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PENTINGNYA NITROGEN
BAGI TANAMAN TEBU
Bahan kajian MK. Pupuk dan Pemupukan
Diabstraksikan oleh Prof Dr Ir Soemarno MS
Jur Tanah FPUB September 2011
Defisiensi N sering terjadi pada tanaman tebu yang ditanam pada tanah-tanah
berpasir. Aplikasi pupuk N secara bertahap selama musim pertumbuhan tanaman
tebu diperlukan untuk mencapai produksi tebu yang baik pada tanah-tanah
berpasir, yang biasanya kandungan bahan organic tanahnya rendah. Kegagalan
mensuplai cukup N pada fase pertumbuhan kritis mengakibatkan tanaman kerdil,
pemasakan premature, dan hasil biomasa serta hasil gula menurun (The Institute of
Food and Agricultural Sciences, IFAS, University of Florida).
Muchovej and Newman (2004) (Southwest Florida Research
and Education Center, University of Florida, Institute of Food
and Agricultural Science, 2686 State Road 29 North, Immokalee,
FL 34142-9514).
“There is limited information on the impact of N fertilizer applied to
sugarcane on sandy soils regarding soil and groundwater quality. This study
determined soil and groundwater characteristics as affected by varying N
rates on a sandy soil planted to sugarcane cultivar CP 78- 1628. Three rates
of N fertilizer (170, 280, and 390 kg N ha-1 yr-1) were evaluated. The N rates
were divided into four split applications. After planting, piezometers were
installed in the center of each plot to a soil depth of 1.3 m. Rainfall and
temperature data were recorded by a weather station located <1 km from
the study site.
Soil macro- and micro-nutrients plus Al, Na, Cl, pH, buffer pH, organic
matter, and electrical conductivity were not affected by the N rates when
sampled at 0-15 and 15-30 cm depths between the plant-cane, first and
second ratoon crops. Soil and groundwater N concentrations indicated a
rapid loss of the applied N due to leaching after the split application.
Lowering the quantity of N ha-1 with each split application and increasing
the frequency of the splits may increase the N utilization efficiency of
sugarcane. Based on results from this study, it is suggested that split
application rates of ammonium nitrate fertilizer to sugarcane grown on
sandy soils in south Florida during June through September should be lower
than 70 kg N ha-1 and at time intervals between 2.5 and 6.5 wk.”
For the sugarcane cultivar CP 78-1628 grown on a sandy soil in south Florida,
positive relationships between rates of ammonium nitrate fertilizer and
plant available soil N concentrations at 2.5 wk after application were
verified. However, the effects of varying N rates were not always present at
6.5 wk after the split applications. The groundwater NO3-N response to
increasing rates of N fertilizer in the first ratoon crop indicated that leaching
might be a major cause of low N use efficiency of sugarcane on sandy soils in
south Florida. Based on the regression analysis of collected groundwater
data, split applications of ammonium nitrate fertilizer should be lower than
70 kg N ha-1 to prevent groundwater NO3-N enrichment above the
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acceptable EPA drinking water concentrations and to provide the needed N
fertilizer to the sugarcane crop during the growing season”.
-----------------------Nitrogen merupakan salah satu unsur hara makro primer yang
sangat diperlukan oleh tanaman tebu, sehingga seringkali diperlukan
pemupukan N untuk mengoptimalkan pertumbuhan dan hasil tebu.
Dosis pupuk N tergantung pada tingkat kesuburan tanah, kandungan
bahan organik tanah, tekstur tanah, KTK, dan jumlah biomas tanaman
yang dihasilkan. Kelebihan dan kekurangan nitrogen menyebabkan
gangguan pada pertumbuhan tanaman, produksi dan kwalitasnya.
Efisiensi penyerapan nitrogen ditentukan juga oleh jumlah, frekuensi,
cara, dan waktu pemupukan N. Analisa daun, analisa tanah dan
percobaan pemupukan di lapangan merupakan dasar pembuatan
rekomendasi pemupukan N yang terintegrasi pada pengelolaan yang
baik.
