中国生态农业学报(中英文)

Biochar's effect on soil N₂O consumption and the microbial mechanism

HE Chaohui, DONG Wenxu, HU Chunsheng, LI Jiazhen

2019, 27(9): 1301-1308. doi: 10.13930/j.cnki.cjea.190175

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Abstract:
Biochar is a promising material for mitigating greenhouse gas emissions. In addition to carbon sequestration, it has positive effect on the ozone-depleting gas nitrous oxide (N₂O), which is with long residence time and strong warming potential. In this research effort, an anaerobic incubation experiment was conducted. Three treatments with different biochar application rates were set, taking account of biochar to soil ratio (w/w):0 (0BC), 1% (1%BC) and 5% (5%BC). Soil gravimetric water content was controlled at 20%. According to the robotized incubation platform providing real-time determination of N₂O and N₂ concentrations and soil denitrification functional gene abundance measurement, we analyzed the impact of biochar on N₂O consumption and biological mechanisms. The main results indicated that after a 20-hour anaerobic incubation, the denitrification functional gene abundance of 0BC treatment was 6.80×10⁷ (nirK), 5.59×10⁸ (nirS), 1.22×10⁸ (nosZ) gene copies per gram soil, respectively. Compared with 0BC treatment, the nirS gene abundance of 1%BC treatment increased from the initial 2.65×10⁸ to 7.43×10⁸ gene copies per gram soil, while, the nosZ gene abundance increased by an order of magnitude from 4.82×10⁷to 1.50×10⁸ gene copies per gram soil. However, there was no significant change in nirK gene abundance. And the denitrification functional gene abundance of 5%BC treatment did not show marked variations. In conclusion, the N₂/(N₂O+N₂) ratio of treatments with biochar application was clearly higher than 0BC treatment. The results of correlation analysis showed that nirS and nosZ gene abundance was significantly correlated with the N₂O concentration at 0.01 level, and the abundance of nirS and nosZ genes all increased as N₂O concentration declined at the end of the experiment. Therefore, in the present trial, a 1% biochar addition significantly increased the abundance of denitrifying bacteria with nirS and nosZ genotypes and N₂/(N₂O+N₂) ratio, and promoted the complete reduction of N₂O to N₂. The main mechanism of the biochar effect on N₂O emission was the enhanced reduction activities and gene expression of nosZ-containing microorganisms, resulting in complete denitrification.

Nitrogen and phosphorus cycling characteristics and balance of the integrated rice-crayfish system

SI Guohan, YUAN Jiafu, PENG Chenglin, XIA Xiange, CHENG Jianping, XU Xiangyu, JIA Ping'an, XIE Yuanyuan, ZHOU Jianxiong

2019, 27(9): 1309-1318. doi: 10.13930/j.cnki.cjea.190088

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Abstract:
The integrated rice-crayfish system is an emerging complex ecological system of planting and breeding in the middle and lower reaches of the Yangtze River in China. The study of N and P cycling characteristics and the profit and loss status of N and P in the integrated rice-crayfish system is of great significance to rationally regulate the nutrient cycling and balancing of the integrated rice-crayfish system and guide the optimal management of the N and P. In this study, a field experiment was conducted to study the cycling characteristics and apparent balance of N and P under the integrated rice-crayfish system using an input-output method, with the rice monoculture system as the control. The results showed that the output/input ratios of N and P in the crayfish subsystem were 0.62 and 0.44, respectively. Inside the crayfish subsystem, the N and P were the largest in the feed input, accounting for 92.9% and 96.4% of the total input, respectively; the output of adult crayfish N and P was the largest, accounting for 53.3% and 59.5% of the total output, respectively. Under the current input levels, the apparent balance of both N and P in the soil subsystems of the two systems were in surplus, and the surplus of N in the soil subsystem of the integrated rice-crayfish system was higher than that of the rice monoculture system, while the surplus of P was lower than that of the rice monoculture system. The N and P output/input ratios of the integrated rice-crayfish system and the rice monoculture system were both less than 1, and the N and P output/input ratio of the integrated rice-crayfish system were less than that of the rice monoculture system. The integrated rice-crayfish system increased the amount of N and P in sequestered soil, and the N and P levels in sequestered soil of the integrated rice-crayfish system were higher than those of the rice monoculture system by 49.2 kg·hm^-2 and 9.1 kg·hm^-2, respectively. The integrated rice-crayfish system increased the apparent loss of N and P in the system, and the apparent losses of N and P of the integrated rice-crayfish system were higher than those of the rice monoculture system by 10.2 kg·hm^-2 and 1.0 kg·hm^-2, respectively. It can be seen that the integrated rice-crayfish system reduces the output/input ratio of N and P and promotes the accumulation of N and P in the soil but increases the apparent loss of N and P in the system.

