中国生态农业学报(中英文)

Review of soil nitrate formation, leaching transport and their control measures in upland farming systems

WANG Dapeng, ZHENG Liang, WU Xiaoping, LUO Xuehua, WANG Wenbin, ZHANG Yongfa, XUE Xinxin

2017, 25(12): 1731-1741. doi: 10.13930/j.cnki.cjea.170425

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Abstract:
Figuring out how to improve nitrogen use efficiency and reduce nitrogen loss to abate its impact on environment in order to ensuring high crop yield production are of leading global research interest today. The leaching of nitrate is the main pathway of nitrogen loss and the main mode of regional groundwater nitrate pollution. It has become a severe agricultural and ecological environmental problem in intensive agricultural regions around the world. Thus it is important to understand nitrate formation, leaching process, influencing factors and to put forward effective control measures. A great number of studies have been carried out by both local and foreign scholars in this area that has led to the generation of abundant information over the years. In this paper, soil nitrification process driven by micro-organisms was briefly reviewed. The advantages and disadvantages of in situ nitrate leaching monitoring methods were compared. The factors that affected nitrate accumulation and leaching were also analyzed. On the basis of the above parameters, effective control measures were summed up and future research directions were suggested strengthening researches on key micro-organism processes, mechanisms and functions of relevant driving factors of nitrification of upland soils. These clear understanding on soil nitrogen would contribute to the critical basis for the optimization of nitrogen management and the development of technologies to control nitrate leaching in upland farming systems. The exploration and establishment of methods of reducing soil disturbance, simple maintenance, less sample pollution and suitable long-term in situ field monitoring was particularly crucial to accurately reveal the soil nitrate leaching and real-time flux. The systematic development of comprehensive studies on nitrate leaching in different upland farming systems, the clarification of various factors that affected nitrate accumulation and leaching, and then the putting forward of effective control measures based on actual field conditions were required to reduce the risk of nitrate leaching at regional scale.

Effect of chicken manure and biochar on CO₂ and CH₄ emission in paddy fields in South China

WEI Jiabin, CHENG Xiaolin, ZHOU Linghong, XU Huaqin, TANG Qiyuan, XIAO Zhixiang, TANG Jianwu, TAN Shuduan

2017, 25(12): 1742-1751. doi: 10.13930/j.cnki.cjea.170493

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Abstract:
The application of biochar to enhance soil carbon sequestration in farmlands is an increasingly investigated research to reverse the effects of climate change. There is little report on the effect of adding manure in situ in combination with biochar application to winter paddy fields on CO₂ and CH₄ emissions during winter fallow and growth period of double rice. To fully use winter fallow paddy fields and determine how biochar and chicken manure affected the emission of CO₂ and CH₄, four treatments were set up—no fertilization (CK), chicken raised in the field and chicken manure addition (C), in situ chicken manure addition and biochar addition (CB), and biochar addition (B). The CO₂ and CH₄ fluxes and total emissions were determined in paddy fields using the chamber method along with Greenhouse Gas Analyzer during winter and the growth period of double cropping rice. The objective was to assess the effects of chicken manure in situ incorporation and biochar on soil carbon emission. The results showed that relationship between CO₂ flux under CK and B treatments and soil temperature at 5 cm soil depth fitted well the non-linear index model. Then CO₂ flux under C and CB treatments had no significant correlation with soil temperature at 5 cm soil depth, which meant that the in situ addition of chicken manure made it more sophisticated for soil to modulate CO₂ emission. The treatment of in situ addition of chicken manure significantly increased soil CO₂ emission in winter paddy fields and during rice growth period with respective emissions of 9 935.39 kg·hm^-2 and 27 756.34 kg·hm^-2, which was 58.7 times (P < 0.01) and 56% (P < 0.05) higher than that of CK. The cumulative CO₂ emissions in winter paddy fields and during rice growth period under biochar addition were 12.3 times (P < 0.01) and 41% (P < 0.05) higher than that of CK during in winter paddy fields and during rice growth period. The emissions of CH₄ in winter paddy fields and during rice growth period under treatment of in situ addition of chicken manure were significantly higher than that under other treatments, while it was not significantly changed in winter paddy fields and significantly decreased during rice growth period under biochar addition treatments. Chicken manure in situ application in combination with biochar treatment also significantly improved CO₂ emission of paddy soils. Cumulative CO₂ emission under chicken manure in situ application along with biochar addition in winter paddy fields was significantly higher than that under chicken manure in situ application. Also during rice growth period, it was significantly lower than that under chicken manure return. This suggested that biochar addition inhibited soil CO₂ emission in the late period. The addition of biochar decreased soil CH₄ emission in both winter paddy field and rice growth stage. In short, the addition of exogenous organic carbon like chicken manure to soils increased carbon emission (both CO₂ and CH₄), while the addition of biochar to soils increased carbon emission in the short-term and decreased CH₄ emission. Therefore, from the longer time view, biochar application to soils was beneficial to soil carbon sequestration, and might mitigate carbon emission caused by in situ application of chicken manure.

