An experiment was carried out in two provinces of Ecuador, at the Equinoctial Technological University (UTE, Campus Santo Domingo; Santo Domingo de los Tsáchilas) and the Laica Eloy Alfaro de Manabí University (ULEAM, Extension in El Carmen, Manabí), to evaluate the export and efficiency in the use of nutrients in ‘Barraganete’ (Musa paradisiaca L.) plantain.
Four levels of fertilization with N and K2O were used (0-200, 80-200, 120-200, 160-200, 120-0, 120-150 and 120-250 kg · ha-1 of N-K2O, respectively) , over 2,500 plants · ha-1 (spacing 2 mx 2 m). The variables evaluated were nutrient concentration (N, P, K, Ca and Mg), nutrient export (N, P, K, Ca and Mg), agronomic efficiency (EA), partial productivity factor (FPP), partial balance of nutrients (BPN) of N and K. The export of nutrients for all the elements was generally higher with the doses of 120-150 kg · ha-1 of N-K2O, except for the export of P that was higher with the dose 120-200 kg · ha-1 of N-K2O; the UTE was the locality that presented the highest nutrient exports.
The EAN and EAK were higher with the doses of 120-200 kg · ha-1 of N-K2O in the UTE (42.88 and 10.69 kg of fruit · kg · ha-1 of N-K2O, respectively), while in ULEAM the highest EAN was observed with the dose 120-250 kg · ha-1 of N-K2O (43.65 kg of fruit · kg · ha-1 of N-K2O) and that of the EAK was presented with the dose 120-150 kg · ha-1 of N-K2O (16.22 kg of fruit · kg · ha-1 of N-K2O), the K2O doses applied showed a positive influence on the EAN, being higher than the EAK in the two study locations, the ULEAM had a higher EAN and EAK. In relation to the FPP in the two study locations, the behavior was inverse between the FPPN and the FPPK; As the applied N doses increased and the K2O dose remained fixed, there was a decrease in the FPPN (307.03 to 168.26 and 258.23 to 140.76 kg of fruit · kg · ha-1 of N- K2O, respectively for the UTE and ULEAM); on the contrary, when the N dose was fixed and the applied K2O dose was increased, an increase in the FPPN was observed in both the UTE and the ULEAM (221.06 to 233.33 and 162.67 to 190, 52 kg of fruit · kg · ha-1 of N-K2O, respectively).
In the case of the FPPK the effect was contrary to that presented in the FPPN, that is, as the dose of N applied increased and the dose of K2O remained fixed, there was an increase in FPPK (117.60 to 143.33 and 88 , 13 to 112.94 kg of fruit · kg · ha-1 of N-K2O, respectively for the UTE and ULEAM); with the exception of the dose 160-200 kg · ha-1 of N-K2O that in both locations generated a decrease in FPPK (134.60 and 112.60 kg of fruit · kg · ha-1 of N-K2O for the TEU and ULEAM, respectively); on the contrary, when the dose of N was fixed and the dose of K2O applied was increased, a decrease in FPPK was observed in both the UTE and the ULEAM (180.83 to 112 and 146.36 to 91.45 kg of fruit · kg · ha-1 of N-K2O, respectively). The BPNN and the BPNK had a similar trend to the FPPN and the FPPK, only that in the FPPN with the dose 120-250 kg · ha-1 of N-K2O there was a decrease of the BPNN in both locations, the N influenced the export of the K through the fruit, with a higher BPNK at a higher dose of N. The nutrients with the highest export for fruits in both the UTE and the ULEAM were K, Ca and N. The EAN, the FPPN and BPNN were higher in both localities that the same indexes related to K.