小农经济国家农业结构调整的经验与启示

不同国情和不同经济发展阶段 ,其农业结构变迁与政策调适重点有所不同。当前中国农业结构调整 ,尤其要借鉴荷兰、日本等小农经济国家农业结构调整的经验教训。运用经济学指标 ,判定日本及中国在不同经济发展阶段农业角色转换始点 ,提出借鉴国外经验 ,应重新审视政府在农业结构调整的角色与作用。适时转换职能 ,调适农业生产、营销和农民福利政策 ,变革农地制度设计 ,推行知识和技术替代土地发展的政策 ,针对不同区域运用不同发展阶段的政策工具 ,促进农业转型升级     

东亚单层低云特性及其短波辐射强迫的季节变化

利用云与地球辐射能量系统CERES(clouds and the earth’s radiant energy system)资料,对2003-2016年东亚不同区域单层低云物理属性及地面短波辐射强迫的季节时空分布特征进行研究。结果表明:①在空间分布上,辐射强迫与单层低云量在春秋两季有着较好的相似性,而与冰/液态水柱含量在春、夏、秋三个季节有着较好的一致性。②在时间变化上,北方地区夏季的单层低云对短波辐射的削弱作用是最强的;南方地区和西北地区最强的削弱作用发生在春季;东部海域则发生在冬季。在空间分布上,春、秋、冬季最强的低云削弱效应在南方地区。夏季,东亚低云对短波辐射的削弱作用各区域都较弱,大部分区域的负辐射强迫的绝对值小于200 W·m^-2。     

蟹爪兰短日照促成栽培试验初报

对蟹爪兰2个品种进行不同起止时间的短日照促成栽培试验表明，以着蕾，如期开花率及如期开花朵数比较，7月30日开始给予短日照的处理优于7月20日开始给予短日照的处理；并且70-78d就能开花，比自然花期提早一个月；7月下旬进行的蟹爪兰短日照促成栽培，短日照处理时间以40d为好。     

Reasons for smallholder farmers discontinuing with low-cost micro-irrigation: A case study from Kenya

The low head drip kit (micro-irrigation) was introduced in Kenya in the late 1990s. It consists of water containers, usually a bucket or a drum(s), raised about one metre to gain gravitational head. The number and length of drip lines used vary according to the areas to be irrigated which can be as low as 15 m². The general objective of this research was to find out why some smallholder farmers in the study areas discontinued micro-irrigation. The research was carried out in 2002 by a survey using face-to-face informal interviews with continuing adopters and those who had discontinued adoption. The study revealed that the majority of farmers who discontinued using micro-irrigation stopped due to lack of maintenance, irrelevant cultural background, and unreliable water supply. The influence of some factors seemed to vary between areas. Homogeneity analysis (SPSS) results associated farmers who discontinued the adoption of the micro-irrigation kit with above factors as well as farmers’ subsidies for acquisition of the kit, the use of the smaller bucket kit, and farmers who did not traditionally grow food crops. The findings suggest critical factors to be addressed for the continued adoption of smallholder micro-irrigation.     

Using Wood Ash to Ameliorate Acidity and Improve Phosphorus Availability in Soils Amended with Partially Decomposed Cattle or Chicken Manure

The application of partially decomposed animal manure can acidify the soil by nitrification and may cause problems with phosphorus (P) availability. This study investigated the influence of applying wood ash to two soils amended with partially decomposed cattle or chicken manure on pH and P. The treatments consisted of two soils, a clay loam and sandy loam, each amended with partially decomposed chicken or cattle manure applied at 0, 5, or 15 t ha^?1, and wood ash was applied to each manure treatment at rates of 0 or 2 t ha^?1. The addition of wood ash significantly increased pH, thereby making more P available in soil and maize (Zea mays L.) tissues for both soils after being amended by manure. Both chicken and cattle manure significantly increased all the measured variables compared to the unamended soils. These results suggest that wood ash is an important amendment that could be used to amend partially decomposed manure, thereby not jeopardizing P availability to crops.     

黄土区退耕草地小尺度土壤水分空间异质性

通过在黄土高原水蚀风蚀交错带选取3块不同年限退耕草地,进行高密度、高频度样带采样,研究分析在表层土壤干旱和湿润状况下,小尺度表层土壤含水率的空间异质性,并分析改变采样间距对土壤含水率空间异质性的影响。结果表明:小尺度表层土壤水分空间异质性为12 a退耕草地>20 a退耕草地>5 a退耕草地;空间变异强度表现为干旱时为中等变异>湿润时为弱变异;表层土壤水分方差与含水率均值呈正相关,土壤水分方差随含水率均值增大而增大;表层土壤水分空间连续性为12 a退耕草地>20 a退耕草地>5 a退耕草地,且与表层土壤含水率呈负相关;小尺度下改变采样间距,在土壤干旱和湿润时均不改变3块退耕草地表层土壤水分空间变异程度。     

