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1Rice-rice rotation is the most important intensive cropping system for food security in China. 2 So far, few studies have examined sustainability of double-rice cropping system using partial 3 substitution of fertilizer N (FN) by green manure (GM). The effects of 100% FN (N 100 ) and 4 different substitution rates of FN by GM (80%, 60%, 40% and 20% FN plus 20%, 40%, 60% 5 and 80% N through GM, and represented respectively by N 80 M 20 , N 60 M 40 , N 40 M 60 and 6 N 20 M 80 ) on the rice productivity and N-supplying capacity of paddy soil were evaluated in 7 double-rice system from 2008 to 2013. Soil organic matter and total N content in the 0-15 cm 8 layer and rice grain yield of early and late rice annually increased in N 80 M 20 and N 60 M 40 plots, 9 but decreased in N 100 , N 40 M 60 and N 20 M 80 plots. Compared with N 100 plots, the NH 4 + -N 10 content and agronomic efficiency of applied N significantly increased in N 80 M 20 and N 60 M 40 11 plots. The grain yield and sustainable yield index of rice crops were improved in N 80 M 20 and 12 N 60 M 40 plots, while declined in N 40 M 60 and N 20 M 80 . Soil NO 3 --N content decreased 13significantly under partial substitutions of GM for FN. It can be concluded that the 14 appropriate substitution of GM for FN (e.g. 20%-40%) is beneficial for improving the 15 productivity and sustainability of paddy field under double-rice cropping system. 16 runoff in double-rice cropping systems, although this point still needs to be further proved. In 1 addition, how the nitrification and denitrification of N and NH 3 volatilization are affected by 2

The identification of phosphorus (P) fractions is essential for understanding the transformation and availability of P in paddy soils. To investigate the soil P fractions associated with soil properties under long-term fertilization, we selected three fertilization treatments, including no fertilization (CK), chemical fertilizers (NPK) and chemical fertilizers combined with manure (NPKM), from three long-term experiments located in Nanchang (NC), Jinxian (JX) and Ningxiang (NX). The results showed that chemical fertilizers combined with manure (NPKM) significantly ( P ≤ 0.05) increased the soil total phosphorus, Olsen P and soil organic matter (SOM) by 2, 3 and 1 times, respectively, compared with the NPK treatment, and by 4, 17 and 2 times, respectively, compared with the CK treatment. NPKM significantly increased the grain yield compared with CK and NPK at all sites. The apparent P balance with NPK was higher in NC and NX but lower in JX compared with NPKM. Hedley fractionation revealed the predominance of most of the organic and inorganic phosphorus (Po and Pi) fractions with long-term fertilization, especially with the NPKM treatment, at all sites. The nonlabile P pool decreased by 14% and 18% whereas the moderately labile P pool proportions increased by 3 and 6 times with the NPK and NPKM treatments, respectively, compared to the CK treatment. The labile P pool showed a significant positive relationship with the SOM, total P and Olsen P contents. The moderately labile P was positively correlated with the total P and Olsen P. A significant positive correlation was observed between soil pH and the nonlabile P pool. Redundancy analysis revealed that the moderately labile P fraction (HCl dil. Pi fraction) was remarkably increased by the NPKM treatment and significantly correlated with the soil pH and total P concentration. The labile P fraction (NaHCO 3 -Pi) showed a strong relationship with the Olsen P and total P. However, the residual P fraction was negatively correlated with the HCl. dil. Pi fraction. We concluded that NPKM application improved P availability by many folds compared to NPK, which could lead to environmental pollution; therefore, the rate of combined application of manure and chemical fertilizer should be reduced compared to chemical fertilizer inputs to minimize the wastage of resources and environmental P losses.

With the rapid expansion of electric vehicles and energy storage markets, the rising demand for rechargeable lithium-ion batteries, as opposed to the limited reserves of lithium resources, poses a great challenge to the widespread penetration of this advanced battery technology. Some monovalent metals, such as sodium and potassium, and multivalent metals, such as magnesium, zinc, and aluminum, which are nontoxic and relatively abundant (compared to lithium), are considered as alternative guest ions to lithium ion, thus generating various new battery systems. However, the major obstacle to their large-scale applications has been a lack of suitable robust hosts to accommodate alkalis (Na+, K+) with large radius or multivalent ions (Mg2+, Zn2+, Al3+) with high electrostatic repulsions. Conversion-type materials provide a unique route to tackle this problem because of their special reaction mechanism, which is different from the traditional intercalation reaction, and flexibility for tuning operating voltage. In this Review, the superiority of conversion electrodes for post lithium-ion batteries is discussed in detail, and the recent progress of the newly developed ions batteries based on the conversion mechanism is comprehensively summarized. Finally, the remaining challenges and the perspectives on research directions of conversion electrodes are proposed to provide guidance for future materials engineering and battery design.