faiz barchia

SERAPAN N, P, K DAN BERAT TANDAN BUAH SEGAR SAWIT
PADA TANAH MINERAL MASAM BENGKULU

Oleh
Muhammad Faiz Barchia

Abstract

Yields of oil palm are related to nutrients in plant, and the content indicates how optimum of the nutrients for the plant growth. The nutrient content in plant could be used as guidelines for fertilizer application. The yields of the oil palm were classified into three groups; low yields were the weight of 12.91 + 3.5 kg fruit-bunch-1, moderate weights with 19.92 + 3.5 kg fruit-bunch-1, and high yields with weight of 26.93+ 3.5 kg fruit-bunch-1. N uptake was related to the yields of oil palm as an equation :
N = -0.0063(TBS)2 + 0.3445(TBS) - 1.8168, (R2 = 0.865). Optimum yield of the palm based on dN/d(TBS) = 0, namely; 27.3 kg fruit-bunch-1. Furthermore, the weight of fruit bunch based on N uptake: TBS = -20.851N2 + 102.17N - 93.648, (R2 = 0.919). N uptake based on d(TBS)/dN = 0, was 2.45 %.
P uptake relating to the yield of the palm such as an equation :
P = 3E-05(TBS)2 + 0.0029(TBS) + 0.0328, (R2 = 0.8992), and the yield based on dP/d(TBS) = 0, was 48.3 kg fruit-bunch -1. Also, the weight of the fruit bunch based on P uptake as follow : TBS = 371.28P2 + 126.96P + 2.0332, (R2 = 0.8991), and P uptake related to d(TBS)/dP = 0, was 0.17 %. Absorption of P nutrient by the oil palm was low as much as the level of deficiency values for plant growth.
K absorption by the oil palm for the growth was as :
K= -2E-05(TBS)2 + 0.0012(TBS) + 0.0054, (R2 = 0.8888), and the TBS yield based on dK/d(TBS) = 0, was the weight of 30.0 kg fruit-bunch-1. At the same time, the TBS yield as followed: TBS = 527630K2 – 17723K + 161.43, (R2 = 0.8402), and based on the equation and d(TBS)/dK = 0, the K uptake was 0.0168%. K absorption was very low and the values in the range of deficiency level for the optimum plant growth. In order to improve the oil palm productivities, fertilizers application should be manage in the range of optimum level.

Keywords : N, P, K uptake, nutrient deficiencies, yield of oil palm

PENDAHULUAN

Produksi kelapa sawit pada tanah mineral masam di Indonesia jauh di bawah potensi genetik dan kesesuaian lahannya (Koedadiri, dkk. 1997). Potensi produksi kelapa sawit pada tanah mineral masam di beberapa kebun di Kalimantan Barat baru mencapai 61% dan Kalimantan Timur 63% sedangkan di Riau baru mencapai 63% dan Sumatera Utara 77% terhadap standar potensi lahan kelas S-3, (Poeloengan, dkk. 1998). Rendahnya produksi ini berkaitan dengan tingkat pengelolaan pupuk dan ketersediaan hara tanaman yang tidak optimal. Hasil buah kelapa sawit sangat dipengaruhi oleh unsur hara yang terkandung di dalam tanaman, diatara unsur hara yang paling berpengaruh adalah unsur hara nitrogen, fosfor, dan kalium (Sutedjo, 1992).
Besarnya unsur hara yang diperlukan dan terdapat pada tanaman kelapa sawit berkaitan erat dengan besarnya unsur hara yang terdapat pada buah pada saat panen. Pada tingkat produksi 25 ton TBS ha-1 tahun-1, unsur hara yang terangkut bersama TBS sebesar 73.2 kg N, 11.6 kg P, dan 93 kg K ha-1 tahun-1 (Sukardji, dkk. 2000). Produksi buah kelapa sawit berhubungan dengan unsur hara yang terdapat pada tanaman itu sendiri, serta dapat menjadi indikator kondisi unsur hara yang terdapat pada tanaman. Produksi tanda buah segar kelapa sawit yang mengandung unsur hara N sebesar 1.09%, P sebesar 0.015%, dan K sebesar 0.02% selama masa panen 13 tahun menunjukkan rata-rata hasil sebesar 15.7 ton TBS ha-1tahun-1 (Pangudijatno, 1987). Tanaman kelapa sawit pada fase produktif dapat menyerap hara sebesar 192.0 kg N, 26 kg P, 251 kg K, 89,3 kg Ca, dan 61, 3 kg Mg kg ha-1th-1, dan yang terangkut oleh hasil panen keluar dari areal kebun sebesar 73.2 kg N, 11.6 kg P, 93 kg K, 19.5 kg Ca, 20.8 kg Mg (Ng dan Cheong, 1985). Tingkat kandungan unsur hara tanaman perlu diketahui sebelum melakukan pemupukan.