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The deterioration of water quality induced by overuse of N and P fertilizers has become one of the main limiting factors of the sustainable economic and social development of the Yangtze River Basin (YRB), China. Three field experiments using 15N-labeled urea were conducted at three locations in upstream, midstream, and downstream regions of YRB to evaluate the impacts of improved fertilizer management (reduced rates and better timing of the applications compared to a traditional, high N application) on crop yield, fertilizer N recovery, and fate in a rice (Oryza sativa L.)-flooded fallow rotation (RF), a rice-wheat (Triticum aestivum L.) rotation (RW), a rice-flooded fallow rotation (RF), a rice-vegetable rotation (RV), and a maize (Zea mays L.) -wheat rotation (MW). The improved fertilizer treatment significantly increased rice grain yield by 12.9% compared with the high fertilizer treatment in a RW rotation in Rugao (Jiangsu), but had no significant effect on rice grain yield in the other rotations. It led to significantly lower maize yields in Jiangjin (Chongqing). The total fertilizer N recoveries in rice and in the 0 to 40 cm soil were 17 to 35% and 17 to 32%, with crop and/or soil recoveries usually higher in the improved fertilizer treatments than in the traditional fertilizer treatments, but not for maize. Fertilizer N losses can be reduced by using improved fertilizer management in a rice-based rotation. An improved fertilizer management which has 60% N and 50% P application of the traditional fertilizer application can produce a sustained high rice yield and reduce the environmental impact compared with traditional fertilizer input used in the YRB. [ABSTRACT FROM AUTHOR]

Over the past 2000 yr, agriculture in China has transformed from a low-input, low-output organic-based system to an intensive production system that relies heavily on inorganic inputs. The modern high-input, high-output system has provided the nation with basic food self-sufficiency, although at escalating environmental costs. Meanwhile, crop production has been nearly stagnant since the mid-1990s, despite continued increases in production inputs, such as chemical fertilizers. In the future, China must increase agricultural output by 50% to meet its growing food demand. New advances to increase agricultural productivity and improve resource (e.g., N and P) use efficiency will be critical in China for sustainable agriculture and ecosystem services. Here, we discuss an integrated soil-crop system management (ISSM) paradigm that may help achieve the sustainable intensification goal. This paradigm features (i) improving soil quality, (ii) enhancing the use of various nutrient resources, (iii) closing the yield gap, and (iv) effectively reducing N losses. Recent on-farm trials based on ISSM principles almost doubled corn yield, while fertilizer N amounts were similar to current farming methods. This ISSM in China is a novel agricultural paradigm that can improve food security and environmental quality worldwide, especially in regions of high input with low-efficiency systems. [ABSTRACT FROM AUTHOR]

The intensification of agricultural production has been accompanied by an overuse of N fertilization and has accelerated global N consumption in the last 20 yr. We undertook 269 on-farm demonstration trials to evaluate variations in the optimal N rate (ONR) and developed regional N rate guidelines for intensive wheat (Triticum aestivum L.)-maize (Zea mays L.) rotation systems in the North China Plain. Large variations in the ONR (coefficient of variation = 38~39%) were observed across the 269 fields, resulting from large variations in the initial soil NO3-N supply before sowing. A negative linear relationship between the ONR and initial soil NO3-N suggested that 1 kg soil NO3-N ha-1 was equivalent to applications of 0.54 and 0.71 kg fertilizer N ha-1 for wheat and maize, respectively. The current cropping system, with excessive N inputs and large variations in residual NO3-N in the top 90-cm soil depth (averaging 188 kg N ha-1 season-1 and ranging 20-987 kg N ha-1 season-1), could be transformed with optimal N management to a steady state, in which the residual NO3-N content is maintained at about 90 to 100 kg N ha-1. Regional N rate guidelines should be 154 to 159 and 164 to 171 kg N ha-1 for yields of 6 and 9 Mg ha-1 for wheat and maize, respectively. This regional N rate guideline may not be completely accurate but is a robust and simple guideline acceptable to the 100 million smallholder farmers in China. [ABSTRACT FROM AUTHOR]

