C. A. Fortes

Nodulação e produção de raízes do estilosantes Mineirão sob efeito de calagem, silicatagem e doses de fósforo

Objetivou-se, com este trabalho, avaliar o efeito do uso de dois corretivos de acidez do solo e de doses crescentes de fosforo, sobre a nodulacao, producao de materia seca, acumulos e teores dos nutrientes nas raizes do estilosantes Mineirao (Stylosanthes guianensis (Aubl.) Sw. cv. Mineirao). O experimento foi conduzido em casa-de-vegetacao com delineamento experimental em blocos casualizados, com tres repeticoes. Os tratamentos foram dispostos em esquema fatorial 5x2, constituido por cinco doses de P (50, 100, 200, 400 e 800 mg dm-3 de solo) e dois tipos de corretivo (calcario dolomitico e silicato de Ca e Mg). A producao de materia seca de raizes, a nodulacao e o acumulo dos nutrientes P, N, Ca e Zn foram maiores quando a adubacao esteve associada ao silicato. Entretanto, a aplicacao de doses superiores a 257 mg dm-3 de P na presenca de silicato, inibiu o desenvolvimento do sistema radicular do Mineirao, provavelmente por causa de uma interacao negativa entre os nutrientes P e Zn, causada pela alta disponibilidade de P.

Níveis de silicato de cálcio e magnésio na produção das gramídeas Marandu e Tanzânia cultivadas em um Neossolo Quartzarênico

This study was conducted in a greenhouse of the Soil Science Department at Universidade Federal de Lavras, Lavras-MG, with the purpose of evaluating the effect of the soil correction acidity, by the application of Ca and Mg silicate levels, in the production of grasses Brachiaria brizantha cv. Marandu and Panicum maximum cv. Tanzânia-1 cultivated in Quartzsandy Neosoil ortic. The experimental design was a randomized complete block, in 2 x 5 factorial scheme with four replicates, being two forages and five levels of base saturation (BS%); (original BS, 40, 60, 80 and 100%). Each experimental unit corresponded to a pot with a capacity of 4.0 dm3 of soil, totalizing 40 pots. The dry matter yield (DMY) for cut and total (TDMY), height and number of tillers were evaluated. There were no variations among the grasses in tiller height. Tanzania grass was superior to Marandu grass in DMY and tiller number. There were linear increases in DMY, TDMY and tiller height as the BS% levels increased. It follows that both grasses responded positively to the rise of BS% in DMY until 54.8%. Tanzania grass produced more DM in relation to Marandu grass.

VALOR NUTRITIVO DO ESTILOSANTES MINEIRÃO EM FUNÇÃO DA CORREÇÃO DO SOLO

The main expectation for using leguminous plants in pastures is improving animal production and reducing production costs . This research was carried out in a greenhouse, in order to evaluate the effect of two soil acidity correctives and P rates on P, Ca, Mg, Si, raw protein (RP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and in vitro dry matter digestibility (IVDMD) contents of Stylosanthes guianensis cv. Mineirao. A randomized blocks design was used in a 5x2 factorial arrangement, with five P rates (50 mg dm -3 , 100 mg dm -3 , 200 mg dm -3 , 400 mg dm -3 , and 800 mg dm -3 of soil) and two soil correctives (lime and Ca and Mg silicate), with three replications. Both lime and silicate applications, previously to the phosphate fertilization, assured P , Mg, Ca, RP, NDF, and ADF contents, in plants of Mineirao, compatible with good performances of grazing animals. The increase in the silicon content in Mineirao, resulting from silicate application, did not reduce the IVDMD. The substitution of lime by Ca and Mg silicate did not affect the nutritional value of the Mineirao subjected to phosphorus rates.