditional polyethylene film) and two irrigation methods (aerated drip irrigation and non-aerated drip irrigation) were set up for a complete combination experiment to analyze the effects of different treatments on the growth, photosynthetic characteristics, yield, and water use efficiency of maize. The results showed that the cracks initially appeared 50 and 70 days after mulching under biodegradable plastic films mulching with induction periods of 60 and 100 days, respectively. Compared to traditional plastic mulching, maize yield and water use efficiency (WUE) under degradable plastic mulching were significantly reduced by 14.81%–27.42% and 16.70%–34.46% (P<0.05), respectively. Aerated drip irrigation increased plant height, stem diameter, and leaf area index, and reduced water consumption of maize. Compared to non-aerated drip irrigation, the net photosynthetic rate, transpiration rate, stomatal conductance, and dry matter accumulation of maize significantly increased under aerated drip irrigation by 10.40%, 12.86%, 25.99%, and 7.57% (P<0.05), respectively. Aerated drip irrigation significantly increased maize yield and WUE by 6.44%–14.41% and 9.09%–17.90% on average (P<0.05) under degradable mulching film and plastic mulching film, respectively. The decline in yield and WUE caused by premature degradation due to degradable film mulching was reduced by aerated drip irrigation. It was concluded that aerated drip irrigation combined with oxidative biodegradable film with an induction period of 100 days can replace the traditional drip irrigation of maize under plastic film mulching in the oasis of Xinjiang. This study provides a theoretical basis for reducing residual film pollution and improving maize yield and water use efficiency by aerated drip irrigation under mulch in Xinjiang.

Effects of mowing and N application on growth characteristics and quality of forage grasses in legume-grass mixtures

WANG Xinyou, CAO Wenxia, SHI Shangli, WANG Xiaojun, WANG Shilin, LIU Wanting, BAI Jie, LI Wen

2022, 30(9): 1439-1450. doi: 10.12357/cjea.20220021

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Scientific and rational modes of grazing utilization and fertilization management are important agronomic measures to maintain the production performance and community structure stability of legume-grass mixtures. The study aimed to explore the regulation and control mechanisms of grazing and fertilization on the production performance and community structure stability of perennial legume-grass mixtures, and to preliminarily determine the optimal mode of grazing utilization and fertilization management for legume-grass mixtures. In the Hexi Corridor area, a 4-year-old mixed grassland with Medicago sativa ‘Qingshui’, Bromus inermis, and Elytrigia elongata (at 1∶1∶1) were used as the study objects. The L₁₆ (3¹×4²) mixed level orthogonal experimental design was used with three heights prior to mowing: 20 cm (S₁), 30 cm (S₂), and 40 cm (S₃); four mowing intensities: 2 cm (E₁), 5 cm (E₂), 8 cm (E₃), and 11 cm (E₄); four nitrogen application rates: 0 kg(N)∙hm⁻² (N₁), 75 kg(N)∙hm⁻² (N₂), 150 kg(N)∙hm⁻² (N₃), and 225 kg(N)∙hm⁻² (N₄); and the impacts of artificial mowing to simulate grazing utilization combined with nitrogen application on the community structure and production performance of mixed grassland were monitored and analyzed. The study showed that the height prior to mowing and the amount of nitrogen added had a greater impact on the production performance of mixed grasslands. The total biomass of grassland under the S₃E₂N₄ treatment was the highest (17 707.80 kg∙hm⁻²), the crude protein content of mixed forage under the S₁E₁N₄ treatment was the highest (15.46%), and the relative feeding value of mixed forage under the S₃E₁N₃ treatment was the highest (184.93). Additionally, reducing the mowing intensity could increase utilization times and the proportion of gramineous forages in the community. Among them, the coverage ratios of leguminous forages and Gramineae grasses under the treatments S₂E₃N₄, S₁E₃N₃, S₁E₄N₁, S₂E₄N₃, and S₁E₁N₁ were close to 1∶1 after simulated grazing utilization, and the treatments S₂E₃N₄, S₃E₃N₁ and S₃E₄N₂ had the best effect on the number of forage branches. Furthermore, compared with the hay harvested by conventional mowing (cutting three times a year in the area), simulated grazing reduced the forage yield but greatly improved the nutritional value of the forage and could effectively inhibit the excessive growth of M. sativa ‘Qingshui’ in the community. At the same time, it maintained the stability of the legume-grass mixture community structure. In conclusion, when the management measures were as follows: the height prior to mowing was 30 cm, mowing intensity was 8 cm, and nitrogen application rate was 225 kg(N)∙hm⁻² (S₂E₃N₄), the stability of community structure and composition balance of mixed grassland were the best. In addition, mixed grassland also had good production performance (total biomass of grassland reached 15 173.41 kg∙hm⁻²; crude protein content of mixed forage reached 13.92%; relative feed value of mixed forage reached 156.93) under the S₂E₃N₄ treatments. This management measure is a suitable reference for grazing utilization and fertilization management of mixed grasslands composed of M. sativa, B. inermis, and E. elongata, and may be popularized and applied in the Hexi Corridor and other similar regions. It can provide a scientific basis and technical support for optimizing the production and utilization of local legume-grass mixtures.