东莞一个小型景观土壤有机碳含量及其分布

Soil organisms in terrestrial systems are unevenly distributed in time and space, and often aggregated. Spatiotemporal patchiness in the soil environment is thought to be crucial for the maintenance of soil biodiversity, providing diverse microhabitats tightly interweaving with resource partitioning. Determination of a ＂scale unit＂ to help understand ecological processes has become one of the important and most debatable problems in recent years. A fieldwork was carried out in the northern Negev Desert highland, Israel to determine the influence of fine-scale landscape patch moisture heterogeneity on biogeochemical variables and microbial activity linkage in a desert ecosystem. The results showed that the spatio-temporal patchiness of soil moisture to which we attribute influential properties, was found to become more heterogenic with the decrease in soil moisture availability （from 8.2 to 0.4 g kg^-1） toward the hot, dry seasons, with coefficient of variation （CV） change amounting to 66.9%. Spatio-temporal distribution of organic matter （OM） and total soluble nitrogen （TSN） was found to be relatively uniformly distributed throughout the wet seasons （winter and spring）, with increase of relatively high heterogeneity toward the dry seasons （from 0.25% to 2.17% for OM, and from 0 to 10.2 mg kg^-1 for TSN） with CV of 47.4% and 99.7% for OM and TSN, respectively. Different spatio-temporal landscape patterns were obtained for Ca （CV = 44.6%）, K （CV = 34.4%）, and Na （CV = 92%） ions throughout the study period. CO2 evolution （CV = 48.6%） was found to be of lower heterogeneity （varying between 2 and 39 g CO2-C g^-1 dry soil h^-1） in the moist seasons, e.g., winter and spring, with lower values of respiration coupled with high heterogeneity of Na^＋ and low levels of TSN and organic matter content, and with more homogeneity in the dry seasons （varying between 1 and 50 g CO2-C g^-1 dry soil h^-1）. Our results elucidate the heterogeneity and complexity of desert system habitats affecting soil biota activity.     

小型装配式恒温贮藏库和土窑洞改造库建设及其贮藏的红富士苹果品质分析

应用100 mm厚聚氨酯彩钢夹心保温板组装冷库墙体及库顶,用150 mm厚聚苯乙烯泡沫板进行地面保温处理,并配备氟制冷机组和智能温控电控箱,新建1座6 m×12 m×3.5 m(宽×长×高,下同)小型装配式恒温贮藏库,在原有土窑洞库顶和墙体喷涂80 mm厚聚氨酯,用150 mm厚聚苯乙烯泡沫板进行地面保温处理,改造1座3.8 m×28 m×4 m传统土窑洞式贮藏库,以未改造的传统土窑洞和大型恒温冷库为对照,以红富士苹果为试材,研究了新建(改造)贮藏设施的降温与保温性能及其对苹果的保鲜效果。结果表明,小型装配式恒温贮藏库和土窑洞改造库均能在1 h之内将空库库温降至0℃以下,贮藏温度可均匀、稳定地控制在0℃左右;苹果贮藏120 d,其果实硬度、可溶性固形物和可滴定酸含量显著高于传统土窑洞,而与大型恒温冷库贮藏苹果的效果无显著差异。小型装配式恒温贮藏库和土窑洞改造库可以满足果农贮藏苹果的需要。     

不同工艺生产茶树油产品质量的研究

以ISO 4730-1996为标准对工业化生产和小型芳香油生产装置(乡村适用的)两种工艺制得的茶树油的理化指标和主要成分含量进行对比分析,发现利用小型芳香油装置生产的茶树油重组分小于 5 %.初步探讨认为重组分沸点高,常压难蒸出.     

I Ssues of Irrigation of Horticultural Crops by Smallholder Farmers in Kenya

Although smallholder farmers have practised irrigation in Kenya, the introduction small-scale irrigation for horticultural production is relatively a recent development. The increase in irrigation practice has been promoted by the rapid increase in the growth of the horticultural industry. This research examined factors influencing irrigation of horticultural crops on smallholdings in Kenya. The key informants were smallholder irrigation farmers (including low-cost drip), representatives of the irrigation industry, Non Governmental Organisations and the government. The informants were interviewed in a survey of semi-structured open-ended questionnaires.The main problems reported were inadequate technical support service, unreliable water supply, and poor marketing of produce. The government policy on promotion of low cost technology was apparently not clear to the extension staff. Manufactures considered the sector especially the low-cost drip irrigation too small to promote actively. Some of these factors are likely to present a major challenge to developers in the promotion of smallholder irrigation technology in parts of the country.