农地转入规模扩大有助于农民农业增收吗?——基于中国中部5省农户调查的实证研究

在全国农地流转、规模经营的呼声越来越高的背景下,农地流转政策的推行是否起到应有的效果有待检验和反思。论文基于来自我国中部5省925个转入户的调查数据,从3组模型全面考察了农地转入规模与农户农业收入之间的关系。实证研究表明：1）农地转入规模与农业收入呈正向关系,但农地转入规模的经济收益率仅为2.9%。2）农地转入规模对农业收入的作用在不同区域、流转方式、农户类型之间有明显差异：安徽、湖北和湖南较之河南、江西的规模经济收益率更高,农户自发流转下的规模经济收益率高于集体主导方式,农地转入规模对纯农户农业收入的影响要大于对兼业农户。3）农户平均收入水平随着转入规模增加呈现出先增加后降低的“倒U型”趋势,农地转入规模等级越大,其经济收益率却越低。因此,目前我们亟待解决的是加强农地流转对农户收入影响的系统机制研究,寻找制约流转规模效益的因子,降低农户大规模流转时的风险和损失,而不是盲目扩大流转面积。     

湛江某对虾基地沉积物重金属含量特征及评价

探讨了湛江某对虾养殖基地虾场沉积物中重金属Cu、Zn、Pb、Cd、Cr的含量特征,并采用单因子、内梅罗综合污染指数以及H(a)kanson潜在生态风险指数等方法评估了几种重金属的环境风险,分析了其主要来源.结果表明,虾场沉积物Cu含量在11.5～38.5mg/kg之间;Zn含量在87.6～176.4mg/kg之间;Pb...     

序批式反应器用于牛场污水的处理

对序批式反应器 (SBR)用于牛场污水的处理进行了试验研究 ,主要研究了三个水力停留时间 (HRT)和有机负荷率对污染物去除率、出水水质和污泥特性的影响。试验结果表明 ,对 10 0 0 0mg/LCOD牛场污水 ,使用 1dHRT ,相应有机负荷率为 10gCOD/L·d时 ,混合出水COD、TS、VS、TKN和TN的去除率分别为 45 %、2 1.4%、34 .2 %、5 3.2 %和 2 2 .2 % ,上清液出水的分别为 80 .2 %、6 3.4%、6 6 .2 %、75 %和 38.3% ;两种出水的SCOD和NH3 N去除率相同 ,分别为 5 0 .0 %和 76 .5 %。经SBR处理后 ,污泥的沉降浓缩性能也有了比较明显的改善。     

臭氧氧化处理养猪场厌氧沼液

实验在MAP沉淀处理的基础上,采用臭氧氧化技术对养猪场厌氧沼液进行处理。研究了氧化过程中臭氧的投加量、反应时间对沼液pH、COD和UV254的去除效果、沼液可生化性、氮形态转化的影响。结果表明,在臭氧氧化过程中,随着反应时间的延长,沼液pH呈逐渐下降的趋势。在臭氧投加量为6 mg/L、反应时间为40 min时,COD和UV254去除率达到最大,分别为21.7%和60%。此外,臭氧氧化能把BOD5/COD的比值从0.24提高为0.41,有效提高了沼液的可生化性。在臭氧投加量为6 mg/L、反应时间为2 h时,TN的浓度基本维持在370~410 mg/L之间,氨氮浓度随时间呈现先升高后降低的变化趋势,且最终维持在132.7 mg/L,然而,硝态氮浓度反而升高了近一倍,由此可见,臭氧氧化不能完全脱氮,只能使氮从一种形态转化为另一种形态。     

非农就业对农户种植多样性的影响:以江苏省泰兴市和宿豫区为例

为分析非农就业对农户种植多样性的影响,通过农户问卷调查手段获得356份农户问卷,以在江苏省泰兴市和宿豫区的农户问卷调查数据为基础,采用Poisson回归方法,估计了农户种植多样性决策模型。依据模型估计结果,分析了非农就业对农户种植多样性的影响。分析表明,农户的种植多样性受到多种因素的影响。负责农业生产家庭成员受教育年限提高1 a,种植多样性提高1.5%左右;种植面积增加1 hm²,则农户种植多样性提高28%左右;就农户参与非农活动的影响而言,与负责农业生产家庭成员不参与非农活动的农户相比较,负责农业生产家庭成员参与非农活动家庭的种植多样性减少11%左右;负责农业生产家庭成员参与非农活动月数增加1个月,农户种植多样性大约降低1.4%。分析说明负责农业生产家庭成员参与非农就业会显著降低农户种植多样性。     

Opportunities and challenges for Common Agricultural Policy reform to support the European Green Deal

The Common Agricultural Policy (CAP) is the European Union's main instrument for agricultural planning, with a new reform approved for 2023–2027. The CAP intends to align with the European Green Deal (EGD), a set of policy initiatives underpinning sustainable development and climate neutrality in the European Union (EU), but several flaws cast doubts about the compatibility of the objectives of these 2 policies. We reviewed recent literature on the potential of CAP environmental objectives for integration with the EGD: protection of biodiversity, climate change mitigation and adaptation, and sustainable management of natural resources. The CAP lacks appropriate planning measures, furthering instead risks to biodiversity and ecosystem services driven by landscape and biotic homogenization. Funding allocation mechanisms are not tailored to mitigate agricultural emissions, decreasing the efficiency of climate mitigation actions. The legislation subsidies farmers making extensive use of synthetic inputs without adequately supporting organic production, hindering the transition toward sustainable practices. We recommend proper control mechanisms be introduced in CAP Strategic Plans from each member state to ensure the EU is set on a sustainable production and consumption path. These include proportional assignment of funds to each CAP objective, quantitative targets to set goals and evidence-based interventions, and relevant indicators to facilitate effective monitoring of environmental performance. Both the CAP and the EGD should maintain ambitious environmental commitments in the face of crisis to avoid further degradation of the natural resources on which production systems stand.     

