Analysis of Differences in Productivity,Profitability and Soil Fertility Between Organic and Conventional Cropping Systems in the Tropics and Sub-tropics

Organic farming aims to stimulate soil fertility by avoiding the use of synthetic fertiliser inputs, relying instead on locally available natural resources. It is regarded by many as a sustainable alternative to conventional fanning because it ensures higher biodiversity, restricts environmental pollution, prevents land degradation and is easy to apply for smallholder and subsistence farmers. Although widely practiced and studied in temperate regions, little is known about the potential overall benefits of organic farming in the tropics and subtropics. This paper addresses this gap by undertaking an analysis of the differences between organic and conventional agriculture in the tropics and sub-tropics based on an extensive literature review including 88 papers with 458 data pairs. The comparison is based on three main indicators： yield, gross margin and soil organic carbon （SOC）. The differences between the organic and conventional systems for each of these main indicators is represented by the ratio of the value of the indicator in the organic system divided by the corresponding value in the conventional system. This was initially calculated for each data pair individually, and grouped by a variety of explanatory factors, such as precipitation, human development level, soil texture, crop type, organic input type, time after conversion and certification. The results demonstrate that under organic management, yields were on average 26% higher, gross margins 51% higher and soil organic carbon 53% higher than under conventional management. The highest yield increases in organic cropping systems were achieved in the least developed countries, in arid regions and on coarse soils. For gross margins, certification was the main reason for differences between organic and conventional systems. Certified farmers, mostly located in developed countries, receive significantly higher prices. Furthermore, organic farming in the driest regions results in higher profits than in other regions. Even though soil organic carbon     

建德市不同农作系统肥料结构的调查与分析

调查农田施肥现状可为深入了解施肥中存在的问题、进一步完善测土配方施肥工作提供科学依据。通过对建德市31块定位农田连续5年的肥料结构跟踪监测,比较分析了8类农作系统农田的氮、磷、钾施用情况。结果表明,该市农田肥料的投入量因种植方式、农户等的不同有较大的差异,氮、磷、钾纯量的年总投入量在219.45~1526.55 kg/hm2之间变化,平均为734.70 kg/hm2;部分农田存在超量施用肥料的现象。有机肥的施用量呈现增加趋势,其对农田氮、磷、钾养分投入总量的贡献平均约为10.89%;投入肥料中氮：磷：钾平均比例大致为1:0.6:0.6。经济作物的肥料施用量明显高于粮食作物,且有机肥及磷、钾肥被优先施于经济作物中。目前建德市在有机肥与化肥配合施用及氮磷钾施用比例方面还不尽合理,建议继续加大力度推广施用有机肥,增加粮食作物农田中磷、钾肥及有机肥的施用,以全面提升耕地地力。     

基于能值分析的德州市种植业生态经济系统可持续评价

采用能值分析的理论与方法,基于德州市2009年统计数据以及调查数据,对德州市种植业生态经济系统的能值投入与产出进行分析。结果表明:在德州市2009年种植业生态经济系统能值投入中,可更新环境资源、不可更新工业辅助能、可更新有机能的能值分别占系统能值投入总量的4.99%、81.31%、13.70%,其中种植业机械能值投入占不可更新工业辅助能的57.80%,说明德州市的种植业生态系统主要依赖工业辅助能的投入,且机械化程度较高。高太阳能值转换率、高净能值产出率与高环境负荷率说明该地区农业现代化种植模式水平较高,但环境压力也很大。基于此,本文提出了下一步的可持续发展建议:降低不可更新工业辅助能的投入,增强种植业发展可持续性;调节环境资源与有机能的投入比例,降低环境负荷率;调节种植结构,增加净能值产出率。     

有机和常规甜瓜果实品质比较研究

比较研究了有机和常规生产系统对甜瓜果实品质的影响。结果表明：有机生产甜瓜获得了和常规生产相同的果实重量,有机和常规生产系统对果实TSS和糖分含量都没有显著影响。有机生产显著提高了甜瓜果肉维生素C含量;降低了氨基酸和硝酸盐含量,这与低的果肉氮素含量显著相关。有机生产在一定程度上提高了甜瓜的果实品质,但这些品质指标都不受有机和常规施肥水平的影响。     