Kecukupan pupuk nitrogen sangat menentukan pertumbuhan
tanaman. Indikatornya terlihat jelas pada ukuran daun, tinggi batang,
luas permukaan daun dan jumlah anakan tanaman tebu. Kekurangan
unsur ini membuat pertumbuhan tanaman merana, ukuran daun
mengecil, kurus dan berwarna kekuningan. Penyebab rendahnya
produktivitas pada tanaman tebu memang cukup banyak, salah satu
yang cukup dominan adalah masalah pemupukan. Pemberian pupuk
buatan yang terus menerus ternyata membuat tanah menjadi keras
dan kecenderungan produktivitasnya semakin rendah. Penggunaan
pupuk organik secara terus menerus tanpa dibantu oleh pemberian
pupuk buatan mempunyai kecenderungan produktivitasnya rendah.
Namun penggunaan keduanya akan menghasilkan sinergi positip
yang dapat meningkatkan produktivitas tanaman. Pemberian pupuk
nitrogen dalam bentuk urea, ZA masih diperlukan dalam jumlah yang
cukup banyak; karena biomas yang dihasilkan tanaman tebu sangat
banyak, setiap tahunnya tidak kurang dari 100 ton biomas per ha yang
dihasilkan tanaman dan tidak kembali ke tanah lagi.
Permasalahan yang muncul adalah seberapa banyak dosis
pupuk N yang diperlukan tanaman tebu untuk mendapatkan
pertumbuhan dan produktivitas optimum? Selain itu seberapa jauh
hasil analisis daun dapat digunakan untuk menyusun rekomendasi
pemupukan secara terintegrasi ”diagnosis and recommendation
integrated system (DRIS)”.
Kandungan hara nitrogen pada daun yang dinyatakan medium
adalah 1.70 %, jika kandungan N-daun 1.70 % - 2.00 %, maka
dikatagorikan “medium-plus” atau “baik-minus”; apabila nilainya 1.40
% - 1.70 % tergolong “medium-minus” atau “kurang-plus”. Apabila
nilainya kurang dari 1.40 % , tergolong “kurang-minus”, sedang jika
kandungan N lebih dari 2.0 %, tergolong “baik-plus”.
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N-tanaman tebu
Peranan nitrogen bagi tanaman tebu adalah (a) meningkatkan
produksi dan kualitasnya, (b) untuk pertumbuhan vegetatif
(pertumbuhan tunas, daun, batang), (c) Pertumbuhan vegetatif berarti
mempengaruhi produktivitas.
Gejala defisiensi nitrogen antara lain (a) daun berwarna kuning
pucat, (b) ruas lebih pendek, (c) pertumbuhan daun semakin lambat,
(d) batang lebih pendek dan kurus, (e) akar lebih panjang, tetapi lebih
kecil ukurannya, (f) jika defisiensi berkelanjutan, ujung daun dan daun
yang terbawah menjadi nekrosis.
Kelebihan unsur nitrogen dapat berakibat negatif juga yakni (a)
efek racun untuk tanaman, (b) pertumbuhan vegetatif memanjang, (c)
memperlambat kemasakan, (d) mengurangi kadar gula, (e)
mengurangi kualitas jus (nira), (f) Menambah nitrogen yang larut pada
jus dalam stasiun klarifikasi, (g) mudah roboh, (h) lebih mudah
terserang hama dan penyakit.
Tanaman menyerap nitrogen dalam bentuk nitrat (NO3‾) dan
ammonium (NH4+). Efisiensi relatif absorpsi ammonium dan nitrat
dipengaruhi oleh pH tanah dan potensial redoks tanah. Pupuk Nitrat
bersifat sangat mobil, cepat diserap dalam bentuk ion nitrat (NO3-),
dan mudah tercuci. Nitrogen dalam bentuk nitrat dapat bergerak ke
atas bersama air kapiler selama musim kemarau. Ammonium tidak
mudah tercuci karena kation ini diikat oleh partikel liat (clay),
pengikatan ini sedemikian rupa sehingga tidak mudah tercuci, tetapi
masih tersedia bagi tanaman.
N-tanah
Tanah yang strukturnya baik memungkinkan udara masuk ke
dalam pori tanah, demikian juga air akan tertahan dalam ruangan
tersebut. Ujung akar dengan bulu akarnya akan mudah tumbuh pada
kondisi seperti ini. Bulu akar merupakan organ tanaman yang
menyerap unsur hara dan air dari dalam tanah. Jumlah bulu akar ini
sangat dipengaruhi oleh (a) jumlah akar yang tumbuh,(b) diameter
akar, (c) diameter batang, dan (d) Panjang akar. Semakin banyak
jumlah bulu akar, akan semakin tinggi kemampuan akar dalam
menyerap air dan unsur hara.
