RESUMOVolatilização de NH 3 é a principal reação que diminui a eficiência de utilização pelas plantas do N proveniente da ureia, quando ela é aplicada sobre a superfície do solo. A fim de minimizar essa perda, produtos têm sido misturados à ureia para inibir temporariamente a ação da urease. Este trabalho objetivou avaliar alternativas de aplicação de um fertilizante com inibidor de urease, visando a diminuir a volatilização de NH 3 relativamente à ureia convencional, em algumas condições ambientais e de solo. Foram desenvolvidos quatro experimentos, todos em condições de laboratório, em 2007 e 2008, em Cambissolo Húmico. Os tratamentos variaram em cada estudo e incluíram combinações de níveis de pH do solo (natural; 5,5; 6,3; e 6,8), umidade do solo (5, 10 ou 20 % de água) e temperaturas ambientais (18 e 35 ºC), além de estados físicos (sólido ou líquido) e de métodos de aplicação dos fertilizantes (na superfície ou incorporado ao solo). As unidades experimentais foram constituídas por bandejas plásticas (23 x 51 x 17 cm) com 12 kg de solo, numa espessura de 15 cm, sobre as quais foram instaladas câmaras coletoras de NH 3 . A amônia volatilizada foi determinada em várias épocas, nos primeiros 28 dias após a aplicação dos fertilizantes. O pico de volatilização diária de NH 3 ocorreu sempre na primeira semana depois da adição dos fertilizantes ao solo, e aconteceu dois a três dias mais tarde para a ureia com inibidor de urease, em relação à ureia convencional. A volatilização de NH 3 nem sempre foi maior para a ureia convencional em comparação ao fertilizante contendo inibidor de urease, tampouco para o estado líquido em relação ao granulado. A volatilização de NH 3 aumentou com a elevação do pH, da temperatura e da dose aplicada de N e foi menor nos extremos de umidade (solo com 5 % ou com 20 % de água). Para os fertilizantes aplicados sobre a superfície do solo, a taxa máxima de perda diária foi(1) Parte da Dissertação de Mestrado do primeiro autor apresentada à Universidade do Estado de Santa Catarina (UDESC).Recebido para publicação em fevereiro de 2010 e aprovado em dezembro de 2010.
ABSTRACT:Determining the chemical composition of poultry litter is important in order to apply this waste as soil fertilizer without causing negative environmental impacts. The aim of this study was to evaluate the average and variability of some chemical parameters of 165 samples of poultry litter produced from confined animal production facilities located in the states of Santa Catarina and Rio Grande do Sul, Southern of Brazil. Samples of approximately 5.0 L were collected on 20 points from the truck at the time the material was unloaded into the application sites. Subsequently, they were oven-dried at 65 °C and analyzed. Values of pH in water, dry matter, N, P and K were determined in all samples; N soluble in water (soluble-N), ammonium (NH + 4 -N) and nitrate (NO − 3 -N) were quantified in 50 samples; organic carbon (organic-C) and C/N ratio were assessed in 20 samples. There was large variation in the contents of N, P 2 O 5 and K 2 O among samples, with the average accounting for 2.2, 3.0 and 2.9 %, respectively; these nutrients correlated with each other. More than 90 % of the N was in the organic form, into which the fraction soluble in water accounted for 21.8 % of the total. Inorganic N was predominantly in the form of ammonium (NH + 4 -N), and nitrate (NO − 3 -N) was absent. Average dry matter was 64.3 %, with a median of 66.5 %; pH was always alkaline (average of 7.8), with a low variation coefficient (7.4 %), and was negatively correlated with NH + 4 -N. The average of organic C and C/N ratio in dry matter was 28.3 % and 11.2, respectively, which results in the immediate release of N to the soil, with no microorganism immobilization. The chemical composition of poultry litters produced in confined systems in Southern Brazil is widely variable. Thus, to be successfully used as soil fertilizer, it is essential to know their composition, mainly in terms of moisture N, P 2 O 5 and K 2 O contents.