Landscape characteristics and utilization in agro-cultural heritage systems in Lianhe Terrace

HU Weifang, ZHANG Yongxun, WANG Weiqi, MIN Qingwen, ZHANG Wenlong, ZENG Congsheng

2017, 25(12): 1752-1760. doi: 10.13930/j.cnki.cjea.170286

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Abstract:
Lianhe Terrace in Youxi County, Fujian Province is an important Agricultural Heritage System (AHS) that is over 1 300 years old. Lianhe Terrace AHS consists of "forest-settlement-terrace-composite landscape" pattern established by the ancestors. Abundant landscape resources have been developed in this subtropical mountain area, including physiographic landscape, biological landscape, astronomical and climate landscape, relic landscape, architectural and engineering landscape, and folk-culture landscape. However, the stability mechanism of social, economic and natural compound ecosystems has failed to adapt to the requirements of productivity development with industrialization, and the landscape ecosystems have faced with threats of unsustainability. Analysis of landscape characteristics using the theory and methods of landscape ecology, study of the status of landscape resource utilization, and conservation strategies of landscape resources in Lianhe Terrace AHS were conducted in this study. Results showed that:1) Forest land and farmland were the dominant landscape types, accounting respectively for 67.93% and 20.40% of the total landscape area. Landscape fragmentation and number of forest patches were relatively low, 0.05 and 83, respectively. This suggested that forest cover was high with a relatively concentrated distribution. The largest number of patches (1 369), patch density (13.27 patches·km^-2), edge density (89.91 m·hm^-2), landscape fragmentation (0.75) and landscape shape index (50.85) in farmland indicated fragmentation, diversification and complex boundary conditions in the region. 2) The vertical distribution of landscape patterns in the key protected areas of Lianhe Terrace AHS was "forest-settlement-terrace-composite landscape" pattern. The sets of virtuous ecological systems and typical regional traits were well established. This landscape pattern functioned at optimum yield, livability, soil and water conservation and aesthetic. 3) Abundant resources (including natural and cultural landscape resources) were developed in Lianhe Terrace AHS. However, some terraced fields were abandoned due to youth labor emigration in search for work elsewhere. This led to terraced field collapse, canal jam, and both water and soil erosion. Furthermore, some landscapes were destroyed by natural or artificial factors such as historic sites of ancient pottery piece (more than 3 000 years) and Shuiwei Bridge (the Southern Song Dynasty). In addition, some humanistic landscape resources such as Min Opera, Temple Fair of Fuhu Rock and Lantern Festival lacked further utilization. That led to a vicious circle of idle landscape resource, poverty, population loss, destruction of landscape ecology, and landscape resource disappearance. 4) The unstable mechanism of the vicious cycle was reversible through reasonable exploitation of landscape resources. Several strategies were proposed, including damaged forestland restoration, establishment of corresponding compensation mechanisms, development of eco-agriculture, secondary industry, agrocultural heritage tourism and ecological tourism. It all aimed at establishing a sustainable eco-system of terraced artificial ecosystems and the integration of protection of terraced ecological landscapes and utilization of landscape resources. This will benefit the rehabilitation of terraced landscapes and agricultural cultural heritage.

Effect of plastic film mulch on soil moisture and salt dynamics under saline water irrigation in coastal saline soils

LIU Haiman, GUO Kai, LI Xiaoguang, LIU Xiaojing

2017, 25(12): 1761-1769. doi: 10.13930/j.cnki.cjea.170037

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Abstract:
Filed experiments were conducted to study the dynamics of soil moisture and salt under saline water irrigation and plastic film mulching in coastal saline soils in spring in Haixing County, Hebei Province. Two field sites were selected—Xiaoshan Town with original soil moisture content ≥ 20% and Haixing Farm with original soil moisture content < 20%. A total of 6 treatments were designed for Xiaoshan Town, involved saline water irrigation at March 29^th and April 13^th with and without plastic film mulching, and plastic film mulching only, with no irrigation without plastic film mulching as the control. The treatments in Haixing Farm were CKN (no irrigation without plastic film mulching) and SE+PMN (saline water irrigation with plastic film mulching). The irrigation water was ponded from the drainage ditch along the field with salinity of 12.12 g·L^-1 and 11.53 g·L^-1 for Xiaoshan Town and Haixing Farm, respectively. The irrigation amount was 180 mm in both sites. Oil sunflower was planted after irrigation. Results showed that soil salt content in plough layer significantly reduced under saline water irrigation and plastic film mulching. The earlier the application of the treatment, the better the salt leaching effect obtained. Moreover, salt leaching effect was affected by the original soil water content. A better salt leaching effect was observed in Haixing Farm, and the average salt leaching depth was 40 cm. This ensured the normal growth of oil sunflower, with germination rate and yield of 73.9% and 920 kg·hm^-2, respectively. Soil salt content decreased from 1.93% before irrigation to 0.32% at harvest stage of oil sunflower, with mean salt leaching rate of 84.07%. For the Xiaoshan Town experimental site, however, water was infiltrated through soil macro-pores and it was difficult for salt to leach out from soil micro-pores. Thus water infiltration at the rate of saturated hydraulic conductivity, which led to slow leaching rate and shallower leaching depth of soil salt. High soil salinity was maintained at sowing of oil sunflower limited its' normal growth and therefore no yield was obtained. In the research, soil salinity in plough layer reduced effectively through saline water irrigation and plastic film mulching in spring. This provided a suitable soil water and lower salinity for the normal germination of crops in coastal saline soils.

