PUPUK UNTUK TANAMAN.

Tanaman untuk tumbuh, hidup dan subur selain perlu air juga diperlukan
nutrient. Nutrient pokok yang diperlukan tanamam adalah N,P,K. Nutrient ini
harus tersedia dalam takaran yang cukup dan seimbang di dalam tanah. Tidak
semua tanah mempunyai/mengandung N,P,K dalam takaran yang memadai  agar
tanaman dapat tumbuh subur. Ada tanah yang sedikit sekali mengandung N, atau
ada yang sedikit mengandung P atau K dan atau ketiga-tiganya. Untuk
mengetahui kandungan nutrient yang ada di dalam tanah pertanian yang
dimiliki dapat ditanyakan ke argonomies. Berdasarkan informasi dari
argonomies tersebut barulah diberikan pupuk (apakah pupuk organik atau pupuk
inorganik). Jumlah pupuk yang dibutuhkan petani untuk lahannya sangat
bergantung kepada seberapa banyak dari setiap unsur nutrient yang telah ada
dalam lahannya. Hal ini penting sekali untuk mencegah AGAR JANGAN TERLALU
BANYAK DUIT YANG DIKELUARKAN UNTUK PUPUK. Adalah sangat bijak untuk
mengirimkan sampel lahan / tanah ke laboratorium terlebih dahulu sebelum
penggunaan pupuk untuk mendapatkan campuran NPK yang sesuai.
Kelebihan pupuk inorganik terhadap pupuk organik adalah komposisi yang
terkandung dalam pupuk inorganik diketahui secara pasti lain halnya dengan
pupuk organik, sehingga pupuk inorganik sering sekali digunakan untuk
mendapatkan jumlah nutrient yang tepat di lahan pertanian.
Mengenai pupuk organik yang ada dipasaran pembeli / petani harap benar-benar
memperhatikan label yang menyatakan kandungan nutrient yang ada dalam pupuk
tersebut. Kebanyakan pupuk organik hanya mencantumkan label dengan bunyi
"Kandungan N maksimum ....., kandungan P maksimum ....., kandungan K
maksimum ....". Kalau seperti itu yang tertulis itu berarti produsen pupuk
organiknya menipu konsumen (petani), karena bisa saja pupuk tersebut hanya
mengandung 0.1 atau 1 % saja dan ini tidak bisa dituntut di pengadilan
karena produsennya tidak salah hanya petani saja yang tidak mengetahui. Juga
bagi produsen pupuk organik mungkin belum mempunyai alat untuk mengecek
kadar nutrinetnya, berhubung pupuk organik umumnya berasal dari "animal
manures and composted (rotting) plant material". Jika pupuk organiknya sudah
mempunyai standarisasi internasional pupuk organik dan inorganik dapat
dipakai. Bedanya pada lokasi dan area pemakaiannya, karena akan berakibat ke
ongkos pemupukannya.
Yang jadi pertanyaan saya, pupuk organik itu kandungan NPKnya relatif KECIL
dibandingkan pupuk inorganik tapi kok HARGANYA LEBIH MAHAL ?

PT. PUPUK SRIWIDJAJA sekarang ini akan mensuplai petani dengan produk baru
dengan nama FERTILIZER MIXTURES yaitu pupuk campuran yang mengandung unsur
nutrient N,P,K yang sesuai dengan tanah yang dibutuhkan. Untuk itu
tanah/lahan pertanaian terlebih dahulu dianalisa kandungan NPK yang
dimilikinya dan kemudian akan disuplai dengan FERTILIZER MIXTURES yang
tepat. Tunggu saja tanggal mainnya. Saat ini 3 pabrik kami sedang direvamp
untuk menaikkan kapasitas sebayak 30 % untuk memenuhi kebutuhan pasar. Urea
bukan saja dibutuhkan petani di Indonesia tapi juga di Vietnam, China,
Jepang, Eropa dsb karena dari urea dapat diolah lagi menjadi sulfamic acid,
isocianoric acid, monosodium glutamat, azodikarbonamide, melamine, glue
resin.

Dibawah ini saya attach-kan tulisan mengenai pupuk inorganik dan organik,
silahkan baca untuk menambah pengetahuan anda.

M. Ismet Ismail

Introduction
Plant roots take up water and nutrients from the soil. We all know that it
is very important that plants get enough water; we also need to make sure
that there are enough nutrients in our soils to allow the plants to grow
well. Fertilizers can be used to supply these nutrients. Both organic and
inorganic fertilizers may be used.

Types of fertilizers
The most common organic fertilizers are animal manures and composted
(rotting) plant material. In addition to supplying plant nutrients, organic
fertilizers improve the movement of water and air into soils, and make the
soil easier to till.
Inorganic fertilizers are chemicals sold in bags. Common examples are
fertilizer mixtures (such as 2:3:2 and 2:3:4), urea, limestone ammonium
nitrate (LAN), superphosphate (supers), diammonium phosphate (DAP),
mono-ammonium phosphate (MAP) and potassium chloride (KCI).
The most important plant nutrients are N (nitrogen), P (phosphorus) and K
(potassium).
· Organic fertilizers contain N, P and K in small quantities.
· Fertilizer mixtures contain N, P and K in fairly large quantities.
· Other fertilizers contain one or two of the nutrients:
o Urea and LAN contain N
o Supers contains P
o KCI contains K
o DAP and MAP contain P and N