-The effect of N addition on apple yield and quality may vary according to the tree vigor. Apple trees developed over vigorous rootstocks had shown no response to N application in Brazil. In this study it was evaluated the effect of N addition to the soil on yield and quality of ´Royal Gala´ apples grafted on a dwarf rootstock (M.9). The orchard was planted in 1995 (2,857 trees ha -1 ) on an Oxisol containing 40 g kg -1 of organic matter and pH 6.0. The experiment was carried out from 1998 up to 2005. Treatments consisted of rates of N (0, 50, 100 and 150 kg ha -1 year -1 from 1998 to 2001, and respectively 0, 100, 200 and 300 kg ha -1 afterwards), all broadcasted within the tree row in two equal splits, at bud break and after harvest, as ammonium sulfate. Addition of N to the soil had no effect on fruit yield over the six years regardless of the applied rate. Averaged across treatments and years, fruit yield was 52.3 t ha -1 . Nitrogen in the leaves (average of 24 g kg -1 ) or in the fruits (average of 346 mg kg -1 ) as well as some attributes related to fruit quality (color, firmness, acidity, soluble solids, physiological disorders) were unaffected by N addition. Some plant parameters related to tree vigor, however, grew higher with the increase on N rate. Thus, it is not necessary to apply N to deep Brazilian soils containing high organic matter in order to assure good fruit quality and yield on high-density orchards carrying dwarf rootstocks probably because the N required for tree growth and fruit production is supplied from soil organic matter decay. Index terms: apple yield, M.9 rootstock, fruit quality, nitrogen. A ADIÇÃO DE NITROGÊNIO NÃO AFETOU O RENDIMENTO E A QUALIDADE DE MAÇÃS EM POMAR COM ALTA DENSIDADE E PORTA-ENXERTO ANÃORESUMO -O efeito da adição de N ao solo no rendimento e na qualidade de maçãs pode variar em função do vigor das plantas. Experimentos conduzidos no Brasil com macieiras cultivadas sobre porta-enxertos vigorosos não têm apresentado aumento no rendimento de frutos pela aplicação de N. Este trabalho objetivou avaliar o efeito da aplicação de N no rendimento e na qualidade de frutos de macieira cultivada em alta densidade sobre porta-enxerto anão (M.9). O pomar com a cultivar Royal Gala foi plantado em 1995, na densidade de 2.857 plantas ha -1 , em um Latossolo Bruno com 40 g kg -1 de matéria orgânica e pH 6,0. O experimento foi implantado em 1998 e foi encerrado em 2005. Os tratamentos consistiram da aplicação anual de 0; 50; 100 e 150 kg ha -1 de N de 1998 até 2001 e de, respectivamente, 0; 100; 200 e 300 kg ha -1 de N a partir da safra 2002-2003. Metade de cada dose foi aplicada no início da brotação, e o restante após a colheita, sempre na forma de sulfato de amônio. A aplicação de N ao solo não influenciou no rendimento de frutos em nenhuma das seis safras, independentemente da dose. Na média das doses e dos anos, o rendimento foi de 52,3 t ha -1 . A adição de N também não afetou a concentração de N nas folhas (média de 24 g kg -1 ) e nos frutos (media de 346 mg kg -1...
