Magnetocaloric effect and magnetostructural coupling in Mn0.92Fe0.08CoGe compound

The structural properties of Mn0.92Fe0.08CoGe have been investigated in detail using synchrotron x-ray diffraction in zero and applied pressure (p = 0-10 GPa). A ferromagnetic transition occurs around TC = 300 K and a large magnetic-entropy change -ΔSM = 17.3 J/kg K detected at TC for a field change of ΔB = 5 T. The field dependence of -ΔSM max can be expressed as -ΔSM max ∞ B. At ambient temperature and pressure, Mn0.92Fe0.08CoGe exhibits a co-existence of the orthorhombic TiNiSi-type structure (space group Pnma) and hexagonal Ni2In-type structure (space group P63/mmc). Application of external pressure drives a structure change from the orthorhombic TiNiSi-type structure to the hexagonal Ni2In-type structure. A large anomaly in heat capacity around TC is detected and the Debye temperature θD (=319(±10) K) has been derived from analyses of the low temperature heat capacity, T ≲ 10 K

An Analysis of China's Fertilizer Policies: Impacts on the Industry, Food Security, and the Environment

China has made remarkable strides in recent decades to grow enough food to feed 20% of the world's 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

Phosphorus in China's Intensive Vegetable Production Systems: Overfertilization, Soil Enrichment, and Environmental Implications

China's vegetable production has experienced a rapid growth in recent years. Total production amounted to 522.7 million Mg (1 Mg = 10(6) 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

Land use for England and Wales: evaluation of management options to support 'good ecological status' in surface freshwaters

This paper analyses historic records of agricultural land use and management for England and Wales from 1931 and 1991 and uses export coefficient modelling to hindcast the impact of these practices on the rates of diffuse nitrogen (N) and phosphorus (P) export to water bodies for each of the major geo-climatic regions of England and Wales. Key trends indicate the importance of animal agriculture as a contributor to the total diffuse agricultural nutrient loading on waters, and the need to bring these sources under control if conditions suitable for sustaining 'Good Ecological Status' under the Water Framework Directive are to be generated. The analysis highlights the importance of measuring changes in nutrient loading in relation to the catchment-specific baseline state for different water bodies. The approach is also used to forecast the likely impact of broad regional scale scenarios on nutrient export to waters and highlights the need to take sensitive land out of production, introduce ceilings on fertilizer use and stocking densities, and controls on agricultural practice in higher risk areas where intensive agriculture is combined with a low intrinsic nutrient retention capacity, although the uncertainties associated with the modelling applied at this scale should be taken into account in the interpretation of model output. The paper advocates the need for a two-tiered approach to nutrient management, combining broad regional policies with targeted management in high risk areas at the catchment and farm scale