Brighenti A.M.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária |
Calsavara L.H.F.,Empresa de Assistencia Tecnica e Extensao Rural Emater
Ciencia e Agrotecnologia | Year: 2017
Elephant grass (Pennisetum purpureum Schum.) is an important forage crop that has been proposed as a potential feedstock for bioenergy production. However, weed interference is a major factor limiting elephant grass production. Field experiments were conducted in 2014 and 2015 to evaluate preemergence herbicides for selective weed control in an elephant grass pasture. Herbicide treatments included atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, diuron + hexazinone, sulfentrazone, imazethapyr, and atrazine at label use rates. Weedy and weed-free treatments were included. Atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, sulfentrazone, and atrazine did not cause phytotoxicity on elephantgrass 35 days after treatment (DAT). However, diuron + hexazinone and imazethapyr were the most phytotoxic on elephantgrass, resulting in 81 and 70% phytotoxicity in 2014, and 7 and 6% phytotoxicity in 2015 respectively 35 DAT. All treatments provided effective weed control (>81%) with the exception of ethoxysulfuron (0 and 11% in 2014 and 2015, respectively), and atrazine (59% in 2014). These results show that atrazine + S-metolachlor, atrazine + simazine, ametryn, ethoxysulfuron, S-metolachlor, sulfentrazone, and atrazine were selectives when applied in preemergence in elephant grass pasture. © 2017 Federal University of Lavras. All rights reserved.
da Silva L.S.,Federal University of Santa Maria |
Pocojeski E.,Federal Technological University of Paraná |
Britzke D.,Federal University of Santa Maria |
Kaefer S.,Empresa de Assistencia Tecnica e Extensao Rural Emater |
And 2 more authors.
Pesquisa Agropecuaria Tropical | Year: 2015
Non-exchangeable potassium (K) forms are not estimated by usual methods of soil K availability, like Mehlich-1, but they can contribute to K nutrition of flooded rice. This study aimed at evaluating K forms in lowland soils by different chemical methods and associate them to K absorption by flooded rice. Fourteen lowland soils cultivated with flooded rice (IRGA 417 cultivar) were sampled and used in a greenhouse experiment. The K forms in the soil samples were extracted before and after rice cultivation by using calcium chlorite, Mehlich-1, sodium tetra phenyl borate (NaTFB) and fluorite acid. The K uptake was measured in rice shoots. There was a wide variation in K forms among the lowland soils. The variation in the amount of K extracted by using the Mehlich-1 method does not explain the K absorption by irrigated rice plants in every soil. The NaTFB method was more sensitive to evaluate K availability in lowland soils cultivated with flooded rice plants. © 2015, Universidade Federal De Goias (UFG). All Rights Reserved.
Terceiro Neto C.P.C.,Empresa de Assistencia Tecnica e Extensao Rural Emater |
Gheyi H.R.,Federal University of Recôncavo da Bahia |
de Medeiros J.F.,Federal Rural University of the Semiarid Region |
Dias N.S.,Federal Rural University of the Semiarid Region |
Campos M.S.,Federal Rural University of the Semiarid Region
Pesquisa Agropecuaria Tropical | Year: 2013
In semi-arid regions, irregular rainfall and scarcity of good quality water contribute to the use of saline water for irrigation. In this context, this study aimed to investigate the effects of saline water use in the yield and quality of melon fruits. Treatments consisted of two melon cultivars (Sancho - C1 and Medellín - C2) irrigated with low (S1 = 0.61 dS m-1) and high (S2 = 4.78 dS m-1) salinity water levels, for each phenological stage. The experimental design was split-plot randomized blocks, with six irrigation management strategies and two cultivars (6×2), with four replications. The results showed that the total and commercial number of fruits were influenced by the saline water management strategies. The irrigation management with good quality water, during two days, followed by saline water, for one day, enabled the commercial production of melon, with a reduction of 33% in the good quality water use.
Mezzalira J.C.,Federal University of Rio Grande do Sul |
Carvalho P.C.F.,Federal University of Rio Grande do Sul |
da Trindade J.K.,Federal University of Rio Grande do Sul |
Bremm C.,Federal University of Rio Grande do Sul |
And 3 more authors.
Ciencia Rural | Year: 2012
In this research it was evaluated the influence of different forage allowances and combinations of forage allowances along the year on the pasture accumulation dynamic and animal performance. The experiment was conducted in a natural pasture area with yearling beef heifers maintained in continuous grazing with variable stocking rate. The treatments utilized with fixed forage allowances during the year were 4; 8; 12 e 16kg 100kg-1 of live weight; and the treatments of forage allowance combinations were 8 on Spring and 12 on Autumn- Winter-Summer (8-12%); 12 on Spring and 8 on Autumn- Winter-Summer (12-8%); 16 on Spring and 12 on Autumn- Winter-Summer (16-12%), constituting a experimental design in randomized blocks with two replicates of area. The primary and secondary productions were evaluated on the accumulation period of 2007-2008. The results proved that in situations of very low forage allowances, e.g. 4%, the individual performance of animals and per area were prejudiced. Management of forage allowance combination of 8-12% promoted increase of 35% on the individual performance of animals (0,345kg animal-1), and of 20% on the production per area (209kg ha-1 of LW) when compared to a management of 12% over the year.
Massoni P.F.S.,Instituto Rio Grandense do Arroz IRGA |
Marchesan E.,Federal University of Santa Maria |
Grohs M.,Empresa de Assistencia Tecnica e Extensao Rural EMATER |
da Silva L.S.,Federal University of Santa Maria |
Roso R.,Federal University of Santa Maria
Revista Ciencia Agronomica | Year: 2013
After harvesting irrigated rice, the straw produced can be managed in different ways, and these may affect the availability of soil nutrients. The objective of this work was to evaluate the effect of different types of soil and straw management, carried out after the rice is harvested, on the levels of mineral nitrogen, phosphorus and potassium available in the soil,. The treatments were arranged in randomized blocks with plot evaluations split up in time, and corresponding to seven different types of soil management:  water at a constant depth, without straw,  straw incorporated into the preparation of dry soil immediately after harvest,  straw incorporated into the preparation of flooded soil immediately after harvest,  straw incorporated into the preparation of dry soil during July only,  straw incorporated into the preparation of flooded soil immediately after harvest, and then harrowing the area with dry soil in July,  straw incorporated into the preparation of dry soil immediately after harvest, and harrowing the area with dry soil in July,  no incorporated straw and no water. Evaluations were made on five different soil-collection dates, with four replications. Keeping straw on the soil surface produced the greatest variations in the concentrations of mineral nitrogen for the period studied, however, regardlesss of the post-harvest rice-straw managn the levels of mineral nitrogen, phosphorus and potassium available in the soil by the end of the season.