Nitrogen and phosphorus use in maize sole cropping and maize/cowpea mixed cropping systems on an Alfisol in the northern Guinea Savanna of Ghana

Summary The use of N and P by mixed and by sole cropping (crop rotation) of maize and cowpeas were compared in a field experiment on an Alfisol at the Nyankpala Agricultural Experiment Station in the northern Guinea Savanna of Ghana, using two levels of N (0 and 80 kg N ha^-1 year^-1 as urea) and P application (0 and 60 kg P ha^-1 year^-1 as Volta phosphate rock). Maize grain yields were significantly reduced in the mixed cropping system. This yield difference became smaller with the application of N and P fertilizer. The N and P concentrations in maize ear leaves at silking indicated that a deficiency in N and P contributed to the maize yield depression in mixed cropping. Competition for soil and fertilizer N between maize and cowpeas was suggested by: (1) A similarity in total N uptake between the two cropping systems; (2) efficient use of soil nitrate by the cowpeas; and (3) low N₂ fixation by the cowpeas, calculated with the aid of an extended-difference method. In general, N₂ fixation was low, with the highest values in the sole cropping (53 kg ha^-1) and a substantial reduction in the mixed cropping system. The application of N fertilizer further reduced N₂ fixation. This was substantiated by nodule counts. The lower N₂ fixation in the mixed cropping system was only partly explained by the lower density of cowpeas in this system. In addition, dry spells during the cropping season and shading by the maize component could have reduced the nodulation efficiency. No N transfer from the legume/rhizobium to the non-legume crop was observed. Impaired P nutrition in the mixed compared with the sole-cropped maize might have been due to less P mobility in the soil. This was indicated by lower soil moisture contents in the topsoil under mixed cropping, especially during the dry year of 1986. The results show that mixed cropping of maize and cowpeas did not lead to improved use of soil and fertilizer N and P or to an enhanced N₂ fixation. On the contrary, an annual rotation of maize and cowpeas was clearly superior.     

Remediation of Soils Contaminated with Molybdenum using Soil Amendments and Phytoremediation

For ruminants, there is a narrow span betweennutritional deficiency of Molybdenum and its potential toxicity. Molybdenosis occurs among cattlefeeding on forage with Mo concentrations above10 μg g^-1 or a Cu:Mo ratio <2. In the areaunder investigation forage Mo contents in the valleyare as high as 180 μg g^-1 due to industrialpollution, while the alpine pastures, where cattlegraze during summer, are nutrient (e.g. Cu) deficient.When driven to the valley pastures in fall, animalsoften fell ill with molybdenosis, and several died.The aim of the study was to remediate this 300 ha area. Two approaches were attempted: (1) to reduce theMo contents of the forage by immobilizing soil Mo, and(2) to increase plant Mo contents by mobilizing soilMo to increase plant Mo which may then be removed fromthe system (phytoremediation).In a soil extraction experiment we demonstrated thatphosphate fertilization, ammonium sulfate amendment,vermiculite, humic acid and sewage sludge increased Moleaching by 30 to 110%. Fe-humate and Mn-humateapplication decreased Mo in the leachate from96 μg L^-1 to 55 and 7 μg L^-1,respectively. Plant Mo contents were increased up to170% by P-fertilizer and up to 150% by vermiculite.Conversely, sewage sludge, Fe- and Mn-humate decreasedplant Mo contents by 60, 40 and 75% in thegreenhouse. In the field study, the effects weresmaller, but Mo export through plant harvest increasedby 88% after P-fertilization and 84% aftervermiculite amendment. Mn-humate and sewage sludgedecreased plant Mo content by 25 and 40%,respectively, rendering the forage suitable forfeeding of ruminants. P-fertilization and vermiculitemay thus be recommended for the severely contaminatedsites to enhance phytoremediation through Mo export,and Mn-humate and sewage sludge application appearsuited to remediate the less severely contaminated sites.     

CD46 in meningococcal disease

The human-specific bacterial pathogen Neisseria meningitidis is a major cause of sepsis and/or meningitis. The pili of N. meningitidis interact with CD46, a human cell-surface protein involved in regulation of complement activation. Transgenic mice expressing human CD46 were susceptible to meningococcal disease, because bacteria crossed the blood-brain barrier in these mice. Development of disease was more efficient with piliated bacteria after intranasal, but not intraperitoneal, challenge of CD46 transgenic mice, suggesting that human CD46 facilitates pilus-dependent interactions at the epithelial mucosa. Hence, the human CD46 transgenic mice model is a potentially useful tool for studying pathogenesis and for vaccine development against meningococcal disease.     