Effects of potassium and silicon fertilization on lignin metabolism and lodging resistance of oil flax stem

XU Qing, GUO Lizhuo, LIU Yahui, GAO Yuhong

2022, 30(9): 1451-1463. doi: 10.12357/cjea.20210849

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Abstract:
The potassium and silicon nutritional status of crops is closely related to lodging resistance, which is often evaluated by using lignin content. Investigating the regulatory effects of potassium and silicon nutrient coupling on lignin metabolism and lodging resistance of oil flax stems can provide a foundation for lodging resistance through fertilizer management. A three-factor split plot design was used, with variety, potassium dosage, and silicon dosage as the main treatment, split treatment, and sub-split treatment, respectively. In the study, the two varieties were ‘Longya No. 11’ (V1) and ‘Dingya No. 23’ (V2); three potassium dosages were 0 (K0), 52.5 (K1), and 105 kg(K₂O)·hm⁻²(K2); and two silicon dosages were 0 (Si0) and 90 kg(SiO₂)·hm⁻² (Si1). The results showed that there were significant differences in the stem lignin content and related metabolic enzyme activities between V1 and V2. Potassium application significantly increased lignin content, as well as the activities of phenylalanine deaminase (PAL), 4-coumaric acid: CoA ligase (4CL), and cinnamyl alcohol dehydrogenase (CAD); the order of the influence effect was K1>K2>K0. Silicon application did not have a significant effect on these test indicators, but the interaction of potassium and silicon significantly increased the lignin content before the budding stage and improved the activities of PAL, 4CL, and CAD throughout the growth stage, with the best enhancing effect derived from K1Si1 treatment. The lignin content was significantly and positively correlated with CAD activity during the entire growth period, and the increase in CAD activity was an important enzymatic basis for the increase in lignin content. The breaking resistance and lodging resistance index of V1 were higher than those of V2. Compared with K0, K1 significantly increased breaking resistance and lodging resistance index, while K2 had the opposite effect, and the influence effect was K1>K0>K2. Silicon application improved stem breaking resistance and lodging resistance index, and lower potassium accompanied by silicon significantly improved the above-mentioned two indicators. Lignin content was significantly and positively correlated with breaking resistance and lodging resistance index, and negatively correlated with the actual lodging rate. Both lower potassium treatment and lower potassium accompanied by silicon fertilizer significantly increased seed yield. In conclusion, ‘Longya No. 11’ had better lodging resistance than ‘Dingya No. 23’; 52.5 kg(K₂O)·hm⁻² accompanied by 90 kg(SiO₂)·hm⁻² most improved the lignin content, as well as the metabolic enzyme activity, lodging resistance properties, and seed yield; applying potassium fertilizer alone had a better promotion effect on lignin metabolism and lodging resistance than fertilizing silicon individually.

Soybean roots architecture and the mechanical properties of the root-soil complex in mountain red soil on sloping farmland