Research advances in vegetation restoration and its ecological effects in earth-rock mountain areas of North China

WANG Zhiyin, CAO Jiansheng

2019, 27(9): 1319-1331. doi: 10.13930/j.cnki.cjea.190108

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Afforestation is a method for building a beautiful China, promoting the construction of ecological civilization, and improving the well-being of people's livelihood. It is a concrete measure to realize the green hills and mountains. The sparse vegetation, poor soil, severe climate, frequent disasters, and unreasonable production from human activities in the northern earth-rocky mountains have caused serious damage to the vegetation in the region, resulting in a series of ecological and environmental problems and forming large exposed areas of rocks, serious soil erosion. Vegetation recovery is the key to ecological restoration in this region. Here, we reviewed the current research status of vegetation restoration in the earth-rocky mountains of North China and the existing problems in current research, including allocation patterns and afforestation technology selection in vegetation restoration, environmental factors affecting vegetation restoration, and ecological effects of vegetation restoration. Further, we discussed the effects of allocating different tree species and afforestation techniques on the survival rate of afforestation. It was pointed out that the variant tree species and rational regulation of tree water use were keys to successful vegetation restoration in the earth-rocky mountains. We also discussed the effects of soil fertility, water, topography, and zonal differences on vegetation restoration, and the hydrological, soil and water conservation, soil environment, and biodiversity effects of vegetation restoration. We found that, in the process of vegetation restoration in the earth-rocky mountains, the vegetation and the environment interacted with and promoted each other; this, in turn, accelerated the restoration and upgrading of the regional ecosystem structure and function. At the same time, it was found that the researches on topographic effect of vegetation change in the earth-rocky mountains was relatively lacking, and the mechanism of soil nutrient impact on vegetation restoration was not yet clear. Finally, there were problems of unreasonable tree species selection, short research scale, limited data, and insufficient economic research on vegetation restoration in the process of vegetation restoration in the earth-rocky mountains. Our study proposed that more attention should be paid to selecting fine native tree species to plant in combination, establishing a long-term monitoring network for vegetation succession, monitoring and evaluating the comprehensive benefits of vegetation restoration, and clarifying the response mechanisms of vegetation to extreme climate; solving these issues was the next step in restoring vegetation research in the earth-rocky mountains.

Effect of nitrogen reduction on yield stability of sweet maize//soybean intercropping system in South China

LIU Pei, SHAO Yuting, WANG Zhiguo, TANG Yiling, WANG Jianwu

2019, 27(9): 1332-1343. doi: 10.13930/j.cnki.cjea.190129

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Abstract:
The increasing demand for fresh sweet maize (Zea mays L. saccharata) in southern China has prioritized the need to find solutions to the environmental pollution caused by its continuous production and excessive use of chemical nitrogen fertilizers. A promising method for improving crop production and environmental conditions is to intercrop sweet maize with legumes and to reduce nitrogen fertilization. In this paper, a field experiment was conducted at the Experimental Center of South China Agriculture University for a total of 9 cropping season in five years (2013-2017) to investigate the dynamic changes of maize//soybean intercropping and system yields in sweet maize farmlands in South China under two nitrogen levels[reduced nitrogen dose of 300 kg·hm^-2 (N1) and conventional nitrogen dose of 360 kg·hm^-2 (N2)] and four cropping patterns[sole sweet maize (SS), sweet maize//soybean intercropping with sweet maize to soybean line ratios of 2:3 (S2B3) and 2:4 (S2B4), sole soybean (SB)]. This study analyzed the dynamic change of land equivalent ratio and actual yield loss index, and evaluated the stability of system yield by W² (Wricke's ecovalence), CV (coefficient of variation) and SYI (sustainability index), and aimed to explore the effects of reduced nitrogen application on the time stability of sweet maize//soybean intercropping system in South China. Results showed that:1) the yields of sweet maize, soybean, and the total system under different treatments showed obvious seasonal dynamic changes and were significantly affected by cropping and planting patterns. Nitrogen application levels only significantly affected the yield of sweet maize. 2) The relative yield of sweet maize under all intercropping treatments was higher than that under monocropping, and the actual yield loss index (AYLs) of the intercropping system was greater than zero, indicating that sweet maize//soybean intercropping could maintain the intercropping advantage stably and significantly improving land use efficiency. 3) There were no significant differences in W², CV and SYI of sweet maize among different treatments, but the W²value of monocropping soybean was significantly higher than that of the intercropping patterns, and the yield stability of monocropping soybean was lower than that of intercropping soybean. Planting pattern had a significant effect on the stability of the total yield of the system, and intercropping soybean increased the stability of the total yield of the system. 4) Nitrogen fixation of intercropping soybean significantly increased the soil fertility contribution rate. The soil fertility contribution rate of S2B3 and S2B4 were 75.07% and 74.27%, respectively, which were 30.29 and 29.47 percentage points higher than that of SS, respectively. 5) Compared with monocropping sweet maize, sweet maize//soybean intercropping in 9 seasons significantly increased soil pH and alleviated the effect of soil acidification induced by a large amount of nitrogen application on soil fertility for a long time. The soil organic matter and total nutrient content in the sweet maize//soybean intercropping system were not affected by continuous reduced nitrogen application, and 300 kg·hm^-2 could meet the needs of sweet maize and soybean for nitrogen. Reducing nitrogen application and intercropping soybean are sustainable and green production models for efficient utilization of resources and stable system yield in sweet maize producing areas in South China.

