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    Special Focus: Meat Consumption in China and Its Impact on International Food Security: Status Quo,T
    Meat consumption in China and its impact on international food security: Status quo, trends, and policies
    Xiaohua Yu
    2015, 14(6): 989-994.  DOI: 10.1016/S2095-3119(14)60983-7
    Abstract ( )   PDF in ScienceDirect  
    Section 1: Consumption
    Demographics, societal aging, and meat consumption in China
    MIN Shi, BAI Jun-fei, James Seale Jr., Thomas Wahl
    2015, 14(6): 995-1007.  DOI: 10.1016/S2095-3119(14)60984-9
    Abstract ( )   PDF in ScienceDirect  
    Drawn on the data collected by surveying 1340 urban households from six cities in China, this paper estimates the impacts of demographic structure and population aging on household meat consumption, by jointly considering meat consumed at home and away from home. Based on the trajectories of population, a simple simulation on meat demand trend in China is conducted subsequently. The results suggest: 1) Meat consumed away from home averagely accounts for near 30% of household total meat consumption in terms of quantity, so that its omission likely leads to a significant underestimate of total meat consumption and misunderstanding the driving forces; 2) population aging significantly and negatively affects per capita meat consumption, suggesting that the expected meat demand in China without considering population aging will be overestimated. The findings from this study have important implications for better understanding the relative issues on China’s meat consumption under the situation of population aging.
    Economic growth and nutrition transition: an empirical analysis comparing demand elasticities for foods in China and Russia
    Christine Burggraf, Lena Kuhn, ZHAO Qi-ran, Ramona Teuber, Thomas Glauben
    2015, 14(6): 1008-1022.  DOI: 10.1016/S2095-3119(14)60985-0
    Abstract ( )   PDF in ScienceDirect  
    This study provides empirical evidence on the link between economic growth and nutrition transition in two emerging economies, China and Russia. Both countries have experienced rising average incomes, accompanied by an increasing rate of nutrition-related chronic diseases in recent years. Given the regional heterogeneity between these two countries, we analyze the extent to which income growth as a major driver of nutrition transition has a significant effect on the consumption of different food aggregates and how these effects differ between Chinese and Russian consumers. Our results indicate that with increasing household incomes over time the demand for carbohydrates decreases, while the demand for meat and dairy products, as well as fruits increases. This is a development generally known as nutrition transition. Further, we estimate a Quadratic Almost Ideal Demand System (QUAIDS) for nine different food aggregates for China and Russia. Our results indicate that in both countries all food aggregates have positive expenditure elasticities and are thus normal goods. Moreover, our results indicate that in 2008/2009 meat is still a luxury good in China yet a necessity good in Russia. For 2009, the highest own-price elasticities in China are found for non-meat protein sources and dairy products. Within the meat group, beef, poultry and mutton have the highest price elasticities in China. In Russia, the milk and dairy group, together with the vegetable group, is the most price-elastic food group in 2008. In line with the definition of a nutrition transition, our overall results underscore the finding that income growth in China and Russia tends to increase the demand for animal-based products much stronger than, for example, the demand for carbohydrates. Despite being a positive signal for problems of malnutrition in rural China, this trend of increasing meat consumption might further increase the incidence of chronic diseases in urban areas since there is convincing scientific evidence that increasing meat consumption, especially red and processed meat, is associated with an increased risk of chronic diseases.
    Sustainable meat consumption in China
    Satoru Shimokawa
    2015, 14(6): 1023-1032.  DOI: 10.1016/S2095-3119(14)60986-2
    Abstract ( )   PDF in ScienceDirect  
    Sustainable meat consumption is critical to achieve a sustainable food system because meat products are among the most energy-intensive, ecologically burdensome, and ethically concerned foods. This paper focuses on the case of China and discusses the difficulties and possibilities to achieve sustainable meat consumption in China by reviewing previous empirical studies and descriptive statistics, particularly considering consumers’ dietary transitions in quantity and quality following China’s rapid economic growth. Given China’s sheer size of population and meat demand, the sustainable meat consumption in China is also a relevant topic in the global food system.
