Under arid and semi-arid conditions, direct application of phosphate rock (PR) as a source of phosphorus (P) for crop production is likely influenced by agricultural practices and soil properties. Different approaches could be used to improve the agronomic efficiency of low-grade PR over a wider range of soils and crops. In this study, biological, physical, and chemical treatments of low-grade Moroccan PR were investigated and compared through agronomic trials on faba bean grown under alkaline soil conditions. The physical treatment was based on blending PR with triple superphosphate (TSP) at 75:25 and 50:50 ratios, the biological treatments involved co-application of PR with compost at 50:50 ratio and phospho-compost elaborated from PR (20%), sewage sludge (46%), and wheat residues (34%), while the chemical treatment was obtained by a 30% acidulation of PR by phosphoric acid. Control treatments consisting of zero P application (control), PR alone, and TSP alone were considered to assess the effectiveness of the abovementioned techniques to improve PR agronomic efficiency. A pot experiment was conducted in sandy soil (Jorf Lasfar, central Morocco) for 60 days in a completely randomized design considering eight treatments. All treatments, except the control, were amended with 52 mg kg?1 of P from different PR-based fertilizers before sowing. At the flowering stage (60-day-old plants), results indicated that all PR treatments significantly improved plant growth, root nodulation, and nutrient uptake compared to the control. The relative agronomic efficiency of pretreated PR was significantly higher with phospho-compost treatment (86%) than the partially acidulated PR (78%) or the PR/TSP blend 50:50 (64%). Likewise, P uptake, P use efficiency, number of root nodules, and N uptake all were improved under PR treatments. Our finding revealed that the biological technique based on phospho-compost yielded better compared to chemical and physical treatments.
Journal of Polymers and the Environment - Modification of cellulose with silver nanoparticles produces various nanocomposites with significantly developed properties. This work aims to prepare a... 相似文献
Currently, attention has shifted to chronic or subclinical disorders attributed to lead (Pb) exposure. The aim of this study was to determine delta-aminolevulinic acid (δ-ALA) levels in urine of Angooran Lead &; Zinc Company workers. This cross-sectional study was conducted on 170 workers, in which 24 h urinary samples were collected and δ-ALA levels were measured spectrophotometrically. Questionnaire forms were completed indicating age, location, and duration of work. The mean δ-ALA level in urine was 5.44 mg L?1. δ-ALA levels were correlated with age, location, and duration of work in the company. The mean δ-ALA level in the urine of workers was in the upper limit of normal ranges. δ-ALA level in urine may not be the best discriminating factor of Pb exposure from the baseline to the high levels, but is recommended as a regular and routine test for all Pb-exposed workers in addition to the measurement of Pb in blood for subjects with higher δ-ALA levels. 相似文献
Small pelagic fishes are particularly abundant in areas with high environmental variability (zones of coastal upwelling and areas of tidal mixing and river discharge), and because of this, their abundance suffers large inter-annual and inter-decadal fluctuations. In Portugal, the most important species in terms of landings are European sardine, Atlantic horse mackerel and Atlantic chub mackerel. Small pelagic fish landings account for 62.8 % of the total fish biomass and represent 32.7 % of the economical value of all catches. We have investigated trends in landings of these small pelagic fishes and detected the effects of environmental factors in this fishery. In order to explain the variability of landings of small pelagic fishes, we have used official landings (1965–2012) for trawling and purse seine fisheries and applied generalized linear models, using the North Atlantic Oscillation index (NAO) (annual and winter NAO index), sea surface temperature (SST), wind data (strength and North–South and East–West wind components) and rainfall, as explanatory variables. Regression analysis was used to describe the relationship between landings and SST. The models explained between 50.16 and 51.07 % of the variability of the LPUE, with the most important factors being winter NAO index, SST and wind strength. The LPUE of European sardine and Atlantic horse mackerel was negatively correlated with SST, and LPUE of Atlantic chub mackerel was positively correlated with SST. The use of landings of three important species of small pelagic fishes allowed the detection of variations in landings associated with changes in sea water temperature and NAO index. 相似文献
Rural livelihoods in West Africa depend largely on livestock. The sub-humid and humid zones of the region, however, are highly
affected by the tsetse flies, vector of trypanosomosis, by severely limiting livestock production and livelihood options.
Endemic ruminant livestock breeds are trypanotolerant, but perceived as inferior compared to other breeds in terms of productivity.
The paper shows trends of relative decline in endemic population as a result of increased crossbreeding, largely with zebu
cattle and Sahelian sheep and goats, and considerable decline in habitat quality due to forest conversion, logging activities
and bushfires. The trade-offs between livelihoods and income strategies and endemic ruminant and habitat conservation are
captured by an understanding of the socio-economic conditions and potential drivers of breed choices and forest use within
households and communities. The paper shows that livelihood analysis is an important step in understanding impacts and therefore
responses to development projects and to ensure that the poorest categories are not excluded from development interventions. 相似文献
The effect of ethylenediaminetetraacetic acid (EDTA) in extracting heavy metal contaminants, namely Pb, Cd, Zn, and Mn, from soils with organometallic complexes, was explored using the coupled electric-hydraulic gradient assisted by ion exchange medium (CEHIXM) decontamination process. The experiments were conducted with a constant electric voltage of 50 DC V and a constant hydraulic flow rate of 4 cm3/min. The results obtained from the experiments demonstrated that EDTA was effective in extracting Pb, Cd, Zn, and Mn from soils in which acidic pH did not produce significant dissolution. Metal removal as high as 99% was achieved with 0.05 M EDTA solution within 200 hr. 相似文献