Effect of conservation tillage on natural resources utilization efficiency and sustainability of integrated wheat-maize intercropping system

WANG Qiming, HU Falong, CHAI Qiang

2019, 27(9): 1344-1353. doi: 10.13930/j.cnki.cjea.190063

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The integrated production system is effective for crop intensification and also plays an important role in improving biodiversity and grain yield. The reduction of greenhouse gas emissions and crop water consumption are important parameters in developing high-efficient and sustainable agriculture in arid areas. Researches on soil carbon emission, water use and characteristic of the integrated production system will benefit the productivity and sustainability of agricultural practices in this region. The experiment was carried out in 2011 and 2012 at the Oasis Agricultural Scientific Researching and Teaching Station of Gansu Agriculture University and Local Government, China. Wheat-maize intercropping system was used as the object of this study due to its long-term application in Hexi Oasis region. Through integration, different conservation practices, including no-till with stubble standing, no-till with stubble mulching, and reduced tillage with stubble incorporation were applied in wheat-maize intercropping system forming three integrated production systems (named NTS, NTM and RTS, respectively), with conventional intercropping (CTI), conventional monocropped maize (CTM) and wheat (CTW) as the control systems. The study mainly focused on soil carbon emission and water use characteristics of different cropping systems, and further compared the differences in system effectiveness and sustainability. Results showed that the energy yield of integrated wheat-maize intercropping system increased by 113% over monocropping wheat, and by 21% over monocropping maize, and the land equivalent ratios of integrated intercropping systems based on energy yield were greater than 1. The integrated system also significantly reduced soil CO₂ emission, especially for the NTM, of which, the soil CO₂ emission was reduced by 12% than CTM, and by 13% than CTI. Also, its' CO₂ emission efficiency increased by 39% over CTM, and by 31% over CTI. In addition, the integrated system significantly reduced the crop water consumption. Compared to CTI, NTM reduced evaporation, water consumption and carbon emission per unit of water by 11%, 5% and 9%, respectively. Nevertheless, the energy yield per unit of water improved by 19%. Compared to CTI, land (1.78), carbon (1.48) and water (1.22) equivalent ratios improved by 14%, 28% and 20% under NTM respectively. Therefore, the sustainability index was enhanced by 13% over the CTI. Consequently, the integrated wheat-maize production system can be used as a high-efficient and sustainable cropping model in the Hexi Oasis Irrigation Area.

Simulation of dry matter accumulation and nitrogen absorption in a maize/soybean intercropping system supplied with different nitrogen levels

