Lotar Siewerdt

Doses de nitrogênio e enxofre na produção e qualidade da forragem de campo natural de planossolo no Rio Grande do Sul

Foram avaliados os efeitos da fertilizacao nitrogenada e sulfurada sobre a producao de materia seca (MS) e o teor de proteina bruta (PB) da forragem de um campo natural em Planossolo, entre outubro de 1996 e marco de 1997, na area experimental de Pastagens da UFPEL, no Capao do Leao-RS. Os tratamentos consistiram de seis doses de enxofre (S) (0, 10, 20, 30, 40 e 50 kg/ha) sob a forma de sulfato de amonio e quatro doses de nitrogenio (N) (50, 100, 150 e 200 kg/ha), sob a forma de ureia e sulfato de amonio, arranjadas num fatorial completo de blocos casualisados, com quatro repeticoes. A fertilizacao foi a lanco, em cobertura, sem parcelamento, em 08/10/96. Foram realizados dois cortes, em 03/12/96 e 14/03/97, utilizando-se segadeira mecânica tipo barra horizontal com altura de corte de 3 centimetros. A producao de MS e o teor de PB aumentaram com o incremento das doses de N e S. Nas variaveis analisadas nao houve interacao entre as doses de N e S. A dose de enxofre de 35 kg/ha e suficiente para maximizar a producao de MS. Ja a dose de 200 kg/ha de N nao foi suficiente para determinar a maxima producao de MS. Doses de nitrogenio de ate 200 kg/ha e de enxofre ate 50 kg/ha, nao foram suficientes para determinar o maximo teor de PB na forragem.

Efeito do fósforo e do potássio sobre o desenvolvimento e a nodulação de três leguminosas anuais de estação fria

This experiment was established in greenhouse at Embrapa Clima Temperado, Pelotas, RS, with the objective to evaluate the effects of different doses of phosphorus and potassium on dry matter production of aerial biomass and roots, length of above ground parts and roots and efficiency and score of nodulation of three cool season annual forage legumes. The treatments were five doses of P (0,0; 1,08; 2,15; 3,23 e 4,30 mg de P2O5/dm3) and K (00,0; 0,43; 0,85; 1,28 e 1,70 mg de K2O/dm3) representing to 0,0 (control ) and 1, 2, 3 and 4 times the soil analysis recommendation, in pots, filled up with 8 kg de soil type Planossolo, mapping unit Pelotas. The legumes used were: Trifolium resupinatum L. cv. Kyambro (persian clover), Trifolium subterraneum L. cv. Woogenellup and Lotus subbiflorus Lag. cv. El Rincon. The experimental design consisted of a 5x5x3 factorial treatment arrangement, in a completely randomized design, with three replications. The experiment was carried out from May to October 2000, and the data were collected at the end of the experimental period, approximately 170 days after sowing. The majority of variables were not affected by K, but by P fertilization. For the variables related with production, persian clover was the most productive species. For nodulation, subterranean clover and Lotus El Rincon showed higher nodule numbers and efficiency.

Desenvolvimento das raízes do azevém cultivado em solução nutritiva completa, adicionada de substâncias húmicas, sob condições de casa de vegetação

This work was carried out under greenhouse conditions, in 1997, at Faculdade de Agronomia, Universidade Federal do Rio Grande do Sul (UFRGS). A split plot randomized complete block experimental design was used, with six replications, to evaluate root lengths, average radius, roots surface and dry matter of roots with the objective to evaluate the effect of humic compounds addition in the development of ryegrass roots. Ryegrass forage was grown in pots with irrigated sand with four levels of humic compounds added to a complete nutritive solution with four-doses of humic compounds (0, 10, 20 and 30-mg/liter). The humic compounds were extracted from the charcoals of the Capane (Palermo CE-4,200 and Palermo CE-4,700), Leao (Leao CE-5,200) and Candiota (Candiota superior layer, Candiota inferior layer, CE-3,300 and Candiota CE-4,700) mines. For all variables, the statistical analyses showed significance for the interaction dose x raw material effects. Results demonstrated that humic compounds promoted roots development, increasing: a) roots length at 100,87%; b) roots weight at 49,23% and c) 68% of the roots surface. The humic compounds influence ryegrass roots development and that these substances from different raw materials distinctly act on the parameters of the four variables analyzed.

Composição bromatológica de três leguminosas anuais de estação fria adubadas com fósforo e potássio

This experiment was established in a greenhouse at Embrapa Clima Temperado, Pelotas, RS, with the objective to evaluate the effects of increasing doses phosphorus (P-P2O5) and potassium (K-K2O) on crude protein (CP), acid detrgent fiber (ADF), neutral detergent fiber (NDF) and minerals (P,K,Ca and Mg) contents of dry matter (DM) in three species of forages legumes. The three cool season annual legumes forage used were: persian-clover (Trifolium resupinatum L. cv. Kyambro), subterraneum-clover (Trifolium subterraneum L. cv. Woogenellup) and Lotus El Rincon (Lotus subbiflorus Lag. cv. El Rincon). It was used a completely randomized desing, according to a 5x5x3 factorial treatment with three replications, during the period from May to October 2000. The treatments were five doses of P (.0, 1.08, 2.15, 3.23 and 4.30 mg de P2O5/dm3) and K (.0, .43, .85, 1.28 and 1.70 mg de K2O/dm3) representing to .0 (control ) and 1, 2, 3 and 4 times the soil analysis recommendation, in pots, filled up with 8 kg de soil type Planossolo, mapping unit Pelotas. The forages samples used for laboratorial analysis were cut, dried up and prepared, at the end of the experimental period, approximately 170 days after sowing. The CP, P and Mg conents in dry matter were positively influenced by P, however for K fertilizations, just the K content. NDF and ADF contents were not influenced by P and K dertillizations.