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The biofertilization of legumes with tolerant acidity rhizobia would allow a better establishment of these plants in acid soils. The objective of this study was to determine the acidity tolerance of rhizobia isolated from Canavalia ensiformis nodules. Five rhizobia isolates were used and their growth capacity at different acidity levels was performed. A second assay was performed where the pH influence on the viable cells number was determined. The statistical software Statgraphics version 5.0 was used to process the second test data. A simple classification variance analysis was performed and the means were compared for the Tukey test. All microorganisms grew at pH 3,5; 4,0; 4,5; 5,0 and 5,5. The isolates Can4 and Can6 had a higher viable cells number at pH 4,5 than pH 6,8. Both isolates are promising to improve the Canavalia ensiformis establishment on cuban acid soils. [ABSTRACT FROM AUTHOR]

The Ecuadorian Amazonia suffers mankind intervention through indiscriminately cutting trees, introducing low-quality pastures to livestock and developing an extremely rudimentary agricultural activity. Consequently, indigenous tree species have been lost in the region and soils are affected by a wrong agronomic management. From February to July, 2007, in collaboration with the Amazonian State University, a diagnosis was performed on the agricultural productive situation of Pastaza province in the Ecuadorian Amazonia, including the observation and evaluation of soil and climatic situation, soil characterization and exchange of opinions with the indigenous communities dwelling in this area, with the objective of drawing up strategies to introduce and increase both species in danger of extinction and plant-producing techniques of agriculture and forest significance, as well as soil preservation and recovery. The diagnosis concluded there was an arbitrary rate of forest exploitation using inappropriate forest techniques, so that valuable forest species are lost; there are not any reforestation nurseries, livestock is rather primitive and soil quality is damaged, agricultural crop yields are very low because of acid soils with low fertility, great amount of heavy metals and a high percentage of bad quality organic matter leading to erosive processes in the region. [ABSTRACT FROM AUTHOR]