休闲农园节约建设规划设计的探索与实践

休闲农业是乡村经济发展的重要途径,也是乡村振兴的有力推手.休闲农园是实现农业多功能、三产融合、增产增收的重要载体.目前,资金短缺成为休闲农园发展的桎梏,研究其低成本打造及管理意义重大.从规划设计角度出发,结合多年规划设计实践经验,对休闲农园的低成本投入、低成本管理、集约高效生产、节约型景观美化提升以及绿色生态可持续发展等方面做了有益探索,以期为乡村振兴添砖加瓦.     

The value of sea urchin,Lytechinus variegatus,egesta consumed by shrimp,Litopenaeus vannamei

Sea urchins produce high‐energy, membrane‐bound fecal pellets that contain residual nutrients and large quantities of microbiota. These egesta are readily consumed by the shrimp, Litopenaeus vannamei. Egesta of the sea urchin, Lytechinus variegatus, were evaluated as a feed supplement or total replacement for a commercial shrimp diet. Shrimp were stocked at 0.49 g ± 0.06 g initial body weight and housed individually in 2.8‐L tanks in a commercial recirculating zebrafish system. Shrimp were assigned to one of six diets: commercial shrimp feed, reference sea urchin feed, collected dried sea urchin egesta, collected wet sea urchin egesta, half ration of shrimp feed and half collected wet sea urchin egesta, and egesta naturally produced by two sea urchins in polyculture. Equivalent dry matter amounts of each diet were proffered to shrimp in each treatment twice daily, except for those that had complete access to natural egesta excreted by sea urchins in polyculture. Sea urchins were proffered a reference sea urchin feed at 2% body weight daily. After 27 days, shrimp proffered collected dried or wet egesta did not differ significantly in percent weight gain and showed the lowest weight gain. The percent weight gain of shrimp fed the commercial shrimp diet did not differ significantly from that of the shrimp fed half commercial shrimp diet and half egesta. The highest weight gain was recorded for those shrimp that consumed the untouched egesta produced by sea urchins in polyculture. These data suggest that consumed egesta have noteworthy nutritional value and therefore would be beneficial to the culture of extractive species in an integrated multitrophic aquaculture system.     

An evaluation of the Olsen test as a measure of plant-available phosphorus in grassland soils derived from basalt parent material

Abstract. Anecdotal and circumstantial evidence have suggested that the Olsen test underestimates plant-available phosphorus (P) in basaltic soils in Northern Ireland. Therefore, the ability of this test to predict plant-available P in basaltic (and non-basaltic) soils was investigated by regressing Olsen-P data against herbage P indices calculated from plant tissue test data using the diagnosis and recommendation integrated system. The average Olsen-P concentration for a range of fields situated on basaltic soils was considerably lower than the average Olsen-P concentration for a range of fields situated on non-basaltic soils, and yet mean sward P status, as given by the herbage P indices, was similar for both groups of fields. Herbage P indices were also much better correlated with Olsen-P measurements in non-basaltic soils than in basaltic soils. Furthermore, at low Olsen-P values (≶9mgPL⁻¹) some swards on basaltic soils were genuinely deficient in P, while others were sufficient or even in surplus for this nutrient. The results confirm that Olsen-P is inadequate as a predictor of plant-available P in basaltic soils. It is concluded that an alternative soil test is needed to provide a reliable assessment of plant-available P in basaltic soils, to prevent overuse of fertilizer and manure P and to minimize the amounts of P entering local watercourses.     

机械化奶站真空系统的设计

阐述了机械化奶站真空系统的组成、真空泵的工作原理、真空系统设计中应遵循的原则及设计过程中的注意事项,提出了设计机械化挤奶站真空系统的方法。     

水电站虹吸式进水口的控制

在对河北省几座已建虹吸式进水口水电站的虹吸控制方式进行分析对比的基础上,给出了一种采用液气射流泵将虹吸体抽成“低管”正虹吸,用“Y”形管中的水封保持真空,事故时利用“高管”自动补气破坏真空的控制系统,并分析了该系统的特点,给出了设计计算方法及计算公式。     