Pada tanah yang subur dekomposisi bahan organik akan terus
terjadi secara berkelanjutan, sehingga kebutuhan nitrogen mudah
dipenuhi. Sedangkan pada tanah berpasir yang miskin bahan organik,
tanpa penambahan pupuk organik akan sulit menyediakan N dalam
jumlah yang cukup. Itulah sebabnya pada tanah yang demikian perlu
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penambahan frekuensi pemupukan nitrogen dan perlu pemberian
pupuk organik.
Apabila mikroba tumbuh dengan baik di daerah rizosfer, maka
unsur hara nitrogen yang tersedia dapat diserap oleh tanaman melalui
akar dengan baik. Nitrogen yang diserap akan semakin banyak
jumlahnya. Apalagi jika ditunjang oleh perakaran yang baik dan
jumlah akar aktif maka kemampuan penyerapan unsur hara semakin
tinggi. Dengan demikian tanaman dapat tumbuh lebih baik dan
menghasilkan produksi yang lebih baik.
Pemupukan N tebu
Tanaman tebu memerlukan unsure hara dalam jumlah yang
tinggi untuk dapat tumbuh dan berproduksi dengan baik. Dalam 1 ton
hasil panen tebu terdapat sekitar 2.00 kg N; 0,40 - 0,80 kg P2O5 dan
1,20 - 6,0 kg K2O yang diserap dari dalam tanah. Oleh karena itu
diperlukan pemupukan N, P dan K yang cukup tinggi agar hasil panen
tebu tetap tinggi dan kesuburan tanah dapat dilestarikan.
Penambahan pupuk N karena hara N yang tersedia dalam tanah
berasal dari luar tanah, yaitu : (1) bahan organik sisa panen tanaman,
(2) fiksasi N dari udara oleh mikroba tanah, (3) air irigasi, dan (4)
pupuk N.
Hasil-hasil
penelitian
menunjukkan
bahwa
efisiensi
pemupukan N pada budidaya tebu masih relative rendah, yaitu sekitar
30 - 35%. Efisiensi pemupukan N rendah tersebut disebabkan karena
sebagian hara N dari pupuk hilang melalui proses-proses penguapan,
pencucian, imobilisasi, denitrifikasi dan erosi & runoff.
Tingkat kekurangan N tanaman tebu sangat bervariasi
tergantung pada kiondisi tanah, dan perkembangan tanaman. Pada
awal pertumbuhan tanaman tebu, kekurangan N dapat mengurangi
jumlah anakan, dan jumlah batang pada ratoon, daun menguning,
pendek dan sempit. Kekurangan N pada masa vegetatif dapat
menyebabkan menurunnya diameter batang dan jumlah batang tebu
yang baik. Kekurangan N yang ringan dapat mengurangi laju
fotosintesis, pengaruhnya sangat besar kalau terjadi pada awal
pertumbuhan tanaman.
Pupuk Urea dan ZA telah lazim digunakan dalam budidaya
tanaman tebu. Namun teknologi inovasi dalam aplikasi pupuk N ini
masih sangat diperlukan untuk meningkatkan efisiensinya.
Frekuensi aplikasi pupuk nitrogen seringkali sangat
berpengaruh selama periode pertumbuhan tanaman. Kegagalan
aplikasi nitrogen tepat waktu akan menyebabkan tanaman menjadi
kerdil, masak sebelum waktunya dan mengurangi jumlah hasil tebu.
Analisa tanah sebagai alat kontrol umumnya tidak dapat diandalkan
karena N tersedia dapat berubah dengan cepat akibat berubahnya
iklim (temperatur, hujan) dan faktor budidaya tanaman. Kehilangan
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nitrogen dapat dikurangi dengan menghatur frekuensi aplikasi
pemupukan.
Pupuk nitrogen dapat digolongkan menjadi tiga yakni:
(1). Pupuk Nitrat (Nitrate), misalnya Sodium Nitrate; Calcium Nitrate;
Potasium Nitrate. (2). Pupuk Amomonium, misalnya A. Sulphate
(S.A./Z.A.); A. Chloride; A. Anhydride; dan (3) Pupuk Amida (Amide),
misalnya Urea; Calcium Cyamnamide.
Pupuk ammonium sulphat (ZA) juga mengandung sulphur.
