[Emission of NH3 and N2O from Spinach Field Treated with Different Fertilizers].

Agricultural management techniques such as fertilizer or manure application have substantial influence on NH3 and N2O emissions and, by understanding this influence, management strategies can be developed to reduce them. An experiment was conducted in a greenhouse at Hunan Agricultural University during 2012 to 2013, to investigate effects of different fertilizers on NH3 and N2O emissions. The treatments included control without fertilizer (CK), swine composting fertilizer (SC), stored swine manure fertilizer (SS), and chemical fertilizer (FC). The fluxes of NH3 and N2O were collected by venting method and static-chamber method, respectively. The results showed that during the spinach growth season, compared with FC, loss of both NH3 and N2O for SC were reduced by 52.9% and 95.12%, respectively(P<0.01). However, loss of NH3 for SS increased by 24.8%, and loss of N2O reduced by 48.8% compared with FC. Loss rate of NH3 were SS (10.97%) > FC (4.19%) > SC(2.74%), and emission coefficient for N2O were FC(4.50%) > SC(2.21%) > SS(0.60%). Yield and utilization of nitrogen for SC were reduced by 19.61% and 13.20% compared with FC, respectively, but not significantly; and significantly reduced by 27.9% and 40.0% compared with SS, respectively. Loss of gases (NH3 and N2O) for SC were 1.83%, which was the lowest, while utilization of nitrogen for SC was 13.20%, similar with FC. Greenhouse temperature was not the critical factor during the spinach planting in winter, but soil water was. Therefore, optimizing manure management could reduce ammonia volatilization and N2O emission loss without decreasing vegetables production, and the present data indicated that SC would be optimal for better yields with reduced ammonia volatilization and N2O emission loss.

[Estimation of N2O Emission from Anhui Croplands by Using a Regional Nitrogen Cycling Model IAP-N].

N2O emissions from seven categories of Anhui croplands in 2011 were estimated by using a regional nitrogen cycling model IAP-N. The required statistical data were from each city's statistical yearbook in Anhui Province. The emission factors were from the published field data. The results showed that total N2O emissions from Anhui croplands in 2011 were 35. 1 thousand ton, in which direct and indirect N2O emissions were, respectively, 27. 6 thousand ton and 6. 6 thousand ton, and N2O emission from residues/straws burning in the field was 800 ton. Huaibei Plain (Region I) and Jianghuai Hilly (Region II) were the main contribution regions in Anhui, accounting for 41% and 35% of its regional total N2O emissions, respectively. The most important source for direct N2O emission is the year round upland fields with 74% contribution of the province total direct N2O emission. The second important source in Region II and Region III is upland cropping season of the rotation fields with rice and upland-crops, accounting for 19% and 14% , respectively. While in Region IV, the second direct N2O emission sources are tea gardens and orchards, accounting for 22%. About two-thirds of the indirect N2O were from atmospheric nitrogen deposition. The results can provide a scientific basis for policy makers to make agricultural soils GHG mitigation measures in Anhui Province, such as reasonable use of fertilizers.

Phosphine in various matrixes.

Matrix-bound phosphine was determined in the Jiaozhou Bay coastal sediment, in prawn-pond bottom soil, in the eutrophic lake Wulongtan, in the sewage sludge and in paddy soil as well. Results showed that matrix-bound phosphine levels in freshwater and coastal sediment, as well as in sewage sludge, are significantly higher than that in paddy soil. The correlation between matrix bound phosphine concentrations and organic phosphorus contents in sediment samples is discussed.

[Effects of turning frequency on emission of greenhouse gas and ammonia during swine manure windrow composting].

It is of great concern for greenhouse gas (GHG) reduction of animal manure management in China due to the extreme lack of GHG emission data during animal manure composting. Therefore, the purpose of this study was to investigate the effects of turning frequency on the emission of GHG (CH4, N2O) and NH3 during swine manure windrow composting through on-site observation of a full scale test in Beijing. Results showed that the turning frequency had significant impacts on the emission of both GHG and ammonia, which did not only increase the emission of GHG and ammonia, but also increased the percentage of total nitrogen loss due to NH3 emission (42.2% at turning once a week and 70.05% at turning twice a week, respectively). Compared with N2O emission, CH4 emission was the main contributor to Global Warming Potentials (GWPs).

[Emissions of NH3, N2O, and NO from swine manure solid storage in winter].

Swine manure solid storage is a typical management in rural area of China. In order to investigate the characteristics of NH3, N2O and NO emissions during manure storage in winter (Nov., 2012 to Feb., 2013), two treatments were conducted: non-covered (NC) and covered (C) with straws, and each treatment had three times of pile-turning during the 73 days storage. The emission fluxes of three nitrogen gases (NH3, N2O and NO) were measured and the profile-N2O concentrations inside the swine pile profile and in the soil under the pile were also measured. The results indicated that 2.1%-2.6%, 0.02% and -0.000 25% of total nitrogen were lost in the form of NH3, N2O and NO respectively during the whole swine manure solid storage. The nitrogen gases in the two treatments had the same variation characteristics, but all the nitrogen gases were reduced in the covered treatment. In the early storage stage, NH3 emission peak occurred first and then the emissions of N2O and NO started increasing. In the middle storage stage, the emissions of NH3 and NO showed mutual growth and decline trend. In the late storage stage, N2O emission peak was twice higher than that in the early stage, while NH3 and NO emissions showed a slight increase. Before and after pile-turning operation, NH3 emission had little change, but N2O emission was decreasing and NO emission was rising after pile-turning.