    The puzzle of the missing meat: Food away from home and China’s meat statistics
    XIAO Hong-bo, CHEN Qiong, WANG Ji-min, Les Oxley, MA Heng-yun
    2015, 14(6): 1033-1044.  DOI: 10.1016/S2095-3119(14)60987-4
    Abstract ( )   PDF in ScienceDirect  
    From 1985, an increasing gap has emerged between the official statistical measures of meat production and meat consumption in China, which has raised concerns from many researchers using such data. In this paper we report the results of 428 observations (survey of 107 urban and rural households×4 quarters) from 7 provinces conducted in 2010, and compare them with the official statistical data from the National Bureau of Statistics of China (NBSC). We conclude that the main reason for the discrepancy is due to the underreporting of consumption, which is due mainly to the omission of consumption away from home.
    Section 2: Production
    Economic evaluation of agricultural pollution control options for China
    David Abler
    2015, 14(6): 1045-1056.  DOI: 10.1016/S2095-3119(14)60988-6
    Abstract ( )   PDF in ScienceDirect  
    Environmental sustainability has become a policy priority in China. In agriculture, China has had major success in rehabilitating desertified lands through programs to convert steeply-sloped cropland to forest and limit grazing on sensitive grasslands. However, little has been done in terms of policies for agricultural nutrient management. Runoff and leaching of nutrients in chemical fertilizers and livestock manure are widely acknowledged as significant problems in China. This paper presents an evaluation of agricultural nonpoint pollution control options for China. Options analyzed include design standards (command & control), performance standards, and design and performance incentives. Evaluation criteria include economic efficiency and effectiveness, environmental impact and risk, and social criteria such as equity and food security. The evaluation indicates that the best options for China involve subsidies to farmers for changing production practices in order to reduce nonpoint emissions, combined with appropriate farmer education and technical assistance.
    Technical efficiency and its determinants in China’s hog production
    TIAN Xu, SUN Fei-fei, ZHOU Ying-heng
    2015, 14(6): 1057-1068.  DOI: 10.1016/S2095-3119(14)60989-8
    Abstract ( )   PDF in ScienceDirect  
    China’s hog production is undergoing a great transformation due to the soaring demand and changing raising system. Regarding the essential role of pork in Chinese diet, a systematic analysis on the productivity and efficiency of hog production can provide significant implications for policy makers. This paper investigates the productivity and efficiency of hog production and the determinants of technical efficiency in China using a household level panel data (2004–2010). A stochastic frontier translog production function with scaling property in inefficiency term is adopted for hog production analysis, and the determinants of technical efficiency are incorporated in a one-step estimation using maximum likelihood estimation. Our results show that the average technical efficiency of hog production in China is 0.5914. More importantly, we find that specialized farmers have higher technical efficiency than others, and technical efficiency in the eastern region is higher than that in Central and West China.
    Technical and environmental efficiency of hog production in China -A stochastic frontier production function analysis
    ZHOU Ying-heng, ZHANG Xiao-heng, TIAN Xu, GENG Xian-hui, ZHANG Peng, YAN Bin-jian
    2015, 14(6): 1069-1080.  DOI: 10.1016/S2095-3119(14)60990-4
    Abstract ( )   PDF in ScienceDirect  
    This article analyses the technical and environmental efficiency of hog production in China using data from the China Agricultural Product Cost-Benefit Compilation (NDRC 2005–2013) and the First National Census of Pollution: Manual of Discharge Coefficient of Livestock and Poultry Industry (IEDA and NIES 2009). The empirical results show a great variation in environmental efficiency, ranging from 0.344 to 0.973 with a mean value of 0.672 that declines over time. Southwest China is found to be the most environmentally efficient region, while the Northeast and the Northwest are the least efficient. Another finding is that technical and environmental efficiencies are highly correlated in hog production; the most environmentally efficient regions are usually found to have high technical efficiency, and vice versa. In addition, we computed the output elasticities with respect to each factor input. The results show that feed is the most efficient input, with an output elasticity of approximately 0.551, which is much higher than the elasticity of the nitrogen surplus, other capital or labour. The output elasticity with respect to the nitrogen surplus is 0.287 on average. Finally, the scale elasticity in hog production is slightly higher than 1.
