Manejo da adubação potássica na cultura da batata-doce
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Data
2019-02-18
Autores
Figueiredo, Ricardo Tajra
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Universidade Estadual Paulista (Unesp)
Resumo
Para a maioria das hortaliças que produzem raízes tuberosas, o potássio (K) é o nutriente mineral exigido em maior quantidade. Entretanto, a aplicação de doses elevadas desse nutriente pode prejudicar o desenvolvimento das plantas, devido ao aumento da concentração salina ou mesmo decorrer em grandes perdas por lixiviação, especialmente em solos arenosos. Desta forma, o objetivo deste trabalho foi avaliar o crescimento e a produtividade da batata-doce submetida a doses e formas de parcelamento da adubação potássica em solos com diferentes teores iniciais de potássio (K). Foram conduzidos quatro experimentos em áreas com diferentes disponibilidades iniciais de K no solo (baixa = 0,7 mmolc dm-3; média = 1,4 e 1,5 mmolc dm-3 e alta = 3 mmolc dm-3) entre os anos de 2016 e 2018. O delineamento experimental utilizado foi o de blocos ao acaso, no esquema fatorial 3x4+1. Os tratamentos foram representados por três doses de K2O (60, 120 e 240 kg ha-1) combinadas com quatro formas de parcelamento (1 = 100% no plantio; 2 = 1/2 no plantio + 1/2 aos 40 dias após o plantio (DAP), 3 = 1/2 no plantio + 1/2 aos 90 DAP; 4 = 1/3 no plantio + 1/3 aos 40 DAP + 1/3 aos 90 DAP), além da testemunha sem K. O crescimento das plantas, em termos de biomassa produzida, aumenta em solos com baixo e médio teor inicial de K até as doses de 145 e 115 kg ha-1 de K2O, respectivamente. Em solos com alto teor inicial de K (≥ 3,0 mmolc dm-3), a adubação potássica não contribuiu para o acúmulo de matéria seca da planta, mas reduz o acúmulo de biomassa nas raízes tuberosas. Em solo com baixo teor inicial de K a produtividade comercial aumenta até os 171 kg ha-1 de K2O, e em solos com médio teor inicial de K o aumento da produtividade comercial ocorre até as doses entre 106 e 111 kg ha-1 de K2O. Porém, sob alta disponibilidade inicial de K a produtividade comercial reduz com a adubação potássica até a dose de 60 kg ha-1 de K2O. O parcelamento da adubação com K em três vezes (plantio+40+90DAP) mostrou-se mais eficiente para incrementar a produtividade comercial da batata-doce em todos os solos estudados.
Among the majority of tuberous roots vegetables, potassium (K) is the most required mineral nutrient. However, the application of high rates of this nutrient may harm the plants development, due to the increase in saline concentration or even in large losses by leaching, especially in sandy soils. Thus, the purpose of this work was to evaluate the growth and yield of sweet potato submitted to rates and forms of K split application in soils with different K concentration. Four experiments were carried out in areas with different initial K availability in the soil (low = 0.7 mmolc dm-3, medium = 1.4 and 1.5 mmolc dm-3 and high = 3 mmolc dm-3) between 2016 and 2018. The experimental design was a randomized block design in the 3x4 + 1 factorial scheme. The treatments were represented by three doses of K2O (60, 120 and 240 kg ha-1) combined with four forms of plotting (1 = 100% at planting, 2 = 1/2 at planting + 1/2 at 40 days after planting (DAP), 3 = 1/2 at planting + 1/2 at 90 DAP, 4 = 1/3 at planting + 1/3 at 40 DAP + 1/3 at 90 DAP), in addition to the control without K. In terms of biomass produced, the plant growth increases in soils with low and medium initial K concentration up to 145 and 115 kg ha-1 of K2O, respectively. In soils with a high initial concentration of K (≥ 3.0 mmolc dm-3), K fertilization did not contribute to the accumulation of dry matter of the plant, but reduces the biomass accumulation in the tuberous roots. In soil with low initial K concentration, the commercial yield increases up to 171 kg ha-1 of K2O, and in soils with a medium initial K concentration, the increase in commercial yield reaches rates between 106 and 111 kg ha-1 of K2O. However, under high initial availability of K, the commercial yield reduces with the potassium fertilization until the rate of 60 kg ha-1 of K2O. The split application of K (planting + 40 + 90DAP) was shown to be more efficient in increasing the commercial yield of sweet potatoes in all studied soils.
Among the majority of tuberous roots vegetables, potassium (K) is the most required mineral nutrient. However, the application of high rates of this nutrient may harm the plants development, due to the increase in saline concentration or even in large losses by leaching, especially in sandy soils. Thus, the purpose of this work was to evaluate the growth and yield of sweet potato submitted to rates and forms of K split application in soils with different K concentration. Four experiments were carried out in areas with different initial K availability in the soil (low = 0.7 mmolc dm-3, medium = 1.4 and 1.5 mmolc dm-3 and high = 3 mmolc dm-3) between 2016 and 2018. The experimental design was a randomized block design in the 3x4 + 1 factorial scheme. The treatments were represented by three doses of K2O (60, 120 and 240 kg ha-1) combined with four forms of plotting (1 = 100% at planting, 2 = 1/2 at planting + 1/2 at 40 days after planting (DAP), 3 = 1/2 at planting + 1/2 at 90 DAP, 4 = 1/3 at planting + 1/3 at 40 DAP + 1/3 at 90 DAP), in addition to the control without K. In terms of biomass produced, the plant growth increases in soils with low and medium initial K concentration up to 145 and 115 kg ha-1 of K2O, respectively. In soils with a high initial concentration of K (≥ 3.0 mmolc dm-3), K fertilization did not contribute to the accumulation of dry matter of the plant, but reduces the biomass accumulation in the tuberous roots. In soil with low initial K concentration, the commercial yield increases up to 171 kg ha-1 of K2O, and in soils with a medium initial K concentration, the increase in commercial yield reaches rates between 106 and 111 kg ha-1 of K2O. However, under high initial availability of K, the commercial yield reduces with the potassium fertilization until the rate of 60 kg ha-1 of K2O. The split application of K (planting + 40 + 90DAP) was shown to be more efficient in increasing the commercial yield of sweet potatoes in all studied soils.
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Ipomoea batatas, potássio, produtividade, potassium, yield