[Emission of CH4, N2O and NH3 from vegetable field applied with animal manure composts].

Greenhouse gas (GHG) emission from vegetable land is of great concern recently because agriculture land is one of the major sources contributing to global GHG emission. In this study, an experiment of Lactuca sativa L. land applied with different animal manure composts was carried out in a greenhouse vegetable land located in the surburb of Beijing to monitor the emission of GHG (CH4 and N2O) and ammonia in situ, and to analyze the affecting factors of GHG and ammonia emission. Results showed that the emission factors (EFs) of CH4 from Treatment NRM, RM and CF were 0.2%, 0.027% and 0.004%, respectively,the EFs of N2O from these three treatments were 0.18%, 0.63% and 0.74%, respectively, and the EFs of ammonia were 2.00%, 3.98% and 2.53%, respectively. CH4 emission flux was significantly affected by soil temperature and humidity, while N2O emission flux was related to soil temperature, surface temperature and humidity. The emission fluxes of CH4, N2O and NH3 were significantly affected by soil moisture, but there was little relation between CH4, N2O and NH3 emissions and the ambient temperature in the greenhouse.

[Nutrients conservation of N & P and greenhouse gas reduction of N2O emission during swine manure composting].

Nitrogen loss and greenhouse gas (N2O) emission occur during animal manure composting, as well as phosphorus loss caused by runoff during land application of animal manure compost. Therefore, the purposes of this study were to simultaneously conserve nutrients of nitrogen & phosphorus and reduce N2O emission during animal manure composting using modified salts which are made from industrial solid waste. Experiments of in-vessel swine manure composting at lab-scale were carried out to investigate and compare effects of modified red-mud (MR) and modified forsterite (MF) as additives on nutrients conservation and greenhouse gas (N2O) reduction. As far as the nitrogen loss calculated on the basis of ammonia and nitrous oxide is concerned, the least nitrogen loss at only 6.38% of TKN occurred in the swine manure composting with MF addition at pH 7.0 +/- 0.2, compared with those of MR addition at pH 5.0 +/- 0.2 at 11.07% of TKN and the control at 14.68% of TKN, respectively. The best results of ammonia and nitrous oxide mitigation during swine manure composting were the treatments with MR addition and MF addition, which nitrogen losses were at 2.13% of TKN as NH3 and 0.65% of TKN, respectively. These results clearly showed that the modified salt additives from red-mud and forsterite were useful for saving nitrogen and reducing N2O emission. Moreover, the contents of soluble orthophosphate in swine manure compost with the addition of both modified salts were less than that of the control, which is helpful to reduce P loss during land application of swine manure compost.

[N2O emissions from agricultural ecosystem in Sichuan-Chongqing region].

A regional nitrogen cycling model IAP-N was adopted to estimate nitrous oxide (N2O) emission from the agro-ecosystem in the Sichuan-Chongqing Region during 1990-2004. The county level agricultural activities data were used, and Sichuan-Chongqing Region was divided into four sub-areas by the geographical characteristics, environment and local climatic conditions and administrative division. The results showed that annual averaged N2O emissions (in nitrogen gauge) in 1990-1994, 1995-1999, 2000-2004, respectively, were 52.3, 58.2, 62.0 Gg/a, of which 55% came from the N2O direct emission of the fertilized croplands. They were 29.6 (7.6-63.3), 33.0 (8.4-71.8), 34.0 (8.5-75.8) Gg/a, equals to 4.73, 5.39, 6.11 kg/(hm2 x a), respectively. Upland/glebe was the primary source of the N2O direct emission. Meanwhile, paddy-upland rotation system also played an important contribution to it. The increasing rates of N2O emission from agro-ecosystem and N2O emission flux in cropland were much higher in 1995-1999 than in 1990-1994. The N2O emission flux in the cropland showed a continuous increasing trend in 2000-2004, but the increasing rates of total N2O emission from agro-ecosystem were stagnant due to the decrease of arable land area. The N2O emission of agro-ecosystem mainly came from Chengdu Plain and Chongqing. The contributions of different sources to the total N2O emission of agro-ecosystem were variable in the region. For instance, the primary source of N2O emission was the direct emission from croplands in Chengdu Plain and Chongqing, whereas, in northwest region of Sichuan province was the N2O emission induced by grazing. The results will provide a scientific basis for policy maker to make fertilizer effectively applied and mitigate GHG emission from agro-ecosystem of Sichuan-Chongqing Region.