    Section 3 : Trade
    Changing structure of China’s meat imports
    CHENG Ya-hao, Zhifeng Gao, James Seale Jr.
    2015, 14(6): 1081-1091.  DOI: 10.1016/S2095-3119(14)60991-6
    Abstract ( )   PDF in ScienceDirect  
    This paper discusses the determinants of meat imports of China. Results indicate that import demand is mostly determined by import price and real GDP. Imported price has a negative effect and real GDP has a positive influence on import quantity. Tariff does not have a significant effect. As GDP and consumption capacity increases, China has a large potential demand for meat imports. Some countries may gain if China’s economy continues expanding, while others, like the United States, are the most sensitive to the trade policy of China.
    Future perspective of China’s feed demand and supply during its fast transition period of food consumption
    DONG Wan-lu, WANG Xiao-bing, YANG Jun
    2015, 14(6): 1092-1100.  DOI: 10.1016/S2095-3119(14)60992-8
    Abstract ( )   PDF in ScienceDirect  
    China has experienced dramatic changes in food consumption patterns over the last three decades. However, there are different opinions regarding the future trends in consumption. By adopting the well-developed partial equilibrium model-China Agricultural Policy Simulation Model (CAPSiM), the demand for livestock products and the main feed crops over 2011–2030 is predicted and analyzed. It is found that China’s per capita consumption of livestock products will continue to rise during this period, even though its growth rate will slow down gradually. Meanwhile, the expansion of livestock production will pose great challenges for feed supply in China. More accurately, China will be confronted with feed security rather than grain security in the future.
    China’s meat and grain imports during 2000–2012 and beyond: A comparative perspective
    YU Wu-sheng, CAO Li-juan
    2015, 14(6): 1101-1114.  DOI: 10.1016/S2095-3119(14)60993-X
    Abstract ( )   PDF in ScienceDirect  
    This paper provides a review on China’s meat trade for the 2000–2012 period and discusses its future development, with reference to China’s grain trade. With marginal decreases in meat exports and slight increases in their imports, China’s net imports of major meat products (including pork, beef, mutton and poultry but excluding meat offal) were just below 1 million tons in 2012, dwarfed by China’s net imports of grains which reached 66.7 million tons in the same year. This slow growth in meat trade seems to contradict earlier expectations on increasing meat demand and imports, based upon projected shifts in consumption patterns driven by rapid per capita income growth. Several plausible explanations of this paradoxical trade pattern are offered, including mass imports of feed grains, persistent (but shrinking) gaps between Chinese and international meat prices, tariff barriers, and non-tariff measures. In the near future China may not be able to maintain such a lower profile on the world meat markets, as per capita income is projected to continue to rise and domestic production cost advantages erode due to rising labor costs. A model-based projection exercise indicates that under plausible assumptions China’s meat imports may rise sharply by 2030.
    Section 4: Price Dynamics
    Nonlinear dynamics of pork price in China
    ZHAO Guo-qing, WU Qiong
    2015, 14(6): 1115-1121.  DOI: 10.1016/S2095-3119(14)60994-1
    Abstract ( )   PDF in ScienceDirect  
    This paper primarily analyzes the evolution path of China’s pork price by employing the threshold autoregression model (TAR). Considering the unit root test with a threshold effect and heteroskedasticity of the TAR model, we show that the pork price series is a unit root process in each regime, and the heteroskedasticity in the TAR model greatly affects the results of linearity test. We find that the changing process of pork price has two regimes: mild regime and expansion regime. In particular, a change belongs to an expansion regime if it is larger than 0.5881; otherwise, it falls in the mild regime.
