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1.
Denis J. Sonwa Ousmane Coulibaly A. Akinwumi Adesina Stephan F. Weise Mathurin Tchatat 《Integrated Pest Management Reviews》2002,7(3):191-199
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. 相似文献
2.
3.
新疆热点旅游城市旅游气候资源评价及分类 总被引:6,自引:2,他引:4
气候资源是一个地区旅游业发展的基本因子。本文利用新疆多年的气象统计资料,通过对风效指数、温湿指数及由此确定的隶属度的测算,来定量分析新疆重点旅游城市的旅游气候资源,得出每个城市适宜旅游的季节,并且将这些城市分为五个旅游气候类型,希望能给旅游者出行和旅游部门制定规划提供一些科学的参考和依据。 相似文献
4.
连栋塑料大棚棚内环境易受寒潮侵扰,为调节棚内热湿环境,将表冷器-风机集放系统应用于连栋塑料大棚中,在白天适宜条件下运行系统,将棚内空气盈余的热量收集并储存在蓄热水箱中,夜间气温较低时,再将储存的热量释放出来用以加温。对表冷器-风机集放热系统的运行效果进行试验,通过集热量、放热量和性能系数等评价集放热性能,并且将水气温差作为主要影响因素对系统运行阶段分别进行热流量分析和分析。结果表明,在寒潮下系统可以保证棚内气温比棚外高5.2~7.8 ℃。集热量达到了390.6~693 MJ,放热量为361.2~609 MJ,系统性能系数达到了4.4~7.2,节能效果较为显著。系统在运行过程中水气温差每增长1 ℃,集热流量增加0.82 kW,放热流量增加0.58 kW,单位时间内换热量较大;此外系统在集热阶段析湿系数约为1.70,表冷器-风机进出口空气含湿量差最高可达1.3×10-3 kg/kg,说明在集热阶段系统具有冷凝除湿的效果;同时在冷凝除湿过程中系统效率随着水气温差的增加而增加,最高可达到82.8%,能量利用率较高。该研究对保证连栋塑料大棚安全越冬生产具有重要意义。 相似文献
5.
为提升甘南青稞产业种源支撑基础,实现青稞新育品种的增产增收潜力,以青稞新品种甘青11号为试材,在甘南高寒阴湿区旱川地进行了不同施肥水平与播量对其生长及产量的影响试验。结果表明,施肥水平为尿素150 kg/hm2、磷酸二铵225 kg/hm2,播量为192.0 kg/hm2时,甘青11号青稞折合产量最高,为3 720 kg/hm2;施肥水平为尿素150 kg/hm2、磷酸二铵300 kg/hm2,播量分别为223.5、256.5 kg/hm2时,甘青11号青稞折合产量较高,分别为3 580、3 510 kg/hm2。由此可见,在施肥水平为尿素150 kg/hm2、磷酸二铵225~300 kg/hm2,播量为192.0~256.5 kg/hm2时,青稞产量高、综合农艺性状优良。综合考虑,该施肥水平和播量为青稞在甘南高寒阴湿区种植适宜的肥料配比和播量。 相似文献
6.
Soil management for Alfisols in the semiarid tropics: erosion, enrichment ratios and runoff 总被引:2,自引:0,他引:2
A.L. Cogle K.P.C. Rao D.F. Yule G.D Smith P.J. George S.T. Srinivasan L. Jangawad 《Soil Use and Management》2002,18(1):10-17
Abstract. Continuous cultivation of soils of the semiarid tropics has led to significant land degradation. Soil erosion and nutrient loss caused by high runoff volumes have reduced crop yields and contributed to offsite damage. We compared a number of soil management practices (tillage, mulch and perennial/annual rotational based systems) for their potential to improve crop production and land resource protection in an Alfisol of the semiarid tropics of India. Runoff and soil erosion were monitored and surface soil and sediment were analysed for nitrogen and carbon to determine enrichment ratios. Amelioration of soils with organic additions (farmyard manure, rice straw) or rotating perennial pasture with annual crops increased soil carbon and nitrogen contents and reduced runoff, soil erosion and nutrient loss. Soil erosion totalled less than 7 t ha–1 , but enrichment ratios were often greater than 2 resulting in up to 27 kg N ha–1 and 178 kg C ha–1 being lost in sediment. Up to an extra 250 mm of water per year infiltrated the soil with organic additions and was available for crop water use or percolation to groundwater. The results show that there are good opportunities for reducing degradation and increasing productivity on farms. 相似文献
7.
