Influences of N, P, K, Ca, and Mg fertilization on soil characteristics and nutrient uptake of ratoon pineapple (Ananas comosus L.) in acid sulfate soil

Ratoon pineapple is a type of pineapple that grows from the existing sucker of a former plant. In this way, the production cost can be decreased while the yield can be increased. Therefore, the study aimed to determine the effects of applying N, P, K, Ca, and Mg nutrients on soil features, nutrient uptake of ratoon pineapple, and its growth and yield. An omission plot trial was conducted on pineapple in acid sulfate soil following a completely randomized block design with 8 treatments and 4 replications each. The treatments included (i) NF: no fertilizer, (ii) NPKCaMg: N, P, K, Ca, and Mg fertilization, (iii) PKCaMg: no N fertilization, (iv) NKCaMg: no P fertilization, (v) NPCaMg: no K fertilization, (vi) NPKMg: no Ca fertilization, (vii) NPKCa: no Mg fertilization, (viii) LFF: local farmer fertilization. The result revealed that the PKCaMg treatment reduced N availability (NH4+) and the NKCaMg treatment reduced soluble P content in the soil, compared with the fertilized treatments. The NKCaMg treatment also reduced insoluble P compounds such as Al-P and Ca-P. Likewise, the NPKMg and NPKCa treatments decreased Ca2+ and Mg2+ concentrations in the soil. The treatments without N, P, K, Ca, or Mg reduced crown, pulp, core, peduncle, butt, and leaf biomass. The treatments without N, P, K, Ca, or Mg also decreased the corresponding nutrient uptake of pineapple. Pineapple yield declined by 28.5, 20.9, 20.1, and 20.1% when N, P, Ca, and Mg were omitted, respectively. The N, P, K, Ca, and Mg fertilizer formula was optimized as 462 N, 341 P2O5, 510 K2O, 1207 CaO, and 618 MgO kg ha-1.