Relação fósforo e magnésio na fertilidade do solo, no estado nutricional e na produção da alfafa

Abstract

RESUMO -Com o objetivo de avaliar a influência da relação P:Mg na fertilidade do solo, no estado nutricional e na produção de matéria seca da alfafa, foi realizado um experimento em vasos com Latossolo Vermelho Amarelo distrófico, segundo delineamento inteiramente casualizado, em esquema de parcelas subdivididas, com três repetições. Os tratamentos foram constituídos de combinações de P (doses: 0, 100, 200 e 400 mg kg -1 , fonte: superfosfato triplo) e Mg (doses: 0, 100 e 200 mg kg -1 , fonte: cloreto de magnésio), nas proporções de 0, 0,5, 1, 2 e 4. No período experimental, foram realizados três cortes, com intervalo de 30 dias (subparcelas). Os resultados demonstraram que o incremento da relação P:Mg e das doses de P e de Mg aumenta a produção de matéria seca. O teor de P e as combinações de P:Mg no tecido vegetal apresentaram estreita relação com a proporção desses nutrientes no solo. A relação 2:1 acarretou maior teor de clorofila e N na matéria seca, enquanto altas quantidades de P no solo diminuíram a absorção de K.Palavras-chave: Medicago sativa, clorofila, composição mineral, macronutrientes Phosphorus and magnesium ratio on soil fertility, nutritional status, and yield of alfalfaABSTRACT -A greenhouse experiment was carried out to evaluate the effect of P:Mg ratios on soil fertility and on mineral composition and yield of alfalfa cultivated in a dystrophic Red Yellow Latosol (Oxisol). It was used a split-plot in a complete randomized design, with three replicates. Treatments were combinations of P (rates: 0, 100, 200, and 400 mg kg -1 , source:triple superphosphate) and Mg (rates: 0, 100, and 200 mg kg -1 , source: magnesium chlorite) at the following P:Mg ratios: 0, 0.5, 1, 2, and 4. Three harvest were performed (subplots), with 30-d intervals. Results showed that dry matter yield increased with the increment of P:Mg ratios and P and Mg rates. Phosphorus concentrations and P:Mg ratios in tissue showed close relationship with the proportion of the nutrients in the soil. The 2:1 ratio caused higher chlorophyll and N concentrations in tissue, while elevating quantity of P in soil decreased K uptake.

Production, nutritional status and chemical properties of soils with addition of cattle manure, reactive natural phosphate and biotite schist in Massai cultivar

“…These values could be used as a reference to define suitable levels of these elements in the soil and plants. Moreira et al (2008), analyzing the P:Mg ratio in alfalfa, observed a positive relationship between these elements and the DMY. …”

Geopolymer Foam Reinforced with Iron Ore Flotation Tailing for Potassium Adsorption and Controlled Release in Water

“…By lowering the pH of the medium is lowered, the solubility of elements as free hydrated cations is likely to occur. This behavior can be explained by some factors: (i) competition between cations for sorption, (ii) a decrease in the negative charge of complexes normally formed in a basic medium, and (iii) dissolution of soil components and consequent release to the external medium, harming the fixation of the chemical elements. , The typical behavior observed when increasing soil pH is that the sorption of cations also increases, following the sorption mechanisms, inner sphere surface complexation, and/or precipitation and multinuclear type reactions. ,− Also, the availability of nutrients in the soil varies according to the pH of the water and maximized in the pH range of 6 to 7 for potassium, calcium, magnesium, nitrogen, boron, sulfur, and phosphorus. , This result is interesting to observe the similarities between the dynamics of chemical elements in water and soil.…”

Expressão da capacidade de troca de cátions radicular e nutrição de aveia-preta (Avena strigosa Schreb.) sob deficiência de nutrientes

“…Em relação à deficiência de P, Zhong et al (1993) demonstraram que a formação de fosfatos de magnésio aumentou a absorção de Mg em Ricinus sp. cultivada em solução nutritiva, demonstrando que o P possui efeito sinérgico na absorção de Ca, Mg (Moreira et al, 2008) e Mn (Büll et al, 2008).…”