海南热带粘菌资源(Ⅰ) 总被引:2,自引:0,他引:2
报道采自海南五指山、尖峰岭等热带林区粘菌28种,隶属于6目7科12属。其中,有7个中国新记录种和变种(^**表示),有8个种和变种是首次在海南采集到的(^*表示)。 相似文献
8.
Patrick Chesney 《Agroforestry Systems》2008,72(2):149-159
The effect of pruning all branches (complete pruning) or retaining one branch (partial pruning) on the dynamics of nitrogen
cycling in aboveground biomass, nitrogen supplying power of an amended Eutric Cambisol, and fine root length, was studied
in an Erythrina poeppigiana (Walp.) O.F. Cook—tomato (Lycopersicon esculentum Mill.) alley cropping practice in Turrialba, Costa Rica during 1999–2000. Over the 1 year pruning cycle, in which trees were
completely or partially pruned four times, respective aboveground biomass production was 4.4 Mg or 7 Mg ha−1 (2-year-old trees) and 5.5 Mg or 9 Mg ha−1 (8-year-old trees); N cycled in aboveground biomass was 123 kg or 187 kg ha−1 (2-year-old trees) and 160 kg or 256 kg N ha−1 (8-year-old trees); mean fine root length was 489 or 821 m (2-year-old-trees), 184 or 364 m per tree (8-year-old-trees).
Pruning intensity did not significantly affect net N mineralisation and net nitrification rates during the tomato-cropping
season. For the tomato crop, pre-plant mean net N mineralisation rate of 2.5 mg N kg−1 soil day−1 was significantly lower than 16.7 or 11.6 mg N kg−1 soil day−1 at the end of vegetative development and flowering, respectively. Mean net nitrification rates of 3.5, and 4.3 mg N kg−1 soil day−1, at pre-plant and end of vegetative development, respectively, were significantly higher than 0.3 mg N kg−1 soil day−1 at end of flowering. In humid tropical low-input agroforestry practices that depend on organic inputs from trees for crop
nutrition, retention of a branch on the pruned tree stump appears to be a good alternative to removal of all branches for
reducing N losses through higher N cycling in aboveground biomass, and for conserving fine root length for higher N uptake,
although it might enhance competition for associated crops. 相似文献
9.
Sediment production from unpaved roads in a sub-tropical dry setting — Southwestern Puerto Rico 总被引:1,自引:0,他引:1
The threat imposed by increased sediment loading rates ranks among the most important stressors affecting coral reef ecosystems worldwide. This study represents an effort to quantify the effects of unpaved roads on erosion rates in a dry sub-tropical area of Puerto Rico and is intended to aid in developing scientifically-based erosion mitigation strategies. Hence, the specific objectives of this study were to: (1) measure sediment production rates from unpaved roads; (2) evaluate the effect of precipitation, rainfall erosivity, slope, plot length, and vegetation cover on sediment production rates; and (3) compare measured sediment production rates to published surface erosion data from roaded and natural sites in the Eastern Caribbean. Sediment production from nine abandoned road segments with varying slopes and plot lengths were measured with sediment traps in southwestern Puerto Rico from August 2003 to September 2005. 相似文献
10.
近年来,我国的水污染现象越来越严重,而对植物处理城市污水方面的研究国内外只局限于芦苇(Phragmites australis)、香蒲(Typha orientalis Presl.)等水生植物,虽对污水净化效率较高,但植物种类单一且观赏价值不高。针对这些不足,探讨了在植物选择上应扩展到耐湿园林植物,在注重污水净化效果的同时又体现植物的美学功能,为现代城市营造出一处生态功能景观。 相似文献