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Additional file 8: Materials and Methods. Supplementary Text. Table S1. Temporal N2O concentrations (μL L-1) in the headspace in the preliminary experiment. Table S2. Primers and PCR conditions used for the PCR. Table S3. Stepwise multiple regression to identify the abundance and expression of key genes involved in N cycling which had the strongest statistical contributions to variation in the cumulative N2O emission in pot expt 2. Independent variables include the abundances and expressions of nirK, nirS and clade I and II nosZ genes. Dependents variable is the cumulative N2O emission. Table S4. Permutational multivariate analysis of variance (PERMANOVA) of the effects of patch type (PT; pot expt 1) or harvest time (HT; pot expt 2) and AMF treatment on microbial communities harbouring nirK, nirS and clade I nosZ based on the gene and transcript sequencing. Table S5. Permutational multivariate analysis of variance (PERMANOVA) of the effect of AMF treatment on clade I nosZ community in different patches (pot expt 1) or harvest time (pot expt 2) based on the gene and transcript sequencing. Table S6. In vitro experiment: metabolite concentrations in the hyphal exudates of Rhizophagus irregularis. Table S7. Effects of patch type and AMF treatment on biomass, N concentration and N content of maize in pot expt 1. Table S8. Effects of harvest time and AMF treatment on biomass, N concentration and N content of maize in pot expt 2.

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, NOx 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 (274 Tg CO2eq yr−1) and use for crop (403 Tg CO2eq yr−1) application occupied a major part of total agricultural emissions in China, in spite of small carbon (C) sequestration in croplands (28–37 Tg CO2eq yr−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.

In this paper,a case study on atmospheric nitrogen(N) deposition in the main regions of China is carried,and the definition,forms and amount of nutrient from environment(NFE) and the relationship between NFE and N discharge to atmosphere caused by human activities are summarized.Based the study results in this paper and the references,it is fund that N wet and dry deposition has become as an important nutrient resources in agricultural and natural ecosystems in China.The total annual amount of N deposition and other N forms from environment in China is up to 1.8×107 t,and equals to approximately 60% of the national N fertilizer consumption.Therefore,it is crucial to fully utilize the environmental nutrient resources by managing the nutrient resources in an integrative so as to achieve the sustainable development of both agricultural and natural ecosystems.It is suggested to develop a nationwide network for monitoring and quantitatively researching the N wet and dry deposition and carrying out the long-term experiment about the ecological response and feedback of some sensitive ecosystems to N deposition from atmosphere.

Field studies were conducted from 2000 to 2002 to quantify how the accumulation and distribution of dry matter and K + in tobacco plants ( Nicotiana tabacum L. variety K326 in 2000 and 2002, and Nicotiana tabacum L. variety Yun 85 in 2001) affects the K + concentration in leaves after apex excision. Dry matter accumulation (DMA) in K326 increased after apex excision but then decreased as the leaves began to mature, while DMA in Yun 85 continuously increased after apex excision. As leaves matured, a net decrease of dry matter occurred sequentially in lower leaves, middle leaves, upper leaves, and even in stems and roots for K326 but only in lower leaves for Yun 85. The patterns of K + uptake by roots and changes in K + content and concentration in different plant organs were similar for all three years of the study. K + content was highest 12–20 days after apex excision and then decreased; until the final harvest of leaves, K + content decreased 15% in 2000, 10% in 2001, and 30% in 2002. Moreover, a net export of K + occurred from leaves to stem and roots such that the percentage of K + in leaves vs. the whole plant dropped from 65% at the time of apex excision to 58% at the last harvest, while that of stem plus roots increased from about 35% at the time of apex excision to about 42% at the last harvest. The K + concentration in all plant organs continuously decreased after apex excision with time. Overall, the results indicate the K + concentration in leaves decreases after apex excision because (1) plant dry matter increases at a greater rate than K + uptake (the dilution effect), (2) there is a net decrease in K + content, and (3) K + is transported from leaves to stems and roots.

La fertilizacion nitrogenada ha tenido un rol significativo en incrementar los rendimientos de los cultivos, y resolver problemas de hambre y malnutricion en todo el mundo. Sin embargo, la fertilizacion nitrogenada excesiva no incrementa los rendimientos de los cultivos significativamente sino que puede conducir a severos problemas ambientales. Los efectos de la tasa de fertilizacion nitrogenada se estudiaron en el contenido de metales pesados en granos de maiz. Nuestros resultados muestran que el manejo de la fertilizacion nitrogenada es benefico para reducir los costos de produccion, proteger el ambiente, y mejorar la calidad de productos agricolas

There is increasing interest in nitrogen (N) deposition because of its importance as a nutrient resource and a component of acid deposition within the overall global N cycle. Precipitation samples were collected for periods varying from 6 months to 6 years (1998–2004) from seven sites in the Beijing area to determine the amount and seasonal distribution of N (bulk/wet) deposition. Bulk deposition of N ranged from 26.6 to 38.5 kg N ha−1 year−1 and averaged 30.6 kg N ha−1 year−1. Bulk deposition of NH4–N was, on average, 2.1 times the NO3–N deposition, suggesting that reduced N is the major form of N deposition in the study area. Concentrations of NH4–N and NO3–N in rainfall averaged 4.8 and 2.2 mg N L−1 and showed great temporal variation from month to month. A negative relationship between rainfall and NH4–N or NO3–N concentration in rainwater was observed by an exponential equation, indicating dilution of NH4–N and NO3–N with increasing precipitation. Bulk deposition of inorganic N occurred mainly from April to September (>80% of total bulk deposition), which was consistent with both the monthly distribution of precipitation and the times of fertilizer applications in local agricultural land. Wet-only deposition of inorganic N, however, was 8.3–8.4 kg N ha−1 lower than that of bulk deposition during similar periods in 2003 (June–November) and 2004 (April–November), suggesting the potential contribution of dry deposition to total N deposition in the Beijing area.

