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China implemented the Action Plan for the Zero Increase of Fertilizer Use in 2015, which led to a decrease in fertilizer use. However, Will fertilizer use continue to reduce? With data obtained from 2006 to 2017, the paper used the logarithmic mean Divisia index (LMDI) method to analyze the scale effect, intensity effect and structural effect of fertilizer use change in China from three aspects: crops, regions and fertilizer types. Our finding suggests that (1) The intensity effect was the most critical factor affecting the decline in fertilizer use in China. (2) The sowing scale and fertilization intensity of grain, vegetables and fruits had the most significant driving effect on fertilizer reduction. (3) The three effects of each region were different in space, and the eastern region contributed most to the fertilizer decrement. (4) Nitrogen fertilizer and compound fertilizer had the most considerable influence on fertilizer reduction, especially in the sowing scale and fertilization intensity since 2009. The government should establish a fertilizer reduction management system, which includes scale control, intensity reduction, structural adjustment and other measures., Competing Interests: The authors have declared that no competing interests exist.

The nitrogen cycle has been radically changed by human activities 1 . China consumes nearly one third of the world's nitrogen fertilizers. The excessive application of fertilizers 2,3 and increased nitrogen discharge from livestock, domestic and industrial sources have resulted in pervasive water pollution. Quantifying a nitrogen 'boundary' 4 in heterogeneous environments is important for the effective management of local water quality. Here we use a combination of water-quality observations and simulated nitrogen discharge from agricultural and other sources to estimate spatial patterns of nitrogen discharge into water bodies across China from 1955 to 2014. We find that the critical surface-water quality standard (1.0 milligrams of nitrogen per litre) was being exceeded in most provinces by the mid-1980s, and that current rates of anthropogenic nitrogen discharge (14.5 ± 3.1 megatonnes of nitrogen per year) to fresh water are about 2.7 times the estimated 'safe' nitrogen discharge threshold (5.2 ± 0.7 megatonnes of nitrogen per year). Current efforts to reduce pollution through wastewater treatment and by improving cropland nitrogen management can partially remedy this situation. Domestic wastewater treatment has helped to reduce net discharge by 0.7 ± 0.1 megatonnes in 2014, but at high monetary and energy costs. Improved cropland nitrogen management could remove another 2.3 ± 0.3 megatonnes of nitrogen per year-about 25 per cent of the excess discharge to fresh water. Successfully restoring a clean water environment in China will further require transformational changes to boost the national nutrient recycling rate from its current average of 36 per cent to about 87 per cent, which is a level typical of traditional Chinese agriculture. Although ambitious, such a high level of nitrogen recycling is technologically achievable at an estimated capital cost of approximately 100 billion US dollars and operating costs of 18-29 billion US dollars per year, and could provide co-benefits such as recycled wastewater for crop irrigation and improved environmental quality and ecosystem services.

Population growth makes food production increase necessary; economic growth increases demand for animal products and livestock feed. As further increase of the cropland area is ecologically undesirable, it is necessary to increase crop yields; this requires, inter alia, more nitrogen and phosphorus fertiliser despite the environmental problems which this will exacerbate. It is probable that a satisfactory food supply and an environmentally benign agriculture worldwide cannot be achieved without reducing population to approximately three billion. The reduction could be achieved by 2200 if the total fertility rate--currently 2.5--declined to 1.5 as a world average by 2050, and remained at that level until 2200, but the probability of such a global fertility trajectory is close to zero. It will also be necessary to replace fossil energy by nuclear and renewable energy in order to stabilise atmospheric carbon dioxide concentration, but the phase-out cannot be completed until the 22nd century, when the atmospheric concentration will be approximately 50% above the 2015 level of 400 ppm.

