Composted MSW Effects on Soil Properties and Native Vegetation in a Degraded Semiarid Shrubland

Three rates of dried composted MSW (40, 80 and 120 Mg ha−1) were surface applied to a degraded semiarid shrubland site near Madrid in central Spain. Various soil and plant parameters were determined one year after its application. MSW amendment had an effect on soil chemistry and nutrient levels. Available P and K, concentration of N-NO3 and EC. increased significantly after the MSW application. The concentration of total soil heavy metals, Zn, Pb, Cd, Ni, Cr and Cu rose with the application of MSW as compared with the control plot, but these increases were only significant in total Zn, Pb and Cu. Zn and Cu amounts of DTPA-extractable soil were also significantly higher in the amended soil. Total plant cover increased significantly in the plots treated with low and intermediate MSW rates. Total biomass production increased as compost rates were added but this rise is not proportional to the amount of MSW added. The degraded soil used in this study may require MSW rates up to 80 Mg ha−1 to improve soil chemical properties as well as to produce minimal changes in the native vegetation. © 2000 Taylor and Francis

Qualidade da água de nascentes com diferentes usos do solo na bacia hidrográfica do córrego rico, São Paulo, Brasil Water quality of springs with different land uses in córrego rico watershed, São Paulo, Brazil

Com o objetivo de verificar a influência de remanescentes de vegetação ciliar e da ação antrópica na qualidade da água, estudaram-se quatro nascentes, sendo duas com a presença de vegetação natural remanescente e duas com predominância de atividades agrícolas. Essas nascentes fazem parte da bacia hidrográfica do Córrego Rico, estando localizadas nos municípios de Taquaritinga e de Guariba - SP, em duas classes de solo: Argissolo e Latossolo, respectivamente. Definiram-se pontos de coleta da água nas nascentes e ao longo dos cursos d'água (entre 0 a 50 m da nascente), em dois períodos (chuvoso e seco). Foram analisadas as seguintes variáveis: cor, pH, temperatura, turbidez, alcalinidade, dureza total, dureza em magnésio, dureza em cálcio, fósforo, nitrogênio e demanda bioquímica de oxigênio. De maneira geral, ocorreu agrupamento por nascentes e também por períodos, confirmando que os períodos de amostragem, assim como as características e diferentes usos do solo influenciam na qualidade da água das microbacias. As variáveis cor, turbidez, alcalinidade e nitrogênio total foram as que apresentaram maior importância relativa nas variáveis canônicas.<br>With the objective of verify the remainders influence of ciliary vegetation and of the human action on the water quality, four springs were studied, with two springs on presence of remaining natural vegetation and two springs with agricultural activities predominance. These springs are part of Córrego Rico watershed, being located in the municipal districts of Taquaritinga and Guariba, São Paulo State, Brazil, in two classes of soil: argisoil and latosoil, respectively. Points of collection of water were defined on the spring and along the water flow (among 0 to 50 m of the spring), in two periods (rainy and dry). The following variables were analyzed: color, pH, temperature, turbidity, alkalinity, total hardness, magnesium hardness, calcium hardness, phosphorus, nitrogen and DBO. It was concluded that, in a general way, a separation for springs and also for periods was observed, confirming that the sampling periods as well as the characteristics and different uses of the soil influence the water quality of the watersheds. Color, turbidity, alkalinity, and total nitrogen are the variables that presented the better relative importance in the canonic variables