    Price transmission in hog and feed markets of China
    ZHOU De, Dieter Koemle
    2015, 14(6): 1122-1129.  DOI: 10.1016/S2095-3119(14)60995-3
    Abstract ( )   PDF in ScienceDirect  
    There is an increasing demand for feed as the industrialization of hog production in China. Land scarcity limits China’s ability to continue increasing its hog production without feed imports, particularly soybean, and the feed markets are increasingly integrated into the global market. This study performs an analysis of price transmission between the hog price in China and feed prices, specifically domestic maize price and international soybean price, from January 2000 to April 2014. We identified a long-term stable equilibrium relationship between the three markets. However, further analyses show that there is no significant Granger causality between hog and feed market, and the long-run equilibrium partially results from Granger causality between the international soybean market and domestic maize market. This suggests that the domestic hog market has been distorted by different policies. The results also indicate that the efficiency of price transmission is very low and it takes about 11 months to correct one-half of any long-run disequilibrium for the hog market in China. Therefore, to stabilize hog price in China, only market intervention to regulate the maize and soybean markets would be insufficient and comprehensive measures need to be taken into account such as hog production modernization, agricultural insurance, epidemic surveillance etc.
    Section 5: Food Safety and International Experiences
    Impacts of bovine spongiform encephalopathy and avian influenza on U.S. meat demand
    Jianhong E Mu, Bruce A McCarl, Amy Hagerman, David Bessler
    2015, 14(6): 1130-1141.  DOI: 10.1016/S2095-3119(14)60996-5
    Abstract ( )   PDF in ScienceDirect  
    This paper examines the U.S. meat demand impacts of the announced outbreaks of bovine spongiform encephalopathy (BSE) and avian influenza (AI). Findings indicate that beef and chicken demand was negatively affected by BSE and AI disease outbreaks. Specifically, in the short run, U.S. consumers shift demand due to both outbreaks but more so due to domestic disease outbreaks than for outbreaks occurring overseas-the impact of U.S. AI outbreaks is about 0.5% for beef and the impact of U.S. BSE cases is around –0.42% for beef and 0.4% for pork, respectively. Regarding the BSE shock on meat demand, there is a high rate of beef demand adjusted from disturbance to the long-run equilibrium and a lower adjustment rate for chicken demand because of the repeated outbreaks of AI worldwide. In the long run, information related to severe, persistently recurring overseas animal disease outbreaks changes U.S. consumers’ meat consumption patterns. Although effects of animal diseases on U.S. meat demand were statistically significant, the magnitudes were small-the impact of WHO reported human death numbers for AI is 0.005% for beef, –0.002% for pork, and –0.006% for chicken and the impact of U.S. BSE cases is 1.1% for pork and –0.7% for chicken.
    Consumer perceptions of food safety risk: Evidence from a segmentation study in Albania
    Edvin Zhllima, Drini Imami, Maurizio Canavari
    2015, 14(6): 1142-1152.  DOI: 10.1016/S2095-3119(14)60997-7
    Abstract ( )   PDF in ScienceDirect  
    Albania is facing serious problems with the national food safety control system in terms of legislation, control and enforcement. The objective of this paper is to analyse consumer perceptions about safety of small ruminant meat in Tirana, in a context of weak enforcement of the food safety system. Applying two-step clustering analyses, consumers were classified in four socio-demographic clusters, and it was found that the cluster composed of female consumers with lower education and income levels, and the two clusters composed of male consumers perceive consumed meat as safe. Consumers in the cluster composed of females with university education and higher income are, on average, more concerned with current meat safety measures and tend to place more trust in the veterinarian stamp on meat carcasses rather than in local butchers.