Mehlich-1 soil extract is currently used in Rio Grande do Sul (RS) and Santa Catarina (SC) States, in Brazil, to evaluate soil phosphorus available to plants and Mehlich-1 is sensitive to soil buffering capacity. This limitation is overcome partly by soil separation into buffering classes based on soil clay content. However, soil clay content has some technical and operational limitations, such as the underestimation of soil clay levels in soils under no-till. The aim of this study was to evaluate the remaining phosphorus (P-rem) compared to soil clay content as an index of the buffering capacity in soils of RS. The relationship between P-rem and soil clay content was assessed using 200 soil samples from a wide range of locations across the state. In 20 representative soil types, P-rem, soil clay content, P maximum adsorption capacity, total and pedogenic Fe contents, amount of P 2 O 5 needed to increase soil P in 1 mg kg -1 extracted by Mehlich-1 and -3 methods and P capacity factor were determined. Furthermore, a pot experiment was carried out with plants to determine soil P content extracted by Mehlich-1 and -3 at the maximum technical efficiency (MET) and the maximum absorption efficiency (MEA). Correlation analyses were performed between P-rem and soil clay content and, with the attributes of soils involving the P buffering capacity. The relationship between P-rem and soil clay content was described as a decreasing exponential function; however, the adjustment was not adequate to propose critical levels for P-rem. The P-rem index was superior to soil clay index in practically all relationships with the attributes related to the soil buffering capacity of the soils. In some cases, the indexes were similar; however, P-rem was not lower than the soil clay content in any case. The P-rem is a more reliable index to represent soil buffering capacity than the soil clay content in soils from RS, and P-rem might be used to implement soil classes for Mehlich-1 and Mehlich-3 determinations of soil P.
-Calcium sprays have normally improved both the quality and the storage life of apples throughout the world because Ca helps to prevent many fruit disorders and that taken up from the soil does not often reach the fruit in adequate amounts. Since the efficacy of Ca sprays varies according to soil, apple cultivar, and weather conditions, this study was carried out from 1998 to 2004, in the Southern of Brazil, in order to assess the effect of Ca sprays on the quality and storability of 'Gala' fruits. The experiment was set up in an orchard planted in 1988, on a density of 1234 trees/ha. Treatments consisted of 0, 4, 8, and 12 annual sprays of 0.5% CaCl 2 regularly distributed 30 days after petal fall until one week before harvest. Fruits of the same size and maturity level were annually analyzed at harvest and after five months of conventional cold storage (-1 o C and 90-95% of RH). In five out of six seasons, fruits from all treatments were free of any physiological disorder, and Ca sprays had no effect on leaf composition and on any fruit attribute (soluble solids, titratable acidity, starch pattern index, flesh firmness, and concentrations of N, K, Ca and Mg). In the season of 2000/ 2001, however, when yield was 18 t ha -1 and fruits had an average weight of 175 g, the incidence of bitter pit plus lenticel blotch pit on stored fruits was 24% in the treatment with no calcium sprays and it decreased up to 2% in that with 12 sprays. Two seasons later, yield was also low (25 t ha -1 ) and fruits were large (168 g each), but they did not show any physiological disorder regardless of the number of Ca sprays. It seems that the incidence of Ca related disorders in 'Gala' apples grown on limed soils in Brazil with no excess of any nutrient only occurs on seasons with low crop yield, as a result of large fruits and a high leaf/fruit ratio, associated with some unknown environmental conditions. Index terms: Malus domestica, nutrition, bitter pit, lenticel blotch pit, calcium chloride. Frutos de mesmo tamanho e com mesmo nível de maturação foram analisados na colheita e após 5 meses de armazenamento em câmaras frigoríficas convencionais (-1 o C e 90-95% UR). Em cinco das seis safras, não houve incidência de distúrbios fisiológicos nos frutos em nenhum tratamento, e as pulverizações com Ca não afetaram a composição química das folhas e nenhum atributo dos frutos (sólidos solúveis, acidez titulável, índice de iodo-amido, firmeza e concentração de N, K, Ca e Mg). Na safra de 2000/2001, entretanto, quando a produtividade foi baixa (18 t ha -1 ) e os frutos apresentavam um peso médio de 175 g, a incidência de "bitter pit" e a depressão lenticelar atingiram 24% das maçãs que não foram pulverizadas com Ca, tendo diminuído para 2% nas que receberam 12 pulverizações. Dois anos mais tarde, a produtividade foi novamente baixa (25 t ha -1 ), e os frutos foram grandes (168 g), mas não houve incidência de nenhum distúrbio fisiológico, independentemente do número de pulverizações com Ca. Verifica-se, portanto, que o aparecimento...
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