WANG Xuerong, ZHANG Runzhi, LI Shumin, XU Ning, MU Yao, ZHANG Chunyi

2019, 27(9): 1354-1363. doi: 10.13930/j.cnki.cjea.190075

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Abstract:
Maize/soybean intercropping has yield advantages to an extent. However, different nitrogen supply levels have different effects on dry matter accumulation and nitrogen uptake in the maize/soybean intercropping system. A field experiment with a split design and logistic model were used to simulate dynamic changes in dry matter accumulation and nitrogen uptake in a maize/soybean intercropping system supplied with four nitrogen levels. Simulation results showed that dry matter accumulation and nitrogen uptake dynamics in maize and soybean were consistent with the logistic model, with correlation coefficients (R²) higher than 0.9 at the four nitrogen levels. The maximum growth rate (I_max-B) of intercropped maize compared with monoculture increased by 34.2%, 46.7%, 25.9% and 25.1% when the nitrogen supply levels were N0 (without N supply), N1 (180 kg·hm^-2), N2 (240 kg·hm^-2), and N3 (300 kg·hm^-2), respectively. The I_max-B of the soybean decreased by 27.7%, 30.3%, 16.5%, and 23.7%, respectively. However, the average I_max-B in the intercropping system was increased by32.1%. The other dry matter simulation parameters of maize and soybean were consistent with the I_max-B. Additionally, nitrogen uptake dynamics showed synchronous changes with dry matter accumulation. Under N1 treatment, the maximum nitrogen uptake (K_-N), maximum uptake rate (I_max-N), and instantaneous uptake rate (r_-N) of intercropped maize was 18.4%, 48.9%, and 25.8% higher than that of the monoculture, while the K_-N, I_max-N, and r_-N of the intercropped soybean was 15.9%, 29.9%, and 16.69% lower than that of the monoculture, respectively. The simulation parameters of K_-N, I_max-N, and r_-N in the intercropping system were 0.4%, 13.7%, and 7.8% higher than those of monoculture, respectively. Nitrogen supply had no significant effect on r_-N of soybean. A significant advantage of nitrogen in the intercropping system was observed with nitrogen land equivalent ration (LER_N)>1, and the LER_N value under N0 treatment was the highest. With the increase in nitrogen application, the LER_N exhibited a downward trend. In the present experiment, the highest dry matter accumulation and nitrogen uptake were observed under N2 treatment, which had obvious advantages for intercropping.

Crop yield increasing and efficiency improving effects and development of technology of ridge-furrow cultivation with plastic film mulching

JIN Lele, QIAO Yunzhou, DONG Baodi, YANG Hong, WANG Yakai, LIU Mengyu

2019, 27(9): 1364-1374. doi: 10.13930/j.cnki.cjea.190153

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Abstract:
The shortage of water resources in northern China limits the sustainable development of agriculture. The crop cultivation technique of ridge-furrow with plastic film mulching can significantly increase the yield and water-use efficiency. This paper reviewed the development and current situation of technology of ridge-furrow cultivation with plastic film mulching, discussed its effects on the yield of several major crops and its mechanisms, and proposed the future development. It was expected to promote the further development of the technology and provide reference for the relevant researches. In the technique of ridge-furrow cultivation with plastic film mulching, a ridge is created, then covered with plastic film; crops are planted between the ridges. The advantages of this technique promote its application, which are:1) it improves the effectiveness of soil water. Film mulching over the ridge inhibits surface evaporation and increases soil water content by collecting rain water and condensation of soil water. 2) It regulates the ground temperature. Ridge mulching increases soil temperature, especially at the crop seedling stage, increasing emergence and seedling rates; it also decreases soil temperature during high temperature period, promoting crop growth and development. 3) It improves soil physical and chemical properties, improves soil structure, adjusts soil enzyme activity, and provides a good soil environment for crop growth. However, the mulching film cultivation mode also has certain deficiencies:1) the development and promotion of the ridge laminating machine is relatively backward. 2) Mulch film creates pollution; this is becoming an increasingly serious problem, and it is laborious to reverse. 3) The technical specifications of ridge mulching technology lack specific standards. The future development directions of the ridge-furrow cultivation with plastic film mulching mode in North China are as follows:1) improving the agricultural machinery needed to implement this technique; 2) applying a new harmless film; and 3) constructing different crop technical regulations. An in-depth study of the basis of high-efficiency water-saving agricultural cultivation techniques, further research and development of new technologies for agricultural planting methods, and full use of water resources are all necessary for the future.

Effects of short-term heat stress on island cotton yield formation of different fruiting branches

