Nutrient cycling in sugarcane. III. Nutrient contents and root distribution in the soil

Abstract

Sugarcane root biomass and its nutrient content were measured in a field experiment with two nitrogen treatments (no nitrogen, and 60 kg.ha^-1 of N) on a sandy Red-Yellow Podzolic soil at the Unidade de Execução de Pesquisa (EUP) at Itapirema (Goiana, PE, Brazil). Roots, underground stems and seed cuttings were collected separately 3, 6, 11 and 16 months after planting by sieving 1 m³ of soil, in triplicate, being 0,8 m along the furrow, 1 m deep (subdivided each 0,2 m) and 1,25 m wide. The only significant differences between N treatments occurred in relation to the root weights at the 6 and 16 month samplings. Total underground weight reached a maximum of 6,5 t.ha^-1 at the eleven month sampling, 30% - 40% of it corresponding to root weight. All the stems and seed cuttings plus 75% of the total root mass were found in the 0 cm - 20 cm layer. The amounts of nutrients in the underground parts were small compared to those of the aboveground parts, reaching a maximum of 22, 2, 9, 6 and 4 kg.ha^-1 of N, P, K, Ca and Mg and 80, 50, and 30 g.ha^-1 of Zn, Mn, and Cu, respectively.