    Crop Genetics · Breeding · Germplasm Resources
    Differential expressions among five Waxy alleles and their effects on the eating and cooking qualities in specialty rice cultivars
    ZHOU Li-jie, SHENG Wen-tao, WU Jun, ZHANG Chang-quan, LIU Qiao-quan, DENG Qi-yun
    2015, 14(6): 1153-1162.  DOI: 10.1016/S2095-3119(14)60850-9
    Abstract ( )   PDF in ScienceDirect  
    Eating and cooking qualities (ECQs) of rice are important attributes due to its major influence on consumer acceptability. To better understand the molecular mechanism of the variation in ECQs, we investigated and compared the expressions among different alleles of the Waxy (Wx) gene and its effect on ECQs in specialty rice cultivars. The results showed that the accumulation of amylose was positively and significantly correlated to the level of mature Wx mRNA and granule-bound starch synthase I (GBSS I) in developing rice grain at 12 days after flowering. The amount of GBSS I and its activity together are the main factors controlling amylose synthesis. Differences in ECQs among five Wx allele types were investigated in samples from 15 rice varieties. The apparent amylose content (AAC) and gel consistency (GC) were similar in each type of Wx allele. The AAC followed the order, Wxa type>Wxin type>Wxb type>Wxmq type>wx. Contrary to this, the GC showed an opposite trend compared to AAC. There was a wide variation in rapid visco analyzer (RVA) profile among five Wx allele types, while varieties sharing a specified Wx allele had basically the similar RVA profile, although there was a slight difference in some RVA parameters, peak, hot paste and cool paste viscosities.
    Stability of PAC (Psy-2A-CrtI) gene and agronomic traits in the F2:3 of IR36/PAC transgenic plants
    Hyun Suk Lee, Gihwan Yi, Kyung Min Kim
    2015, 14(6): 1163-1170.  DOI: 10.1016/S2095-3119(14)60865-0
    Abstract ( )   PDF in ScienceDirect  
    This study was carried out to evaluate the expression of yellow endosperm color in the progeny of Psy-2A-CrtI (β-carotene gene, PAC) transgenic plants crossed with IR36. The selected 25 lines of F2 progeny exhibited stable expression of yellow endosperm color and high agronomic characteristics. IR36 and PAC transgenic plant of the grain length, width and ratio showed the same tendency of normal distribution. For progeny selection, colorimeters were as employed to distinguish differing visible colors. Correlation analysis was conducted to investigate the relationship between b* value and the expression of specific genes. b* value was associated with the relative expression of the PAC-Rev and MAR product by real-time PCR and t-test revealed significant difference. Based on this study, correlation between colorimetric values and real-time PCR was effective to detect gene expression. Yellow endosperm progenies represent a new genetic pool that might be useful to increase the genetic diversity of yellow endosperm rice.
    Whole-genome identification and expression analysis of K+ efflux antiporter (KEA) and Na+/H+ antiporter (NHX) families under abiotic stress in soybean
    CHEN Hua-tao, CHEN Xin, WU Bing-yue, YUAN Xing-xing, ZHANG Hong-mei, CUI Xiao-yan
    2015, 14(6): 1171-1183.  DOI: 10.1016/S2095-3119(14)60918-7
    Abstract ( )   PDF in ScienceDirect  
    Sodium toxicity and potassium insufficient are important factors affecting the growth and development of soybean in saline soil. As the capacity of plants to maintain a high cytosolic, K+/Na+ ratio is the key determinant of tolerance under salt stress. The aims of the present study were to identify and analyse expression patterns of the soybean K+ efflux antiporter (KEA) gene and Na+/H+ antiporter (NHX) gene family, and to explore their roles under abiotic stress. As a result, 12 soybean GmKEAs genes and 10 soybean GmNHXs genes were identified and analyzed from soybean genome. Interestingly, the novel soybean KEA gene Glyma16g32821 which encodes 11 transmembrane domains were extremely up-regulated and remained high level until 48 h in root after the excessive potassium treatment and lack of potassium treatment, respectively. The novel soybean NHX gene Glyma09g02130 which encodes 10 transmembrane domains were extremely up-regulated and remained high level until 48 h in root with NaCl stress. Imaging of subcellular locations of the two new Glyma16g32821-GFP and Glyma09g02130-GFP fusion proteins indicated all plasma membrane localizations of the two novel soybean genes. The 3D structures indicated that the two soybean novel proteins Glyma09g02130 (NHX) and Glyma16g32821 (KEA) all belong to the cation/hydrogen antiporter family.
