Resposta do cafeeiro à adubação potássica em safras de baixa e alta produção

Abstract

Foram realizados dois experimentos em lavouras cafeeiras das Fazendas Experimentais da Epamig, em Minas Gerais, com o objetivo de estudar a resposta do cafeeiro à adubação potássica (fontes e doses) nas safras de baixa e alta produção em dois Latossolos. Os experimentos foram instalados em lavouras de café da cultivar Catuaí Vermelho, linhagem MG-99, plantadas seis anos antes, no espaçamento de 3,5 x 0,7 m. O delineamento experimental foi em blocos casualizados, com quatro repetições, no esquema de parcelas subdivididas. Nas parcelas, foram aplicadas as fontes de K: cloreto de potássio, sulfato de potássio e nitrato de potássio; e nas subparcelas, as doses de K (0, 100, 200 e 400 kg ha-1). Foram avaliados a produção de grãos de café beneficiados, os teores de K disponível no solo (Mehlich-1) e nas folhas durante quatro safras (1995 a 1998): duas safras baixas (1995 e 1997), e duas altas (1996 e 1998), em ambos os solos. A resposta do cafeeiro às doses de K é diferenciada entre as safras de baixa e alta produção. A alternância de produção do cafeeiro mostra que, nessa cultura, os níveis críticos de K no solo e nas folhas devem ser obtidos em safras de alta produção.

Effect of potassium sources and rates on arabica coffee yield, nutrition, and macronutrient export

“…According to Matiello et al (2010), N and K are the most required nutrients by coffee trees, but N is the most required in the low-yielding growing season (leaf growth) and K is the most required in the high-yielding growing season (fruit and grain filling). The results are consistent with those of Silva et al (2001), who demonstrated that this behavior is due to greater nutrient uptake and thus, a higher nutrient export in the high-yielding growing season.…”

“…According to Alvarez V. et al (1999), the probability of coffee response to K fertilization is high, if soil K concentration ranges from 1.0 to 1.75 mmol c dm -3 . Nevertheless, Silva et al (2001) observed K fertilization effects on coffee when soil K concentration in a Red Latosol was 1.8 mmol c dm -3 and the highest yields were harvested at a mean available soil K of 6.4 and 4.0 mmol c dm -3 K (Mehlich-1) in low and high-yielding growing seasons, respectively.…”

“…However, for all treatments with K application, leaf K concentration was within the range from 18 to 25 g kg -1 , considered appropriate according to Raij et al (1997), but below the 22 to 25 g kg -1 proposed by Malavolta et al (1997). Nevertheless, Silva et al (2001) studied K sources and application rates to coffee cultivar Catuaí Vermelho MG-99 in a growing season with high coffee yield and found that greatest yields were reached at leaf K concentration of 16.7 and 14.2 g kg -1 on a Red Latosol and Red-Yellow Latosol, respectively. Therefore, the appropriate rates depend on several factors, including sampling time.…”

“…Oliveira & Pereira (1987) also reached highest yields with the application of 200 kg ha -1 of K 2 O in form of KCl for cultivar 'Catuaí Amarelo', with soil K of 1.0 mmol c dm -3 ; these conditions were very similar to those of this study. Silva et al (2001) studied the effects of K sources (KCl, potassium sulfate (K 2 SO 4 ) and potassium nitrate (KNO 3 )) as well as K rates applied to cultivar Catuaí Vermelho MG-99, and reported that the maximum coffee green bean yield could not be reached by applying the highest K 2 O rate (482 kg ha -1 ) in the (2) Values followed by the same letter in the row, for sources, are not significantly different at 5 % by the LSD test, in the analysis considering only factorial. ns: not significant; * and ** are significant at 5 and 1 %, respectively, by the t test.…”

“…Potassium plays a role in photoassimilated compounds translocation for bean formation, increasing their weight and volume as well as activating maturation (Malavolta et al, 1974), therefore, it is removed in large quantities by coffee, especially from well-nourished trees and in growing seasons with higher yields (Silva et al, 2001).…”