湘南红壤丘陵区农户经济行为对土地退化的影响分析——以祁东县紫云村为例

通过在湖南省祁东县紫云材进行的土地利用及农户经济行为调查,从土地状况、从业选择、农具、农田设施、耕作方式和效益等方面,分析了湘南红壤丘陵区农户社会经济行为对土地质量的影响。结果表明：紫云村农户重“品种”轻“土壤”,水田土壤有机质含量减少,理化性状变差,土壤自然肥力降低,旱地、林地粗放经营,质量退化。改变农户只重“品种”而忽视“土壤”的观念、提高耕地复种指数、建立合理的轮作体系和水土保持型高效集约持续的耕作制度、加强林业管理和经营、加大农业投入、搞好农田水利建设是防止本区土地退化和保证本区农业可持续发展的对策。     

中国农村居民食品消费碳排放的时空格局及其影响因素

在全球气候变化背景下,研究居民食品消费碳排放具有重要的意义。本文基于全国和地区农村居民家庭食品消费量调查数据及其人均食品消费碳排放的测算,运用ArcGIS空间统计分析、地理探测器因子探测等方法,分析2000—2019年中国农村居民家庭食品人均碳排放的时空格局及其驱动因素。结果表明：①碳排放结构中升降因素叠加,人均碳排放量增速不明显。②人均碳排放量存在空间集聚效应,但集聚程度呈下降趋势。③人均碳排放量、直接与间接排放量空间分异的影响因素不同。其中,人均碳排放量主要受到猪牛羊肉消费量、食品消费支出的影响。建议从优化农村居民的饮食结构,适度减少猪牛羊肉的消费量、增加综合碳折算系数较低的禽肉、蛋类、牛奶和鱼类等动物性食品的消费量,以及加强人均碳排放量较高地区饮食结构调整和优化的指导等方面,减少农村居民食品消费的人均碳排放量。     

Sediment organic matter and meiofauna community response to long-term fish-farm impact in the Ligurian Sea (Western Mediterranean)

Quantitative and qualitative changes in meiofauna community structure were investigated to assess the impact of a fish farm, which was operating continuously for 15 years (La Spezia Gulf, W Mediterranean). Sediment samples were collected in June, July, September, October 2000 and February 2001 for the analysis of phytopigments (chlorophyll-a and phaeopigments), the biochemical composition of organic matter (proteins, carbohydrates and lipids) and related to meiofaunal parameters.

Sediment organic matter reached extremely high concentrations beneath the fish cages when compared to the control. Particularly lipids, carbohydrates and chlorophyll-a were significantly higher in fish-farm sediments. On a long-term basis meiofauna displayed adaptations in sediments beneath the cages resulting in an increase of density. Organic impact on meiofaunal community structure was evident in terms of an increase of the nematodes to copepods (Ne/Co) and nauplius to copepods (Na/Co) ratios in fish farm sediments. Cumaceans and kinorhynchs were encountered in control sediments, but disappeared in fish-farm samples. These data suggest that meiofauna is a sensitive tool for evaluating the effects of organic enrichment in fish farm impacted areas.     

Impact of cocoa agricultural intensification on bird diversity and community composition

To meet the growing demand for chocolate, cocoa (Theobroma cacao) agriculture is expanding and intensifying. Although this threatens tropical forests, cocoa sustainability initiatives largely overlook biodiversity conservation. To inform these initiatives, we analyzed how cocoa agriculture affects bird diversity at farm and landscape scales with a meta-analysis of 23 studies. We extracted 214 Hedges' g* comparisons of bird diversity and 14 comparisons of community similarity between a forest baseline and 4 farming systems that cover an intensification gradient in landscapes with high and low forest cover, and we summarized 119 correlations between cocoa farm features and bird diversity. Bird diversity declined sharply in low shade cocoa. Cocoa with >30% canopy cover from diverse trees retained bird diversity similar to nearby primary or mature secondary forest but held a different community of birds. Diversity of endemic species, frugivores, and insectivores (agriculture avoiders) declined, whereas diversity of habitat generalists, migrants, nectarivores, and granivores (agriculture associates) increased. As forest decreased on the landscape, the difference in bird community composition between forest and cocoa also decreased, indicating agriculture associates replaced agriculture avoiders in forest patches. Our results emphasize the need to conserve forested landscapes (land sparing) and invest in mixed-shade agroforestry (land sharing) because each strategy benefits a diverse and distinct biological community.