    Soil & Fertilization﹒Irrigation﹒Plant Nutrition﹒ Agro-Ecology & Environment
    Effects of different nitrogen fertilizer management practices on wheat yields and N2O emissions from wheat fields in North China
    LIU Ya-nan, LI Ying-chun, PENG Zheng-ping, WANG Yan-qun, MA Shao-yun, GUO Li-ping, LIN Er-da, HAN Xue
    2015, 14(6): 1184-1191.  DOI: 10.1016/S2095-3119(14)60867-4
    Abstract ( )   PDF in ScienceDirect  
    Nitrogen (N) is one of the macronutrients required for plant growth, and reasonable application of N fertilizers can increase crop yields and improve their quality. However, excessive application of N fertilizers will decrease N use efficiency and also lead to increases in N2O emissions from agricultural soils and many other environmental issues. Research on the effects of different N fertilizer management practices on wheat yields and N2O emissions will assist the selection of effective N management measures which enable achieving high wheat yields while reducing N2O emissions. To investigate the effects of different N management practices on wheat yields and soil N2O emissions, we conducted field trials with 5 treatments of no N fertilizer (CK), farmers common N rate (AN), optimal N rate (ON), 20% reduction in optimal rate+dicyandiamide (ON80%+DCD), 20% reduction in optimal rate+nano-carbon (ON80%+NC). The static closed chamber gas chromatography method was used to monitor N2O emissions during the wheat growing season. The results showed that there were obvious seasonal characteristics of N2O emissions under each treatment and N2O emissions were mainly concentrated in the sowing- greening stage, accounting for 54.6–68.2% of the overall emissions. Compared with AN, N2O emissions were decreased by 23.1, 45.4 and 33.7%, respectively, under ON, ON80%+DCD and ON80%+NC, and emission factors were declined by 22.2, 66.7 and 33.3%, respectively. Wheat yield was increased significantly under ON80%+DCD and ON80%+NC by 12.3 and 11.9%, respectively, relative to AN while there was no significant change in yield in the ON treatment. Compared with ON, overall N2O emissions were decreased by 29.1 and 13.9% while wheat yields improved by 18.3 and 17.9% under ON80%+DCD and ON80%+NC, respectively. We therefore recommend that ON80%+DCD and ON80%+NC be referred as effective N management practices increasing yields while mitigating emissions.
    comparison of phytotoxicity of copper and nickel in soils with different chinese plant species
    LI Bo, LIU Ji-fang, YANG Jun-xing, MA Yi-bing, cHEN Shi-bao
    2015, 14(6): 1192-1201.  DOI: 10.1016/S2095-3119(14)60906-0
    Abstract ( )   PDF in ScienceDirect  
    Ecological risk assessment of metals in soils is important to develop the critical loads of metals in soils. Phytotoxicity is one of the endpoints for ecological risk assessment of soils contaminated with metals. The sensitivity of eight Chinese plant species (bok choy, mustard, tomato, green chilli, paddy rice, barley, spinach and celery) to copper (Cu) and nickel (Ni) toxicity in two Chinese soils was investigated to assess their potential use for ecological risk assessment in the region. The results showed that bok choy and mustard were the two most sensitive species to Cu and Ni toxicities. Assessment of metal accumulation by the plants demonstrated that bok choy shoot had the highest bioconcentration factor (BCF, the ratio of metal concentration in plant shoots to metal concentration in soil). Given the importance of bok choy to agricultural production in Asia, it is therefore important that these sensitive plant species are included in species sensitivity distributions for ecological risk assessment of Cu and Ni in soils.