Effect of granulated straw incorporation on soil nutrient and grain yield of winter wheat

ZHANG Li, WANG Jing, PANG Huancheng, ZHANG Juntong, GUO Jianjun, DONG Guohao, CONG Ping

2017, 25(12): 1770-1778. doi: 10.13930/j.cnki.cjea.170451

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Abstract:
To clarify the feasibility of incorporation of granulated straw into soil in Huang-Huai-Hai region, a micro-plot field experiment was conducted in winter wheat/summer maize rotation cropping system at Dezhou Agricultural Research Academy of Shandong Province. The effects of granulated straw incorporation on soil nutrients contents, wheat growth and yield components were investigated. A total of three treatments were included in the experiment—no straw incorporation (CK), conventional chopped straw incorporation into the 0-15 cm soil layer (CCSI) and granulated straw incorporation into the 0-15 cm soil layer (GSI). All the treatments were arranged in a completely randomized design with three replicates. The indexes determined during the winter wheat season included wheat tiller number, chlorophyll content and net photosynthetic rate of flag leaf, dry matter accumulation and its contribution to yield, and soil nutrients contents, and wheat yield after harvest. The results showed that compared with CK, CCSI and GSI treatments had significantly higher soil nutrients contents. The contents of soil organic matter, available nitrogen and available phosphorus under GSI treatment were higher than those under CCSI treatment by 8.54%, 6.12% and 6.25%, respectively. GSI treatment also improved seedling emergence and increased tiller number. The number of basic seedlings under GSI treatment increased by 1.63% and 19.39%, tiller number increased by 3.16%-13.23% and 11.28%-16.64%, fertile tillers rate increased by 9.88% and 4.92%, and spike number increased by 13.23% and 16.64% over those of CK and CCSI treatments, respectively. Meanwhile, GSI treatment delayed leaf senescence and increased leaf area index at filling stage by 21.79% and 16.97%, increased chlorophyll content by 7.56%-47.24% and 0.53%-12.88%, increased net photosynthetic rate of flag leaf at grain-filling stage by 15.76% and 3.33%, respectively, over those of CK and CCSI treatments. Improvement in leaf photosynthetic characteristics contributed to the increase in aboveground dry matter production and translocation from vegetative organs to grain. Compared with CK and CCSI treatments, GSI treatment increased aboveground biomass at flowering stage by 17.09% and 6.33%, aboveground biomass at maturity stage by 18.91% and 9.85%, translocation of accumulated dry matter after flowering stage to grain-filling stage by 19.65% and 14.75%, respectively. Finally, GSI treatment had the highest grain yield, which was 9.69% and 10.71% higher than those under CK and CCSI treatments. Further analysis showed that grain yield had no significant correlation with kernel number per spike and thousand-kernel weight, but it had significant positive correlation with effective spike number. This indicated that spike amount was the main reason for the grain yield increasing. Therefore, the granulated straw incorporation was an effective option for straw return to the soil in agricultural production in Huang-Huai-Hai region.

Effects of amount and time of straw mulching on soil temperature, root growth and yield of winter wheat

YAN Zongzheng, CHEN Suying, ZHANG Xiying, NIU Junfang, SHAO Liwei

2017, 25(12): 1779-1791. doi: 10.13930/j.cnki.cjea.170977

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Abstract:
In order to take full advantages of straw mulching and improve straw mulching benefits, the effects of different straw mulching practices on soil temperature, root growth and yield of winter wheat under irrigation condition in a typical site was explored through a field experiment with different straw mulching times and amounts in the North China Plain. Times of straw mulching included immediately after planting and after three leaves of winter wheat. The amounts of straw included total straw yield, 1/2 straw yield and 1/3 straw yield of preceding summer maize, and no mulching as the control (CK). The results showed that:1) compared with CK, the winter wheat yield of mulching after planting and after three leaves was reduced by 8.6% and 2.0%, respectively. The yield decrease for the treatment of mulching after planting was more than that of mulching after three leaves for winter wheat. The reason for yield reduction of mulching after planting was decreases in 1000-seed weight, kernel numbers per spike and harvest index, which were 4.1%, 6.6% and 2.4%, respectively. The reason for yield reduction of mulching after three leaves was the decrease in spike numbers per area, which was 5.8%. 2) Straw mulching significantly affected soil temperature at the earlier growth stages of winter wheat. The straw mulching increased mean daily soil temperature averagely by 0.56℃ at tillering and overwintering stages. Straw mulching decreased soil temperature, compared with CK, after regreening stage of winter wheat. The contribution of straw mulching to soil temperature increase in winter was mainly due to the increase in night soil temperature, while the cooling effects after regreening stage was due to reduction in daytime soil temperature. The temperature increasing/decreasing effects of straw mulching were enhanced with straw amount increase though no significant differences among different straw amounts treatments were observed. 3) Root growth of winter wheat was improved under straw mulching due to the higher soil temperature. The root length density (RLD) under straw mulching treatment was higher than that under CK before regreening stage, after that RLD was reduced due to lower soil temperature under straw mulching as compared with CK. At flowering stage, with the increase of canopy coverage, the effects of straw mulching on soil temperature was weakened or disappeared, resulting in similar RLD among treatments. Higher soil temperature at tillering and wintering stages and larger root system under straw mulching induced higher consumption of soil nitrogen of winter wheat, which lead to lower soil nitrogen content at regreening to jointing stages under straw mulch treatments. In conclusion, straw mulching at three leaves stage of winter wheat had less negative effect on grain production of winter wheat. One third or half straw yield of preceding summer maize was appropriate amount for maintaining yield of winter wheat.