Being a new cultivar, the physiology of transgenic cotton, especially dual-toxin transgenic (Bt+CpTI) cotton, is not yet completely understood. Twelve elements in three organs of dual-toxin transgenic cotton seedlings were analyzed by ICP-MS. The distributions of the 12 elements were substantially different from those of non-transgenic cotton. In particular, the contents of B, Mg, P, K and Ca were the highest in leaves, while those of Si, Fe, Rb and Cu were the highest in roots; other elements had similar contents in the two organs, which were higher than those in the stem. Compared with non-transgenic cotton, the 12 elements could be classified into four groups according to their contents and distributions in the three organs: (a) P, K and Cu: their contents in transgenic cotton were remarkably lower, especially contents of P and K in leaves that were one times lower than those in leaves of non-transgenic cotton; (b) B, Mg and Mo: their contents in leaves and roots of transgenic cotton were high...

The traditional Chinese soybean paste was produced by cooked transgenic soybean fermentation with the composition of moisture 53%, amino acid 0.84% (calculated by nitrogen), votive sugar 6.21% and total acid 1.66%. A number of microorganism species were isolated and identified, including fungi and bacteria, and the bacterium species Rhizopus oryzae Went and Prinsen Geerligs were dominant in transgenic soybean paste. The results showed that the transgenic soybean paste contain abundant amino acids and vitamins (vitamin A, 42.87 IU; vitamin B, 10.31 mg; vitamin B, 20.64 mg; nicotinamide, 2.54 mg; pantothenic acid, 0.63 mg; vitamin B, 6,847 microg; folic acid, 105 microg; vitamin B, 123.85 microg; and biotin, 56.34 microg). Pathogenic microorganisms were not be detected in the transgenic fermented soybean paste.

Variable rate fertilization (VRF), a kind of precision management, was attempted in an experiment farm of winter wheat. The farm was divided into 48 test cells, which the level of the field nutrient varied in different cells in 2004. The hyperspectral reflectance and the remote sensing images of the farm were acquired using a handheld spectroradiometer and an unmanned aircraft respectively, and then the characteristics of the hyperspectral data and the aerial images were calculated. A yield map was obtained by using a combine with yield monitor and DGPS. Soil total nitrogen of each test cells was analyzed by grid-sampling method. The vegetation indices and the color characteristics calculated denoted fertilization status and growing condition of winter wheat. The reflectance showed obvious negative correlation with soil total nitrogen and yield in 520-700 nm and positive correlation with R/(R+G+B). The grain yield showed negative correlation with R/(R+G+B). Soil total nitrogen had a great effect on yield when total nitrogen was less than 200 kg/hm2 at elongating stage of winter wheat. After performing VRF management, the difference of the yield was reduced and the total yield was increased. The efficiency of the fertilizer was improved and the environment pollution was decreased. It could be concluded that the precision management based on the aerial images and the hyperspectral data could promote farming production.

Agronomic traits and quality indices are closely related to patterns of nutrient uptake among different sugarcane varieties. Knowing the optimal nutrient needs of specific varieties could help growers provide adequate fertilizer while avoiding over-fertilization. Field trials on the variations of growth, uptake of nitrogen (N), phosphorus (P), potassium (K) and related quality indices among different new varieties of sugarcane were compared to the widely planted variety ROC 22, which was conducted in Zhanjiang, Guangdong, in southern China. The results showed that the highest germination rate was observed in YT 55, and both the highest tillering rate and both the formative rate of stalk and millable canes were observed in BC 2–32, respectively. YT 55 had the highest cane yield (154.1 t/ha) and sugar yield (20.4 t/ha). The accumulation of N, P and K in YT 55 reached 290.5, 67.9 and 447.5 kg/ha, respectively, which was 1.6, 1.6 and 1.4-fold higher than observed in ROC 22. The nutrient use efficiency of nitrogen/phosphorus/potassium fertilizer (NPK) to produce cane and sugar in ROC 22 and YT 60 was superior among the tested varieties. The differences in cane and sugar yield, and nutrient utilization efficiencies among the investigated varieties point out the need for variety specific nutrient recommendations. This study also confirmed that distinct differences existed in the yield of both cane and sugar produced in different sugarcane varieties if more fertilizers are supplied to sugarcane during the tillering and elongation stage.

Since the 1980s, the widespread use of N fertilizer has not only resulted in a strong increase in agricultural productivity but also caused a number of environmental problems, induced by excess reactive N emissions. A range of approaches to improve N management for increased agricultural production together with reduced environmental impacts has been proposed. The 4R principles (right product, right amount, right time and right place) for N fertilizer application have been essential for improving crop productivity and N use efficiency while reducing N losses. For example, site-specific N management (as part of 4R practice) reduced N fertilizer use by 32% and increased yield by 5% in China. However, it has not been enough to overcome the challenge of producing more food with reduced impact on the environment and health. This paper proposes a new framework of food-chain-nitrogen-management (FCNM). This involves good N management including the recycling of organic manures, optimized crop and animal production and improved human diets, with the aim of maximizing resource use efficiency and minimizing environmental emissions. FCNM could meet future challenges for food demand, resource sustainability and environmental safety, key issues for green agricultural transformation in China and other countries