CHEN Zhen, CHEN Ping, ZHANG Jusong, Abudukadier•KUERBAN, LIN Tao, GUO Rensong

2019, 27(9): 1375-1384. doi: 10.13930/j.cnki.cjea.181102

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High temperature is an important environmental factor affecting cotton yield. An experiment was conducted on the effects of short-term heat stress during the full bloom stage on fruit branch yield and yield components of island cotton; it is helpful to provide theoretical methods for breeding heat-resistant and stable-yielding varieties and formulating high-yield and stress-resistant cultivation techniques for island cotton. Using 'Xinhai 43' and 'Xinhai 49', a warming shed was set up in the field during the full bloom stage, and treatments of four warming levels[lasting for 0 (control), 3 (H3), 6 (H6), and 9 d (H9)] were employed to simulate the effects of short-term high temperature stress. The effects of temperature increase on dry matter accumulation, net photosynthetic rate, abscission rate of squares and bolls, yield, and yield components were analyzed. The results showed that short-term heat stress at the full bloom stage resulted in a significant increase in abscission rate of squares and bolls of the middle fruit branch of 'Xinhai 43' and 'Xinhai 49', and total dry matter accumulation of cotton plants decreased. At 30-50 days after anthesis, the dry matter of cotton bolls was significantly lower than that of the control. However, at 40-50 days after anthesis, the dry matter of the stems and leaves of two varieties with H6 and H9 treatments were significantly greater than those of the control. As the growth process progressed, compared with the control, the maximum dry matter of 'Xinhai 43' and 'Xinhai 49' with H3, H6 and H9 treatments decreased by 8.9%, 29.3% and 36.3%, and 11.8%, 28.1%, and 42.6%, respectively; and the daily average accumulation of cotton bolls decreased by 10.9%, 32.8%, and 42.2%, and 12.8%, 30.3%, and 45.9%, respectively. The time needed to reach the terminating date of fleet accumulation period increased by 5, 8, and 14 d, and 1, 5, and 10 d in 'Xinhai 43' and 'Xinhai 49', respectively. During the warming treatment, the P_n of the two varieties leaves decreased significantly with longer warming duration. After the end of warming, the senescence rate of P_n in each treatment was different. At the later stage of reproductive growth (40 days after anthesis), the P_n of leaves treated with H3, H6, and H9 was higher than those of the control, and in the order of H9 > H6 > H3 > CK. Short-term high temperature resulted in a significant decrease in boll number per plant, boll weight, and lint percentage. Among them, the coefficient of variation of boll number per plant (15.4% to 18.5%) was the largest, and the coefficient of variation of lint percentage (4.1% to 4.7%) was the smallest. Under the treatments of H3, H6, and H9, the boll number per plant of 'Xinhai 43' and 'Xinhai 49' decreased by 21.6%, 22.5%, and 28.9% and 16.6%, 26.4%, and 34.7%, respectively. However, the warming significantly increased the number of bolls in the upper fruit branches, and the number of bolls in the upper fruit branches of 'Xinhai 43' and 'Xinhai 49' increased by 0-24.9% and 2.7%-58.2% compared with the control. This, in turn, increased the yield and yield contribution rate of the upper fruit branches. Among varieties, the decrease in P_n, boll number, boll weight, and abscission rate of squares and bolls of 'Xinhai 49' were greater than those of 'Xinhai 43', suggesting that 'Xinhai 43' has better heat resistance.

Backscattering characteristics and texture information analysis of typical crops based on synthetic aperture radar: A case study of Nong'an County, Jilin Province

WANG Lihua, JIN Huihu, WANG Chencheng, SUN Ruixi

2019, 27(9): 1385-1393. doi: 10.13930/j.cnki.cjea.190274

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Agriculture is the foundation of the national economy. Clarifying crop type, spatial and temporal distribution, and planting structure is an important scientific basis for the rational adjustment of agricultural framework. Optical remote sensing relies on solar radiation and is often subject to the influence of clouds. Therefore, optical remote sensing images cannot be obtained during cloudy weather. Synthetic aperture radar (SAR) images are not affected by cloud and fog and can provide all-day, all-weather data. Therefore, the backscatter characteristics and texture information of typical crops can be analyzed by using SAR images, which may improve accuracy of large area monitoring of crops in all weather conditions. In this study, Nong'an County in Jilin Province was taken as the study area, and 12 Sentinel-1B SAR images with dual-polarization were pre-processed. Then the SAR backscattering characteristics and texture information of typical crops with dual polarization were analyzed. The results showed that the co-polarization (VV) SAR backscattering coefficients of three crops (soybean, corn, rice 1 and rice 2) were higher than the cross-polarization (VH) coefficients during the growth period, and the ability of crop plants to change the polarization mode was about -25 to -15 dB. Over the whole growth seasons of crops, the backscattering coefficients showed large fluctuations. The backscattering characteristics of each growth stage were different. During the early growth stage of three crops, the soil played a major role in determining the backscattering characteristics, and the roughness of soil was small. Therefore, the three crops on the SAR images were dark in color. With the growth of the crops, the backscattering from crops was mainly due to canopy scattering and soil scattering. The backscatter coefficient value increased with crop growth, which meant that the color of the crops changed to a relatively bright shade on the SAR image. When crops reached the jointing stage or branching stage (after July 10), in addition to canopy scattering, their backscattering signal was strongly affected by the soil water content and its interaction with respective crops. The soil water content of rice was high. Therefore, the backscattering coefficient of rice considerably decreased after the jointing stage. The absorption of radar waves by rice was stronger than those of corn and soybean, which meant that the backscattering coefficient of rice was smaller than the coefficients for corn and soybean, especially in the VH polarization SAR images. The crop SAR texture information analysis showed that the mean, variance, and homogeneity could accurately identify crops on SAR images. The best texture information was the mean of VH polarization. The variance and homogeneity of VV polarization could also accurately identify the two kinds of rice. The best recognition phase for the crops on SAR images was from May 23 to July 10.

