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Water erosion process induces differences to the nitrogen (N) functional microbial community structure, which is the driving force to key N processes at soil-water interface. However, how the soil N transformations associated with water erosion is affected by microorganisms, and how the microbial respond, are still unclear. The objective of this study is to investigate the changes of microbial diversity and community structure of the N-cycle function microorganisms as affected by water erosion under application of organic manure and straw cover. On the basis of iso-nitrogen substitution, four treatments were set up: 1) only chemical fertilizer with N 150 kg ha−1, P2O5 60 kg ha−1 and K2O 90 kg ha−1 (CK); the N was substituted 20% by 2) organic manure (OM); 3) straw (SW); and 4) organic manure + straw (1:1) (OMSW). The results showed that applying organic manure and straw to sloping farmland can increase soil N contents, but reduce runoff depth, Kw, sediment yield and N loss, especially in the OMSW. Straw cover and straw + organic manure increased the diversity (Chao1) of nitrifier (AOB), and both diversity and uniformity (Shannon) of denitrifier (nirK/S) were increased in the OMSW. All erosion control measures reduced N-fixing bacteria diversity and increased their uniformity, and the combined application of organic manure and straw cover was a better erosion control measure than the single application of them. Improved soil chemistry and erodibility were the main drives for the changes of N-functional microbial community structure and the appearance of dominant bacteria with different organic materials.

The discrepancy between livestock breeding and crop planting in integrated crop-livestock system (ICLSs) usually cause nutrients surpluses to the arable land. Evaluation of regional land bearing capacity and identification of environmental critical regions associated with livestock in China are benefit to nationally- and regionally-specific livestock rearing. This study was conducted to demonstrates the changes in livestock industry from 1996 to 2016 in China and identify the environmentally critical regions of livestock farming by calculating the indexes of bearing capacity of cropland based on nitrogen (IN) and phosphorus (IP). The results revealed that the scale of livestock and poultry farming, manure production, and manure nutrients has increased over the past two decades. The livestock and poultry breeding quantity was 1290.8 million heads with a manure production of 4238.0 million tons in 2016. The manure N and P were 12.0 and 1.9 million tons with an increase of 5.8% and 5.9%, respectively. The N and P demand of crops from manure were 29.1and 4.5 million tons with an increase of 31.5% and 27.2%, respectively. The bearing capacities based on N and P were 2668.9 and 2554.7 million heads in pig equivalent, respectively. On the national level, the IN and IP were 0.43 and 0.45, respectively, which is categorized as Grade II. Livestock rearing in China was still within the bearing capacity of cropland. Both the Northeast and Northwest regions were categorized as Grade I, while Southeast region, Southwest region, the Middle and Lower Reaches of the Yangtze River and the North China were categorized in Grade II. There is still enough space for expansion of livestock and poultry farming in the Northeast and Northwest regions. In the North China region, Southwest region, the Middle and Lower Reaches of the Yangtze River, and the Southeast region, manure generated can be accommodated without any expansion in livestock breeding quantity. While livestock industry in Sichuan, Yunnan, Beijing and Tianjin need to be strictly controlled because of the grade of IV and V.

Atmospheric nitrogen (N) deposition caused by anthropogenic activities may alter litter decomposition and species composition, and then affect N cycling and carbon (C) sequestration in an ecosystem. Using the litterbag method, we studied the effects of N addition (CK: no N addition; low-N: 1 g N m-2 y-1; high-N: 2 g N m-2 y-1) on changes in mass remaining of shoot litter decomposition of three grasses (Stipa baicalensis, Carex pediformis and Leymus chinensis) over 28 months in the Hulun Buir meadow steppe of Inner Mongolia. The results showed that the addition of high and low N had no significant effect on the decomposition of single-species litter, but low N addition slightly inhibited the decomposition of litter mixtures. In addition, litter decomposition was strongly species dependent. Our results suggest that species type is likely the main determinant of litter decomposition, and low N deposition in natural ecosystems does not influence single-species litter decomposition.

Er3+ and Yb3+ ions codoped calcium aluminum germanate glass has been synthesized by solid-state reaction. An intense infrared emission at 1534 nm, which corresponds to the minimum losses of silica based fibers used in optical communications, and visible emissions at 416, 490, 525, 548, and 660 nm, corresponding to the 4I13/2→4I15/2, 2H9/2→4I15/2, 4F7/2→4I15/2, 2H11/2→4I15/2, 4S3/2→4I15/2, and 4F9/2→4I15/2 transitions of Er3+ ions, respectively, were simultaneously observed in this glass under the excitation of a 978 nm diode laser at room temperature. These emissions are mainly attributed to energy transfer from Yb3+ ions to Er3+ ions. The up-conversion processes involve a sequential two-photon absorption for the red (660 nm), the green emissions (525 and 548 nm) and the blue emission (490 nm), and a sequential three-photon absorption for the violet-bluish emission (416 nm). The up-conversion fluorescence of Ca3Al2Ge3O12:Er,Yb glass can be used to detect 980 nm infrared laser light.

In this work, erbium-doped calcium aluminum silicate (CAS) glass has been synthesized by solid-state reaction. Intense emission at 1534 nm, corresponding to the 4 I 13/2 → 4 I 15/2 transition of the Er 3+ ion, was observed upon both 488 nm Ar + laser and 978 nm diode laser excitations at room temperature. The luminescence mechanisms in the glass are discussed. These results indicate this glass is a promising laser material with its high chemical durability and thermal stability.