Phosphorus (P) and Potassium (K)
The amount of P and K fertilizer needed for a good crop depends on how much
P and K is already in the soil. Soils can be tested at Cedara to find out
how much P and K needs to be added as fertilizer.
Most KwaZulu-Natal soils are very deficient in P, and large amounts of P
fertilizer are often necessary for satisfactory yields (Figure 1). For
example, many fields require 40 to 60 kg of P/ha; this is equivalent to a
recommendation of four to six bags of DAP per hectare (four to six 500mL oil
tins of DAP for a 10 m x 10 m plot).
Levels of K in the soils of KwaZulu-Natal vary from very low to very high.
At Makatini, and in the Tugela valley, there is often enough K in the soil
for good crop growth. In areas with higher rainfall, soil K levels are often
very low, especially where crops have been grown for many years without K
fertilizer. For example, some fields may need as much as eight bags ofKCI
per hectare (seven 500 mL tins per 10 m x 10 m plot).

P and K are both important for crops. If the soils are deficient in these
nutrients, and none is applied, the crop will be poor. It is important to
remember that fertilizer that has no P (such as LAN) will not improve a crop
if there is little P in the soil.  If P and K fertilizers are applied this
year, but it does not rain, and the crop does not grow, the fertilizer
remains in the soil and will be useful for the next year's crop.  However,
more P fertilizer will need to be added when the next crop is planted
because the soil holds tightly onto the P, making it difficult for the
plants to use.

Nitrogen (N)
The amount of N fertilizer needed depends on the type of crop,the type of
soil, and the expected yield.
· In most soils in KwaZulu-Natal that are not sandy, very little N is needed
to produce a reasonable maise crop (4 t/ha).
· Crops on sandy soils need more N than those on clayey soils.
· Some crops (such as soyabeans and cowpeas) produce their own N and do not
need N fertilizer; they also leave N in the soil for the following crop to
use.
If there is little P or K in the soil, or the soil is acid, N fertilizer
will not improve the crop.
However, if soil P and K are adequate, and acidity not excessive, and lands
are well tended, a good crop may be possible, and N fertilizer will often
help improve the crop. Very good maise yields (7 t/ha) require 120-160 kg
N/ha (8-10 oil tins of LAN for a 10 m x 10 m plot).

What fertilizer to use
If organic fertilizers (manures) are available close to where crops are
being grown, they are often cheaper to use than inorganic fertilizers.
However, if fertilizer needs to be transported some distance to the fields,
inorganic fertilizer is often cheaper to use, because smaller quantities are
needed to get the same crop improvement.
Some farmers use both organic and inorganic fertilizers; the inorganic
fertilizers are used to ensure that the crop gets the correct balance of
nutrients. Other farmers use more than one type of inorganic fertilizer if
there is no fertilizer mixture with the right balance of nutrients for their
soil.
Some inorganic fertilizers used often are:
· MAP or DAP - if no K is needed. These supply P and some N.
· 2:3:2 - if some K is needed as well as P and N.
· 2:3:4 - if more K is needed as well as P and N.
· DAP together with KCI - if a lot of K is needed.
· Supers (superphosphate) - can also be used to supply P, but is more
expensive than DAP for a particular amount of P; it is also more bulky to
transport.
· LAN or Urea - these are used if more N is needed - they can be applied
when the crop is already growing (but they should be used when the crop is
still fairly small).
The amount of fertilizer the farmer needs depends on how much of each of the
nutrients is already in the soil; to before spending a lot of money on
fertilizer, it is usually worthwhile sending soil samples to a laboratory
that can supply a fertilizer recommendation. The recommendation will provide
information regarding which fertilizer to buy, and how much to use.



----- Original Message -----
From: fendi KOTO <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Cc: Heri Hansyah <[EMAIL PROTECTED]>
Sent: Friday, March 01, 2002 4:33 AM
Subject: [RantauNet] Organik versus konvensional


> >
> Da Eri bisa sajo mandapek bahan caro batani organik itu dari ambo. Nan
jaleh
> pertanian organik (SA=sustainable agriculture) atau petanian ramah
> lingkungan, sabananyo sangat mauntungkan. Tambah pulo trend konsumsi
urang-urang
> golongan menengah ke atas adolah berasal dari produk pertanian organik.
Karano
> haragonyo memang agak maha dari produk pertanian konvensional (kimia-an
> organik). Pertanian organik indak pakai pupuk kimia pusri, racun pabrik,
dan benihnyo
> saeloknyo banih lokal. Hingga nan dimakan konsumen memang batua sehat,
indak
> maracun urang. Walaupun produk nan dihasilkan sacaro konvensional alah
> dicuci barulang-ulang, tapi residunyo tatap ado. Nah, residu ikolah nan
marusak
> kesehtan kito. Mudah diserang panyakik. Racun iko basifat karsinogen nan
bisa
> manyababkan kanker rahim, peradangan utak. Jadi ambo raso banyak utak
urang
> nan sakik (kerusahan2, KKN, pemimpin nan egois) adolah karano infeksi
racun
> kimia iko mungkin. Tambah pulo agamo alah manyuruh, makanlah makanan nan
sehat
> dan halal. Tapi awak maracun diri surang. Ambo walau ekonomi pas-pasan
memang
> indak namuah makan sayua atau buah nan dihaasilkan sacaro konvensional.
> Labiah lamak juo nan asli.
>
> .
> --
> GMX - Die Kommunikationsplattform im Internet.
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