Characteristics of nitrogen accumulation and utilization in indica hybrid rice under different planting methods and nitrogen rates

WANG Chunyu, YU Huaqing, HE Yan, GUO Changchun, ZHANG Shaowen, YANG Zhiyuan, MA Jun

2017, 25(12): 1792-1801. doi: 10.13930/j.cnki.cjea.170484

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Abstract:
There has been remarkable transition in rice planting methods in recent years, including mechanical transplanting and direct seeding. Different planting methods inevitably have different effects on rice growth and development. However, rice growth, nutrient accumulation, heat and light utilization are different under different planting methods. Nitrogen application has been one of the most common field management practices in rice cultivation. Thus a field experiment was conducted to study the characteristics of nitrogen accumulation and utilization in indica hybrid rice under different planting methods and nitrogen rates. A two-factor split-plot designed field experiment was conducted using indica hybrid rice 'F-you-498', a widely planted cultivar in Sichuan Basin. The main plot had three planting methods, including mechanical transplanting (T₁), precision hill direct seeding (T₂) and manual planting (T₃), the subplot was nitrogen (N) fertilizer rate, including 0 kg·hm^-2 (N₀), 90 kg·hm^-2 (N₁), 135 kg·hm^-2 (N₂) and 180 kg·hm^-2 (N₃). Nitrogen accumulation and transfer, yield and yield components, and nitrogen use efficiency under different treatments of the indica hybrid rice were analyzed. The study showed that nitrogen accumulation, transfer, yield and yield components of rice were significantly affected by planting method and N rate. In different planting methods, total nitrogen accumulation at heading and maturity stages was in the order of T₃ > T₁ > T₂. Nitrogen accumulation rate under T₂ was significantly higher than that under T₁ and T₃ from sowing to jointing stage and from heading to maturity stage. However, nitrogen accumulation rate was in the order of T₃ > T₁ > T₂ at jointing to heading stage. Agronomic efficiency of nitrogen and nitrogen harvest index were in the order of T₃ > T₁ > T₂. The results showed that the order of nitrogen requirement for 100 kg grains was T₂ > T₃ > T₁. Grain yield under manual transplanting was significantly higher than that under precision hill direct seeding, but not significantly different from that of mechanical transplanting. Nitrogen accumulation of total plant and panicle increased significantly with increasing nitrogen fertilization rate. However, leaf nitrogen contribution to panicle de-creased with increasing nitrogen fertilization rate. Planting method and nitrogen application rate significantly influenced nitrogen use efficiency. Rice agronomic efficiency of nitrogen under mechanical transplanting increased with increasing nitrogen fertilization rate, although the increase was insignificant. However, agronomic efficiency of nitrogen under precision hill direct seeding and manual transplanting decreased with increasing nitrogen application. With increasing nitrogen fertilizer rate, the nitrogen apparent recovery efficiency under manual transplanting and mechanical transplanting first increasing then decreasing, while that under precision hill direct seeding gradually decreased. Nitrogen grain production efficiency and nitrogen harvest index decreased with increasing nitrogen fertilization rate, and there was no significant difference among nitrogen fertilizer treatments. In combination with grain yield and nitrogen use efficiency, nitrogen fertilizer rate of 135 kg·hm^-2 under precision hill direct seeding, and 135-180 kg·hm^-2 under mechanical transplanting and artificial transplanting not only achieved stable rice yield, but also had high nitrogen use efficiency.

Effect of irrigation management and nitrogen rate on nitrogen and water utilization of direct-seeded rice