Early warning system of field phosphorus loss risk for double cropping area in North China

JI Hongjie, ZHANG Huaizhi, ZHANG Renlian, XU Aiguo, TIAN Changyu

2019, 27(9): 1394-1401. doi: 10.13930/j.cnki.cjea.190229

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Rotation is a relatively fixed crop combination pattern that forms in various places over a long period. It is also the basic unit for the calculation of farmland nutrient balance. The accumulation of nutrient surplus or deficiency over the years directly affects the environment. Among the three essential nutrients for plants, the most important for the environment are phosphorus and nitrogen. Compared with nitrogen, the phosphorus cycle is relatively stable, has no gas loss, and reveals a high correlation between apparent nutrient balance and environmental pollution of phosphorus, and the calculation for which is convenient. Therefore, phosphorus was selected as the indicator for environment risk in this study. In order to establish a simple and effective method to detect early warnings of environmental effects, starting with the screening of key elements suitable for early warning and key links to phosphorus loss in farmland, this article proposed an early warning indicator system based on farmland plots suitable for small-holder farmers in China. The study also performed trial calculations with survey data from 38 plots, including five typical rotation systems in North China. The early warning system included three evaluation indicators-annual phosphorus balance, plough layer soil texture, and annual phosphate fertilizer operation. A total of six early warning levels of phosphorus loss was set in the early warning system-dark green, light green, light yellow, deep yellow, light red, and deep red, in which the red meant high phosphorus loss risk, the green meant low phosphorus loss risk, the yellow meant medium phosphorus loss risk, deep and light mean degree of the level. The characteristics of the early warning system were 1) measuring the entire rotation cycle rather than a single crop; and 2) the phosphorus balance considered the total balance of the anniversary (i.e., the phosphorus input and output balance of the entire rotation cycle) and considered the difference between different crops. Scientific allocation (i.e., phosphorus co-ordination) used relative equilibrium values rather than absolute equilibrium values so that the phosphorus balance between different rotation types could be uniformly quantified and compared. Soil texture was simplified to sand, loam, and clay species. The trial results showed that a low early warning level (dark green) which was rational in application of phosphate fertilizer with reasonable application rate and co-ordination between rotation crops only occupied 10.53% of all plots analyzed, while the high environmental risk (dark red, light red) rotation plots accounted for 57.89%, i.e., more than half of the plots using the current rotation methods had high or extremely high environmental risks. The early warning system was scientific, practical, and simple, and the required data were easy to be obtained. It can be used for farmers to judge the risk of phosphorus loss in their own plots and for national, regional, or local agricultural authorities to reference when adjusting planting structures.

Growth and nutrient uptake rates of duckweed cultivated on anaerobically digested dairy manure

Kruger Kevin, He B.Brian, Chen Lide

2019, 27(9): 1402-1408. doi: 10.13930/j.cnki.cjea.190251

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Nutrient cycling from flushed dairy manure systems to croplands is a national research priority for sustainable dairy operations, resource utilization, and environmental protection. Cultivating aquatic plants on dairy wastewaters has been considered an effective approach for wastewater treatment/reuse and nutrient recycling. This study aimed to investigate nutrient uptake and biomass production of duckweed strains on dairy wastewater. Three duckweed strains, namely Landoltia punctata 0128, Lemna gibba 7589, and Lemna minuta 9517, were cultivated on anaerobically digested (AD) dairy manure wastewater over a period of 28 days. The highest reduction rate of total nitrogen (TN) was achieved by L. punctata from the AD dairy manure with a dilution ratio of 1:18 (83.1 mg·L^-1 TN) at 11.6% (±1.64%). The highest reduction rate of total phosphorus (TP) was achieved by L. punctata from the AD dairy manure with a dilution ratio of 1:27 (6.7 mg·L^-1 TP) at 15.4% (±4.4%). The corresponding fresh weight-based growth rate constants of L. punctata were 0.11 g·d^-1 and 0.17 g·d^-1 for the dilution ratios of 1:18 and 1:27, respectively. It has been shown that, among the three duckweed strains tested in this study, L. punctata has the greatest potential to be cultivated on the medium of diluted AD dairy manure for best N and P reduction and biomass production.

