Physical and chemical segregation of mixed fertilizers

Abstract

In Brazil, mixed fertilizers are used as the main kind of fertilization at sowing time; however, the quality of mixed fertilizers and the occurrence of segregation may alter the applied fertilizer amounts. This study aimed to evaluate physical and chemical segregation of mixed fertilizers in sowing fertilization, in a no-tillage system. A completely random experimental design in a 4x6 factorial arrangement was used with four mixed fertilizers, six sampling moments and three replications. The mixed fertilizers consisted of the following granular mixtures : () 4-4-8+0.3% Zn, (2) 4-4-8+3% Ca+8% S, and (3) 4-4-8+4% Ca+% S, and a granular mixed fertilizer (4) 8-28-6+0.3% Zn. The mixtures in the fertilizer deposit were sampled at 6 moments: () when the deposit was full and after (2) 20%, (3) 40%, (4) 60%, (5) 80%, and (6) 00% of the mixtures had come out of the deposit. The physical segregation occurred both in the granular mixture and in the granular fertilizer, and the highest amounts of particles were found on top of 2 mm and 0.5 mm mesh screens. The movement of the seeding-fertilizing machine intensified the segregation. As to the chemical segregation, alteration of the nutrient distribution occurred along the application area, mainly for Zn. Physical and chemical segregation occurred due to the seeding-fertilizing machine movement and the fertilizer deposit lowering which allow the deposit of smaller particles at the beginning of the process and the larger ones at the end. Additional keywords: chemical fertilizer; segregation; mixed fertilizer; granular mixture.