ZHANG Hong, ZHU Conghua, LI Qiyong, LI Xingyue, GUO Zhan, ZHENG Jiaguo, LI Xuyi

2017, 25(12): 1802-1814. doi: 10.13930/j.cnki.cjea.170334

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Abstract:
Direct-seeded rice has advantages of less labor, lower labor strength and cost. But it meantime has different development characteristics from the transplanted rice. It is necessary to investigate the cultivation and growth of direct-seeded rice. In this study, a field experiment was conducted to investigate the effects of irrigation managements and nitrogen application rates on nitrogen and water utilization and yield of direct-seeded rice. In the experiment, a split-split plot design was set with rice varieties ('Dexiang 4103' and 'Jinnongsimiao') as the main factor, irrigation managements (shallow water irrigation, alternate irrigation with wetting and moderate drying, alternate irrigation with wetting and severe drying) as the sub-plot factor, and N rate (0 kg·hm^-2, 120 kg·hm^-2, 180 kg·hm^-2 and 240 kg·hm^-2) as the split-split plot factor. The photosynthetic rate, dry matter accumulation, nitrogen utilization, water utilization and yield of direct-seeded rice were measured at different growth stages. There was a significant interaction between irrigation management and N rate on nitrogen utilization, water utilization and yield of direct-seeded rice. Compared with the shallow water irrigation, the net photosynthetic rate at jointing stage, dry matter accumulation at jointing-heading stage, nitrogen transport amounts of stems and leaves at mature stage, nitrogen accumulation of grains at maturity stage, nitrogen agronomic efficiency and nitrogen fertilizer recovery efficiency were significantly increased in the alternate irrigation with wetting and moderate drying; however, the leaf area index at heading stage, dry matter accumulation before jointing and nitrogen accumulation in stems and leaves at mature stage were significantly decreased. The effect of N rates on nitrogen accumulation, nitrogen utilization efficiency and yield of 'Dexiang 4103' and 'Jinnongsimiao' were different. Under the shallow water irrigation, compared with nitrogen free treatment, the yields of 'Dexiang 4103' and 'Jinnongsimiao' increased by 31.79%-48.77%, 29.72%-45.36%, respectively, under treatments of applying nitrogen fertilizer. But with the N rate increase (higher than 180 kg·hm^-2), the yield of 'Dexiang 4103' was significantly decreased, and the corresponding indicators of 'Jinnongsimiao' were not significantly changed. Under the alternate irrigation with wetting and moderate drying, compared with nitrogen free treatment, the yields of 'Dexiang 4103' and 'Jinnongsimiao' increased by 32.58%-61.10%, 36.49%-48.45%, respectively, under treatments of applying nitrogen fertilizer. When N rate was more than 180 kg·hm^-2, for 'Dexiang 4103', the yield was not significantly changed, nitrogen fertilizer recovery efficiency, the nitrogen agronomic efficiency decreased with the increase of N rate. For 'Jinnongsimiao', the yield, dry matter accumulation not changed significantly, and the nitrogen accumulation at maturity stages increased significantly. Under the alternate irrigation with wetting and severe drying, compared with nitrogen free treatment, the yields of 'Dexiang 4103' and 'Jinnongsimiao' increased by 37.01%-42.88%, 30.11%-42.63%, respectively, under the treatments of applying nitrogen fertilizer. When N rate was more than 180 kg·hm^-2, the yield of two cultivars was not changed significantly, their nitrogen agronomic efficiency decreased with the N rate increaseing. The nitrogen accumulation of 'Dexiang 4103' at maturity stage increased significantly and that of 'Jinnongsimiao' was not changed significantly with N rate increasing. In summary, alternate irrigation with wetting and moderate drying was more suitable for high yield, water saving and high efficiency cultivation of direct-seeded rice. Furthermore, the highest yields of 'Dexiang 4103' and 'Jinnongsimiao' were observed under N rates of 240 kg·hm^-2 and 180 kg·hm^-2, respectively.

Effects of different fertilization modes on rice yield and nitrogen loss in paddy soils under double cropping rice

DUAN Ran, TANG Yuefeng, WANG Yanan, WANG Weizheng, BAI Lingyu, WU Cuixia, WEN Jiong, ZENG Xibai

2017, 25(12): 1815-1822. doi: 10.13930/j.cnki.cjea.170420

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Abstract:
To ensure food security, there has been an extravagant use of nitrogen (N) fertilizer in paddy fields. Both the increase in N fertilizer efficiency and reduce in N loss in paddy soils are important in agricultural management and environmental protection. Here, we investigated the effects of side bar fertilization on paddy yields, N use efficiency and N loss in paddy soils and to provide reference for improvement of rice N utilization. Six fertilization treatments were used in the study-control (T1), common fertilizers with conventional fertilization method (T2, N 280 kg·hm^-2, P₂O₅ 165 kg·hm^-2, K₂O 120 kg·hm^-2), slow-release fertilizer with conventional fertilization method (T3, N 230 kg·hm^-2, P₂O₅ 165 kg·hm^-2, K₂O 120 kg·hm^-2), high slow-release fertilizer plus side bar application (T4, 230 kg·hm^-2, P₂O₅ 138 kg·hm^-2, K₂O 120 kg·hm^-2), medium slow-release fertilizer plus side bar application (T5, N 180 kg·hm^-2, P₂O₅ 123 kg·hm^-2, K₂O 120 kg·hm^-2) and low slow-release fertilizer plus side bar application (T6, N 140 kg·hm^-2, P₂O₅ 123 kg·hm^-2, K₂O 120 kg·hm^-2). The study was done in one cropping calendar at the Agricultural Environmental Sciences Observation Station in Yueyang City, Hunan Province, China. The results showed that combined application of slow release N fertilizer and side bar application method increased rice yield, promoted N utilization rate and reduced N loss in paddy fields. Particularly for T4, yields of both early and late rice increased respectively by 13.17% and 4.72%, and decreased rice planting density and applied N amount, compared with T2. The yields of both early and late rice under T4 treatment were 7.27% and 1.74% higher, respectively, than that of T3 treatment. Side bar fertilization significantly reduced N loss by 0.466-0.673 kg(N)·hm^-2 due to surface runoff decreasing by 3.54%-29.36%, compared with T2 treatment. Side bar fertilization significantly increased N use efficiency. N use efficiency under T4 treatment was 1.70 and 1.22 times that of T2 and T3 treatments, respectively. High slow-release fertilizer plus side bar application was the best fertilization mode in the study area. Our results were beneficial for improving productivity efficiency in agricultural, resources and environmental protection.

