Nitrogen mobility,ammonia volatilization,and estimated leaching loss from long-term manure incorporation in red soil

Nitrogen（N） loss from fertilization in agricultural fields has an unavoidable negative impact on the environment and a better understanding of the major pathways can assist in developing the best management practices. The aim of this study was to evaluate the fate of N fertilizers applied to acidic red soil（Ferralic Cambisol） after 19 years of mineral（synthetic） and manure fertilizer treatments under a cropping system with wheat-maize rotations. Five field treatments were examined： control（CK）, chemical nitrogen and potash fertilizer（NK）, chemical nitrogen and phosphorus fertilizer（NP）, chemical nitrogen, phosphorus and potash fertilizer（NPK） and the NPK with manure（NPKM, 70% N from manure）. Based on the soil total N storage change in 0–100 cm depth, ammonia（NH_3） volatilization, nitrous oxide（N_2O） emission, N plant uptake, and the potential N leaching loss were estimated using a mass balance approach. In contrast to the NPKM, all mineral fertilizer treatments（NK, NP and NPK） showed increased nitrate（NO_3~–） concentration with increasing soil depth, indicating higher leaching potential. However, total NH_3 volatilization loss was much higher in the NPKM（19.7%） than other mineral fertilizer treatments（≤4.2%）. The N_2O emissions were generally low（0.2–0.9%, the highest from the NPKM）. Total gaseous loss accounted for 1.7, 3.3, 5.1, and 21.9% for NK, NP, NPK, and NPKM treatments, respectively. Estimated N leaching loss from the NPKM was only about 5% of the losses from mineral fertilizer treatments. All data demonstrated that manure incorporation improved soil productivity, increased yield, and reduced potential leaching, but with significantly higher NH_3 volatilization, which could be reduced by improving the application method. This study confirms that manure incorporationis an essential strategy in N fertilization management in upland red soil cropping system.

Embodied Pollution in China-U.S.Trade——An Empirical Study Based on Estimation of Input-Output Technology Matrix

Using input-output tables of China and the U.S., this paper has calculated the pollution embodied in trade and structure of pollution, the balance of emissions embodied in trade （BEET） and the pollution terms of trade （PTT） for 18 manufacturing sectors of China and the US. between 2001 and 2010. The calculation aims to verify whether China has become a ＂pollution haven＂ in bilateral trade with developed countries represented by the U.S., and whether Chinese exports are ＂dirtier＂ compared with imports from the U.S., and further conducting an industry structure analysis and effect decomposition study on pollution embodied in trade in industrial goods between China and U.S.. Result of our research indicates that according to our calculation of the BEET, China remains a country with environmental deficits in bilateral trade with the U.S. while the gaps between pollution embodied in China＇s export and import are narrowing. Pollution embodied in China＇s export has the tendency of increase before decline while pollution embodied in import demonstrates no significant tendency of decline. Through effect decomposition, we further found that the effect of technology arising from the substantial decline of pollution intensity effectively lowered pollution embodied in export and narrowed the environmental deficits of China in its bilateral trade. The effect of scale arising from growing export volumes significantly increased China＇s environmental deficits while the structural effect arising from changes in the structure of import and export is insignificant in reducing environmental deficits. Our calculation of the PTT led to the finding that China＇s export goods are more pollution intensive compared with import goods and that the structure of US exports to China is cleaner than the structure of Chinese exports to the US., which requires further improvements of China＇s import and export structure.

Estimation of China'S Embodied CO_2 Emissions during 2000-2009

The problem of CO2 embodied in international trade has attracted increasing attention in China. To analyze this issue, the present paper directly calculates emission factors for 15 industries in 2002, 2005 and2007. We then examine a consumption-based system and a single-region input-output model to estimate China＇s embodied emissions during 2000- 2009. Our results show that, when a consumption-based system is adopted, China＇s emissions are lower than those reported by some international organizations. The rapid growth in China ＇s exports＇ is a key determinant of China＇s rising total emissions. All countries shouM strengthen their cooperation in improving their current greenhouse gas inventories. Furthermore, China needs to encourage trade in low-carbon products and technology.