Role of adenine nucleotide translocator 1 in mtDNA maintenance

Autosomal dominant progressive external ophthalmoplegia is a rare human disease that shows a Mendelian inheritance pattern, but is characterized by large-scale mitochondrial DNA (mtDNA) deletions. We have identified two heterozygous missense mutations in the nuclear gene encoding the heart/skeletal muscle isoform of the adenine nucleotide translocator (ANT1) in five families and one sporadic patient. The familial mutation substitutes a proline for a highly conserved alanine at position 114 in the ANT1 protein. The analogous mutation in yeast caused a respiratory defect. These results indicate that ANT has a role in mtDNA maintenance and that a mitochondrial disease can be caused by a dominant mechanism.     

Effect of forest structure and health on the relative surface temperature captured by airborne thermal imagery – Case study in Norway Spruce-dominated stands in Southern Finland

The effect of forest structure and health on the relative surface temperature captured by airborne thermal imagery was investigated in Norway Spruce-dominated stands in Southern Finland. Airborne thermal imagery, airborne scanning light detection and ranging (LiDAR) data and 92 field-measured sample plots were acquired at the area of interest. The surface temperature correlated most negatively with the logarithm of stem volume, Lorey’s height and the logarithm of basal area at a resolution of 254?m² (9?m radius). LiDAR-derived metrics: the standard deviations of the canopy heights, canopy height (upper percentiles and maximum height) and canopy cover percentage were most strongly negatively correlated with the surface temperature. Although forest structure has an effect on the detected surface temperature, higher temperatures were detected in severely defoliated canopies and the difference was statistically significant. We also found that the surface temperature differences between the segmented canopy and the entire plot were greater in the defoliated plots, indicating that thermal images may also provide some additional information for classifying forests health status. Based on our results, the effects of forest structure on the surface temperature captured by airborne thermal imagery should be taken into account when developing forest health mapping applications using thermal imagery.     

Increased utilization of different tree parts for energy purposes in the Nordic countries

The review gives an overview of the increased utilization of forest biomass for energy. The emphasis is on Nordic countries, especially on Sweden and Finland with large biomass potentials and a high share of renewable energy in gross final energy consumption. The utilization and potential of forest chip sources such as logging residues, small-size tree stems and stumps that are normally not harvested in conventional harvesting are described. Environmental potential and impacts that may reduce the utilization of forest biomass are discussed based on recent publications. Finally, the review summarizes the future developments based on their relationship to policies, certifications and guidelines and forest owners' decisions.     

Regional differences in aspen (Populus tremuloides Michx.) seedling response to an established nursery protocol

New Forests - In seedling-based reforestation operations, seed source is known to be an influential variable affecting outplanting success. Adaptive variation among seed sources may also be an...     

Information Needs of Non-industrial Private Forest Owners After Logging Operations in Finland: A Case Study

In this study, the information needs of non-industrial private forest owners in Finland, after logging operations, were investigated. The study was carried out as an online survey in 2017. The survey was targeted at non-industrial private forest owners who had sold their timber during the previous 10 years (2008–2017) and whose email addresses were in the customer relationship management system of a large wood procurement company in Finland. A response link for the survey was successfully sent to 31,988 forest owners, of whom 3323 replied (response rate: 10.4%). The final study data included 3284 non-industrial private forest owners. The results of the study, which need to be interpreted cautiously due to the low response rate, showed that the forest owners want better-quality reporting after logging operations. Furthermore, the results suggested that gender, age, education, occupational status, place of living, size of, and access to, forest property, and length of, and objectives for, forest ownership have a significant effect on their information needs. Younger, highly-educated, female, urban-living and multi-objective forest owners with larger forest holdings and short forest ownership tenures desired more information. Particularly, the respondents conveyed that they would like more and better information about thinning harvesting result. The results also indicated that when different groups of forest owners call for certain information, there is a need for producing different types of reports after logging operations for different forest owner segments.