Green/blue water allocation as affected by Grain-for-Green practices in the upper reaches of the Yiluo River

LIAN Xie, HUANG Feng

2019, 27(9): 1409-1420. doi: 10.13930/j.cnki.cjea.190032

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Land use/cover change (LUCC) is of significant impact on regional water cycle. Land use decision-making is water resources decision-making, which has been confirmed by many studies and recognized by researchers and decision makers. Taking the upper reaches of Yiluo River in the middle reaches of the Yellow River Basin as the case study area, this paper applied the distributed watershed agricultural eco-hydrological model SWAT (Soil and Water Assessment Tool). According to the important background of ecological restoration and reconstruction of Grain-for-Green in China, six different land use change scenarios were set up to study the impact of land use/cover change on watershed water cycle from the perspective of blue/green water. This paper calibrated and validated the monthly runoff output of SWAT model, and proved that the model achieved acceptable accuracy and rationality in simulating the hydrological cycle of the river basin. One-way ANOVA and multiple comparisons were used to analyze the effects of land use change on the changes of various hydrological factors based on different hydrological years. The results showed that:1) From 2010 to 2015, the annual average precipitation resources was 3.494 billion m³, and the annual average of total blue water and green water resources was 3.409 billion m³. Blue water resources accounted for 33.73%, and green water resources accounted for 66.27% of the total blue water and green water resources in multi-year average. 2) Under different scenarios of Grain-for-Green, the amount of blue water resources decreased, the green water flow increased, and the green reservoirs decreased. In the year of the wet year and normal year, the impact of land use/cover change on the surface runoff component of the blue water resources was more obvious. This conclusion has certain significance for deepening the understanding of the relationship between land use/cover and water resources in the upper reaches of the Yiluo River, and provides a scientific basis for efficient and rational utilization of water and soil resources in the region.

Effects of conservation tillage on soil wind erosion characteristics in the Hexi oasis irrigational area

LI Yinke, LI Jingjing, ZHOU Lanping, LIU Guangwu, ZHANG Jinhu, ZHANG Zhiping, ZHENG Qingzhong

2019, 27(9): 1421-1429. doi: 10.13930/j.cnki.cjea.181038

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Abstract:
In arid areas, conservation tillage has the important advantage over conventional tillage reduction of soil erosion. Up to now, there have been few reports on effects of conservation tillage on soil wind erosion in the Hexi oasis irrigational area of China. A spring wheat field experiment was conducted to investigate the effects of different conservation tillage measures on field sediment discharge, wind erosion depth, wind erosion sediment granulometric composition, and wind speed in the Hexi oasis irrigational area, Gansu Province, Northwest China. The conservation tillage measures adopted in this study over three years included no-tillage with no stubble mulching (NT), no-tillage with stubble mulching (NTS), standing stubble (SS), and stubble overwhelm (SO), with conventional tillage (CT) as the control. The results showed that a sediment discharge of 0-30 cm could sensitively reflect the differences in sediment discharge among different tillage measures. Compared with CT, the sediment discharge of 0-30 cm decreased by 17.4%-46.7% in NT, 21.7%-45.2% in NTS, 24.7%-48.2% in SS, and 10.7%-42.4% in SO. The wind erosion depth was 1.22-1.44 mm for conventional tillage, and zero for each conservation tillage. Compared with CT, the wind erosion sediment granulometric composition of conservation tillage was no significant change, but the proportion of size of fine-grained soil (< 0.063 mm) had a decreasing tendency. The wind speed at 20 cm depth was significantly reduced by 24.1%-39.5% in SS and non-significantly reduced under other conservation tillage measures. In summary, different conservation tillage measures can control soil wind erosion to different extent in the Hexi oasis irrigational area; standing stubble was the most optimal conservation tillage measure and proved suitable for application in this area.

Model optimized construction and technology integrated application of intercropping in kiwifruit orchard

LAI Ruilian, LONG Yu, CHENG Chunzhen, FENG Xin, WU Rujian, CHEN Yiting, WENG Boqi

2019, 27(9): 1430-1439. doi: 10.13930/j.cnki.cjea.190057

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Abstract:
Intercropping, an important production method in modern ecological agriculture plays a vital role in the construction of ecological orchards. The application of intercropping in kiwifruit orchards has developed rapidly. Many vegetables, Chinese herbal medicines, edible fungus, grain crops, and green manure crops have been successfully intercropped in those orchards. In practice, several key technologies such as variety selection and system collocation, timely sowing and proper intercropping, and scientific fertilization and rational irrigation should be concerned. Additionally, other major factors should be fully considered, including economic benefit, infrastructure support, transformation and upgrade, and green revitalization of the intercropping models. The comprehensive benefits of intercropping in kiwifruit ecological orchards are providing straw and agricultural waste, promoting rhizosphere microorganism activity, improving soil fertility and moisture conservation, and increasing additional agricultural and sideline products etc. These positive effects benefit the utilization of idle space, increase early income, optimize resource utilization efficiency and save expenditure, enhance soil fertilization capacity, and improve rhizosphere environment. They also offer surface water and soil erosion prevention and orchard ecology protection, as well as achieve a high fruit yield and quality that enhances intercropping's comprehensive benefits. Based on a summarization of the research and review of the technical application of intercropping system in kiwifruit orchards, this paper puts forward new prospects for the development of intercropping models in kiwifruit orchards. These prospects take full consideration of the biological characteristics of intercropping crop and kiwifruit, as well as the natural resources and environmental characteristics of orchards. We hope that exploring and improving the standardized application technology of kiwifruit intercropping can lead to excavating new crops, which would be suitable for kiwifruit intercropping. Theory and mechanism research for kiwifruit intercropping systems should be strengthened to promote green revitalization and leapfrog development of the kiwifruit industry in order to promote a positive role in the transformation of the agricultural industry.

