Rogério Gonzatto

FITOMASSA E DECOMPOSIÇÃO DE RESÍDUOS DE PLANTAS DE COBERTURA PURAS E CONSORCIADAS

O cultivo de plantas de cobertura, no outono/inverno, na regiao do Planalto do Rio Grande Sul contribui para o sucesso do sistema plantio direto. No entanto, informacoes relativas a producao de fitomassa e decomposicao de residuos dessas especies ainda sao escassas para a regiao, sobretudo para especies consorciadas. O experimento foi conduzido em Nao-Me-Toque, RS, em um Latossolo Vermelho distrofico tipico, avaliando-se nove tratamentos, sendo quatro constituidos por plantas de cobertura em culturas puras [centeio (Secale cereale L.), aveia-preta (Avena strigosa Schreb), ervilha forrageira (Pisum sativum subesp. arvense) e nabo forrageiro (Raphanus sativus L. var. oleiferus Metzg)] e cinco por consorcios [(centeio + ervilha forrageira, centeio + nabo forrageiro, aveia + nabo forrageiro, centeio + ervilhaca (Vicia sativa L.) e aveia + ervilhaca)]. A dinâmica de decomposicao dos residuos culturais das plantas de cobertura foi avaliada em bolsas de decomposicao, as quais foram distribuidas na superficie do solo e coletadas aos sete, 14, 21, 28, 57, 117 e 164 dias. O consorcio entre leguminosas e crucifera com gramineas resultou em maior producao de fitomassa em relacao ao cultivo destas em culturas puras. O nitrogenio (N) acumulado na parte aerea dos consorcios formados por ervilha forrageira e nabo com centeio e aveia foi semelhante ao da leguminosa e da crucifera em culturas puras e superou em 220,4 % os valores de N observados para as gramineas em culturas puras. Por meio do consorcio entre as especies de cobertura foi possivel reduzir a taxa de decomposicao dos residuos culturais, em comparacao com as culturas puras da leguminosa e da crucifera.

Injection of Dicyandiamide-Treated Pig Slurry Reduced Ammonia Volatilization without Enhancing Soil Nitrous Oxide Emissions from No-Till Corn in Southern Brazil.

There is a lack of information on how placement in soil and nitrification inhibitors affects nitrous oxide (NO) and ammonia (NH) emissions from pig slurry (PS) applied under no-till (NT) conditions. Our objective was to determine the impact of injecting PS and treating it with the nitrification inhibitor dicyandiamide (DCD) on NH and NO emissions from soils under NT in subtropical southern Brazil. The emissions of these gases were compared for shallow (∼ 10 cm) injection and surface broadcasting of PS with and without DCD (8.1-10.0 kg ha; 6.5-8.4% of applied NH-N). Measurements were made at two sites during two summer growing seasons under NT corn crops. Injection reduced NH volatilization by 70% but increased NO emissions 2.4-fold (from 2628 to 6198 g NO N ha) compared with surface broadcast application. Adding DCD to PS inhibited nitrification and reduced NO emissions by an average of 28% (730 g NO-N ha) for surface broadcast and 66% (4105 g NO-N ha) for injection but did not increase NH volatilization. Consequently, NO emission factors were much higher for injection (3.6%) than for surface broadcast (1.3%) application and were reduced (0.9%) when DCD was added to injected PS. In conclusion, the injection of DCD-treated slurry is a recommendable practice for reducing NH and NO emissions when applying PS on NT corn in southern Brazil.

Volatilização de amônia e emissão de óxido nitroso após aplicação de dejetos líquidos de suínos em solo cultivado com milho

The nitrogen (N) losses through gaseous emissions of ammonia (NH3) and nitrous oxide (N2O) after pig slurry (PS) application in soil is a subject still little studied in Brazil, especially under no-till conditions. Therefore, the objective of this study was to evaluate, under field conditions, the NH3 volatilization and the N2O emission after PS application in corn, with and without surface oat straw. The treatments for measuring N2O emissions, during 90 days, were: T1-unamended soil (control), T2 - Soil + PS, T3 - Soil + oat straw and T4 - Soil + PS + oat straw. The NH3 volatilization was quantified only in the last three treatments. PS, at the dose 60m³ ha-1, was applied prior the sowing of corn, in a randomized design, with three replications. Oat straw on the soil surface reduced NH3 volatilization by 34%, but enhanced N2O emission by 167%. The higher N2O fluxes occurred during the first 40 days after PS addition, always after rain and/or irrigation events.