湖南省不同种植制度农田土壤肥力长期演变特征北大核心CSCD

明确不同种植制度农田肥力长期演变特征可为选择合适种植制度以提升耕地质量提供参考依据。以湖南省12个国家和省级农田长期定位试验点的种植制度试验为研究对象,选择当地习惯施肥条件下的水稻—水稻—黑麦草(RRR)、水稻—水稻—紫云英(RRC)、水稻—水稻—大麦(RRB)、水稻—水稻—冬闲(RRW)和水稻—水稻—油菜(RRO)5种双季稻模式,烤烟—水稻(RT)、水稻—冬闲(RW)、水稻—油菜(RO)和水稻—绿肥(RG)4种一季稻模式,棉花—油菜(CR)、大豆—红薯(SS)和玉米—萝卜(MR)3种旱作模式,研究其土壤基础肥力指标和综合肥力的演变趋势。结果表明,双季稻模式有机质含量高于旱作模式,长期习惯性施肥条件下,除RRO、RT和RW有机质含量下降外,其余均有上升。RRW、RRO、RT和RW全氮含量相对较高但均有下降,其余则均有增加。RRO和RG碱解氮含量下降明显,而旱作模式均呈增加趋势。RRO和RRW速效磷含量下降明显,而旱作模式年均增加约1.23~4.76 mg/kg。双季稻模式速效钾含量均有下降,而一季稻和旱作模式除RT和MR增加外呈下降趋势或无明显变化。双季稻模式综合肥力下降,而一季稻和旱作模式均有上升。研究表明,湖南省不同种植制度农田肥力变化差异较大,双季稻模式应控氮重钾,一季稻模式应减施氮磷,旱作模式应培肥地力和控施磷肥。     

Can organic farmers be ‘good farmers’? Adding the ‘taste of necessity’ to the conventionalization debate

Recent decades have seen a rapid increase in the rate of conversion from conventional to organic farming, as organic farming shifted from an alternative production approach practiced by a small number of idealists, to the de facto alternative to mainstream conventional production. Although there has been considerable academic debate as to the role of agri-business penetration into the production and marketing chains of organic farming (‘conventionalization’), less is known about how the economic drivers of conventionalization are negotiated into practices at the farm level. Drawing on Bourdieu’s conceptualization of economic and cultural capitals, the direct connection between symbols of ‘good farming’ and the economic requirements of maintaining a viable farming business (i.e., the ‘taste of necessity’) is demonstrated. Findings indicate that conventional and organic farmers in the study sites identified a similar range of cultural symbols, but organic farmers emphasized different symbols within this range. This diversity and selectivity demonstrates the fragmentation and contestation of ideals resulting from economic challenges at the time of the study. Economic capital is important to the decision to consider conversion to organic farming, but formal conversion reflects re-weighting of forms of cultural capital. The author argues that recognition of the impact of economic pressures on conventional farming, which in the study sites often led to reduced input use rather than intensification, is missing from the conventionalization debate. The mainstreaming of organic farming production has presented conventional farmers with a set of alternative or re-weighted symbols and a crucible for reflexive consideration of their own standards and practices of farming.     

农田能量测算原理与指标体系的研究

本研究根据美国、英国和中国等国对农业能量的大量研究和测算方法,结合国内农田投入和产出的实际情况,研究确定了农田系统主要农业生产资料,如：灌溉水、化肥、有机肥、耕作和主要作物产品的能量测算方法与折算标准,初步建立了适合我国农业生产条件的农田能量指标体系,为开展农田能量的广泛研究提供重要依据。     

水稻-红鳌螯虾共作对稻田土壤养分、碳库与稻米品质的影响

近几年来,稻虾综合种养模式快速发展。红鳌螯虾作为名贵的淡水经济虾类,发展前景广阔。研究水稻-红鳌螯虾共作模式对稻田土壤养分、碳库,以及稻米品质的影响,对今后合理调控稻虾共作系统养分循环和平衡,优化施肥管理具有重要的意义。通过大田试验,设置水稻单作和水稻-红鳌螯虾共作2种模式,研究2种模式对稻田土壤养分、碳库动态变化,以及稻米品质的影响。结果表明:与水稻单种模式相比,在水稻整个生育期内,水稻-红鳌螯虾共作模式土壤氨态氮和速效磷平均含量分别显著(P<0.05)增加了24.16%和48.10%;土壤的硝态氮、速效钾、易氧化有机碳、可溶性有机碳和微生物量碳含量分别降低了1.00%、16.40%、3.93%、16.59%和52.80%。稻米产量和品质方面,水稻-红鳌螯虾共作模式的水稻实际产量有所降低,但是可以降低稻米垩白度,稻米品质整体优于水稻单作模式。综上所述,水稻-红鳌螯虾共作模式可以增加稻田土壤氨态氮和速效磷含量,降低稻田活性碳库含量,降低稻米垩白度,提高稻米品质。     

