Current Situation and Prospect Analysis of Biogas Project in Scale Farms in Chengdu

In order to implement National Sustainable Development of Agriculture 2015-2030 and supply-side reform of agriculture, and seek the way to replace chemical fertilizer by livestock and poultry manure, the animal breeding scale and the demand space for biogas project were analyzed according to the changes in farm scale and farm quantity, the present situation of livestock breeding, the biogas technical pattern and present project quantity in Chengdu. Furthermore, based on the cultivated land area in Chengdu, a principle that ＂land decides production, pro- duction decides fertilizer, and fertilizer decides livestock＂ was proposed, and a pro- gram for the livestock quantity and biogas projects in Chengdu in ＂The 13th Five- Year＂ was suggested. Suggestions were also made for government to modify the allowance standards for biogas project construction.

Sustainable Intensification of Cultivated Land Use and Its Influencing Factors at the Farming Household Scale: A Case Study of Shandong Province, China

Promoting the sustainable intensification of cultivated land use(SICL) has become crucial for ensuring a sufficient supply of grain and important agricultural products, as well as for the sustainable use of resources. Taking widely used areas of Shandong Province in China as examples, an analytical scale and level framework for SICL is constructed in this study. It measures the level of SICL through material flow analysis, constructs Tobit models to analyze the influencing factors of SICL at the farming household scale,and analyzes the transition mechanisms of SICL. The results show that the overall level of SICL in Shandong Province is low, and the spatial distribution is uneven. There are relatively more farmers participating in unsustainable intensification than in medium or low levels of SICL, with farmers working at a high level of SICL making up the smallest proportion. The factors that determine the level of SICL at which farmers work vary significantly. More male farmers operate at a low SICL level than female farmers, while females outnumber males at a high SICL level. This is mainly related to the regional distribution of age and population. Meanwhile, with larger cultivated land areas, there is a lower degree of land fragmentation, with a higher level of SICL corresponding to a smaller distance to the nearest town closer within 1–5 km from the town center. We can see the level of SICL and its processes themselves are closely related to time and space scales. Based on the above analysis, it is necessary to clarify the standard processes of SICL to adapt them to local conditions. This includes instructing managers on how to improve resource utilization, increase the sustainable development of cultivated land and establish a comprehensively efficient and functional SICL mechanism. The sustainable intensification of cultivated land use and its specific application in the new era are conducive to enriching the frontier theories and methodology of sustainable development, and are of great significance to the advancement of green agriculture and the decision-making of rural high-quality development.

Farm-Scale Applicability of Three Covers (Peat, Polystyrene Balls and Synthetic Sheet Roof) to Reduce Ammonia Emissions from Pig Slurry Storage

Covering the slurry pit has been shown to be one of the best ways to reduce ammonia emissions (NH3) during manure management. Yet, few studies have been conducted at farm scale. We studied the feasibility of three cover materials (peat, polystyrene balls and synthetic sheet roof) to reduce ammonia (NH3) emissions during on-farm storage of pig slurry. The impact on greenhouse gas emissions, methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2) of covering the slurry pit was also evaluated. Simultaneous field experiments were carried out using two similar pits at a farm with peat and polystyrene ball covers, which allowed direct comparison of the feasibility of the two covers to reduce gas emissions (measured using the dynamic chamber technique). Emissions from the third option (using a synthetic sheet roof) were estimated by measuring the concentrations in the headspace under the cover and the air leakage from the cover with a tracer gas (CO2). Results showed that the polystyrene balls cover reduced emissions of NH3 during storage by up to 80% whatever the season, but increased potential greenhouse gas emissions by 20% in summer. No consistent reduction was achieved with the peat cover even though some individual results seemed to indicate up to 25% reduction in ammonia emissions;moreover, there was a 30% increase in CH4 and CO2 emissions during the storage period. The use of a synthetic sheet roof enabled up to 90% reduction in NH3, CH4 and CO2 emissions whatever the season.

Utilization Survey of Livestock Manure Resources in Large-scale Farms of Yangzhou

Based on surveying the conditions of large -scale farms and commercial manure in the each county of Yangzhou city, the situations and problems for utilization of livestock manure resources were grasped. After an analysis of the potential value of livestock manure, the suggestion and strategy for utilization of livestock manure resources were proposed based on the actual conditions in Yangzhou city.