泰山月观峰和索道站冲沟生态治理探讨

为保护自然生态，对泰山月观峰和索道站冲沟采取了生态治理措施，取得了良好的效果，恢复了泰山自然景现，达到了保护生态环境的目的。     

The significance of VA-Mycorrhiza to future arable farming in the Netherlands

Present conditions of high inputs and narrow rotations render the importance of vesicular-arbuscular mycorrhiza (VAM) in arable farming in the Netherlands rather low. Changes expected in the near future under the influence of economic pressures and environmental problems may change this situation. This is discussed in the light of some such expected changes in Dutch arable farming.De huidige Nederlandse akkerbouw is zeer intensief. Ze heeft in het algemeen een nauwe rotatie met slechts enkele gewassen (aardappelen, granen en suikerbieten) en een ruime toepassing van kunstmest en bestrijdingsmiddelen. Het is te verwachten dat er onder invloed van toenemende problemen met het milieu, afnemende bodemproduktiviteit en lagere prijzen voor nu geteelde gewassen ten gevolge van overschotten een tendens zal zijn in de richting van een meer geïntegreerde landbouw. In de bestaande akkerbouw werken zowel hoge kunstmestgiften (met name N en P) en bestrijdingsmiddelen negatief op VAM-vorming. Naarmate het gebruik van kunstmest en bestrijdingsmiddelen in de nabije toekomst wellicht zal verminderen, kan worden verwacht dat zowel de aanwezigheid als het belang van VAM in de nederlandse landbouw zal toenemen. Het laatste zal vooral het geval zijn indien de vruchtwisseling wordt verruimd met de teelt van andere gewassen (zoals vlinderbloemigen) met een hogere VAM-afhankelijkheid dan die van het huidige gewasassortiment. Het zou zeer verstandig zijn zich reeds nu te beraden over vormen van bedrijfsvoering die VAM zoveel mogelijk stimuleren en daardoor meer profijt trekken van de door deze symbiose geboden voordelen.     

Effects of winter wheat cultivars and seed rate on the biological characteristics of naturally occurring weed flora

Summary Differential competitive ability of six winter wheat cultivars and traits that confer such attributes were investigated for a range of seed rates in the presence or absence of weeds for a naturally occurring weed flora in two successive years in split-plot field experiments. Crop height and tillering capacity were considered suitable attributes for weed suppression, although competitiveness is a relative rather than an absolute characteristic. Maris Huntsman and Maris Widgeon were the most competitive cultivars whereas Fresco was the least competitive. Manipulation of seed rate was a more reliable factor than cultivar selection for enhancement of weed suppression, although competitiveness of cultivars Buster, Riband and Maris Widgeon was not enhanced by increased seed rate. Crop densities ranging between 125 and 270 plants m⁻² were found to offer adequate weed suppression. Linear relationships were observed between individual and total weed species dry weight and reproductive structures per unit area.     

Integrated Pest Management in Cocoa Agroforests in Southern Cameroon: Constraints and Overview

Imports of pesticides have long been subsidised for use in the cocoa agroforests of the humid forest zone of southern Cameroon. With the liberalisation of the cocoa and pesticides sectors and the devaluation of the local currency (CFA franc), farmers are facing fluctuations in the price paid for cocoa and the high cost of farm inputs. Without the support of the extension services, they themselves have developed traditional integrated control methods based on the use of plant extracts mixed with conventional pesticides. From a survey of 300 cocoa farmers, the study assesses the farmers' command of these methods, the pests controlled, the problems encountered and the institutional constraints in the definition and dissemination of integrated control methods. The study concludes with recommendations for research and development towards the better definition and dissemination of integrated control methods. This revised version was published online in July 2006 with corrections to the Cover Date.     

Responding to Economic Crisis in Sub-Saharan Africa: New Farmer-Developed Pest Management Strategies in Cocoa-Based Plantations in Southern Cameroon

Cocoa is a key or source of income and poverty reduction in the humid forest of Southern Cameroon. Cameroon like other African countries went through a major economic crisis in the early 1980s with a decline in international commodity prices and significant changes in macroeconomic policies. Structural adjustment reforms following the economic crisis led to removal of fertilizers and pesticides subsidies, cocoa price liberalization and the overall withdraw of Government interventions from the cocoa sub-sector. Cocoa input price increases have been compounded by the devaluation of the CFA Franc, which doubled the prices of the imported pesticides which were considered key to the control of cocoa pests. This overall economic shock led to changes in cocoa producer's production decisions as a response to minimize cost. Among the changes the use of alternatives to imported chemicals for cocoa pest control. Farmers responded to the high prices of pesticides by developing, from local botanical knowledge and pest management strategies, which include plant extracts and plant extracts mixed with pesticides at different proportions. This is a major decision given the importance of imported chemical in the cost of production of cocoa. Valuable indigenous knowledge from farmers could be used also as an effective support system for communicating and diffusing modern knowledge and technologies to farmers. The paper describes the farmer knowledge-based alternatives to chemical pesticides for pest control in cocoa fields as a response to high pest control costs. Pest management specialists are urged to take advantage of this shift in practice and assess their effectiveness for further use. Two sets of questions are posed: (1) were the conventional insecticides, with all their problems, really necessary? and (2) are the materials derived from locally grown plants effective pest management agents or are they, in some way, placebos?