ZHANG Liyun, DUAN Qingsong, LI Yongmei

2022, 30(9): 1464-1476. doi: 10.12357/cjea.20220003

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The sloping farmland area in Yunnan accounts for 70% of the total arable land area, and its sustainability is affected by severe soil erosion. Approximately 89.4% of the sloping farmland in the province is utilized for planting crops, and soybeans are one of the main crops in summer. Previous studies have shown that the soil fixing capacity of vegetation roots plays a significant role in soil and water conservation. This study was conducted to explore the soil-fixing capacity of soybean roots and to provide a basis for the calculation of the soil-fixing ability of crop roots. Thus, a field experiment was designed to have two treatments with three replications for a total of six plots: bare land (CK) and mono-soybean field (SS). Unconfined compression tests were used to determine the shear strength and stress-strain characteristics of rootless soil and root-soil complexes during the three main growth stages of soybeans (blooming stage, initial grain forming stage, and seed filling stage). The WinRHIZO (Pro.2019) system was employed to analyze the geometric characteristics, fractal characteristics, and topological structure of the roots. The structural characteristics of soybean roots at different growth stages and their effects on soil mechanical properties were analyzed. The results indicated that:1) the fractal dimension of soybean roots was the smallest at the seed filling stage, and the fractal abundance was the smallest at the blooming stage, while both were the largest at the initial grain forming stage. 2) The topological index of soybean roots was the largest at the seed filling stage, followed by the blooming stage, and was the smallest at the initial grain forming stage, when it was approximately 0.5, with the smallest average link length, suggesting that the soybean roots tended to have a dichotomous topology pattern and reached the most complicated branching status at the initial grain forming stage. 3) The fractal characteristics of soybean roots were significantly and positively correlated with the main morphological parameters, such as root length (P<0.01), while the topological characteristics were significantly and negatively correlated with them (P<0.01). 4) Compared with rootless soil, soybean roots could significantly enhance the strength of root-soil complexes. The unconfined compressive strength of the soybean root-soil complexes was the highest at the initial grain forming stage, followed by the seed filling stage, and was the lowest at the blooming stage, at 41.44 kPa, 37.95 kPa, and 29.29 kPa, respectively. The fractal dimension and fractal abundance were significantly and positively correlated with the mechanical properties of the root-soil complexes (P<0.01). In conclusion, the greater the fractal dimension and fractal abundance of soybean roots are, and the smaller the topological index is, the greater the unconfined compressive strength of the root-soil complex is, and the more significant the soil-fixing capacity of soybean roots is. The fractal and topological characteristics of crop roots can not only be used to express the branching status, spatial distribution, and expansion mode of roots in soil, but can also be used as the main parameters to evaluate the soil-fixing capacity of crop roots. This study provides a reference for crop configuration on sloping farmlands in mountainous areas. Soil erosion can be prevented by cultivating soybean varieties with complex branches and well-developed roots.

Comparison of the applicability of phenological models in major maize production areas in China

KANG Xiaofeng, WU Dingrong, TIAN Qi, TAN Jiaojiao, MA Yuping, YU Qiang

2022, 30(9): 1477-1489. doi: 10.12357/cjea.20220186

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Crop growth simulation models are the primary instrument used for predicting crop developmental responses to climate change. The understanding of the applicability of phenological models is critical for measuring how climate change affects crop yields, particularly under warm climate conditions. Machine learning algorithm (MLP), maize simulation model (MAIS), response and adaption model (RAM), and Beta model (Beta) in warm climate were compared in this study. Based on phenological observation data of over 20 years for spring maize in Northeast China and summer maize in North China from agricultural meteorological station records and daily weather data, we separated the data into two categories: cold and warm years. Data were obtained by calculating the abnormality based on the mean temperature during the maize growing season. Cold years data were used to calibrate the models, and warm years data were used to validate them and subsequently evaluate their performance. The normalized root mean square error (NRMSE), mean bias error (MBE), and systematic bias of the simulation error against the average temperature of the growth period were used to evaluate the deviation between the simulated and observed maize phenology of the four models. The results showed that MLP performed much better than the three mechanistic phenology models during cold years. RAM outperformed the other mechanistic phenology models, followed by Beta and MAIS models. Our results indicated that the dates of MAIS and Beta were earlier than the observations, whereas the simulations of RAM and MLP were later than the observations. The proportion of sites with a significant trend of simulation error against the average temperature of the growth period for the RAM, MAIS, and Beta models was lower than that for MLP. Compared to that for MAIS and RAM, the proportion of sites with a significant trend for Beta was the smallest. In warm years, Beta performed better than the other models, followed by MLP, RAM, and MAIS. The simulations of the three mechanistic phenology models were earlier than the observations, but the simulations of MLP were later than the observations. Beta showed the smallest proportion of sites with a significant trend, followed by MLP, MAIS, and RAM. Overall, the models did not benefit from both calibration and validation. MLP performed well during calibration in cold years, but poorly in warm years. The overall performance of the mechanistic phenology models was worse than that of MLP in cold years, but they performed better in warm years. Different models are appropriate in various contexts. The MLP can be recommended to precisely reverse the impact of historical climate change on growth period. However, mechanistic models should be used to precisely predict the impact of future climate change on growth period.