Spring maize yield and soil potassium balance under replacement of potassium with straw in karst peak-cluster depression

FU Wei, LIU Kunping, CHEN Hongsong, CHEN Xiangbi, LIN Haifei, ZHANG Wei, WANG Kelin

2017, 25(12): 1823-1831. doi: 10.13930/j.cnki.cjea.170800

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Abstract:
Based on a long-term experiment on maize-soybean relay intercropping system in Huanjiang Observation and Research Station for Karst Ecosystem, Chinese Academy of Sciences, the effects of straw in place of chemical potassium on spring maize yield and soil potassium (K) balance were investigated, aiming to provide scientific basis for the rational use of straw and fertilizer in karst peak-cluster depression. The experiment was started in 2006, and the data were collected during 2010-2014. Four treatments with four repetitions were set in this study, including CK (no fertilizer), NPK (chemical fertilizer), C7S3 (30% K from straws and 70% K from chemical fertilizer), C4S6 (60% K from straws and 40% from the chemical fertilizer). The results showed that:1) the annual yields of spring maize in fertilization treatments from 2010 to 2014 were 4.12-4.17 times that in CK treatment. The spring maize yields in C7S3 and C4S6 were 98.3% and 98.7% of that in NPK, respectively. The yields of grain and straw increased with time under fertilization treatments. 2) Compared with CK, fertilization treatments significantly increased K amount in maize straw, with 2.21-2.53 times that in CK. N, P and K absorption amounts in maize grain under fertilization treatments significantly increased (P < 0.01), but there was no significant difference among fertilizer treatments (P > 0.05). 3) There were no significant differences in recovery efficiency, absorption efficiency, agronomic efficiency and partial factor productivity of K among treatments of NPK, C7S3 and C4S6. 4) The annual surplus amount of K in NPK treatment was 3.00 kg·hm^-2, which was significantly higher than that in C7S3 (-1.90 kg·hm^-2). The most annual surplus amount of K was in C4S6, 8.22 kg·hm^-2, with the surplus rate of 7.4%. 5) Compared to the beginning of the experiment in 2006, soil rapidly available K declined by 15.9% in 2014. The fertilization treatments significantly increased amount of soil rapidly available K (P < 0.01). The order of annual increase of soil rapidly available K from 2010 to 2014 in fertilization treatments were NPK > C7S3 > C4S6, but no significant difference among treatments was observed (P > 0.05). 6) After 8 years of cultivation, soil slowly available K declined by 10.9% and 4.9% in CK and C4S6, while increased by 1.3% and 22.4% in NPK and C7S3, respectively. Overall, the straw returning to replace some K fertilizer was suitable for the soil in karst peak-cluster depression, which not only maintained the yield of spring maize, but also sustained soil K dynamic balance. And 60% of the straw K substitution was more suitable for sustaining K balance, while 30% of the straw K substitution was more beneficial to improve soil slowly available potassium.

Diagnosis of nitrogen nutrition of winter wheat and summer corn using images from digital camera equipped on unmanned aerial vehicle

