Soil samples from thirty sites representing four agro-ecological zones in the Western Usambara Mountains (WUM) of the Lushoto District in northern Tanzania were collected and analyzed for different nutrients. The resu...Soil samples from thirty sites representing four agro-ecological zones in the Western Usambara Mountains (WUM) of the Lushoto District in northern Tanzania were collected and analyzed for different nutrients. The results suggested that the major soil fertility constraint was P deficiency. On the basis of critical levels established in other areas, 90% of the soils were ranked as P deficient. This was followed by N, which was ranked as inadequate in 73% of the sites. Magnesium, K, and Ca also appeared limiting with 67%, 53% and 50% of the soils falling below the established critical values, respectively. A few soils (10%) were also found to contain exchangeable Al. The metallic micronutrients (Cu, Fe, and Zn) were adequate in all soils. Two sites had excessive Mn that could lead to toxicity in crops, and one was Mn deficient.展开更多
Analysis of phospholipid fatty acids (PLFAs) was used to estimate the microbial community structures of eight Chinese red soils with different fertility levels and land use histories. The total amounts of PLFAs in the...Analysis of phospholipid fatty acids (PLFAs) was used to estimate the microbial community structures of eight Chinese red soils with different fertility levels and land use histories. The total amounts of PLFAs in the soils were significantly correlated with soil organic carbon, total nitrogen, microbial biomass C and basal respiration, indicating that total PLFA was closely related to fertility and sustainability in these highly weathered soils. Soils for the eroded wasteland were rich in Gram-positive species. When the eroded soils were planted with citrus trees, the soil microbial population had changed little in 4 years but took up to 8-12 years before it reached a significantly different population. Multivariate analysis of PLFAs demonstrated that land use history and plant cover type had a significant impact on microbial community structure. However, the difference of soil microbial community structure in the paddy field compared to other land uses was not larger than expected in this experiment.展开更多
基金Project supported by the Norwegian Agency for Development Cooperation (NORAD), Tanzania.
文摘Soil samples from thirty sites representing four agro-ecological zones in the Western Usambara Mountains (WUM) of the Lushoto District in northern Tanzania were collected and analyzed for different nutrients. The results suggested that the major soil fertility constraint was P deficiency. On the basis of critical levels established in other areas, 90% of the soils were ranked as P deficient. This was followed by N, which was ranked as inadequate in 73% of the sites. Magnesium, K, and Ca also appeared limiting with 67%, 53% and 50% of the soils falling below the established critical values, respectively. A few soils (10%) were also found to contain exchangeable Al. The metallic micronutrients (Cu, Fe, and Zn) were adequate in all soils. Two sites had excessive Mn that could lead to toxicity in crops, and one was Mn deficient.
基金Project supported by the Science and Technology Development Bureau of European Union (CⅠ1-CT93-0009), by the National Key Basic
文摘Analysis of phospholipid fatty acids (PLFAs) was used to estimate the microbial community structures of eight Chinese red soils with different fertility levels and land use histories. The total amounts of PLFAs in the soils were significantly correlated with soil organic carbon, total nitrogen, microbial biomass C and basal respiration, indicating that total PLFA was closely related to fertility and sustainability in these highly weathered soils. Soils for the eroded wasteland were rich in Gram-positive species. When the eroded soils were planted with citrus trees, the soil microbial population had changed little in 4 years but took up to 8-12 years before it reached a significantly different population. Multivariate analysis of PLFAs demonstrated that land use history and plant cover type had a significant impact on microbial community structure. However, the difference of soil microbial community structure in the paddy field compared to other land uses was not larger than expected in this experiment.