Effects of irrigation methods on distribution characteristics, stability and nutrient contents of calcareous brown soil aggregates

SHI Xionggao, LI Xiaoming, DANG Jianyou, ZHANG Huiyu, ZHANG Dingyi, PEI Xuexia

2022, 30(9): 1490-1500. doi: 10.12357/cjea.20220073

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A field experiment was conducted at the Hancun Experimental Base of the Wheat Research Institute, Shanxi Agricultural University, from 2016 to 2021 to explore the effects of different irrigation methods (continuous micro-sprinkler irrigation, SI; continuous drip irrigation, DI; continuous flooding irrigation, FI; and annual rotation of flooding irrigation and micro-sprinkler irrigation, RI) on the distribution characteristics, stability, and nutrients contents of calcareous brown soil aggregates. After five years of positioning, >0.25 mm aggregates weight percentage of machine-stable aggregates (DR_0.25) and water-stable aggregates (WR_0.25), mean weight diameter (MWD), geometric mean diameter (GMD), destruction rate (PAD), fractal dimension (D), and nutrients (organic carbon, available phosphorus, and available potassium) contents of soil water-stable aggregates were determined. In addition, the correlations among the distribution characteristics, stability, and nutrients contents of soil water-stable aggregates were analyzed. The main results were as follows: 1) In the 0–10 cm soil layer, the dominant particle sizes of mechine-stable soil aggregates of treatments SI, DI, and RI were 0.5–1 mm, that of treatment FI was <0.25 mm. In the 10–20 cm soil layer, the dominant particle sizes of mechine-stable soil aggregates of treatments DI, FI, and RI were > 5 mm, while that of treatment SI was 0.5–1 mm; that for all treatments were > 5 mm in the 20–50 cm soil layer. The dominant particle size of the water-stable aggregate of the four treatments was <0.25 mm in the 0–50 cm soil layer, but the highest percentage of weight was observed in FI. 2) SI and DI effectively increased WR_0.25, reduced D, and resulted in higher MWD and GMD overall in the 0–50 cm soil layer, as well as decreased PAD in the 30–50 cm soil layer compared to FI and RI. However, the aggregates stability indices of treatments FI and RI were largely affected by the soil depth. 3) Compared to FI and RI, SI and DI resulted in higher contents of organic carbon, available phosphorus, and available potassium in soil water-stable macro-aggregates (>0.25 mm), and had obvious advantages in increasing available phosphorus content in the 0–30 cm soil layer and available potassium content in the 30–50 cm soil layer. 4) The results of the correlation analysis showed that the relationships between soil depth, WR_0.25, MWD, GMD, PAD, D, and nutrients (organic carbon, available phosphorus, and available potassium) contents of soil water-stable macro-aggregates were significant (P<0.05) or extremely significant (P<0.01). Overall, SI and DI were more advantageous in improving the structure and properties of soil, promoting the formation of soil macro-aggregates, and increasing the level of stability and nutrients contents of water-stable aggregates, and should be popularized and applied.

Comparison of resource utilization efficiency and comprehensive benefits among different multiple cropping rotation patterns in the middle reaches of Yangtze River