LI Hongjun, LI Jiazhen, LEI Yuping, ZHANG Yuming

2017, 25(12): 1832-1841. doi: 10.13930/j.cnki.cjea.170996

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Abstract:
The large number of population and scarce land resources require crop yield per unit area to be increased greatly to ensure the food supplies and food security in China. To meet this requirement, chemical fertilizer application is an important and simple measure. Consequently, the agricultural non-point pollution caused by chemical fertilizer is becoming more and more serious. Precision fertilization is one of the important technologies to control agricultural non-point source pollution, while soil nutrient testing and crop nutrition diagnosis are indispensable works of precision fertilization. With the increasing of agriculture scale management, it is urgent to develop fast, economic and nondestructive techniques of the nitrogen nutrition diagnosis of crops. In this study, in the light of related researches of diagnosis of nitrogen nutrition in winter wheat and summer corn using digital photographs, cost-effective unmanned aerial vehicle (UAV) system was introduced and digital camera mounted on its platform was used to obtain the canopy photographs of crops. To determine the appropriate aerial heights and sensitive color parameters of aerial photographs for the diagnosis of nitrogen nutrition of winter wheat and summer corn, the relationships between a variety of color parameters retrieved from the aerial photographs obtained at different heights and the status of nitrogen nutrition of winter wheat and summer corn measured in situ in 2015 were analyzed. It was indicated that VARI (visible atmospherically resistant index based on digital photography) and B/(R+G+B) were the most sensitive color parameters for the diagnosis of nitrogen nutrition in winter wheat and summer corn, respectively. For the winter wheat, 16 m was the suitable aerial height at jointing stage, and the diagnosis model was:stem sap nitrate concentration= 2.103 4e^18.874VARI. 50 m was the best aerial height for summer corn at big trumpet stage, and the diagnosis model was:vein nitrate concentration=1.526×10³²×[B/(R+G+B)]^50.445. The established diagnose models were verified at the same field in 2016. The results showed that the determination coefficients of relationship between predicted and observed nitrate nitrogen concentrations of stem sap of winter wheat and vein of summer corn were 0.80 and 0.85, respectively, with significant levels of P < 0.01. In 2017, the method was applied to the diagnosis of nitrogen nutrition of winter wheat and summer corn in Nanpi County, Hebei Province, and the prescription maps of top-dressing nitrogen fertilizer for winter wheat and summer corn were made. The nitrogen fertilization rates of winter wheat and summer corn given by the prescription maps were fitting well with the growth status of crops. As shown in this study, diagnosis of nitrogen nutrition of winter wheat and summer corn using photographs from digital camera equipped on UAV was a cost-effective way to achieve precision management of fertilization. Beyond the achievements of this study, there were still problems should be solved to enhance the practicability and applicability of this method.

Identification and genetic analysis of powdery mildew resistance at seedling stage in 'Hongyouzi' Chinese wheat landrace

CAO Yanwei, XU Hongxing, LI Xiuquan, AN Diaoguo

2017, 25(12): 1842-1847. doi: 10.13930/j.cnki.cjea.170321

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Abstract:
Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a devastating foliar disease of wheat. The identification and utilization of elite resistant germplasm is an effective control measure of the disease. At present, most wheat cultivars/lines in China's wheat production are susceptible to powdery mildew. Moreover, few powdery mildew resistance genes are used in China. Therefore, it is essential to identify more effective and elite resistance sources and genes. The 'Hongyouzi' Chinese wheat landrace ('Jing 2350') has shown immune to high resistant of 34 out of 38 Bgt isolates at seedling stage and immune or nearly immune in the field to a composites of Bgt isolates at mature stage in Shijiazhuang, China. To further study the resistance feature and identify the resistance gene (s) of 'Hongyouzi', genetic analysis of F₁ plants, F₂ populations and their derived F_2:3 families respectively from crosses of 'Huixianhong'×'Hongyouzi' and 'Hongyouzi'×'Mingxian169' were conducted at seedling stage. The results showed that all F₁ plants derived from the combinations of 'Huixianhong'×'Hongyouzi' and 'Hongyouzi'×'Mingxian169' were susceptible to Bgt isolate E09. The ratios of resistant F₂ plants to susceptible plants conformed as 1︰3 and those of homozygous resistant F_2:3 lines︰heterozygous lines︰homozygous susceptible lines conformed as 1︰2︰1. These results indicated that the resistance of 'Hongyouzi' to Bgt isolate E09 was conferred by a single recessive resistance gene, temporarily named PmHYZ. 'Hongyouzi' was the elite powdery mildew resistance sources of Chinese wheat landraces, thus it was useful to effectively use elite resistance source and resistance gene in breeding resistant crops.

Dynamic simulation of farmland SOC in parallel ridge valley area in eastern Sichuan in the next 30 years

ZHANG Lin, SHAO Jing'an

2017, 25(12): 1848-1857. doi: 10.13930/j.cnki.cjea.170423

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Abstract:
The relationship between greenhouse gas emission reduction and soil carbon sequestration has become the focus of global climate change research amidst the worsening global climate change. As a core interface of terrestrial ecosystem, farmland soils have a huge potential to sequester carbon. Exploring the response and feedback of the dynamic balance of farmland soil organic carbon (SOC) to global climate change is significant in understanding the relationship between global carbon cycle and agricultural ecosystems. Dianjiang County is a typical representation of parallel ridge valley area in eastern Sichuan. It is an important grain and oil producing area in Chongqing. In the process of transformation from traditional to modern agriculture, the area has been faced with double pressures of food security and increasing farmland SOC. Therefore in this region, it is very important to study farmland SOC and its dynamic change using specific climate model in the next 30 years. It provides data support and scientific basis for sustainable utilization and management of future cultivated lands in the study area. Supported by GIS regional database established for soil properties and agricultural management system, this study simulated the dynamic change in SOC in the study area for the period 2011-2041 using the biogeochemical model DNDC. The study also used the B₁ climate model within BCCR_BCM 2.0 in the IPCC AR4 report. The results showed that:1) The DNDC model fairly simulated farmland SOC and dynamic change under specific climate conditions. The correlation coefficient between the simulated and measured values was 0.981, which was significant at the 0.01 confidence level. The RMSE value of the simulated and measured values was 16%, indicating better simulated results. 2) The SOC density and storage in the 0-20 cm soil layer in the study area significantly increased for the next 30 years. The increase in carbon per unit area was 2 637.07-8 091.55 kg(C)·hm^-2 or 10%-34%, that in carbon sequestration was 2.7×10⁵-8.3×10⁵ t, and that in average increase rate was 87.9-269.7 kg(C)·hm^-2·a^-1. 3) For the next 30 years, the farmland soil in parallel ridge valley area in eastern Sichuan was generally under continuous carbon sink. In the study area, the differences among carbon sink, carbon loss and carbon relative balance gradually increased for the next 30 years.

