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Poor Soil (poor + soil)
Selected AbstractsLimits of life in hostile environments: no barriers to biosphere function?ENVIRONMENTAL MICROBIOLOGY, Issue 12 2009Jim P. Williams Summary Environments that are hostile to life are characterized by reduced microbial activity which results in poor soil- and plant-health, low biomass and biodiversity, and feeble ecosystem development. Whereas the functional biosphere may primarily be constrained by water activity (aw) the mechanism(s) by which this occurs have not been fully elucidated. Remarkably we found that, for diverse species of xerophilic fungi at aw values of , 0.72, water activity per se did not limit cellular function. We provide evidence that chaotropic activity determined their biotic window, and obtained mycelial growth at water activities as low as 0.647 (below that recorded for any microbial species) by addition of compounds that reduced the net chaotropicity. Unexpectedly we found that some fungi grew optimally under chaotropic conditions, providing evidence for a previously uncharacterized class of extremophilic microbes. Further studies to elucidate the way in which solute activities interact to determine the limits of life may lead to enhanced biotechnological processes, and increased productivity of agricultural and natural ecosystems in arid and semiarid regions. [source] Neotyphodium endophyte infection affects the performance of tall fescue in temperate region AndisolsGRASSLAND SCIENCE, Issue 1 2006M. Hasinur Rahman Abstract A pot experiment was conducted for 75 days to observe the effect of Neotyphodium coenophialum endophyte on three tall fescue (Festuca arundinacea Schreb.) ecotypes grown in two Andisols viz. Black Andisol and Red Andisol. Black Andisol with a naturally low content of P was high in other nutrients such as N, K, while Red Andisol, with a naturally high content of P, was low in other nutrients. Tiller number, plant height, chlorophyll content, shoot dry weight and agronomic efficiency of water use (WUEag) showed higher values in endophyte-infected (E+) plants than noninfected (E,) plants. Plants growing in Black Andisol performed better than those in Red Andisol. Among the three tall fescue ecotypes, one of them (ecotype Showa) had the best performance regardless of soils and endophyte infection. When considering the effect of endophyte infection in different soil conditions, higher WUEag was observed in endophyte-infected plants grown in Black Andisol. Endophyte infection significantly enhanced all plant parameters in Black Andisol but they were reduced in Red Andisol. Our results indicate that infected plants grew better in soil that was naturally low in P whereas uninfected plants had increased vegetative growth in soil that was naturally high in P. In nutrient poor soil with comparatively high P content (Red Andisol) the cost of endophyte infection may override its benefit. The presence of endophyte had a variable impact on plant performance and the effect of endophyte varied with ecotype of grass it infected into. [source] INTEGRATED LANDSCAPE ANALYSES OF CHANGE OF MIOMBO WOODLAND IN TANZANIA AND ITS IMPLICATION FOR ENVIRONMENT AND HUMAN LIVELIHOODGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 1 2009LENNART STRÖMQUIST ABSTRACT. Landscapes bear witness to past and present natural and societal processes influencing the environment and human livelihoods. By analysing landscape change at different spatial scales over time the effects on the environment and human livelihoods of various external and internal driving forces of change can be studied. This paper presents such an analysis of miombo woodland surrounding the Mkata plains in central Tanzania. The rich natural landscape diversity of the study area in combination with its historical and political development makes it an ideal observation ground for this kind of study. The paper focuses on long-term physical and biological changes, mainly based on satellite information but also on field studies and a review of documents and literature. The miombo woodlands are highly dynamic semi-arid ecosystems found on a number of nutrient-poor soil groups. Most of the woodlands are related to an old, low-relief geomorphology of erosion surfaces with relatively deep and leached soils, or to a lesser extent also on escarpments and steep Inselberg slopes with poor soils. Each period in the past has cast its footprints on the landscape development and its potential for a sustainable future use. On a regional level there has been a continual decrease in forest area over time. Expansion of agriculture around planned villages, implemented during the 1970s, in some cases equals the loss of forest area (Mikumi-Ulaya), whilst in other areas (Kitulangalo), the pre-independence loss of woodland was small; the agricultural area was almost the same during the period 1975,1999, despite the fact that forests have been lost at an almost constant rate over the same period. Illegal logging and charcoal production are likely causes because of the proximity to the main highway running through the area. Contrasting to the general regional pattern are the conditions in a traditional village (Ihombwe), with low immigration of people and a maintained knowledge of the resource potential of the forest with regards to edible plants and animals. In this area the local community has control of the forest resources in a Forest Reserve, within which the woody vegetation has increased in spite of an expansion of agriculture on other types of village land. The mapping procedure has shown that factors such as access to transport and lack of local control have caused greater deforestation of certain areas than during the colonial period. Planned villages have furthermore continued to expand over forest areas well after their implementation, rapidly increasing the landscape fragmentation. One possible way to maintain landscape and biodiversity values is by the sustainable use of traditional resources, based on local knowledge of their management as illustrated by the little change observed in the traditionally used area. [source] Effects of Fertilizer Phosphorus on Yield Traits of Dekoko (Pisum sativum var. abyssinicum) Under Field ConditionsJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 1 2003A. Yemane Abstract Cool-season food legumes (CSFLs) are important supplementary protein sources and soil fertility restorers for subsistence farmers in Ethiopia. Yields of CSFLs, however, are limited by low soil fertility, as they are grown in poor soils, often without fertilizer. Dekoko (Pisum sativum var. abyssinicum) is one of the CSFLs cultivated in Tigray, Northern Ethiopia. It is highly appreciated by the local people for its taste. This paper reports on the effect of phosphorus (P) on the yield and nutrition value of Dekoko under field conditions, and compares the results with those obtained for Ater (Pisum sativum var. sativum). The experiment was conducted in the 1998 and 1999 growing seasons. Three rates of P equivalent to zero, 30, and 60 kg ha,1 P2O5 were tested. Biomass, leaf area index, branches/plant, pods/m2 and yield responded positively while seeds/pod and seed weight were not significantly affected by P. Tissue P contents in shoots and roots increased with an increase in P application rate, while P in the nodules was not affected. Crude protein (CP) content increased from 24.9 % of dry matter (DM) at P0 to 26.2 % at P2, and from 24.3 % at P0 to 25.2 % at P2, in Dekoko and Ater seeds, respectively, while total sugars decreased with an increase in P application rate. Cysteine in Dekoko and asparagine and threonine in both varieties decreased, while lysine and other amino acids were not significantly affected by P. P improved seed yield and CP content without greatly affecting the amino acid profile of Dekoko, when compared with that of the FAO/WHO (1991, Protein Quality Evaluation. Food and Nutrition, Paper 51. FAO/WHO, Rome) standard pattern of amino acid for children 2,5 years of age. Thus, improving yield through fertilization may help to improve nutritional quality and household food security for subsistence farmers. [source] | ||||||||||