An Empirical Study on the Moderate Scale of Food-production-based Family Farm in Guangxi

The moderate scale family farm is the future agricultural business entity in China,and the scale of family farm is a key factor affecting its development.With Guigang City in Guangxi as a point for the study,from the perspective of maximizing income of rural households,this paper uses production function model to calculate the moderate scale of food-production-based family farm at 5.7 ha,and makes policy recommendations.

Efficiency Comparison and Influencing Factor Analysis of Dairy Farms over/at Different Scales:Based on the Survey Data of 263 Scale Farms in 22 Provinces of China

China's dairy farming has presented a striking development in recent years.Under the dual constraints of environment and resources,it is of practical significance to increase the output of dairy farming and ensure the healthy and stable development of the dairy industry,by accurately comparing the differences in the farming efficiency of dairy farms at different scales and grasping key factors influencing the farming efficiency.This study,through the cost analysis of 263 scale farms across 23 provinces and regions of China in 2019,reaches a result that the cost of a single cow in a certain scale farm increases with the enlargement of the scale,and shows an inverted-U shaped curve with the relatively large scales(1001-2000 cows)at the highest point.It measures the farming efficiency of dairy farms at different scales through the data envelopment analysis and finds that the scale efficiency and allocation efficiency of scale farms in China are relatively high,while the technology efficiency and cost efficiency are relatively low.The efficiency of different scale farms is obviously different,where the cost efficiency,allocation efficiency and scale efficiency show a U-shaped curve as the scale enlarges(with the relatively large scale as the lowest point),while the technology efficiency gradually decreases as the scale expands.It is concluded that for the scale farms,feed conversion ratio and forage-to-concentrate ratio have a significantly negative impact on the scale efficiency,while the labor cost,number of employees,and depreciation of fixed assets are negatively correlated to the technology efficiency and cost efficiency of dairy farming.

High-Resolution Micro-Siting Technique for Large Scale Wind Farm Outside of Japan Using LES Turbulence Model

The spatial distribution of wind speed varies greatly over steep complex terrain, thus the selection of an optimal site in such terrain for wind turbine construction requires great care. We have developed a numerical model for simulating unsteady flows called RIAM-COMPACT (Research Institute for Applied Mechanics, Kyushu University, COM putational Prediction of Airflow over Complex Terrain), which is based on the LES (Large-Eddy Simulation) technique. The computational domain of RIAM-COMPACT can be varied from several meters to several kilometers, and the model is able to predict airflow over complex terrain with high accuracy. The present paper discusses the application of RIAM-COMPACT to the micro-siting of wind turbines at sites outside Japan. The results from two case studies will be presented.

安徽部分地区鸡场鸡毒支原体与鸡滑液囊支原体感染与垂直传播调查

为了解安徽部分地区规模鸡场鸡毒支原体(Mycoplasma gallisepticum,MG)和鸡滑液囊支原体(Mycoplasma synoviae,MS)流行感染情况,试验采集21家鸡场鸡血液样品进行血清学调查,并对3家种鸡场的种鸡群及其后代雏鸡进行MG和MS的病原检测,分析种鸡及其后代雏鸡的感染情况。结果显示,MG和MS的鸡场血清阳性率分别为95.24%和90.48%,鸡群平均血清阳性率分别为75.08%和77.01%;商品蛋鸡和种鸡的MG和MS血清阳性率高于育雏育成鸡;鸡群日龄越大,MG和MS的血清阳性率越高,其中300日龄以上鸡群的血清阳性率均为100%。病原检测发现,种鸡场存在不同程度的MG和MS感染,其中MS感染率高于MG;种鸡感染率与其后代雏鸡的垂直感染存在显著正相关,并且在垂直感染的雏鸡关节组织检测出MS病原。结果表明,MG和MS在安徽鸡场中的感染较为严重,垂直传播是雏鸡早期感染的重要途径,并且MS在雏鸡垂直感染的早期即可侵入关节组织。

