Antônio Ricardo Evangelista

Degradação de pastagens em regiões de cerrado

A degradacao das pastagens tem sido um grande problema para a pecuaria brasileira, desenvolvida basicamente em pasto. Estima-se que 80% dos 50 a 60 milhoes de hectares de pastagens cultivadas no Brasil Central encontram-se em algum estado de degradacao, ou seja, em processo evolutivo de perda de vigor, sem possibilidade de recuperacao natural e incapazes de sustentar os niveis de producao e qualidade exigido pelos animais, bem como de superar os efeitos nocivos de pragas, doencas e plantas invasoras. Essa degradacao e consequencia de varios fatores que atuam isoladamente ou em conjunto, como, preparo incorreto do solo, escolha errada da especie forrageira, uso de sementes de baixa qualidade, ma formacao inicial, manejo inadequado e, principalmente, em razao da nao-reposicao dos nutrientes perdidos no processo produtivo, por exportacao no corpo dos animais, erosao, lixiviacao e volatilizacao ao longo dos anos. A persistencia desse processo culmina com a degradacao do solo e dos recursos naturais, com prejuizos irrecuperaveis para toda a sociedade.

Intervalo hídrico ótimo como indicador de melhoria da qualidade estrutural de latossolo degradado

Grass pastures, if well-established and managed, play an important environmental role as soil cover, for aggregate formation and stabilization and in the reduction of dense or compacted layers. The objectives of this study were to quantify the least limiting water range (LLWR) of a physically degraded Red-Yellow Latosol (Oxisol) on which bermudagrass (Cynodon spp., cultivar coastcross) was planted, and to use the LLWR as an indicator of changes in the soil structural quality. Undisturbed samples were collected in volumetric rings (height 0.025 m, diameter 0.065 m) from the layers 0-0.05, 0.20-0.25 and 0.80-0.85 m (Bo horizon), in areas without machine traffic, during the rainy season of 2008/2009 in november 2008, march 2009 and may 2009. Based on these samples, the water retention curve, penetration resistance curve, bulk density, LLWR, and soil critical density were determined. The LLWR proved to be an adequate indicator of changes in the Latosol structure. The grass cultivar coastcross is potentially suitable for improving the soil structural quality, and is suggested for this purpose, instead of agricultural implements. The soil critical density of 1.24 Mg m-3 restricts the adequate development of the studied grass root system.

Avaliação de algumas características da silagem de gramínea estrela roxa (Cynodon nlemfuensis Vanderyst)

This experiment was conducted to evaluate the characteristics of the silage of the star grass (Cynodon nlemfuensis Vanderyst) with or without addition of citric pulp and submitted to different wilting time. The grass was harvested after 45 days of sprouting and stored for 35 days. The treatments were: 1 - ensilage immediately after the cut, 2 - ensilage immediately after the cut with the addition of 4% citric pulp, 3 - ensilage after wilting for one hour, 4 - ensilage after wilting for one hour with the addition of 4% citric pulp, 5 - ensilage after wilting for two hours, 6 - ensilage after wilting for two hours with the addition of 4% citric pulp, 7 - ensilage after wilting for three hours, and 8. ensilage after wilting for three hours with the addition of 4% citric pulp. The citric pulp was added to the fresh green forage. The analyzed characteristics (pH, DM, CP, NDF and ADF) allowed to conclude that the star grass, stored immediately after the cut or submitted to a wilting period up to three hours, with or without the addition of citric pulp, could be preserved satisfactorily in the form of fodder in a silo.

Valor nutritivo de silagens de milho colhido em diversos estádios de maturação

This work evaluated the bromatologic characteristics of corn silages, ensiled at different maturity stages. It was used a split plot in time in a randomized block design, with four replicates. Cultivars evaluated were Geneze 2004, Agroceres 1051, Pioneer 30S40 and Pioneer 30F90 ensiled in the following maturity stages: 0% milk line kernels (SLL), reduction of milk line in 1/3 of the kernel (1/3 LL), 1/2 of the kernel (1/2 LL), 2/3 of the kernel (2/3 LL), and formed black layer (CN). The percentage of DM of the silages ranged from 26.5% to 45.0%. The highest losses of effluents occurred in the silages from the cultivars AG1051 and P30S40, at the SLL stage, with no losses from the 1/2 LL stage. As the maturity stage advanced, increased values of pH occurred. Maturity stages influenced the percentage of CP of the silages which ranged from 10.7% to 8.1%. The greatest values of NDF (neutral detergent fiber) and ADF (acid detergent fiber) were found at the 2/3 LL and CN stages. The percentage of lignin was influenced by the cultivars, with the greatest values observed in the silages from the cultivar P30S40. The IVDDM (in vitro dry matter digestibility) was influenced by cultivar and maturity stage, varying from 51.1% to 69.8%, with the cultivar P30F90 presenting the greatest IVDDM. The 1/2 LL stage showed better IVDDM, reducing its value after this stage. The cultivars GNZ 2004, AG1051 and P30F90 are more indicated for ensiling and the best maturity stage for ensiling these two cultivars was when grains presented reduction of the milk line in half of the kernel (1/2 LL).

