Phosphorus utilization by corn as affected by green manure, nitrogen and phosphorus fertilizers

The objective of this work was to evaluate the utilization by corn plants of P from triple superphosphate fertilizer labeled with P-32 (P-32-TSP), and of P from soil as affected by N rates and by the green manures (GM) sunn hemp (Crotalaria juncea) and millet (Pennisetum glaucum). The experiment was carried out using pots filled with 5 kg Oxisol (Rhodic Hapludox). A completely randomized design was used, in a 4x4x2 factorial arrangement, with four replicates. The treatments were: four P rates as TSP (0, 0.175, 0.350, and 0.700 g P per pot); four N rates as urea (0, 0.75, 1.50, and 2.25 g N per pot); and sunn hemp or millet as green manure. The additions of N and P by the GM were taken into account. After grain physiologic maturation, corn dry matter, P contents, accumulated P, and P recovery in the different treatments were measured. P-32-TSP recovery by corn increased with N increasing rates, and decreased with increasing rates of P-32-TSP. The mineral fertilizer provides most of the accumulated P by corn plants. The recovery of P-32-TSP by corn was 13.12% in average. The green manure species influence the assimilation of P-32-TSP by the plants.

Growth of seedlings Schizolobium amazonicum (Huber ex Ducke) on substrate fertilized with nitrogen, phosphorus and potassium

The nutritional management of seedlings in the nursery is one of the most important practices that influence seedling quality. The aim of this work was to evaluate the effect of nitrogen, phosphorus and potassium on the development of Schizolobium amazonicum seedlings grown in 250 cm(3) containers with a commercial substrate in the North of Mato Grosso State, Brazil. The experimental design was completely randomized design with five treatments and five replications, each replication being represented by 24 seedlings. The treatments were: control (only commercial substrate); nitrogen fertilization (150 g m(-3) N using ammonium sulfate + 1.0 kg of ammonium sulfate dissolved in 100 L of water and applied in coverage); phosphorus fertilization (300 g P2O5 m(-3) using simple superphosphate); potassium fertilization (100 g m(-3) K2O using potassium chloride + 0.3 kg of potassium chloride dissolved in 100 L of water and applied in coverage) and; complete (a mixture of the three nutrients, 150, 300 and 100 g m(-3) N, P2O5 and K2O, respectively + 1.0 kg of ammonium sulfate + 0.3 kg of potassium chloride). The commercial substrate was composted milled pine bark plus vermiculite. Evaluations of the seedlings were performed at 90 days after sowing. The complete treatment (NPK) gave the highest values for biometric and best plant indices, which express the quality. When analyzing nutrients in isolation; potassium had the lowest effect. Based on these results it can be recommended to fertilize Schizolobium amazonicum seedlings in nurseries with 150, 300 and 100 g m(-3) of N, P2O5 and K2O, respectively, plus 1.0 kg of sulfate ammonium and 0.3 kg of potassium chloride applied in coverage.

O ensino libertário e a relação entre trabalho e educação: algumas reflexões

Um dos principais desafios nos estudos a respeito da pedagogia escolar anarquista consiste, precisamente, em apreender os conteúdos de ensino. Com essa preocupação, este texto tem triplo objetivo: analisar a proposta educativa da instituição a cargo do professor libertário João Penteado, em São Paulo, nas primeiras décadas do século XX; indicar aspectos considerados relevantes relacionados à concepção de educação integral e à forma como o trabalho está presente na organização do ensino; e, por fim, apresentar alguns apontamentos de pesquisa que possam contribuir para sua continuidade e seu aprofundamento. Optou-se por abarcar período relativo a dois momentos de existência da escola dirigida por João Penteado - a Escola Moderna Nº 1 (1912-1919) e a Escola Nova (1920-1923). Entende-se que a cronologia definida consegue abranger a pluralidade de práticas escolares necessárias aos propósitos da análise. A documentação utilizada limita-se basicamente a jornais e demais fontes produzidas e/ou acumuladas nos diferentes períodos de existência da(s) escola(s), em particular, os jornais Boletim da Escola Moderna, Boletim da Escola Nova, Boletim da Academia Saldanha Marinho, O Início, O Iris. No estudo do primeiro período, que coincide com o da Escola Moderna, são também utilizadas notícias publicadas por alguns jornais da imprensa operária e anarquista, como A Lanterna, A Vida e O Amigo do Povo, entre outros.