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Soil degradation is a severe global problem of modern times. About six (6) million hectares of agricultural land worldwide become unproductive every year due to the various soil degradation processes. The problem is much more serious in tropical than in temperate areas since tropical soils are generally more prone to degradation because of the nature of their properties (e.g. they are more weathered) and the prevalent climatic conditions. Countries in Asia and Africa that depend upon agriculture as the engine of economic growth are believed to suffer the greatest impact of soil degradation. In the Philippines, soil degradation is one of the most serious ecological problems today. The National Action Plan (NAP) for 2004 to 2010 identified soil degradation as a major threat to food security in the country. NAP reported that about 5.2 million hectares are seriously degraded resulting to 30 to 50% reduction in soil productivity. A degraded upland in Leyte Soil degradation is defined as t

Geology Mt. Pangasugan is generally built up by andesitic and basaltic pyroclastic rocks (referred to as Pangasugan formation) which are mostly of Quaternary and Tertiary origin. This rock formation is characterized by weak consolidation, lithologic disco ntinuities, abundance of rock outcrops, and shearing due to the occurrence of the Philippine fault line approximately at the center of the mountain range. Minor earthquakes are relatively frequent in the area. All these geological characteristics indicate that the area is unstable. Geomorphology The morphology of Mt. Pangasugan is largely the result of the combined effects of volcanism, erosion, faulting and tectonic uplift. Mt. Pangasuagn rises abruptly from the narrow alluvial coastal plain along the Camotes Sea into a vertical wall-like rock mass with a maximum height of about 1100 m above sea level (asl). The air distance between the sea level and the peak of the mountain is less than 3 km. This short distance suggests extremel

Corn ( Zea mays L.) can establish rhizospheric or endophytic associations with various nitrogen-fixing bacteria (diazotrophs) such as Azospirillum, Klebsiella, Pantoea, Herbaspirillum, Bacillus, Rhizobium etli and Burkholderia . Most of these diazotrophs can grow in the intercellular tissue of plants without causing any disease. Biological nitrogen fixation (BNF) is the biological process by which nitrogen (N2) in the atmosphere is converted to ammonia by an enzyme called nitrogenase. The screening of plant genotypes for their enhanced ability to acquire nitrogen by BNF can reduce the use of expensive nitrogen fertilizers in several important crops like sugarcane, rice, wheat and corn. It can greatly benefit particularly the poor farmers of developing countries. In a recent study aimed to quantify the symbiotic biological nitrogen fixing activity of a range of commercial corn cultivars, Montanez et al. (2009) demonstrated that corn cultivars obtain significant nitrogen from BNF, the