YANG Binjuan, LI Xinmei, HU Qiliang, LIU Ning, HUANG Guoqin

2022, 30(9): 1501-1510. doi: 10.12357/cjea.20220026

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Rational and efficient utilization of light, temperature, water, soil, and other agricultural resources is the premise and guarantee of sustainable agricultural development. To optimize and promote green and efficient rotation-fallow patterns in paddy fields, the effects of different multiple cropping rotation patterns on resource utilization and comprehensive benefits were studied via field experiments for two consecutive years. The experiment had 5 treatments: milk vetch-early rice-late rice → milk vetch-early rice-late rice (treatment A, CK), milk vetch-spring soybean-autumn soybean → rape-sugar cane||spring soybean (treatment B), milk vetch-early rice-maize||sweet potato → milk vetch-spring soybean-autumn soybean (treatment C), rape-sugar cane‖spring soybean → milk vetch-early rice-maize||sweet potato (treatment D), and rotation fallow → rotation fallow (treatment E); in which “-” represents rotation, “||” represents intercropping, “→” indicates to the next year. Results showed that the rotation pattern of rape-sugar cane||spring soybean → milk vetch-early rice-maize||sweet potato (treatment D) had higher effective utilization rate of accumulated temperature and precipitation of bioavailability than the CK treatment. The annual effective accumulated temperature utilization rates of the three multiple cropping rotation modes (B, C, and D treatments) were 8.60%−39.78% higher than that of CK. In 2018 and 2019, the economic and social benefit evaluation indexes of the treatment D performed the best, with values of 0.94, 0.97, and 0.96, 1.00, respectively. The ecological benefit evaluation index results showed that the treatment B was better in 2018, and the treatment C was better in 2019, with values of 0.77 and 0.73, respectively. The two-year comprehensive benefits of different rotation fallow patterns were as follows: treatment D ˃ treatment B ˃ treatment C ˃ treatment A (CK) ˃ treatment E. Therefore, the resource utilization and comprehensive benefits of “rape-sugar cane||spring soybean → milk vetch-early rice-maize||sweet potato” performed better for double rice areas in southern China. This mode could promote better crop growth and be widely applied.

Simulation of water-induced erosion and transport of particulate elements in a catchment by extending the CNMM-DNDC model

LI Siqi, LI Yong, ZHANG Wei, ZHENG Xunhua, HU Pengcheng, FAN Jihui, WANG Tao, ZHU Bo

2022, 30(9): 1511-1521. doi: 10.12357/cjea.20210781

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Abstract:
Water-induced erosion is one of the most widely distributed and severely impaired types of soil and water loss in China. Particulate carbon (C), nitrogen (N), and phosphorus (P) losses associated with soil erosion has led to several environmental problems, such as a decline in soil fertility and eutrophication of rivers and lakes. Quantitative assessment of soil erosion intensity and the identification of soil erosion spatial distribution characteristics are of great significance for control of soil and water loss and prevention of non-point source pollution. In this study, based on a well-applied soil erosion physical model of ROSE, we extended several modules of simulating the soil erosion loss and particulate C/N/P enrichments in a catchment-scale hydrology and biogeochemistry coupled model of CNMM-DNDC to simulate soil erosion and particulate C/N/P losses at a high spatiotemporal resolution on the scales of plots and catchments. For instance, the Jieliu catchment in Yanting County, Sichuan Province was used for model verification and application. The results indicated that the CNMM-DNDC with soil erosion extension performed well in simulating the seasonal dynamics of sediment yield (R²=0.83, RMSE=32.0%) and particulate N loss (R²=0.85, RMSE=88.0%) in the runoff plot with a maize-wheat rotation in the Jieliu Catchment. Therefore, the extended CNMM-DNDC model was able to simulate and evaluate the spatial distribution of soil erosion and particulate C/N/P loss intensity in the catchment. The soil erosion and particulate C/N/P loss intensity caused by land surface runoff are related to land use types and topographical features of the catchment, where severe soil erosion and high particulate C/N/P loss came from sloping cultivated lands and residential areas. From 2004 to 2006, the simulated soil erosions in the Jieliu Catchment were 400, 701, and 1550 t∙km⁻²∙a⁻¹, respectively, and were classified as the low erosion category. Meanwhile, the simulated annual particulate C losses caused by the water-induced erosion in Jieliu in 2004, 2005 and 2006 were 63.9, 107.2, and 200.2 kg(C)∙hm⁻²∙a⁻¹, respectively. Consequently, the simulated annual particulate N losses from 2004 to 2006 were 6.3, 10.5, and 19.5 kg(N)∙hm⁻²∙a⁻¹, respectively; and the simulated annual particulate P losses were 0.9, 1.5, and 2.8 kg(P)∙hm⁻²∙a⁻¹, respectively. This study extended the erosion functionality of the CNMM-DNDC model in terms of simulating soil sediment yield and particulate C/N/P loss and can provide useful supporting tools for the research and control of soil erosion and non-point source pollution.