China's vegetable production has experienced a rapid growth in recent years. Total production amounted to 522.7 million Mg (1 Mg = 106 g) in 2009, which was more than nine times that in 1980 and represented >50% of the world production. Meanwhile, excessive use of animal manures and chemical fertilizers in vegetable fields has brought various production and environmental challenges, including excessive accumulation of nutrients in soils and accelerated water pollution problems. In this study, we have evaluated the current status of phosphorus (P) in China's intensive vegetable production systems based on data summarized from nearly 100 publications plus results from our recent experiments. Gross overfertilization occurred in greenhouse (571 kg P ha-1) and open-field (117 kg P ha-1) vegetable systems compared with P removal in harvested crops (44 and 25 kg P ha-1) per season. Excess P input led to soil enrichment of labile P, measured as Olsen-P, averaging 179 (greenhouses) and 100 mg P kg-1 (open fields) in the 0- to 20-cm soil depth, and in some cases led to P leaching, as evidenced by increases in Olsen-P and CaCl2-P at the 40- to 60-cm soil depth. The vast majority of vegetable soils had Olsen-P exceeding the critical level (46.0-58.0 mg P kg-1) for optimum vegetable yield. Innovative policies and strategies are urgently needed to implement science-based nutrient management practices to attain sustainable vegetable production while protecting natural and environmental resources. [ABSTRACT FROM AUTHOR]

China has made remarkable strides in recent decades to grow enough food to feed 20% of the worlds population with only 9% of the world's arable land. Meanwhile, the nation is experiencing exacerbated air and water pollution problems. Agricultural growth and the pollution aggravation are closely linked with policies affecting fertilizer production and use. Essentially nonexistent in 1950, China's fertilizer industry is now a robust conglomerate producing fertilizers in amounts that not only meet domestic demand but also contribute to international trade. The industry's growth stemmed from a series of policy progressions, featuring (i) a total control system with state ownership and central planning (1949-1984), (ii) a dual system of central planning and market adjustment (1985-1997), (iii) a market-driven system with government-mandated price caps (1998-2009), and (iv) a complete market-oriented system (since 2009). In conjunction with the policy changes were massive subsidy programs totaling more than $18 billion in 2010. The support policies and subsidies helped grow the industry and safeguard an adequate supply of fertilizers at affordable costs to farmers, but the artificially low-priced fertilizers also contributed to a nationwide trend of fertilizer overuse, leading to nutrient pollution. China needs innovative policies and programs to address food security and sustainability challenges. In this study, we review and analyze policies and programs related to China's fertilizer production and use in a 60-yr span (1950-2010) and discuss its impact on the development of the industry, food security, and pressing environmental issues. Finally, our study analyzes long- term trends in fertilizer use in China and offers some key viewpoints to stimulate debates among all stakeholders. [ABSTRACT FROM AUTHOR]

Chinese farmers believe that more fertilizer and higher grain yields are synonymous. A better understanding of the relationship between corn (Zea mays L.) yields and N rate could help agronomists match fertilizer rates with plant requirements. The objective of this study is to evaluate corn yield response to applied N fertilizer and to understand the factors affecting yield response to N fertilizer by 737 on-farm experiments in northeastern China. Corn grain yield without applied N fertilizer averaged 7.6 Mg ha-1. Increased yield for applied N fertilizer (IYN, the difference between maximum yield across all treatments and yield of the N0 treatment) averaged 2.5 Mg ha-1 and varied from 0 to 9.3 Mg ha-1. Farmers' practices and corn hybrids resulted in large variability in IYN, whereas no changes in IYN occurred among years or soil types. Under the current cropping system, the maximum corn yield significantly increased and IYN decreased with increasing yield of the N0 treatment, suggesting that increasing IYN with high yield of the N0 treatment using integrated hybrids along with strategic management of crops, soils, and N is crucial for achieving high yields with a high N use efficiency (NUE). [ABSTRACT FROM AUTHOR]

