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Master's Dissertation
DOI
https://doi.org/10.11606/D.11.2019.tde-20191218-120659
Document
Author
Full name
Adônis Moreira
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 1997
Supervisor
Title in Portuguese
Efeito de fontes e doses de fósforo na alfafa (Medicago sativa L.) e centrosema (Centrosema pubescens Benth.) e avaliação de extratores
Keywords in Portuguese
ADUBAÇÃO
ALFAFA
CENTROSEMA
FERTILIZANTES FOSFATADOS
FÓSFORO
LATOSSOLO VERMELHO-AMARELO DISTRÓFICO
Abstract in Portuguese
O estudo foi desenvolvido em casa de vegetação do Centro de Energia Nuclear na Agricultura (CENA), e teve por objetivos determinar a eficiência de adubos fosfatados na produção e na composição das leguminosas forrageiras alfafa e centrosema. As plantas foram cultivadas em vasos de 5 kg contendo um latossolo-vermelho amarelo distrófico, coletado no município de Nova Odessa, São Paulo. O delineamento experimental foi o inteiramente casualizado com 3 repetições. Três fontes foram usadas nas doses 0, 50, 100 e 200 mg kg-1, na forma de superfosfato triplo (SPT), fosfato natural de Arad, fosfato natural da Carolina do Norte (FCN) e termofosfato Yoorin. Em todos os casos o teor total de P2O5 foi considerado para determinar as doses de aplicação. As sementes foram inoculadas e tratadas com cobalto e molibdênio. Foram aplicadas adubações uniformes de K e micronutrientes (B, Cu, Fe, Mn e Zn), e utilizou calcário dolomítico para ajustar a saturação de bases. Seis cortes foram realizados. No início do experimento e após cada corte, amostras de solo de cada vaso foram coletadas para análise. O P disponível foi extraído por resina, Mehlich 1 e Mehlich. O material vegetal foi analisado após cada corte. As doses de P aplicadas aumentaram a produção de matéria seca (MS) e o teor de P, sendo que a alfafa apresentou maior resposta. O Yoorin proporcionou a maior produção de MS estimada: em 6 cortes 49,9 e 75,6 foram obtidas, respectivamente com a alfafa e centrosema. A eficiência dos adubos fosfatados foi avaliada por três métodos, dois convencionais e um para representar uma nova tentativa. Os métodos convencionais utilizados foram o "Índice de Eficiência Agronômica" (IEA), "Equivalente Superfosfato Triplo" (EqSPT). O método proposto, considerou todas as doses e todos os pontos da curva de resposta, sendo chamado "Índice de Eficiência" (IE). Ele foi definido como a relação entre a produção de matéria seca e dose de P aplicada, ambos correspondendo à produção máxima calculada. Na alfafa, não houve diferença significativa na dose 50 mg de P no IEA e EqSPT para o FCN, Arad e Yoorin; com a dose 100 mg de P, entretando, o Yorrin e Arad foram iguais e superiores a FCN; na presença da maior dose a ordem foi Yoorin > Arad = FCN. O mesmo ocorreu com o EqSPT. O IE foi maior no Yoorin e Arad, não diferindo ao nível de 5% de probabilidade, mas foram superiores ao SPT e FCN. No caso da centrosema, o IEA foi igual para os três fosfatos na dose 50 mg de P; com 100 mg de P a ordem foi Yoorin > Arad > FCN. O Arad e FCN não apresentaram diferença significativa e foram inferiores ao Yoorin na dose 200 mg de P. A variação do EqSPT na dose 50 mg de P foi semelhante ao observado no IEA; na dose 100 mg a ordem foi Yoorin = Arad > FCN, entretanto Arad foi igual ao FCN; na dose 200 mg de P a ordem de equivalência foi Yoorin > FCN = Arad. No IE, os valores encontrados foram Yoorin = Arad = SPT > FCN. Considerando a média das três doses aplicadas e todos os cortes, a quantidade total de P obedeceu a seguinte ordem crescente: Yoorin > SPT > FCN > Arad. Os extratores Mehlich 1, Mehlich 3 e resina apresentaram alta correlação entre si e foram similares na avaliação do fósforo disponível. Os fosfatos naturais apresentaram a maior taxa de recuperação. A aplicação de P aumentou significativamente o teor de N na centrosema. O teor de Ca aumentou em todas as doses e fontes, enquanto que o Yoorin aumentou a concentração de Mg. O pH do solo diminuiu com SPT, enquanto que os fosfatos naturais não tiveram efeito. O Yoorin entretanto, diminuiu a acidez. As doses de P reduziram o teor de Zn na matéria seca. O teor de Zn apresentou correlação negativa com a produção de MS no termofosfato Yoorin. Este, entretanto não evitou que o termofosfato tivesse a maior produção de MS, o que não ocorre normalmente. Os teores de Cu, Fe e Mn não foram afetados nem pelas doses e nem pelas fontes de P aplicadas.