有机、特别及常规栽培体系对蔬菜品质的影响

采用田间定位试验法研究有机、特别和常规3种栽培体系对8种常见蔬菜品质的影响。结果表明,有机、特别栽培体系中各蔬菜的硝酸盐含量低于常规栽培体系;有机蔬菜的蛋白质含量最低;栽培体系对蔬菜维生素C和可溶性糖含量无显著影响。综合各指标可见,西兰花以有机栽培为最好,而芹菜、菜豆分别以特别栽培和常规栽培品质最佳,其它蔬菜则无明确的趋势。     

稻区农牧沼复合生态模式能流特征分析

对“紫云英－猪－沼肥－水稻”复合生态模式能流特征进行了分析。试验结果证明：作物种植是该系统主导产业，水稻光能利用率为２．７０％。紫云英较大幅度提高了系统的光合效率。家畜养殖亚系统饲料转化率高，转化为肉能比例较大。紫云英青贮用作饲料在饲料能投中占有重要地位。沼气生产亚系统能量产投比为０．９１，产出能中以沼肥含能为主。紫云英、沼肥和稻草归还农田可大大节约化肥能投，有机能投为主要人工辅助能投，有机肥料为肥料主要能投。整个系统有机能输入输出比为３．１８。说明农牧沼复合生态系统是一个良性循环系统，具有能投少，能量转换率高，养分利用率高，高功能、高效益等特点     

Efficiency and productivity analysis of vegetable farming within root and tuber-based systems in the humid tropics of Cameroon

The study analyzes the technical efficiency of vegetable farmers in root and tuber-based farming systems within selected sites of the humid tropics of Cameroon. Multistage sampling was used to collect primary data from a cross-section of vegetable farmers drawn from eight selected sites in Santa sub division, Northwest region of Cameroon. Stochastic frontier analysis was used to estimate the technical efficiency of vegetable farmer and to examine its determinants. The results showed that farmyard manure was the most productive factor input, followed by farm equipment and labor. The mean technical efficiency level was 67%, revealing production shortfalls and indicating possibilities of significantly increasing production with the current input levels. Female, as well as more educated farmers were found to be significantly more efficient than their counterparts. The results also showed that farmers become less technical efficient as farm sizes become larger. Our study findings suggest that smallholder farmers' access to manure, farm implements, and increased women participation in vegetable farming, will produce huge payoffs in vegetable production efficiency in Cameroon.     

有机、SEQ、特别与常规栽培对8种蔬菜产量、品质的影响

文章分析比较了田间试验第2年,有机、SEQ、特别与常规栽培对8种蔬菜产量、品质的影响。结果表明,不同栽培方式8种蔬菜的产量趋势基本一致,即常规最高,有机最低,特别与SEQ居中。与常规栽培相比,有机栽培蔬菜减产幅度达到11．1％～64．4％。有机与常规栽培萝h、西兰花、番茄的产量差异达到1％水平显著,其他5种蔬菜的产量差异未达到5％水平显著。有机栽培番茄、芹菜的品质显著优于常规栽培的,Vc、干物质、可溶性糖含量较高,硝酸盐含量较低。但是有机与常规栽培西兰花、黄瓜、毛豆的品质差异不大。SEQ、特别栽培蔬菜的品质介于有机与常规栽培之间。     

Public agricultural researchers: Reactions to organic,low input and sustainable agriculture

This paper offers a preliminary assessment of the reactions of public agricultural researchers to three terms used currently in the debate surrounding reduced input farming systems: organic, alternative, and sustainable agriculture. It is argued that these terms have been appropriated by the land grant system and their critical content removed to make them palatable to more mainstream agricultural researchers. A national sample of agricultural production researchers is explored, and disciplinary differences in attitudes toward the three terms are assessed. We conclude that sustainable and alternative agriculture do appear acceptable to the mainstream of production researchers, consistent with the hypothesis that they have been appropriated by the land grant system. Moreover, reasons why organic agriculture remains unacceptable are suggested.Aaron Harp is an Assistant Professor of Rural Sociology at the University of Idaho. His research focuses on issues of adoption in sustainable agriculture, and rural development.     

