This work was carried out in collaboration between all authors. Authors BH and MS collected the literature along with references pertaining to zinc and wrote the first draft of the manuscript. Author YMK managed the literature searches and improved its English. All authors read and approved the final manuscript.

Isolation of phosphate solubilising bacterial strains was carried out from rhizosphere, roots and nodules of chickpea, to study the viability for solubilisation of tri-calcium phosphate and the effect on growth of chickpea plants. The potential of isolated bacterial strains to solubilise phosphate was qualitatively evaluated by the measurement of a clear zone around the colonies. The diameter of this zone ranged from 21 to 83 mm. Phosphate solubilisation, by phosphate solubilising bacterial isolates, was quantified by spectrophotometry and was found to range from 65 to 130.5 μg/mL. The drop in pH ranged from 5.6 to 3.6. The plant growth, shoot phosphorus and nitrogen concentrations, nodulation efficiency and nitrogenase activity were significantly enhanced, showing the positive effect of phosphate solubilising bacteria inoculation. Phosphate solubilising bacterial strains CPS-2, CPS-3 and Ca-18 had the maximum positive effect on shoot length, shoot dry weight and nodulation of chickpea plants. Treatments inoculated with non-phosphate solubilising bacterial strains IFA1 and IFA2 showed the minimum values in all the parameters.

The effect of grazing pressure on infiltration, runoff, and soil loss was studied on a natural pasture during the rainy season of 1995 in the Ethiopian highlands.The study was conducted at two sites with 0-4'/0 and 4-8% slopes at the International Livestock Research Institute (ILRI) Debre Zeit research station, 50 km south ofAddis Ababa. The grazing regimes were: light grazing stocked at 0.6 animal-unit-months (AUM)/ha; moderate grazing stocked at 1.8 AUMlha; heavy grazing stocked at 3.0 AUMlha; very heavy grazing stocked at 4.2 AUMl ha; very heavy grazing on ploughed soil stocked at 4.2 AUMlha; and a control with no grazing. Heavy to very heavy grazing pressure significantly reduced biomass amounts, ground vegetative cover, increased surface runoff and soil loss, and reduced infiltrability of the soil. Reduction in infiltration rates was greater on soils which had been ploughed and exposed to very heavy trampling. It was observed that, for the same Yo vegetative cover, more soil loss occurred from plots on steep than gentle slopes, and that gentle slopes could withstand more grazing pressure without seriously affecting the ground biomass regeneration compared to steeper slopes. Thus, there is a need for developing 'slope-specific' grazing management schedules particularly in the highland ecozones rather than making blanket recommendations for all slopes. More research is needed to quantify annual biophysical changes in order to assess cumulative long-term effects of grazing and trampling on vegetation, soil, and hydrology of grazing lands. Modelling such effects is essential for land use planning in this fragile highland environment.

The ethyl acetate fraction of an aqueous alcoholic extract from the stem of Parthenocissus tricuspidata yielded 11 known compounds (1-11) and two new stilbene dimers parthenostilbenins A (12) and B (13) upon purification either by preparative TLC or reversed phase HPLC. The structures of the new isolates were identified using a combination of FAB-MS and NMR. These compounds were assessed for antioxidant activities in three different bioassay systems. Among them, piceatannol showed the strongest inhibitory activity in these assay systems. Two new compounds, parthenostilbenins A (12) and B (13) inhibited lipid peroxidation (IC (50) = 20.35 +/- 1.22 and 18.68 +/- 0.51 microg/mL, respectively) in a rat liver homogenate.

No abstract

Summary. Effects of livestock grazing on surface runoff and soil erosion at varying slopes were studied in pasture lands within Ginchi watershed, Ethiopia. The results showed that livestock grazing in the watershed followed distinct seasonal and spatial patterns. During the rainy season, grazing pressure was greatest on the upper slopes (>5% slope) while the pressure shifted to the lower slopes during part of the dry season. Seasonal grazing pressure in different parts of the watershed was further complicated by the fact that during the rainy season and immediately after the rains, grazing was limited to individually designated pasture lands while during most part of the dry season, the entire watershed became a common grazing resource for livestock of watershed residents as well as those farmers outside the watershed. It was observed that, on pastures above 4.2% slope, there is the risk of erosion rates exceeding the estimated soil loss tolerable limit under the current grazing pressures (heavy grazing), while slopes exceeding 5.8% are likely to suffer soil erosion under moderate grazing pressure at the current level of biomass productivity. Since livestock are mobile, farmers tend to take advantage of this attribute by seasonally moving the livestock to different parts of the watershed. This study has demonstrated the need for better understanding of the resource use patterns beyond the individual farmlands, most preferably at watershed level, so that on-site and off-site effects of seasonal concentration of livestock can be incorporated into developing feed production and management strategies for improving the system productivity and environmental protection.

Understanding the problems of grazing land in vertisol areas and seeking long-lasting solutions is the central point where mixed crop livestock is the second stay for the majority of the population. In order to understand this, the current study was conducted at two sites, one with 0-4% slope and the other with 4--8% slope at Ginchi watershed, 80 km west of Addis Ababa, Ethiopia. The specific objectives of the study were to quantify changes in plant species richness, biomass, plant cover, and soil physical and hydrological properties. The grazing regimes were: moderate grazing (regulated), heavy grazing (free grazing), and no grazing (closed to any grazing), which was considered the control treatment. The results showed that the biomass yield in nongrazed plots was higher than in the grazed plots. However, the biomass yield in grazed plots improved over the years. Species richness and percentage of dominant species attributes were better in medium grazed plots than the other treatments. Soil compaction was higher in very heavily grazed plots than in nongrazed and medium-grazed plots. In contrast to that, the soil water content and infiltration rate were better in nongrazed plots than in grazed plots. Soil loss in grazed plots decreased with the increase of biomass yields and as the soil was more compacted by livestock trampling during the wet season. Finally since the medium stocking rate is better in species richness and plant attributes, and lies between nongrazed and heavily grazed plots in the rest of the measured parameters, it could be the appropriate stocking rate to practice by the smallholder farmer.

No abstract