China is facing great challenges in both food security and environmental sustainability against the background of global climate change. In order to meet the increasing demand for food in China, increasingly more reactive nitrogen (Nr) species have been synthesized by the Haber–Bosch process. Overuse of nitrogen (N) fertilizer has occurred widely in Chinese agriculture. Motor vehicles, power plants and industrial facilities are consuming large amounts of fossil fuels. As a consequence, gaseous Nr emissions including NH3, NO x and N2O have increased substantially since 1980, directly or indirectly contributing to the greenhouse gas (GHG) balance and climate change. The GHG emissions from N fertilizer production and transport (274TgCO2eqyr−1) and use for crop (403TgCO2eqyr−1) application occupied a major part of total agricultural emissions in China, in spite of small carbon (C) sequestration in croplands (28–37TgCO2eqyr−1) induced by N fertilizer. Strategies to reduce N fertilizer loss and GHG emissions are mentioned briefly. China has also witnessed detectable climate warming, fluctuations in precipitation and other extreme weather conditions over the last 30 years. This climate change has threatened national cereal production and may accelerate N cycling (i.e., N2O emissions) in croplands and non-arable soils. These N feedbacks should be taken into account when considering mitigation of GHG emissions. [ABSTRACT FROM AUTHOR]

The article presents a study on the use of integrated soil-crop management systems (ISSM) for corn production in the north China plain. Key points in the approach include taking all possible soil quality improvement measures, utilizing nutrient resources and match nutrient supply to crop requirements and integrating soil and nutrient management with high yielding systems of cultivation. ISSM leads to an increase in crop yields and increase nutrient use efficiency and reduce environmental risk.

Potassium fertilization is uncommon in the North China Plain (NCP), especially in maize (Zea mays L.) production. Our specific objectives in this study were to determine yield response to K fertilization as affected by conventional as well as high-yielding production practices. Seven field experiments were conducted in the NCP. The factorial study compared three levels of K fertilization (K0 = no K; K1 = medium K rate; K2 = high K rate) and two levels of production practices: conventional (CP) and high yielding (HP). At all sites, HP outperformed CP in terms of maize grain yield except at ZD in 2006. On average, maize grain yields were enhanced by 9.9 and 14.9% under CP and 15.7 and 21.0% under HP at the K1 and K2 levels, respectively. Maize yield response, as well as economic profit from applied K, were greater under HP than CP, on average, across seven site-years. Medium K inputs improved partial factor productivity (PFP) of applied N and P, while higher rates had inconsistent results. Overall, PFP and agronomic efficiency of applied K were improved under HP, as was the apparent recovery efficiency of applied K, which suggests positive interactions among K and other high-yielding production practices. Negative K balances were observed in all of the K0 and K1 treatments in both years and under both production practices, especially under HP. In intensive agricultural soils of the NCP with higher K content relative to South China, optimal K fertilization will improve soil fertility and support high grain yield. [ABSTRACT FROM AUTHOR]

The article discusses the effect of pollution control on air quality during the 2008 Beijing Olympics in China. The event provides an opportunity for testing the clean-up controls on air quality in the country. It was found that atmospheric concentrations of several pollutants decrease during the game due to strict emission controls but a year after the Olympics, the mean concentrations of the pollutants increase again. It is considered that the results suggest the need of the country to implement long-lasting decreases in its air pollution.

The article discusses the study which aims to quantify the nitrogen mass flow in the animal production system in China. A comprehensive analysis indicates that approximately 18Mt of nitrogen has flowed from various feed materials which contribute significantly to nutrients polluting the groundwater or surface waters and accelerating environmental degradation. The study recommends that China should develop and implement management practices to maximize the benefits of nitrogen outputs while minimizing its environmental footprints.

The article presents a study on the contribution of nitrogen (N) deposition to the extremely managed agricultural ecosystems. The study measured total N deposition in Quzhou in Hebei, China and Dongbeiwang near Beijing, China from 2005 to 2007 with the integrated total N input (ITNI) system. It found that both places had total airborne N inputs ranging from 99 to 117 kg in a maize-wheat rotation system. It concluded that atmospheric N deposition is vital in managed agricultural ecosystems.

The article discusses an analysis on malate exudation by six aerobic rice genotypes that vary in zinc (Zn) uptake efficiency. It states that a rhizotron experiment with low Zn clay soil and a nutrient solution experiment are conducted to determine if this occurs in six rice genotypes varying in tolerance to low Zn supply. In both experiments, low Zn supply lead to a decrease in biomass production of most genotypes than with adequate Zn supply. Also, the genotypes showed a variation in Zn efficiency and plants responded to low Zn supply with increased root exudation of malate. On average, low supply of Zn in rhizotron experiment increased the concentration of rhizosphere malate by 64%, but the malate exudation of genotypes at low Zn was not related to Zn efficiency in the experiments.