Alternative sources of phosphorus in beet production aiming at the organic system

Fontes alternativas de fósforo na produção de beterraba visando ao sistema orgânico

ABSTRACT

The demand for beet produced in the organic system has increased. This study aimed to evaluate the beet production with the use of different proportions of phosphorus sources. A randomized block design was used. The treatments were established in a 6 x 2 + 1 factorial arrangement, corresponding to 6 proportions of the phosphorus fertilizers Yoorin® thermophosphate (YT) and bone meal (BM) (100 % of P₂O₅ with YT; 80 % of P₂O₅ with YT + 20 % of P₂O₅ with BM; 60 % of P₂O₅ with YT + 40 % with BM; 40 % of P₂O₅ with YT + 60 % with BM; 20 % of P₂O₅ with YT + 80 % with BM; and 100 % of P₂O₅ with BM), 2 doses of P₂O₅ (180 - recommended - and 360 kg ha^-1) and 1 control without these phosphorus fertilizers. The plant height, number of leaves, root and shoot fresh and dry weight, transverse and longitudinal root diameter and total root yield were evaluated. The recommended fertilizer dose resulted in higher values, when compared to twice the recommendation. The proportion of 0 % of thermophosphate and 100 % of bone meal provided the highest mean values for the evaluated parameters. High phosphorus doses showed to be harmful to beet production.

KEYWORDS:
Beta vulgaris L.; thermophosphate; bone meal; organic fertilization