Spatio-temporal variation of land consolidation projects in Sichuan Province

XIONG Bingyao, XIA Jianguo, LIN Wanpin, YAN Weinan, XIAO Xinjuan

2017, 25(12): 1858-1869. doi: 10.13930/j.cnki.cjea.170310

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Abstract:
Land consolidation has developed into a strategic national deployment. Analysis of the distribution characteristics of land consolidation projects can provide a reference for decision-making on developing new plans and optimizing spatial patterns of future land consolidation. Based on 2011-2015 data on county-scale land consolidation projects in Sichuan Province combined with coefficient of variation analysis, gravity center model, and spatial auto-correlation analysis, the paper analyzed spatio-temporal variation of land consolidation in Sichuan Province. The novelty of the study was in the analysis for the balances in land consolidation activities in different periods at different spatial scales. Multi-scale land consolidation has gained considerable attention in recent time. There was a negative trend in total land consolidation projects number in Sichuan Province for the period 2011-2015. By calculating standard deviation and coefficient of variation of land consolidation projects, absolute differences were found among land consolidation projects in each district or county with a general declining trend for 2011-2015. The absolute scale of land consolidation projects in each district or county and the relative difference also declined, which indicated a balanced development trend in the districts or counties. Remarkably different features were noted at different spatial scales. At regional scale, land consolidation projects were concentrated in agricultural land consolidation region in basin hilly area. The realization of the macro-objectives of land consolidation should be based on regional natural conditions. At city-scale, land consolidation projects were mainly concentrated in Chengdu and Yibin Cities, with less distribution in Ganzi Tibetan Autonomous Prefecture, Liangshan Yi Autonomous Prefecture and Panzhihua City. The number of land consolidation projects was positively correlated with population concentration. Gravity centers of land consolidation projects were mostly in agricultural land consolidation region in basin hilly area, with basicaly balanced spatial variation of the projects. The gravity center of land consolidation projects moved eastward compared with the standard gravity center (102°41'29.92"E, 30°37'44.83"N). It was found that the spatial patterns of land consolidation projects had strong spatial autocorrelation. High-high concentration areas were mainly in the northeastern region of the agricultural land consolidation region in basin hilly area. On the contrary, low-low concentration areas were in the ecological rehabilitation region in Northwest Plateau of Sichuan. In general, due to the socio-economic, demographic, terrain and policy conditions of the project area, the spatial and temporal patterns of land consolidation projects needed further improvement. This study explained the focus of land consolidation planning on agricultural land consolidation in hilly areas of Sichuan Province. Timely and appropriate execution of land consolidation projects in agricultural land remediation in mountain valley area of Southwest Sichuan was also explained. Ecological rehabilitation region in Northwest Plateau of Sichuan was the direction of future land consolidation development. It was conducive to optimize landscape development and utilization patterns in Sichuan Province.

Ecological circle way and coupling effect of fruit-grass-chicken mode in dry highlands of the Loess Plateau

LIU Xingyuan, JIANG Chengfang, LI Juncheng, SHEN Yuying

2017, 25(12): 1870-1877. doi: 10.13930/j.cnki.cjea.170406

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Abstract:
Because of ecological fragility and lack of water resources, traditional planting mode of grain and industrial crops has severely affected and restricted the sustainable development of agriculture in dry highlands of the Loess Plateau. Thus based on resource characteristics and ecological conditions of dry highlands of the Loess Plateau, a mode for sustainable agricultural development was established based on ternary planting of grain crops, industrial crops and grasses. The mode involved the application of the theory of system coupling and ecological cycle along with the combination of ecological conservation and efficient production. It provided the critical link for the realization of sustainable development of regional ecological and economic co-ordination in dry highlands of the Loess Plateau. Using Qingyang City in the Central Loess Plateau as the study area, an ecological cycle mode of fruit-grass-chicken was designed based on the characteristics of agricultural resources and economic development. Then the cyclic structure of the mode was configured using coupled functionality of industries in Qingyang City. Technical specifications were put forward and the effect of coupling analyzed for Qingyang City. The results showed that the mode output coupling production by the combination of the three subsystems of fruits, grass and chicken. The mode improved species structure of orchard ecosystems, increased utilization rate of agricultural resources, enhanced energy conversion and recycling of the orchard ecosystems. Compared with single orchard cultivation, per-unit-area profit increased by 3.82 times, water use efficiency increased by 54.1%, water/soil erosion decreased by 58.82%, application rate of chemical fertilizers/pesticides decreased by 25.24%/5.56% and utilization rate of land resources increased by 36.84%. Therefore, the established mode had significant ecological and socio-economic benefits, with a wide range of applications and promotional values in the Loess Plateau.

2017 Vol. 25, No. 12