Oil palm plantations change land into desert.

Perkebunan kelapa sawit dalam jangka panjang akan menyebabkan lahan menjadi tandus sehingga areal perkebunan sawit akan berubah menjadi gurun.

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Common sense alone would make it easy to comprehend that any plant on Planet Earth functions to preserve to environment. There is no theory that says plants damage the environment. Plants were created by God. On the contrary, we are asked to cultivate plants to help improve the environment. The “1 million plant movement” has long been carried out by officials, including by environmental activists. The Arabian countries, which have many deserts, are trying to green their deserts by planting vegetation, including palm species – namely dates.

As early as 1911 (104 years ago) Indonesia developed oil palm plantations on Raja Island (Asahan, North Sumatra),  Tanah Itam Ulu (Batubara regency, North Sumatra) and Sei Liput (Aceh), which thus far still exist and have not changed into deserts. On the contrary, the productivity of the existing oil palm plantations even continues to increase.

Many studies also prove that biomass (one of the important components for soil fertility) on oil palm plantations increases in line with the advancing age of the oil palm plants. Chan (2002) discloses that the older the oil palm, the larger the volume of biomass produced (Table). Four-yea- old oil palm plants produce about 40 tons of biomass per ha per year, which increases to about 93 tons by the age of 15. By the age of 24 (the age for rejuvenation), the production of biomass reaches its peak, namely about 113 tons per ha per year. When the plantations are rejuvenated, the biomass is left in the soil.

Then, a part of the biomass that is harvested in the form of fresh fruit bunches is returned to the plantation areas. Out of oil palm production of 24 tons per ha per year, only about 5 tons are processed into palm oil and the remaining 19 tons remain in the form of biomass, namely empty fruit bunches, shells and sludge, which are all returned to the plantation areas to maintain fertility.

Besides by adding back biomass, soil fertility is also maintained by providing fertilizer in accordance to the age and productivity of the plants.

Table   Biomass volume and carbon stocks on oil palm plantations

Age

(year)

Biomass stocks

(tons/ha)

Carbon stocks

(tons/ha)

1-314.55.80
4-840.316.12
9-1370.828.32
14-1893.437.36
19-24113.245.28
>25104.541.00

Source:  Chan, K.W (2002).

 

Oil palm Carbon Sequestration and Carbon Accounting: Our Global Strength. MPOABiomass content is not only increased above ground, but also underground in the oil palm rooting zone, the rhizosphere, specifically in the oil palm root bio-pores (Figure).

The older the oil palm, the more organic ingredients are stored in the ground bio-pores. Therefore, if the organic ingredients are returned to the ground, the fertility of the oil palm plantation areas will not decline. Moreover, the oil palm plantation management system provides fertilizer based on the principle of at least replacing the nutrients contained in the fresh fruit bunches being harvested so as to render impossible a decline in soil fertility that would create a desert.

The experience of soybean farming in the US can provide an analogy. The US’ soybean farms now cover 34 million ha and are more than 100 years old. The soybean farms produce less than about 20 percent of the biomass produced on oil palm plantations. Have the soybean farms in the US changed into infertile desert? Of course not. If the soybean farms where only a small quantity of biomass is returned to the farm areas (compared to oil palm plantations) do not change into desert, then oil palm plantations will not change into deserts either.

Nalar umum (common sense) saja sangat mudah memahami bahwa tanaman apa pun di planet bumi ini berfungsi sebagai pelestarian lingkungan hidup. Tidak ada satu teori pun yang mengatakan tanaman itu merusak lingkungan. Tumbuhan/ tanaman diciptakan Tuhan. Bahkan sebaliknya, kita diminta menanam tanaman apa saja untuk perbaikan lingkungan. Gerakan tanam sejuta tanaman/pohon sejak dahulu sering digerakkan oleh para pejabat temasuk aktivis lingkungan. Di negara-negara Arab yang banyak gurun, justru sedang berupaya dihijaukan dengan menanam tanaman termasuk tanaman palma yakni kurma.

