沼气工程高效稳定运行技术现状及展望

总结分析了沼气工程相关技术现状和技术需求,并对其未来发展进行了展望。我国的原料收贮和预处理技术亟待升级,仍需大量的科研投入以研发关键的核心技术装备。实现沼气工程运行情况的有效监测和及时预警,以及开发合适的微量元素添加剂和功能微生物菌剂对推动我国沼气工程的高效稳定运行具有重要意义。试验并研发新型膜材料和对常规材料的共混与改性处理是提高沼气膜分离提纯能力的主要手段。沼液的资源化利用技术是摆脱沼气工程可持续发展瓶颈的关键。结合沼气工程产业发展需求,充分论证技术瓶颈,合理配置科技资源,加大科技攻关投入,实现自主化技术研发、标准化工程设计、工厂化装备制造、模块化安装建设以及专业化安装调试等标准化集成,同时创新沼气工程技术的应用模式能更好地推动沼气工程技术的发展。

Carbon and Nitrogen Mineralization Kinetics from Organically-Amended Upland Purplish Soil

The application of organic amendments in upland soils may influence soil carbon (C) and nitrogen (N) mineralization, which are very important for understanding plant nutrition. However, the kinetics of C and N mineralization from organically amended upland purplish soils has been poorly studied. Therefore, this study investigates C and N mineralization kinetics in organically amended upland purplish soils. Incubation experiments were conducted using soil samples collected from experimental plots that have been under long-term organic amendment fertilization, which includes: Organic manure (OM), crop residues (CR), combined organic manure with inorganic fertilizers (OMNPK), combined crop residue with inorganic fertilizers (CRNPK), conventional inorganic fertilizer (NPK), and no fertilizer (CK). The results showed that organically amended treatments increased C and N mineralization rates by 8 - 24% and 17 - 33%, respectively, compared with NPK. Likewise, the amount of potentially mineralizable carbon (Co) and nitrogen (No) increased by 4 - 9% and 15 - 20%, respectively, compared to the conventional NPK treatment. The rate constants for labile C (kC) and N (kN) were 6 - 29% and 3 - 27% higher than the NPK treatment, respectively. In addition, the initial potential rate of C (Co × kC) and N (No × kN) in organically amended soils were 10 - 37% and 18 - 52% higher compared to NPK. This study tried to show that the mechanisms of N supply was direct application of mineral N fertilizer and mineralization of organic N, while the N retention was reducing soil active N loss and storing more active N in cropland of purplish soil. These results suggest that the long-term application of organic amendments to upland soils may increase nutrient bioavailability.

EFFECTS OF SUBSTITUTION OF MINERAL NITROGEN WITH ORGANIC AMENDMENTS ON NITROGEN LOSS FROM SLOPING CROPLAND OF PURPLE SOIL

Nitrogen loss from purple soil can lead to large negative impacts to the environment considering the wide distribution of this soil type in the upper reaches of the Yangtze River.Therefore,nitrogen loss patterns from sloping cropland of purple soil in the Sichuan Basin with the following fertilization regimes were studied in a wheat-maize rotation system:100%organic fertilizer(OM),using pig manure to replace 30%of mineral N(OMNPK)and crop residue to replace 15%of the mineral N(CRNPK)plus standard mineral fertilization(NPK)and no fertilizer control.The cumulative hydrological N loss could be as high as 45 kg·ha^(−1) N.The interflow accounted for up to 90%of the total N loss followed by sediment and overland flow losses.The high N loss via interflow found in this study highlighting that sloping cropland of purple soil may be one of the hot spots of N leaching.Compared to the NPK regime,organic substitution regimes(i.e.,OM,OMNPK and CRNPK)decreased total hydrological N loss loadings by 30%−68%.In addition,they can maintain annual crop yields and decrease yield-scaled total hydrological N losses by 18%−71%.In conclusion,long-term substitution of mineral N with organic amendments can maintain high crop productivity and reduce environmental N loss loadings,and thereby recommended as good N management practices to minimize the risk of agricultural non-point source pollution in the purple soil region of China.