西柏店村级养殖种植园区氮素流和能量流分析

将西柏店村畜禽养殖规模折合为1.50万头猪场当量污染负荷,并将整个园区生产工艺分为养殖、废弃物处理和种植3个阶段,不考虑隐藏流的情况下,以1a为系统边界,通过数据调查、已有资料研究和小区种植试验,采用物质流和能量流分析方法分析了该村养殖种植园区在整个生产工艺过程的氮素和能量流动,以期为村级养殖种植园区大力发展低碳经济提供新的方法和视角,为村级区域循环经济及可持续发展提供减少环境压力解决方案的科学依据。园区养殖种植过程的氮素分析表明,养殖阶段年输入N素总量为7.14×104kg,其中猪身总固氮量为2.68×104kg,粪氮和尿氮总量为3.93×104kg,氮损耗为0.53×104kg。废弃物处理阶段输入的氮主要为粪氮3.28×104kg,而0.65×104kg尿氮直接进入种植阶段,粪氮通过厌氧处理由有机氮转变为无机氮,其中有2.78×104kg无机氮通过沼渣和沼液进入种植阶段,有0.50×104kg氮损失。由于作物对氮的吸收,植株增加氮为7.53×104kg,土壤减少氮为6.37×104kg,不计其他作物种植,如果沼渣、沼液能满足施用于全村43hm2农田,若以保持土壤中N素计算,种植一季玉米土壤还需氮素2.94×104kg,若以作物需求的N素计算,种植一季玉米土壤还需氮素4.10×104kg。整个园区能量流分析表明,饲料投入能为443.51×108kJ,产出的畜产品能179.94×108kJ,养殖阶段能量产出率为40.57%,废弃物处理阶段沼气能产出为26.30×108kJ,种植阶段一季玉米产出能为198.84×108kJ,其中玉米籽粒81.22×108kJ的能量可用于饲料进入新的循环,要满足养殖种植园区的能量循环,以一季玉米种植计算,还需补充饲料能量362.29×108kJ。由氮素流动分析可知,西柏店村具有可容纳该村养殖废弃物的环境容量,有较好实现养殖废弃物循环利用的条件,还可加强养殖业的发展,但需大力加强畜禽废弃物的管理和处理,提高园区养殖废弃物循环利用效率。由园区的能量流分析表明,该园区能较好地实现系统的能量投入产出。

Material Flow Analysis on Nitrogen Cycle and Energy Flow Analysis of Planting and Breeding Park of Village Scale at Xibaidian Village

Xibaidian Village is a representative Planting and Breeding Park（PBP） of village scale.The pollution load of Xibaidian Village＇s livestock breeding quantity is equivalent to a scale swine farm with 15 000 pigs,and the production in this village is divided into breeding stage,waste treatment stage and planting stage.Taking the system boundary for 1 year and not considering the hidden flow,through data investigation,the previous research and plot experiments,we applied the material flow analysis（MFA） and energy flow analysis（EFA） methods to analyze the nitrogen and energy flow of Xibaidian Village.The objective of this study was to provide a new method and a new perspective for PBP of village scale to develop low-carbon economy and to provide a feasible solution for PBP of village zone to promote cycle economy and sustainable development and decrease the environmental pressure.Results of the nitrogen flow analysis showed that the total amount of N annual input was 7.14×104 kg during the breeding stage,among which the amount of N sequestration in swine body was 2.68×104 kg,the amount of N in feces-nitrogen and urine-nitrogen was 3.93×104 kg,and the amount of N loss was 0.53×104 kg.During the waste treatment stage,the N input was mainly feces-nitrogen with an annual amount of 3.28×104 kg entering biogas plants where organic nitrogen was converted to inorganic nitrogen,and 0.65×104 kg of urine-nitrogen entered the planting stage directly.Among the inorganic nitrogen,the amount of N which entered the planting stage through biogas slurry and residue was 2.78×104 kg and approximately 0.50×104 kg N was lost.Because of the absorbtion of nitrogen by the plants,the nitrogen in the soil decreased 6.37×104 kg,while in plants increased to 7.53×104 kg.It still needed 2.94×104 kg N in the soil to keep the amount of nitrogen in the soil during a quarter of corn planting,without considering other crop planting and assuming 43 hm2 of arable land in the village could be applied of biogas slurry and residue.And still needed 4.10×104 kg N in soils meeting the plant＇s nitrogen during a corn planting season.Analysis of energy flow shows that the total amount of energy annual input was 443.51×108 kJ and the annual energy output in animal products was 179.94×108 kJ during the breeding stage,and the energy conversion ratio was 40.57%.The amount of annual energy output in biogas in the waste treatment stage was 26.30×108 kJ compare with 198.94×108 kJ in a corn planting season,among which 81.22×108 kJ of energy in maize enters into next circle as feed.It still needed 362.29×108 kJ feed energy,meeting the requirement of the new energy circle in the village.The nitrogen flow analysis showed that Xibaidian Village has the environmental capacity to accommodate the breeding wastes,and has the conditions to carry out the recycling use the breeding wastes.But attention should be paid to strengthening the management and treatment of the breeding wastes,and to increasing the efficiency of wastes reuse.From the energy flow analysis,it is known that the village can achieve more in energy management.