Performance evaluation of phonolite through mineral form and enrichment of filter cake in sugarcane ratoon
In order to evaluate the performance of phonolite as a source of potassium in fertilization management of sugarcane ratoon through mineral and organo-mineral forms, an experiment was installed in November of 2011 in Casa Branca, SP, Brazil, in soil type red-yellow Latosol Dystrophic medium texture, with variety SP 801816, in third yield, harvested mechanically with no fire. The experiment was designed using random blocks with four replications. The treatments were: T1-Control; T2- Mineral Phonolite 8.5% dose 70 kg ha-1 of K2O; T3- Mineral Phonolite 8.5% dose 100 kg ha-1 of K2O; T4- Mineral Phonolite 8.5% dose 130 kg ha-1 of K2O; T5- Mineral Phonolite 14% dose 100 kg ha-1 of K2O; T6- Mineral KCl 58% dose 100 kg ha-1 of K2O; T7- Organo-mineral KCl 58% dose 100 kg ha-1 of K2O; T8- Organo-mineral Phonolite 8.5% dose 70 kg ha-1 of K2O; T9- Organo-mineral Phonolite 8.5% dose 100 kg ha-1 of K2O; and T10- Organo-mineral Phonolite 8.5% dose 130 kg ha-1 of K2O. The following components were evaluated: sugarcane ratoon productivity, and potassium levels in soil and leaves. It was observed that productivity and potassium levels in soil and leaves were significantly affected by treatments. The treatments with potassium provided an average increase of productivity and potassium absorption of 21% and 59%, respectively, compared to the control treatment. Regarding the three sources of potassium, all were used in mineral form and in doses of 100 kg ha-1 of K2O (T3, T5 and T6). They did not show any significant difference in productivity. Regarding the organo-mineral form and the dose 100 kg ha-1 of K2O, a significant difference was observed between potassium sources. The filter cake enriched with phonolite 8.5% provided a productivity increase of 21% compared to the cake enriched with KCl. The three doses of potassium using phonolite 8.5% did not show significant increments in productivity with increased doses (70, 100 and 130 kg ha-1 of K2O), for both mineral and organo-mineral forms. However, the overall mean for the three doses used in organo-mineral form (T8+T9+T10) indicated a productivity increase of 15% compared to the mineral form.