A disponibilidade do fósforo de oiversos fosfatos estudada por meio do método de Neubauer"

In order to study the phosphorus availability from various phosphates fertilizers an experiment was performed according to the biological seedling method of Neubauer. The physico-chemical properties of the soil "terra roxa-misturada", a red soil derived from basaltic rocks are given in the Portuguese text. Rice (Oryza sativa, L.) instead of rye (Secale cereale, L.) was used. Five replications of each of the following treatments were made: 1 - check, with 350 g of sand 2 - 350 g of sand plus 100 g of soil 3 - 350 g of sand and plus 100 g of soil plus 40 mg of P2O5, from superphosphate. 4 - 350 g of sand plus 100 g of soil plus 40 mg of P2O5. from Olinda (Brazil) phosphorite. 5 - 350 g of sand plus 100 g of soil plus 40 mg of P2O5 from Florida (U. S. A.) phosphorite. 6 - 350 g os sand plus 100 g of soil plus 40 mg of P2O5 from Hyperphosphate, a commertial name of a North African (Gafsa) phosphorite. 7 - 350 g of sand plus 100 g of soil plus 40 mg of P2O5 from Araxá (Brazil) apatite. After 18 days of growth, the roots and tops of rice seedlings were harvested and analysed for phosphorus, and the results are summarized in table 1. Table 1 - Milligrams of P2O5 determined in rice seedlings. Treatments Mean of 5 replications mg of P2O5 1 ..................... 24.196 2 ..................... 23.850 3 ..................... 30.724 4 ..................... 27.620 5 ..................... 27.480 6..................... 30.210 7 ..................... 26.032 The least significant difference at the 5% level by Tukey's procedure for comparisons among the treatments means is 1.365 mg of P(2)0. It is interesting to observe that rice plants did not take any phosphorus from the soil according to he data of the treatments n.° 1 and n.° 2. This can be explained by the high phosphorus fixing capacity of the soil "terra roxa misturada".

Nova espécie do complexo oliveirai (nova denominação para o complexo matogrossensis) (Hemiptera, Reduviidae, Triatominae) do estado do Rio Grande do Sul, Brasil

The authors describe a new species of Triatominae (Hemiptera, Reduviidae) from the State of Rio Grande do Sul, Brazil. The study was made with specimens captured in basaltic formations, at an average altitude of 750 m.o.s.l. The new species is included in the oliveirai complex together with other four species T. williami, T. matogrossensis, T. guazu and T. jurbergi). The new species was compared with the most similar one, T. oliveirai, from which the main differences are on the proportions of head, ante and postocular regions, the general color pattern and the male genitalia, specially on the median process of the pygophore, the support of phallosome, the vesica and the process of the endosome.

Determinação de cobre, alumínio e ferro em solos derivados do basalto através de extrações seqüenciais

Copper, aluminum and iron concentrations were determined in four geochemical fractions of three different basaltic soils from the northwest region of the Parana State, Brazil. The fractions examined were the reducible manganese dioxide and amorphous iron oxide, crystaline iron oxide, organic and residual. Metal concentrations were determined in the extracts by flame atomic absorption spectrophotometry. High Fe concentrations were extracted from the crystalline iron oxide (>20%), as well as the amorphous iron oxide (>12%). Copper was extracted from the amorphous and crystalline iron oxides in the range 5 to 12%, but low concentrations were bound to organic matter. Low concentrations of aluminum were extracted (<8%) from the amorphous and crystaline iron oxides, and organic matter. High concentrations of aluminum were found in the residual fraction.