    Changes in soil organic carbon and aggregate stability after conversion to conservation tillage for seven years in the Huang-Huai-Hai Plain of China
    SHU Xin, ZHU An-ning, ZHANG Jia-bao, YANG Wen-liang, XIN Xiu-li, ZHANG Xian-feng
    2015, 14(6): 1202-1211.  DOI: 10.1016/S2095-3119(14)60862-5
    Abstract ( )   PDF in ScienceDirect  
    Soil aggregate stability and organic carbon (OC) are regarded as effective indicators of soil structure and quality. A longterm field experiment was established in 2006 to examine the influence of tillage systems on soil aggregation and OC in a sandy loam soil in the Huang-Huai-Hai Plain of China. The study involved eight treatments: plowing every year with (TS) and without residue (T), plowing every 2 years with (2TS) and without residue (2T), plowing every 4 years with (4TS) and without residue (4T), and no plowing with (NTS) and without residue (NT). In 2013, soil samples were collected at depths of 0–5, 5–10 and 10–20 cm, and separated into three aggregate-size classes: macroaggregates (>250 μm), microaggregates (53–250 μm) and the silt+clay fraction (<53 μm) using wet sieving method. Soil parameters measured were water-stable aggregates, geometric mean diameter (GMD), mean weight diameter (MWD) and OC concentrations in different aggregate- size fractions and in bulk soil. The tillage treatments significantly (P<0.05) influenced soil aggregate stability and OC distribution. Higher MWD and GMD were observed in 2TS, 4TS and NTS as compared to T. With increasing soil depth, the amount of macroaggregates and MWD and GMD values were increased, while the proportions of microaggregates and the silt+clay fraction were declined. The OC concentrations in different aggregate fractions at all soil depths followed the order of macroaggregates>microaggregates>silt+clay fraction. In the 0–5 cm soil layer, concentrations of macroaggregateassociated OC in 2TS, 4TS and NTS were 14, 56 and 83% higher than for T, whereas T had the greatest concentration of OC associated with the silt+clay fraction in the 10–20 cm layer. Soil OC concentrations under 4TS and NTS were significantly higher (P<0.05) than that of T in the 0–10 cm layer. Residue retention promoted formation of macroaggregates, increased macroaggregate-associated OC concentrations and thus increased total soil OC stock. The macroaggregate-associated OC was positively correlated (R2=0.96) with soil OC concentration, while the silt+clay fraction-associated OC was negatively correlated (R2=0.82) with soil OC concentration. The concentration of soil OC was positively correlated with MWD (R2=0.94) and GMD (R2=0.92). We concluded that increasing tillage intensity led to a loss of carbon (C)-rich macroaggregates and an increase of C-depleted silt+clay fraction. The conservation tillage system, especially NTS and 4TS, increased soil aggregate stability and promoted OC accumulation in macroaggregates, provided the potential to improve soil C sequestration and soil structure in the Huang-Huai-Hai Plain of China.
    Carbon and nitrogen allocations in corn grown in Central and Northeast China: different responses to fertilization treatments
    MIAO Hui-tian, Lü Jia-long, XU Ming-gang, ZHANG Wen-ju, HUANG Shao-min, PENG Chang, CHEN Li-ming
    2015, 14(6): 1212-1221.  DOI: 10.1016/S2095-3119(14)60790-5
    Abstract ( )   PDF in ScienceDirect  
    In order to reveal the impact of various fertilization strategies on carbon (C) and nitrogen (N) accumulation and allocation in corn (Zea mays L.), corn was grown in the fields where continuous fertilization management had been lasted about 18 years at two sites located in Central and Northeast China (Zhengzhou and Gongzhuling), and biomass C and N contents in different organs of corn at harvest were analyzed. The fertilization treatments included non-fertilizer (control), chemical fertilizers of either nitrogen (N), or nitrogen and phosphorus (NP), or phosphorus and potassium (PK), or nitrogen, phosphorus and potassium (NPK), NPK plus manure (NPKM), 150% of the NPKM (1.5NPKM), and NPK plus straw (NPKS). The results showed that accumulated C in aboveground ranged from 2 550–5 630 kg ha–1 in the control treatment to 9 300–9 610 kg ha–1 in the NPKM treatment, of which 57–67% and 43–50% were allocated in the non-grain organs, respectively. Accumulated N in aboveground ranged from 44.8–55.2 kg ha–1 in the control treatment to 211–222 kg ha–1 in the NPKM treatment, of which 35–48% and 33–44% were allocated in the non-grain parts, respectively. C allocated to stem and leaf for the PK treatment was 65 and 49% higher than that for the NPKM treatment at the both sites, respectively, while N allocated to the organs for the PK treatment was 18 and 6% higher than that for the NPKM treatment, respectively. This study demonstrated that responses of C and N allocation in corn to fertilization strategies were different, and C allocation was more sensitive to fertilization treatments than N allocation in the area.