In cultures containing multiple sources of nitrogen, Saccharomyces cerevisiae exhibits a sequential use of nitrogen sources through a mechanism known as nitrogen catabolite repression (NCR). To identify proteins differentially expressed due to NCR, proteomic analysis of S. cerevisiae S288C under different nitrogen source conditions was performed using two-dimensional gel electrophoresis (2-DE), revealing 169 candidate protein spots. Among these 169 protein spots, 121 were identified by matrix assisted laser desorption ionization-time of flight/time of flight mass spectrometry (MALDI-TOF/TOF). The identified proteins were closely associated with four main biological processes through Gene Ontology (GO) categorical analysis. The identification of the potential proteins and cellular processes related to NCR offer a global overview of changes elicited by different nitrogen sources, providing clues into how yeast adapt to different nutritional conditions. Moreover, by comparing our proteomic data with corresponding mRNA data, proteins regulated at the transcriptional and post-transcriptional level could be distinguished. Biological significance In S. cerevisiae, different nitrogen sources provide different growth characteristics and generate different metabolites. The nitrogen catabolite repression (NCR) process plays an important role for S. cerevisiae in the ordinal utilization of different nitrogen sources. NCR process can result in significant shift of global metabolic networks. Previous works on NCR primarily focused on transcriptomic level. The results obtained in this study provided a global atlas of the proteome changes triggered by different nitrogen sources and would facilitate the understanding of mechanisms for how yeast could adapt to different nutritional conditions., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Fibrolytic enzyme production by Aspergillus japonicus C03 was optimized in a medium containing agro-industrial wastes, supplemented with peptone and yeast extract. A 2(3) full factorial composite and response surface methodology were used to design the experiments and analysis of results. Tropical forages were hydrolyzed by A. japonicus C03 enzymatic extract in different levels, and they were also tested as enzymatic substrate. Optimal production to xylanase was obtained with soybean bran added to crushed corncob (1:3), 0.01% peptone, and 0.2% yeast extract, initial pH 5.0, at 30 °C under static conditions for 5 days of incubation. Optimal endoglucanase production was obtained with wheat bran added to sugarcane bagasse (3:1), 0.01% peptone, and 0.2% yeast extract, initial pH 4.0, at 30 °C, for 6 days, under static conditions. Addition of nitrogen sources as ammonium salts either inhibited or did not influence xylanase production. This enzymatic extract had a good result on tropical forage hydrolyzes and showed better performance in the Brachiaria genera, due to their low cell wall lignin quantity. These results represent a step forward toward the use of low-cost agricultural residues for the production of valuable enzymes with potential application in animal feed, using fermentation conditions.

Solid-state fermentation obtained from different and low-cost carbon sources was evaluated to endocellulases and endoxylanases production by Aspergillus japonicus C03. Regarding the enzymatic production the highest levels were observed at 30 °C, using soy bran added to crushed corncob or wheat bran added to sugarcane bagasse, humidified with salt solutions, and incubated for 3 days (xylanase) or 6 days (cellulase) with 70% relative humidity. Peptone improved the xylanase and cellulase activities in 12 and 29%, respectively. The optimum temperature corresponded to 60 °C and 50-55 °C for xylanase and cellulase, respectively, both having 4.0 as optimum pH. Xylanase was fully stable up to 40 °C, which is close to the rumen temperature. The enzymes were stable in pH 4.0-7.0. Cu++ and Mn++ increased xylanase and cellulase activities by 10 and 64%, respectively. A. japonicus C03 xylanase was greatly stable in goat rumen fluid for 4 h during in vivo and in vitro experiments.

The study of nitrogen (N) balance in stock farming system is the basis of nutrient management in animal husbandry production, and the determination of N cycling parameters is the foundation of this study. Through documents checking and data collecting, this paper analyzed the items and values of input/output parameters of N cycling in stock farming system, and ascertained the estimation parameters of N balance in the system, which could offer the theoretical foundation for nutrient management in animal husbandry production.

