Attributes of the soil with cactus pear under organic fertilization, different spacings and sampling times/Atributos do solo com palma forrageira sob adubacao organica, diferentes espacamentos e epocas de amostragem

The objective of this study was to evaluate the chemical attributes of the soil cultivated with 'Gigante' cactus pear under different doses of organic fertilizer, planting spacings and sampling times. Four doses of organic fertilizer with bovine manure (0, 30, 60 and 90 Mg [ha.sup.1] [year.sup.-1]), three spacings (1.0 * 0.5, 2.0 * 0.25 and 3.0 * 1.0 * 0.25 m) and three sampling times (0, 390 and 600 days after planting) corresponding to the periods prior to planting, growth and harvest of the first cycle, were evaluated in a randomized block design in a 4 * 3 * 3 factorial scheme, with three repetitions. The pH in water, macronutrients (P, K, Ca, Mg), micronutrients (B, Cu, Fe, Mn, Zn), variables of the soil sorption complex (H + Al, SB, CEC, T, V) and soil organic matter (SOM) were determined. Organic fertilization increased the values of SOM, P, K, Ca, Mg, SB, CEC, T and V and reduced H + Al in soils cultivated with 'Gigante' cactus pear at different times. The doses of manure increased pH and Mn, regardless of sampling time and spacing. The spacings did not influence the chemical attributes of the soil. Key words: Opuntia, planting arrangements, fertility, nutrients Objetivou-se com este estudo avaliar os atributos quimicos do solo cultivado com palma forrageira 'Gigante' sob diferentes doses de adubo organico, espacamentos de plantio e epocas de amostragem. Foram avaliadas quatro doses de esterco bovino (0;30;60 e 90 Mg [ha.sup.1] [ano.sup.-1]),tres espacamentos (1,0 * 0,5; 2,0 * 0,25 e 3,0 * 1,0 * 0,25 m) e tres epocas de amostragem de solo (0; 390 e 600 dias apos plantio) correspondentes as epocas antes do plantio, crescimento e colheita do primeiro ciclo, dispostos no delineamento experimental em blocos casualizados em esquema fatorial 4 * 3 * 3, com tres repeticoes. Foram determinados o pH em agua, macronutrientes (P, K, Ca, Mg), micronutrientes (B, Cu, Fe, Mn, Zn), variaveis do complexo sortivo do solo (H + Al, SB, CTC, T, V) e materia organica do solo (MOS). A adubacao organica incrementou os valores de MOS, P, K, Ca, Mg, SB, CTC, T, V, e diminuiu o de H + Al nos solos cultivados com palma forrageira 'Gigante' em diferentes epocas. As doses de esterco incrementaram o pH e Mn, independentemente de epoca e espacamento. Os espacamentos nao influenciaram nos atributos quimicos do solo. Palavras-chave: Opuntia, arranjos de plantio, fertilidade, nutrientes