河南省牛羊规模场布鲁氏菌病感染情况调查

[目的]掌握河南省牛羊布鲁氏菌病流行情况,为牛羊布病防控和净化工作提供理论和科学依据。[方法]2022年对河南省168个场次的4 902头牛羊血清样品进行布病感染抗体检测,并按动物种类、场点类别等对检测结果进行统计分析。[结果]2022年河南省牛羊布病感染抗体平均场群阳性率为5.36%,平均个体阳性率为0.47%;牛布病感染抗体场群阳性率为3.61%,个体阳性率为0.24%;羊场群阳性率为7.06%,个体阳性率为0.71%;阳性样品均来自商品代养殖场(户),种畜场、屠宰场无阳性样品检出。[结论]河南省牛羊布病流行情况整体处于可控水平,种畜场布病净化工作取得了一定成效,随着牛羊养殖规模化程度的提升,当前牛羊布病防控的重点在于商品代规模场(户),应依据调查结果,结合场群实际,进一步完善和推进布病净化工作。

规模化猪场粪污处理利用现状及案例分析

规模化猪场在养殖过程中会产生大量的粪污,如果不加以妥善处理与利用,将对环境和公共健康造成严重威胁。粪污处理与资源化利用成为实现养猪业可持续发展的关键环节。本文探讨了规模化猪场粪污的危害,介绍了规模化猪场粪污集中收集系统及目前规模化猪场在猪舍粪污处理中使用的尿泡粪和机械清粪2种清粪工艺,并详细讨论了生物发酵、厌氧消化、好氧处理等多种方法对固体粪污和液体污水的处理技术,以满足不同规模化养猪场的清粪需求。同时,探讨了规模化猪场种养结合生态循环利用和工业化深度处理2种主要的粪污处理利用模式。展望了未来科技创新对粪污处理与利用的推动作用,呼吁各方共同努力,以实现养猪企业的可持续发展、保障环境和人类健康的计划。本文为规模化养猪场选择粪污处理技术和利用模式提供了有益的参考,有助于环境保护和养猪业可持续发展。

加入合作社对家庭农场适度规模经营的影响

本文在探讨家庭农场适度规模经营两种理论观点之争的基础上,基于中国社会科学院农村发展研究所2020年中国乡村振兴综合调查(CRRS)数据,采用普通最小二乘法(OLS)系统考察了家庭农场加入合作社的规模扩大效应及其作用机制。研究发现:首先,加入合作社能够扩大家庭农场经营规模,推动家庭农场适度规模经营。经测算,当前中国家庭农场最优经营规模为188亩,因而家庭农场经营规模仍有扩大的空间。其次,家庭农场加入合作社的规模扩大效应存在异质性,收入水平高、社会资本水平低和自有机械化水平低的家庭农场加入合作社的规模扩大效应更明显。再次,加入合作社扩大家庭农场经营规模主要来自内部服务获取机制和外部资源获取机制,且合作社所提供的销售服务和金融支持对家庭农场经营规模扩大具有更强的促进效应。最后,耕地细碎化程度负向调节家庭农场加入合作社的规模扩大效应,耕地细碎化不利于加入合作社的家庭农场扩大经营规模。本文的研究为推动家庭农场适度规模经营,促进其与合作社融合发展提供了理论指导和决策依据。

再小农化视域下回流农民助推乡村振兴的内在逻辑与实践向度

再小农化是宏观经济体系变革与农村社会制度变迁的微观缩影,是家庭结构调整与代际情感维系下回流农民的自主选择。再小农化下回流农民为乡村振兴带来新的发展机遇,市场分工与商品契约冲击了回流农民群体原本的小农思想,使得回流农民经历了由生存属性向理性属性的嬗变。基于小农属性嬗变,回流农民家庭超越了传统小农家庭“内卷化”生产的落后性,促进了乡村新质生产力系统性发展,塑造了乡村经济体系与社会结构的现代化形态。再小农化不能简单视为一场归农运动,而是乡村生产要素能动适应乡村振兴的自主形态,回流农民通过促进多层次产业体系转型发展、完善人才外部引进与内部培育机制、重塑现代文明与民俗教化融合形态、推进复合型生态环境修复、建立乡村关系型治理秩序等实践路径,实现乡村产业、人才、文化、生态与组织多维度振兴。