Características bromatológicas, fermentativas e população de leveduras de silagens de cana-de-açúcar acrescidas de ureia e aditivos absorventes de umidade

Este trabalho foi conduzido com o objetivo de avaliar os efeitos da utilizacao de aditivos sobre as caracteristicas fermentativas e bromatologicas e a populacao de leveduras da silagem de cana-de-acucar. O experimento foi conduzido em delineamento inteiramente casualizado, com quatro repeticoes. Foram testadas diferentes quantidades de aditivos a cana-de-acucar no momento da ensilagem (com base na materia verde da forragem): 1,5% ureia; 0,5 ureia + 4% de milho; 0,5 ureia + 4% de mandioca desidratada; 1,5% de amireia e cana-de-acucar controle. A cana-de-acucar da variedade RB-72454, com 18 meses de rebrota, foi armazenada em silos experimentais de concreto com capacidade de 500 kg durante 180 dias. Foram avaliados os teores de materia seca, proteina bruta, fibra em detergente neutro, fibra em detergente acido, carboidratos nao-fibrosos, cinzas, pH, nitrogenio amoniacal e lignina e a contagem de leveduras. O maior teor de materia seca e o menor teor de fibra em detergente neutro sao obtidos com a associacao de ureia e milho, que melhora o padrao fermentativo na silagem.

Effects of different compaction degrees, inclusion of absorbent additive and wilting on the chemical composition of tanzania grass silages

The objective of this work was to evaluate the effects of different compaction degrees, inclusion of absorbent additive and wilting on the chemical composition of tanzania grass silages. The experiment was conducted using tanzania grass (Panicum maximum Jacq. cv. Tanzânia I) harvested at 60-65 days of growth. The forage was ensiled in experimental PVC silos fitted with Bunsen type valves, with capacity for about 4 and 8 kg each. The treatments consisted of three types of silages (control, 5% of citric pulp and pre-wilted) with five compaction degrees (400, 500, 600, 700 and 900 kg/m3). The experimental design was random blocks, with four replicates. Citric pulp and pre-wilting increased the dry matter content of tanzania grass silages. The increased density resulted into decreases in the pH values and amoniacal-N contents; the greatest densities resulted in pH values within the ideal range. The presence of citric pulp and the pre-wilting practice reduce the losses by effluent and gas relative to the control. As the density increased, the amount of effluent increased in the control silage and decreased in silages with citric pulp.

Influência da relação cálcio:magnésio do corretivo na nodulação, produção e composição mineral da alfafa

This study evaluated the effect of different Ca:Mg ratios on dry matter yield, mineral composition of alfalfa, and nodulation. A dystrophic Dark-Red Latosol (Oxisol) soil was used in the experiment. A randomized design was adapted with five Ca:Mg ratios (1:0; 1:1; 2:1; 3:1 and 4:1) at a recommended limestone dosage of 3.9 t ha-1. An additional treatment was included at a ratio of 3:1 with the dosage of 7.8 t ha-1. All treatments had four replicates in six cutting times. The analyzed variables were dry matter production, concentrations (g kg-1) of N, P, K, Ca, Mg and S in dry matter and weights of fresh and dry nodules. The changes in the ratios of Ca:Mg at the recommended limestone rate did not affect the dry matter production. The highest dry matter yield was obtained in the treatment that used twice the recommended dosage. The concentrations of Ca and Mg in the aerial dry matter were directly proportional to their availability in the soil, while the K concentrations were inversely proportional to the rate Ca applied. No treatment influenced the concentration of P in the aerial dry matter. The concentration of S was influenced by the ratio of Ca:Mg and diminished with increases in Ca. The 4:1 treatment showed the highest concentration of N in the dry matter. The N fixation enhanced as the Ca rate in the soil increased.

Chemical and fermentative changes during the storage period of the sugar cane silage with or without ground dried ear corn.