Effect of Phanerochaete chrysosporium inoculation in different times of rice husk and chicken manure composting on humification of compost

MA Liting, XU Zhi, ZHAO Bing, CHEN Yan, DENG Yaqin, WANG Yuyun

2022, 30(9): 1522-1530. doi: 10.12357/cjea.20210903

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Abstract:
In the process of rice processing, a large amount of agricultural organic solid waste (e.g., rice husk) is produced, and composting is an effective way to realize resource utilization of rice husk. However, lignin in rice husk has a complex structure and is not easy to be degraded, and the high content of lignin limits the composting of rice husk, and exogenous inoculation of Phanerochaete chrysosporium can accelerate the degradation of lignocellulose. However, the effect of inoculation of P. chrysosporium in different composting times on the humification process of rice husk composting is not clear. Therefore, in this study, rice husk and chicken manure were used as raw materials, P. chrysosporium was inoculated in the 18^th day of composting (cooling stage of composting, T2), and 0 day of composting (T3, beginning of composting), for aerobic composting, with T1 (no inoculation) as the control. By analyzing composting temperature, pH, C/N, seed germination rate, lignin peroxidase, manganese peroxidase, lignin content, cellulose content and humus to explore the effect of inoculating P. chrysosporium at different composting times on the degradation of lignin and cellulose, the changes of key enzyme activities and their coupling with the process of humification, the promoting effect of inoculating P. chrysosporium on composting humification was determined. The results showed that the lignin peroxidase (LiP) and manganese perosidase (MnP) activities, lignin and cellulose degradation rates and humification degree were significantly increased after P. chrysosporium inoculation during the cooling period (T2). At the end of composting, the cellulose content of T2 treatment decreased from 0.30 g∙g⁻¹ of initial compost to 0.09 g∙g⁻¹, and the lignin content decreased from 0.24 g∙g⁻¹ of initial compost to 0.03 g∙g⁻¹. Compared with T1, the contents of lignin and cellulose decreased by 78.57% and 52.63% (P<0.05) under T2 treatment, and 57.14% and 40.00% (P<0.05) under T3 treatment. T2 treatment increased the humus content by 67.84% and 52.33% (P<0.05), respectively, compared with T1 and T3. Various maturity indexes showed that the compost quality of T2 treatment was significantly improved, the humification rate (HR), ratio of humic acid to fulvic acid (HA/FA) and percentage of humic acid (PHA) reached 51.64%, 2.72 and 73.39%, respectively, significantly higher than T1 and T3 (P<0.05). The results of correlation analysis showed that the contents of lignin and cellulose were significantly negatively correlated with the activities of lignocellulosic degradation enzymes (LiP and MnP) (P<0.05, P<0.01); Redundancy analysis (RDA) showed that degradation rate (explanatory degree=88.2%, P=0.002), cellulose content (explanatory degree=74.3%, P=0.002) and lignin content (explanatory degree=72.5%, P=0.002) had the most significant effects on the maturity index. These results indicated that the degradation of lignin and cellulose promoted the formation of HS, the deep degradation of lignin and cellulose promoted the complexity of HS structure and made the HS structure more stable. Therefore, inoculation of P. chrysosporium in the cooling period of composting promoted the deep degradation of lignin and cellulose by improving the activities of LiP and MnP, thus strengthened the humification process of composting and improved the quality of compost, and provided theoretical basis for the composting production of rice husk.

Empirical analysis of agricultural economic growth and planting non-point source pollution emissions from the perspective of spatial effects