藏粮于地:土地利用对粮食单产的影响

基于“藏粮于地”战略背景,采用全国10省(区、市)950户农户数据,在将土地利用分为规模经营、可持续耕作、结构调整的基础上,利用普通最小二乘法、两阶段最小二乘法和调节效应模型实证分析土地利用对农户粮食单产的影响效应与路径。结果表明:规模经营对粮食单产的影响呈先增后减趋势,即呈倒“U”形关系,可持续耕作能够显著提升粮食单产,而结构调整显著负向影响粮食单产;规模经营在可持续耕作、结构调整影响农户粮食单产中具有正向调节效应;对于耕地禀赋不同的农户,规模经营、可持续耕作对农户粮食单产的影响存在差异性。

4种消毒剂对规模化奶牛场常见病原菌消毒效果的评价

试验旨在探讨常见消毒剂对规模化奶牛场环境气载和动物体表优势病原菌的杀灭效果,为进一步制定科学合理的消毒技术规范提供参考。研究以优势病原菌(金黄色葡萄球菌、大肠杆菌、产气荚膜梭菌)为指示菌,通过悬液定性和定量试验探讨常见消毒剂(安灭杀、辉胜-30、过硫酸氢钾、聚维酮碘)对细菌繁殖体的杀灭效果。结果显示,1∶100倍稀释的安灭杀消毒液作用1、20及5 min能够有效杀灭金黄色葡萄球菌、产气荚膜梭菌和大肠杆菌;1∶200倍稀释的辉胜-30消毒液作用10、20及15 min能够有效杀灭金黄色葡萄球菌、产气荚膜梭菌和大肠杆菌;1∶200倍稀释的过硫酸氢钾消毒液作用3、5、5 min能够有效杀灭金黄色葡萄球菌、产气荚膜梭菌和大肠杆菌;1∶400倍稀释的聚维酮碘消毒液作用15、20、20 min能够有效杀灭金黄色葡萄球菌、产气荚膜梭菌和大肠杆菌。研究表明,金黄色葡萄球菌和大肠杆菌对安灭杀消毒液敏感,产气荚膜梭菌对过硫酸氢钾复合物粉较敏感,4种消毒剂宜交替使用可避免耐药性菌株的产生。

福建省部分规模化畜禽场隐孢子虫感染情况调查

为了解福建省规模化畜禽场隐孢子虫感染情况,对10个规模化畜禽场(牛场、猪场、羊场、鸡场、鸭场各2个)100份粪样采用隐孢子虫通用引物进行荧光定量PCR检测,结果相应牛场、猪场、羊场、鸡场、鸭场的隐孢子虫平均检出率分别为60.0%、45.0%、42.1%、42.9%和15.0%。该结果可为福建省规模化畜禽场的隐孢子虫防控及保障公共卫生安全提供参考。

我国深远海养殖高质量发展动力机制研究

论文基于动力来源的不同,分析深远海养殖高质量发展的内生动力机制和外生动力机制。其中,养殖企业的经济利益、创新发展和效率提升驱动力形成产业发展的内生动力机制,政策推动力、市场拉动力、技术资金支持力和协同合作力构成产业发展的外生动力机制。依据内外生动力发挥作用的大小不同,将其划分为外生动力主导和内生动力主导两种混合动力机制。通过分析我国深远海养殖案例发现,目前我国深远海养殖高质量发展主要由外生主导的混合动力机制驱动,并形成了“政策+技术+资金”的产业发展启动模式。为确保深远海养殖的高质量发展,未来应进一步激发内生驱动力。

浙江省农地规模化的空间潜力与减氮增效研究

我国农业以小农经营为主,为解决浙江省细碎化经营带来的收益和资源利用效率低、面源污染严重等问题,本研究通过分析浙江耕地分布格局,量化浙江农地规模化潜力和空间优化路径,结合农田氮平衡和成本收益分析,评估农地规模化对浙江农业生产和环境效应的影响。结果表明:浙江耕地平均田块面积为0.4 hm^(2),面积低于0.6 hm^(2)的耕地占70%。通过土地整理,73%的耕地连片面积在16 hm^(2)以上。耕地连片规模化经营可以使氮肥投入减少53%,促进氮素利用效率从38%增加至56%。农业劳动力需求从每公顷4人减少至1人,农业投入成本降低77%,劳动力农业年均收入可提高9 457元。浙江省推动实施农地规模化具备良好的资源条件,在全省范围内推行有助于发挥农业生产提质增效和环境资源保护作用。政府应当加强政策引导、加大财政支持、推动农业转型,以农地规模化提升浙江农业可持续发展潜力。