Indonesia sejak tahun 1911 (104 tahun silam) sudah mengembangkan perkebunan kelapa sawit yakni di Pulu Raja (Asahan, Sumatera Utara), Tanah Itam Ulu (Kab. Batubara, Sumatera Utara) dan Sei Liput (Aceh) yang sampai sekarang masih tetap kebun sawit dan tidak berubah menjadi gurun. Bahkan sebaliknya kebun sawit yang ada justru produktivitasnya semakin meningkat.

Banyak penelitian juga membuktikan bahwa biomas (salah satu komponen penting kesuburan lahan) pada kebun sawit meningkat dengan semakin tua umur kelapa sawit. Chan (2002) mengungkapkan bahwa dengan semakin tua umur kelapa sawit volume biomas yang terbentuk makin meningkat (Tabel). Tanaman kelapa sawit umur 4 tahun, menghasilkan biomas sekitar 40 ton per hektar/tahun, kemudian meningkat menjadi sekitar 93 ton pada umur 15 tahun. Pada saat umur 24 tahun (umur peremajaan kembali) volume biomas mencapai puncak yakni sekitar 113 ton/ha/tahun. Dan ketika diremajakan kembali, biomas tersebut dibiarkan di lahan untuk kesuburan lahan.

Kemudian, dari biomas yang dipanen berupa buah sawit (Tandan Buah Segar) sebagian besar kembali ke lahan. Jika produksi buah sawit 24 ton/ha/tahun, maka minyak sawit yang diambil (dijual) hanya sekitar 5 ton dan 19 ton sisanya merupakan biomas yakni berupa tandan kosong, cangkang dan lumpur (sludge) yang semuanya dikembalikan ke lahan agar tetap subur.

Selain dari penambahan biomas tersebut, untuk mempertahankan kesuburan lahan juga dilakukan penambahan kesuburan lahan melaui pemupukan sesuai dengan umur dan produktivitas tanaman.

Tabel     Volume Biomas dan Stok Karbon pada Perkebunan Kelapa Sawit

Umur

(tahun)

Stok Biomas

(ton/ha)

Stok Karbon

(ton/ha)

1-314,55,80
4-840,316,12
9-1370,828,32
14-1893,437,36
19-24113,245,28
>25104,541,00

Sumber:     Chan, K.W (2002). Oil palm Carbon Sequestration and Carbon Accounting: Our Global Strength. MPOA

 

Kandungan biomas yang makin meningkat bukan hanya terjadi pada biomas di atas tanah (above ground biomass) tetapi juga di dalam tanah zona perakaran kelapa sawit (rhizosphere) yakni pada biopori-biopori perakaran kelapa sawit (Gambar).

Semakin tua umur kelapa sawit semakin meningkat bahan organik yang tersimpan di dalam biopori tanah. Dengan demikian jika bahan organik tetap dikembalikan ke tanah, kesuburan tanah perkebunan kelapa sawit tentu tidak mengalami penurunan. Selain itu, sistem pengelolaan perkebunan kelapa sawit dimana pemberian pupuk didasarkan pada prinsip minimal mengganti hara yang terikut dalam TBS yang di panen, maka kemungkinan penurunan kesuburan tanah menjadi gurun hampir tidak mungkin.

Pengalaman Amerika Serikat dengan kebun kedelainya juga dapat menjadi analogi. Kebun kedelai Amerika Serikat saat ini yang luasnya 34 juta hektar, sudah berumur lebih dari 100 tahun. Kebun kedelai hanya menghasilkan biomas yang jauh lebih kecil (sekitar 20 persen) dari biomas yang dihasilkan kebun sawit. Apakah kebun kedelai Amerika Serikat sekarang berubah menjadi gurun-tandus? Tentu tidak bukan. Jika kebun kedelai yang biomasnya hanya sedikit saja kembali ke lahan (dibanding kebun sawit) tidak menjadi gurun, tentu kebun sawit tidak akan jadi gurun.

Figure The content of organic and c-organic ingredients in the oil palm rooting zone increases with age of growing oil palm

The content of organic and c-organic ingredients in the oil palm rooting zone increases with age of growing oil palm

Source : Harianja, 2009

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