Inibidor de nitrificação e aplicação parcelada de dejetos de suínos nas culturas do milho e trigo

Nas areas com producao intensiva de suinos, os dejetos liquidos dos animais constituem importante fonte de nitrogenio (N) as culturas; entretanto, esses dejetos sao uma das principais causas de poluicao do solo, do ar e da agua. E preciso buscar estrategias que reduzam as perdas de N desse residuo orgânico para o ambiente e que melhorem a sua eficiencia agronomica, relativa ao fornecimento de N as culturas comerciais. O objetivo deste trabalho foi avaliar o efeito do uso de inibidor de nitrificacao (IN) e da aplicacao parcelada de dejetos liquidos de suinos (Dls) sobre o acumulo de N e a produtividade de milho e trigo em plantio direto. Os tratamentos avaliados constaram da aplicacao da dose recomendada de Dls em aplicacao unica e parcelada (1/3 em pre-semeadura e 2/3 em cobertura), com e sem IN. Alem desses quatro tratamentos, foi avaliado um tratamento com adubacao mineral (NPK) recomendada ao milho e ao trigo e outro sem IN e sem fertilizantes (testemunha). O IN, a base de dicianodiamida (DCD), foi misturado aos dejetos na dose de 7 kg ha-1. A aplicacao de Dls, em dose unica ou parcelada, aumentou o acumulo de N e a produtividade de milho e trigo, proporcionando resultados similares aos observados com a adubacao mineral recomendada as duas culturas. As estrategias de parcelar a dose recomendada de Dls ao milho e ao trigo e de usar a DCD para inibir a nitrificacao nao influenciaram o acumulo de N e a produtividade do milho e trigo em plantio direto.

Uso de malhas pigmentadas e mulching em túneis para cultivo de rúcula: efeito no ambiente e nas plantas modelo

The use of pigmented screens for growing vegetable crops provides an opportunity for adjusting environmental conditions, especially for roquette. This vegetable crop is consumed mainly as raw, and has a large proportion in Brazilian vegetable market since 1990s. The present research was aimed to evaluate the effect the altered environmental conditions (by using pigmented screens tunnels) on agronomic performance of roquette, grown inside tunnels having different color covers. Coverage screens colors were blue, red, silver, screen of shading 50% and transparent plastic. Beside this the effect of different mulching practices was also evaluated inside the tunnels. The experiment was laid out under randomized complete blocks design with 24 treatments and three replications. The results of the experiment under such conditions changed environmental and soil conditions and resulted in improved agronomic response by roquette plants.

Formação continuada dos professores das escolas técnicas da Universidade Federal de Santa Maria

This article highlights the importance of the presence of teachers in continuing education courses, aiming to analyze the participation of teachers of Polytechnic and Technical Industrial - Ctism - Colleges of Federal University of Santa Maria - UFSM - in continuing education courses. For this, we conducted a quantitative survey and the data collected through a multiple choice questionnaire that was applied to teachers in these institutions. It was concluded that most teachers of Polytechnic and Ctism Colleges of UFSM participate in continuing education courses and institutions to receive this incentive. Still, teachers attend refresher courses in education, even those that are embedded in more technical areas. Key-words: professional development, technological education.

Redução na velocidade da nitrificação no solo após aplicação de cama de aviário com dicianodiamida

The fast nitrification of ammoniacal nitrogen (N) of organic and mineral sources in soil can result in losses of nitrate (NO3-) to the environment. One strategy to reduce these losses involves the use of nitrification inhibitors. The objective of this study was to evaluate, in laboratory conditions, the efficiency of Agrotain® Plus (AP), which contains dicyandiamide (DCD), as a nitrification inhibitor of ammoniacal nitrogen from poultry manure (PM) in soil. Were evaluated five treatments, one with PM incorporated into the soil, three with PM incorporated into the soil with AP at the doses of 3.5, 7.0 e 14.0kg ha-1 and one treatment without PM and AP. Nitrification was monitored by measuring changes in soil mineral N (NH4+ and NO3-) periodically over 69 days. The highest rate of nitrification occurred in the treatment in which PM was incorporated into the soil without AP. The doses of 3.5 and 7.0kg ha-1 of AP inhibited partially the nitrification of ammoniacal nitrogen of PM in the initial phase of incubation, losing the ability to inhibit this process in the period between 12 and 27 days. The treatment with the higher dose of AP (14kg ha-1) was on in which the DCD exerted more inhibitory effect on nitrification, preserving most NH4+ and delaying the onset of NO3- in soil. The results of this study indicate that the DCD, contained in the Agrotain® Plus, reduces the nitrification rate of ammoniacal nitrogen from PM in soil, that may contribute to reduce NO3- losses to the environment.