保持主导振荡模态的双馈风电场动态聚合等值方法

针对风电场详细建模出现的“维数灾”问题,计及双馈风电机组各控制环节与系统振荡模态的关系,以保持等值前后主导振荡模态一致为目标,提出考虑风电机组多时间尺度级联特性的风电场站等值聚合方法。首先考虑风电机组多控制环节级联建立风电场状态空间模型;其次,利用振荡能量级判别系统主导振荡模态,并基于参与因子分析不同模态的关键影响因素;在此基础上,以主导振荡模态的关键影响因素为分群指标,结合自编码器进行数据降维处理,经改进聚合算法聚类和拓扑变换获取等值参数等环节后得到等值模型。最后,在Matlab平台分别搭建单机模型和含24台双馈风电机组的风电场模型,验证了所提等值方法的有效性。

漂浮式风电技术现状及中国深远海风电开发前景展望

随着海上风电高速发展及近海场址资源趋紧,适用于深远海域风资源利用的海上漂浮式风电成为中国海上风电未来发展方向。本文介绍国外和国内漂浮式风电发展历程与现状,详细阐述了漂浮式风电从样机示范、小型漂浮式风电场到大规模商业化开发的发展路径,分析不同漂浮式风电基础概念及其特点。剖析了中国漂浮式风电本土化发展所需要面临的技术挑战,主要包括大容量漂浮式风力发电机组、低成本漂浮式风电基础平台、新型系泊系统国产化研制、动态缆系统研制、高效建造安装施工模式和智慧运维安全保障等。针对中国独有的海洋环境、港口码头状况和风电产业链情况,提出了海上漂浮式风电研究方向和发展建议:研发设计适用于中国深远海抗台型大容量漂浮式风电,突破漂浮式风电降本平价发展瓶颈;考虑高效集约用海布局,规模化发展漂浮式风电场;强健漂浮式风电产业完整供应链,推进核心部件和设备国产化进程;创新“海上风电+”新模式新路径,探索海上风电与油气田多能互补融合发展。本文研究对海上漂浮式风电平价商业化开发和扩展海洋能源利用空间具有重要意义。

生猪规模养殖粪污资源化利用不同模式效益及其影响因素研究——基于湖北省襄阳市襄州区的实地调研

为了分析襄阳市襄州区生猪规模养殖场粪污资源化利用不同模式的效益及其影响因素,本研究运用熵值法从经济、社会、生态和技术4个维度13项指标测算生猪规模养殖粪污资源化利用模式评价指标权重;运用TOPSIS法建立生猪规模养殖粪污资源化利用模式综合评价模型,分析各模式综合效益;运用Tobit回归模型从养殖场主的基本特征、养殖场的经营状况和外部社会环境3个方面探究不同生猪粪污资源化利用模式综合效益的影响因素。结果表明:准则层中经济效益、社会效益、生态效益和技术效益的权重分别为0.337 7,0.360 8,0.223 8,0.077 7,其中社会效益权重最大,然后依次是经济效益、生态效益、技术效益。指标层中带动就业、粪污资源化收益和种养平衡率三个指标权重较大,分别为0.329 1,0.299 7,0.170 0。中、小规模养殖场采用沼气发酵模式综合效益最高,大规模养殖场采用综合利用模式综合效益最高。养殖收入、养殖规模和配套耕地面积对粪污资源化利用模式综合效益影响显著,其中养殖收入、配套耕地面积与粪污资源化利用模式综合效益呈正相关关系,养殖规模与粪污资源化利用模式综合效益呈负相关关系。据此,笔者提出加快研发粪污处理和利用相关技术,改进粪污资源化利用模式;强化种养循环发展模式,大力推行种养结合;培育第三方服务主体,解决中、小规模养殖场粪污利用问题;加大政府扶持力度,完善政府激励等措施。