Risk assessment of hot damages for single-cropping rice based on accumulation index of heat stress in Sichuan

LIU Jia, QING Qingtao, CHEN Chao, ZHANG Yufang, ZOU Yujia

2019, 27(9): 1440-1452. doi: 10.13930/j.cnki.cjea.190019

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Abstract:
Under global climate change, agricultural meteorological disasters have been increasing. Heat stress has been one of the most important agro-meteorological disasters in Sichuan Province, and the affected area and frequency and intensity of heat stress have significantly changed. Therefore, research on the effect of heat stress on rice is critical for sustainable agricultural development and safe production in Sichuan Province. Heat damage risk of single-cropping rice in Sichuan was studied using meteorological, agricultural meteorological, statistical, and geographic data during 1986-2015. Four factors, which were hazard, sensitivity, exposure, and disaster prevention and mitigation capacity, were created with the cumulative high temperature-induced damage index, topography, yield variation, and rural economy as the basic indexes to evaluate heat damage risk during the sensitive stages of heading, flowering, and filling. A "Four Factors" multi-risk assessment index system of heat injury for single-cropping rice in Sichuan Province was established by using the Grey Correlation method, and used in the risk regionalization of single-cropping rice of the study area. The results of the multi-risk assessment model were valuable for making decisions to relieve disaster risk. The assessment results showed that the parallel ridge-valley region of the eastern basin, the shallow hilly area of the central basin, the west part of mountain area around the basin, and the southern hilly area of the southern basin were divided into high-risk areas with gentle topography and frequent heat damage. Plain and hill areas of the western basin and mountain area of southwest Sichuan were roughly divided into medium risk areas with good irrigation conditions, higher socioeconomic developmental levels, and good coping abilities. The wide valley area of Southwest Sichuan and mountain area around the basin were roughly divided into low risk areas where the regional topography is complex, and less rice is planted. In summary, there were clear differences in heat damage risks on single-cropping rice in different regions in Sichuan. Reasonable varieties and cultivation modes should be chosen to raise prevention and reduction ability based on different regional risk characteristics.

Measurement of rural multi-dimensional poverty in the Taihang Mountains by using Beiye Township of Pingshan County as a model

YU Shuhui, LI Ludan, CAO Mengmeng, SHANG Guofei

2019, 27(9): 1453-1462. doi: 10.13930/j.cnki.cjea.181126

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Abstract:
China has been working to alleviate since its reformation, and has made certain success. However, the poverty-stricken populations in China distributes in rural in mountainous areas for a long time. It is difficult to get rid of poverty in these lagging areas. A comprehensive understanding of the poverty situation in mountainous areas and effective techniques to reduce it have become important tasks for building a healthy society. We chose six typical villages in Taihang Mountain, Beiye Township, Pingshan County, Hebei Province based on elevation and geographical characteristics as the objectives. A question-based survey was conducted to obtain relative data. The evaluation index system was established with three dimensions-income, capital and living standard-and 9 indexes. The A-F (Alkire-Foste) method was used to analyze the results of multidimensional poverty measurement. The results showed that:1) the single-dimensional poverty situation in Beiye Township was still serious, and the causes of poverty were significantly different in all dimensions. Poverty mainly manifested as the absence of capital dimension. 2) The degree of multi-dimensional poverty in Beiye Township was deep. More than 90 percent of poor households lived in poverty. With an increase in dimension k, the multi-dimensional poverty index decreased. 3) The contribution of each index to the multi-dimensional poverty of Beiye Township was significantly different. The indexes of per capita cultivated land area, education, skill training and health facilities all contributed more than 15% and changed little when dimension k increased. 4) The lack of education was an internal factor that led to poverty. Compared to families with education, families without education had lower monthly income, single income source, and larger family size. In view of the above conclusions, this paper put forward the suggestions of using a hierarchical optimization mode to organize rural residential areas so as to integrate and optimize educational resources and help mountainous areas eliminate poverty.

2019 Vol. 27, No. 9