Early season leaf growth depends largely on nitrogen (N) provided by remobilization from storage, and many studies have tested the effect of N availability to roots on the amount of N provided for new leaf development by remobilization. Although it is well known that the light regime experienced by a leaf influences the amount of N per unit leaf area (LA), the effect of the local light regime on the amount of N derived either directly from root uptake or from remobilization for early season leaf growth has never been tested at an intra- canopy scale. The objective of this study was to quantify the relative importance of (1) N availability to roots, (2) local light regime experienced by the foliage (at the shoot scale) and (3) leaf rank along the shoot, on the total amount of N allocated to leaves and on the proportions of N provided by remobilization and root uptake. To quantify the importance of N uptake and remobilization as sources of leaf N, potted hybrid walnut trees (Juglans nigra L. x regia L.) were grown outdoors in sand and fed with a labeled ((15)N) nutrient solution. By removing the apical bud, the trees were manipulated to produce only two shoots. The experimental design had two factors: (1) high (HN; 8 mol N m(-3)) and low (LN; 2 mol N m(-3)) N availability; and (2) high (HL; 90% of incident photosynthetically active photon flux (PPF)) and low (LL; 10% of incident PPF) light. Total leaf N per tree was unaffected by either N availability or irradiance. The HN treatment increased the amount of leaf N derived from root uptake at the whole-tree scale (typically around 8 and 2% in the HN and LN treatments, respectively). Nitrogen allocation within foliage of individual trees was controlled by the local light regime, which strongly affected individual leaf characteristics as leaf mass per unit LA and area- based amount of leaf (N(a)). Decreasing the light availability to a branch decreased the amount of N allocated to it, benefiting the less shaded branches. In contrast, shading of the lower branch did not affect the fraction of total leaf N remobilized for either the lower, shaded branch or the upper, unshaded branch. The relevance of these findings for tree growth modeling is discussed.

Dutch nutrient policy aims at reducing leaching of agricultural nutrients by internalizing the negative externalities associated with inefficient nutrient use. This is done by taxation of nitrogen and phosphate surpluses that exceed a hectare-based threshold of maximum-allowed surpluses. One management strategy farmers may use to reduce the nutrient surpluses on their farms is to improve the nutrient efficiency of the agricultural production process. This study employs Data Envelopment Analysis (DEA) to calculate nitrogen and phosphate efficiencies and an overall nutrient efficiency measure for a 3-year panel of 114 Dutch dairy farms. Subsequent analyses show the impact of both farm intensity and nutrient efficiency on the nitrogen and phosphate surpluses. It appears that farm intensity has a positive effect on efficiency, but efficiency and intensity exert opposite influences on nutrient surpluses. This is especially the case for nitrogen. The magnitude of a possible reduction of nitrogen surpluses through a strategy of efficiency improvement is therefore limited by the intensity of the farming system, unless the technology with which nutrients are used by the farming system can be further improved or input/output ratios will be altered.

Annual nitrogen (N), phosphorus (P), and potassium (K) flows in agriculture in The Netherlands were identified and quantified in 1990, with special emphasis on pig production. Also, the effects that various management strategies in pig production have on NPK emission in 1990 were compared using a static deterministic simulation model. Ammonia emission from pig production in 1990 (60.9 Gg N) exceeded the defined target for the year 2000 (12.7 Gg N). Measures that affect volatilization of ammonia directly (i.e., introduction of low-emission stables, manure storage facilities, or manure application techniques) reduced ammonia emission most effectively. These measures, however, should be combined with a reduction in application of artificial N fertilizer to avoid an increase in N losses through leaching, run-off, or denitrification. Targets for ammonia emission in the year 2010 require a reduction in the pig population of 24 to 62%, in addition to implications of measures described in this article. National NPK losses in 1990 through leaching, run-off, or denitrification, predicted at 223.5 kg/ha for N, 32.7 kg/ha for P, and 67 kg/ha for K, exceeded government targets for the year 2010 (185 kg N/ha; 8.7 kg P/ha; norm not set for K). Reducing application of artificial NPK fertilizer reduced national NPK losses most effectively. For P, use of phytase and feeding pigs in accordance with their P requirements is required, in addition to limited use of artificial P fertilizer to meet targets for the year 2010. Hence, from an environmental point of view, pig production in The Netherlands is limited primarily by ammonia emission targets for the year 2010.