The chemical and fermentative changes of the sugar cane ensiled without or with (control) ground dried ear corn (GDEC) were evaluated during 100 days of storage period. The pH values, buffer capacity (BC), dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose (HM) ammonia nitrogen in relation to the total nitrogen (N-NH3/TN) were evaluated. The experiment was conducted in a complete randomized design as a factorial (2 × 21) scheme with three replications. The factor A was composed of sugar cane silage with or without GDEC, and the factor B was the 21 storage periods. The data were submitted to the regression analyses. The pH values decreased in the first five days of storage, from 5.2 to 3.5 and from 5.2 to 3.6, respectively on the silage without and with GDEC. Silages with GDEC showed higher pH values when compared to the control, on average of 0.09 units. The inclusion of GDEC resulted in higher N-NH3/TN values in all storage periods. In the control silage, the reduction on the DM content was 14.1 units and 8.8 units for those with GDEC. The inclusion of GDEC resulted in the reduction of 17.0 units in the NDF, probably due to the low fiber content of the additive. Sugar cane silage presents chemical changes up to 100 days of storage, and should not remain stored for long periods.The chemical and fermentative changes of the sugar cane ensiled without or with (control) ground dried ear corn (GDEC) were evaluated during 100 days of storage period. The pH values, buffer capacity (BC), dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose (HM) ammonia nitrogen in relation to the total nitrogen (N-NH3/TN) were evaluated. The experiment was conducted in a complete randomized design as a factorial (2 × 21) scheme with three replications. The factor A was composed of sugar cane silage with or without GDEC, and the factor B was the 21 storage periods. The data were submitted to the regression analyses. The pH values decreased in the first five days of storage, from 5.2 to 3.5 and from 5.2 to 3.6, respectively on the silage without and with GDEC. Silages with GDEC showed higher pH values when compared to the control, on average of 0.09 units. The inclusion of GDEC resulted in higher N-NH3/TN values in all storage periods. In the control silage, the reduction on the DM content was 14.1 units and 8.8 units for those with GDEC. The inclusion of GDEC resulted in the reduction of 17.0 units in the NDF, probably due to the low fiber content of the additive. Sugar cane silage presents chemical changes up to 100 days of storage, and should not remain stored for long periods.

Relação cálcio e magnésio na fertilidade de um latossolo vermelho escuro distrófico cultivado com alfafa

Realizou-se com este trabalho com o objetivo de verificar os efeitos da relacao Ca e Mg na fertilidade de um Latossolo Vermelho Escuro distrofico, fase cerrado, cultivado com alfafa (Medicago sativa L.). O delineamento experimental utilizado foi o inteiramente casualizado em parcelas subdivididas, com seis tratamentos e quatro repeticoes. Os tratamentos consistiram de cinco relacoes Ca:Mg: 1:0; 1:1; 2:1; 3:1 e 4:1 (3,9 t ha-1) e mais um tratamento adicional com a mesma relacao 3:1, porem, com o dobro da quantidade aplicada (7,8 t ha-1). As quatro coletas de solo realizadas durante a conducao do experimento consistiram nas subparcelas. Os resultados mostraram que com o aumento da relacao K/(Ca+Mg) ocorre diminuicao do teor de Ca e Mg na materia seca da parte aerea e da quantidade Ca e Mg trocavel, que as saturacoes de K, Ca e Mg estao diretamente relacionadas com a producao de materia seca total e o aumento da relacao K/(Ca+Mg) diminui o indice de pH e aumenta a acidez potencial do solo.

Effect of the addition of Lactobacillus sp. in sugarcane silages

Objetivou-se avaliar o efeito de aditivos microbianos com bacterias heterofermentativas ou homofermentativas sobre as caracteristicas de silagens de cana-de-acucar (Saccharum spp.). A cana-de-acucar foi inoculada com as bacterias Lactobacillus plantarum (LP), L. paracasei (LPARA), L. brevis (LBREVIS), L.buchneri (LB), isoladas da silagem de canade-acucar, e tres inoculantes comerciais, dois contendo L. buchneri (Pioneer 11A44TM-LBP e Lalsil Cana-LBLC) e um, L. plantarum (Biomax®-LPB), e avaliada em comparacao a uma silagem controle (sem inoculante). Todos os inoculantes foram aplicados com populacao de 105 ufc da bacteria por g de forragem. O delineamento utilizado foi o inteiramente casualizado com oito tratamentos e tres repeticoes. O efeito da inoculacao sobre as caracteristicas bromatologicas foi variavel. A silagem contendo a bacteria L. plantarum apresentou maior teor de MS (32,6%), enquanto, para os outros inoculantes, nao houve diferenca, com media de 28,4%. Os teores de proteina bruta variaram de 3,6 a 4,9% e os de FDN, de 60,0 a 66,7%. As porcentagens de FDA, hemicelulose e cinzas foram semelhantes em todas as silagens. O consumo de carboidratos soluveis foi superior a 85% durante a fermentacao, para todas as silagens, o que resultou em pH em torno de 3,5. Os valores de pH e nitrogenio amoniacal para todas as silagens estiveram no padrao aceitavel para silagens de boa qualidade. Os inoculantes retardaram o aumento da temperatura, em aerobiose, conferindo maior estabilidade aerobia. Os melhores resultados foram obtidos com os inoculantes LBLC, LB e LPB.