桂东地区早稻稻鸭共作有机栽培试验初报

为探索适合本地水稻生态安全、优质高效生产技术,在桂东地区进行早稻有机栽培、稻鸭共作有机栽培和传统栽培三种模式试验研究。结果表明,三种模式水稻平均产量分别是394.6kg/667m2、430.2kg/667m2、508.9kg/667m2,稻鸭共作有机模式比传统模式每667m2低18.3%,比有机模式高9.0%;平均净收益分别为797.5元/667m2、936.8元/667m2、664.3元/667m2,以稻鸭共作模式最高,比有机栽培和常规栽培增加20.1%和24.3%。此外,稻鸭共作模式在控制稻田杂草和病虫害、提高肥力和改善稻田生态环境优于其它两种模式。     

北京市主要农作模式的碳效益分析

本研究利用投入产出法的理论和方法,研究了北京地区主要农作模式的碳投入、产出及碳效益情况。结果表明:氮肥和电能在总碳投入中占较大比重,达70%～90%;蔬菜类作物的碳投入远大于非蔬菜类作物,设施蔬菜模式的碳投入分别比麦-玉两熟、春玉米一熟、春花生一熟模式高80.4%、92.0%、94.3%,其余模式间差异较小。春玉米易于田间施肥等管理,资源利用率较高,其碳效益最高,为4.59;春玉米一熟模式的碳效益分别比麦-玉两熟、春花生一熟、蔬菜模式高30.8%、8.31%、96.8%。因此,北京地区种植春玉米有利于减少农田碳排放。     

高州市水稻施肥状况分析

通过对2007—2008年高州市典型农户开展的4 048份水稻施肥情况进行调查,结果表明:高州市水稻施肥表现为氮磷盈余、钾亏缺,其中氮肥平均盈余量为37.8 kg/hm2,磷肥平均盈余量为16.1 kg/hm2,钾肥亏损量为120.83 kg/hm2;高州市有35.73%的农户水稻氮肥用量合理,0.65%的农户水稻氮肥用量不足,63.62%的农户水稻氮肥施用过量;有31.91%的农户磷肥用量合理,20.75%的农户磷肥用量不足,47.34%的农户磷肥施用过量;98.98%的农户水稻钾肥用量合理,只有1.02%的农户钾肥施用不足。土壤养分投入盈亏状况评价宜以年度为周期进行,若仅以单季作物养分投入评价耕地土壤养分投入盈亏状况,可能得出片面甚至错误的结论。     

有机种植对盐碱土壤N2O、CO2排放通量的影响

以黑龙江省大庆市盐碱土壤为研究对象,探讨有机种植对盐碱土主要温室气体(N₂O和CO₂)排放的影响。采用IPCC(1992)的方法对试验结果进行计算及对比,结果表明,相较于常规种植,有机种植的温室气体(N₂O、CO₂)排放通量值较低,说明有机种植对盐碱土旱田的温室气体(N₂O、CO₂)有减排作用。在盐碱土上有机种植大豆、玉米,随着有机种植年限的增加,温室气体(N₂O、CO₂)的排放值略有变化,但差异不显著,且总体的增温潜势依然低于常规种植。而且,有机种植增加了试验区土壤微生物量碳、氮的含量。     

白洋淀流域核心区农牧系统未利用氮量及空间分布

【目的】农牧系统过量投入产生的未利用氮素是地表水体中污染负荷的重要来源之一，量化农业未利用氮素的空间分异特征，为氮素的分区管理，实现流域农业源氮素有效管理提供基础。【方法】以白洋淀流域核心区保定市范围内的农牧系统为研究对象，根据氮素输入、输出量，分析2016年保定市各县(区)种植业、畜牧业以及农牧系统的未利用氮素空间分布情况。种植业的未利用氮量为各输入项(化肥、有机肥、大气干湿沉降、灌溉水、种子、非共生固氮和秸秆还田)与输出项(作物籽粒和秸秆)的差值；畜牧业未利用氮量为养殖粪污产生量与施用量的差值；农牧系统未利用氮量为种植业与畜牧业未利用氮量之和。【结果】(1)保定市各县(区)种植业氮未利用强度在90.27—581.73 kg·hm^-2之间，其中定兴县氮未利用强度最小，满城区的氮未利用强度最大；种植业中蔬菜生产是未利用氮贡献最多的产业，占种植业未利用氮量的31.3%，其次是果树(29.0%)、小麦(27.8%)和玉米(11.9%)；化肥是种植业未利用氮的主要输入源(占61.8%)，其次是有机肥(16.8%)、秸秆还田(8.9%)、大气沉降(5.2%)、灌溉(3.4...     

湖南稻田现代农作制特征及发展对策

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