Title in English
Effects of sources and rates of phosphorus on alfalfa (Medicago sativa L.) and centrosema (Centrosema pubescens Benth.) and evaluation of extractants
Abstract in English
Plants were grown in 5 kg pots containing a Red Yellow Latosol, dystrophic, collected in the Nova Odessa Country, São Paulo, placed in a greenhouse of the Centro de Energia Nuclear na Agricultura, University of São Paulo, Piracicaba, SP, Brazil. The treatments were completely randomized, with 3 replicates. Three sources of P were used at the rates of 0, 50, 100 and 200 mg kg-1, supplied as triple superphosphate (TSP), Arad rock phosphate (ARP), North Carolina rock phosphate (NCRP), and Yoorin magnesium thermophosphate (YTP). In all cases total P2O5 content was considered to fulfill the rates of application. Seeds were inoculated and treated with cobalt and molybdenum. Uniform dressing of K and micronutrients (B, Cu, Fe, Mn and Zn) were also applied, and dolomitic limestone was used for adjustment of base saturation. Six cuttings were made. At the start of the trial and after each cutting soil samples from each pot were taken for analysis. Available P was extracted by resin, Mehlich 1 and Mehlich 3. Plant material was also analyzed after each cutting. The various rates of P applied increased both dry matter (DM) and P level, alfalfa being more responsive. YTP ranked first in the estimation of total DM production: in 6 cuttings 49,9g and 75,6 g were obtained, respectively with alfalfa and centrosema. The efficiency of the phosphatic fertilizers was evaluated by three different methods, two conventional and one which represents a new attempt. The conventional approaches are the "Index of Agronomic Efficiency" (IEA) and "Triple Superphosphate Equivalent" (EqTSP). The proposed one, which considers all rates and all points of the response curves, is tentatively called "Efficiencies Index" (EI). It is simply defined a the quotient between DM yield and rate of P applied, both corresponding to the calculated maximum DM production. Ranking of the phosphates varied as follows. When alfalfa was the test crop and P was supplied at the lowest rate, there was no significant difference among the IAE for YTO, ARP and NCRP; with 100 mg P added, however, TYP and ARP were equal and higher than NCRP; in the presence of the highest rate application the order was TYP > ARP = NCRP at the 5% level. The same was observed with the EqTSP index. The EI was higher for YTP and ARP which did not differ at the 5% level of probabilities, both being higher than NCRP and TSP which did not differ. In the case of centrosema the IAE was the same for the three phosphates at the 50 mg P rate of application. With 100 mg the order was YTP > ARP > NCRP; there was no significant difference between NCRP and ARP which were lower than YTP when 200 mg P was supplied. The variation in EqTSP at the 50 mg P rate was the same observed in IAE; with 100 mg the order was YTP = ARP > NCRP, being ARP = NCRP; when 200 mg P were given the values followed the order YTP > NCRP = ARP. Highest EI values were found with TYP, ARP and TSP which did not differ among themselves being higher than NCRP. Soil P values obtained using Mehlich 1 and 3 and resin extraction correlated well among each other and gave similar results. Highest recovery percentages were provided by the rock phosphates. Considering the average of the three rates of application and all cuttings total P taken up obeyed the following decreasing order: YTP > TSP > NCRP > ARP. Applied P was able to raised N level only in centrosema. Ca level was raised by all sources, whereas only YTP increased Mg concentration. Soil pH was decreased by TSP, whereas the rock phosphates had no effect. YTP however, decreased acidity. P rates reduced Zn level in the dry matter, and a negative relationship was found between Zn concentration the plants and yield due to the application of YTP. This, however did not prevent the termophosphate from giving the top yield, as pointed out. Levels of Cu, Fe and Mn in the dry matter were not affected neither by sources nor by rates of P applied.
 
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Publishing Date
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