LI Xin, SHANG Jie

2022, 30(9): 1531-1544. doi: 10.12357/cjea.20210840

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Abstract:
Agricultural resources and environment are the basic resources and necessary conditions for the development of agricultural production and realization of agricultural economic growth. Analyzing the relationship between agricultural economic growth and planting non-point source pollution from the perspective of spatial effects can help to explore a new direction for prevention and control of planting non-point source pollution, and provide theoretical support for promoting the implementation of the policy of prevention and treatment of planting non-point source pollution. Based on the provincial panel data from 2000 to 2019, this study used the equal-standard pollution load method to measure the planting non-point source pollution emissions; and used the spatial Durbin model to empirically analyze the spatial effect of agricultural economic growth, consumption capacity, technological progress, agricultural modernization level, risk perception, financial support, disaster situation, and industrial structure on the emission of planting non-point source pollution, and to split the spatial effect of the influencing factors into direct and indirect spatial effects. The results are as follow: 1) A significant positive global spatial autocorrelation among the planting non-point source pollution in 31 provinces (cities, autonomous regions) was noted. In 2019, the spatial pattern was characterized by “high-high” and “low-low” aggregations, and the agglomerations were mainly in large agricultural provinces and economically developed areas. 2) The planting non-point source pollution had a significant negative spatial spillover effect, with a spatial lag coefficient of −0.11, and agricultural economic growth had a significant effect on the region and adjacent regions in a mutually exclusive direction. 3) The results of the effect of decomposition showed that the direct and indirect effects of agricultural economic growth, consumption capacity, technological progress, agricultural modernization level, and risk perception were significant at 5% confidence level. Among them, agricultural economic growth had a relieving effect on planting non-point source pollution discharge, and the estimated coefficient was −0.175; however, it had an aggravating effect on the planting non-point source pollution discharge in the adjacent area, with an estimated coefficient of 0.397. Therefore, by paying more attention to the guiding role of the significant influencing factors, such as agricultural economic growth, technological progress, and financial support, local governments should actively give full play to their own advantages and linkage with adjacent areas to play a spatial interaction, carrying out new agricultural technology training, and establishing an effective supervision and management system to achieve balanced development. From the perspective of the research object, this study analyzed the relationship between agricultural economic growth and agricultural non-point source pollution from the perspective of the planting industry, and it enriches existing research on planting non-point source pollution and improves the attention to the prevention and control of planting non-point source pollution. Moreover, the emissions of planting non-point source pollutants were calculated based on the emissions of ammonia nitrogen, chemical oxygen demand, total nitrogen, and total phosphorus from agricultural chemical fertilizer and farmland solid waste, and this helps to ensure the comprehensiveness of the data required for empirical analysis and can more accurately describe the relationship between agricultural economic growth and planting non-point source pollution emissions. The combination of the two dimensions of time and space to analyze the relationship between agricultural economic growth and agricultural non-point source pollution emissions can provide a new analytical perspective and play an important role in putting forward more practical countermeasures and suggestions.

Development and trend in Chinese agricultural green technology: Knowledge map analysis based on CiteSpace

WANG Xin, SONG Yanping, CHEN Tianyu, LI Tan

2022, 30(9): 1545-1554. doi: 10.12357/cjea.20210872

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Abstract:
Green technology is an important driving force that underlies the high-quality development of agriculture in China. However, there is little in-depth research on the scale and type structure of the technology. Clarifying the agricultural green technology development status and trends in China will significantly promote agricultural innovation and drive agricultural sustainability. In this study, the CiteSpace software was used to systematically sort and analyze the knowledge map based on the agricultural green technology achievement data for the national and provincial science and technology awards from 2004 to 2019. The results showed the following: 1) The number of agricultural green technology achievements was generally increasing, with an average annual growth rate of 5.15%. The number of achievements associated with planting was significantly higher than that with breeding, accounting for about 80.19% of the total achievements, but the average annual growth rate for agricultural green technology achievements for planting was relatively low. 2) Agricultural green technology keywords formed 17 clusters, including wide adaptability breeding, virus detection, deep processing, efficient cultivation, and so on. They mainly focused on four aspects of agricultural green technology: safe and harmless inputs, environmentally friendly production processes, economical and efficient resource use, and environmental monitoring and early warning. China had established an agricultural green technology system, but there were only a few technologies related to quality standards. 3) There were seven emergent words for green technology achievements in Chinese agriculture from 2004 to 2019, and green technology associated with comprehensive prevention and control, quality and efficiency improvement of agricultural production, and green prevention and control had become new research hotspots in recent years. Agricultural green technology R&D and innovation are closely related to agricultural policies, and results had shown that policy guidance effectively promoted the technology. 4) The number and clusters of regional agricultural green technology achievements differed and decreased from east to central to west. The influence of regional characteristics means that research hotspots in different regions have unique characteristics. Based on these results, we proposed the following policy recommendations: promoting the integrated development of agricultural green industrial technology and green rural comprehensive development technology, improving the coordination of agricultural green technology by combining policy guidance and market pull, strengthening regional green agricultural technology characteristics, and promoting the structural optimization and upgrading of agricultural green technology. This study provides a visual analysis of agricultural green technology development in China. The study also improves the current understanding of the research progress in this field and promotes the exploration of new developments and trends.

2022 Vol. 30, No. 9