Pemakaian ZA terus menerus dapat mengasamkan tanah. Aplikasi
pupuk ZA dengan dosis 4-6 ku/ha (beragam tergantung kondisi
tanah) dapat menghasilkan hablur gula yang diharapkan.
Pupuk amida bersifat lambat tersedia, N dalam pupuk ini tidak
langsung tersedia bagi tanaman tetapi harus melalui beberapa
perubahan kimia dahulu. Hasil akhirnya dalam bentuk Ammonium
(NH4+) dan Nitrat (NO3-). Jenis pupuk ini berkadar N tinggi, misalnya
Urea = 46%. Sifat urea yang mudah larut dalam air memungkinkannya
untuk dipakai sebagai pupuk daun.
Dengan bantuan mikroba tanah, nitrogen yang ada dalam
pupuk dapat dikonversi menjadi bentuk yang tersedia bagi tanaman.
Proses perubahannya banyak tergantung pada iklim dan kondisi
tanahnya. Konversi berjalan cepat apabila kadar air, aerasi,
temperatur dan pH nya sesuai.
Aplikasi pemupukan sebaiknya 3 sampai 4 kali yakni pada
saat sebelum tanam (pupuk dasar), setelah perakaran tumbuh (1-2
bulan), pada masa pertumbuhan tunas (tillering, 3 bulan) dan masa
pertumbuhan, namun minimal dua kali setahun. Semakin sering
frekuensi aplikasi pupuk dengan dosis rendah, hasilnya akan semakin
baik, terutama bagi jenis pupuk yang cepat larut dalam air seperti
pupuk ZA dan Urea.
Pada akhir musim kemarau yang panjang, akar banyak yang
mati , itulah sebabnya waktu pemupukan harus menunggu pada saat
akar mulai tumbuh kembali sekitar 1 sampai 1.5 bulan setelah hujan
pertama datang.
Semakin rendah kandungan bahan organik tanah, maka dosis
pupuk nitrogen akan semakin besar. Dosis pupuk N ini juga
tergantung pada frekuensi aplikasi, karena nitrogen yang sifatnya
sangat mobil mudah tercuci (leaching) dan menguap (volatile). Cara
aplikasi menentukan efisiensi pemupukan nitrogen, misalnya ”disebar
(broadcast)” akan lebih boros dibanding dengan ”dibenam
(placement)”. Waktu aplikasi tidak dapat setiap saat dilakukan, karena
curah hujan dan kelembaban tanah tidak setiap saat cocok. Pada
prinsipnya, semakin tinggi kandungan bahan organik tanah, semakin
tinggi KTK akan semakin banyak nitrogen yang tersedia dan dapat
diserap tanaman. Itulah sebabnya analisa daun dibutuhkan untuk
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melihat sejauh mana nitrogen dapat diserap oleh tanaman, karena
analisa tersebut dapat segera dibandingkan dengan hasil pengamatan
secara visual. Analisa tanah saja tidak dapat diandalkan, karena
pergerakan nitrogen dalam tanah yang begitu cepat sebagai akibat
perubahan iklim (suhu, hujan) yang dinamis.
Teknologi Pupuk N
Pemupukan N tanaman tebu memegang peranan sangat
penting, selain dapat meningkatkan produksi biomassanya, pupuk N
juga dapat meningkatkan keragaman dan kualitas hasil tebu. Masalah
utama penggunaan pupuk N pada lahan kebun tebu adalah
efisiensinya yang relatif rendah karena kehilangan N akibat pencucian
dan penguapan. Untuk itu diperlukan rekayasa teknologi pupuk N
untuk peningkatan efisiensi pemupukan N, misalnya dengan rekayasa
urea-humat. Teknologi pelapisan urea dengan asam humat
diharapkan dapat menghasilkan pupuk urea yang lebih tidak mudah
larut. Dengan pelepasan N yang lebih lambat diharapkan
ketersediaan N dalam tanah lebih besar dan pemupukan menjadi
lebih efisien.
Secara spesifik asam humat dapat digunakan untuk stabilisasi
urea, sehingga meningkatkan efisiensi pemupukan urea pada
tanaman tebu. Dengan menstabilkan urea memakai asam humat ini
diperkirakan efisiensi urea dapat ditingkatkan hingga menjadi sekitar
50%. Proses stabilisasi urea dengan asam humat sangat sederhana
dan dapat dilakukan dengan cara konvensional, yaitu dengan cara
meyemprot secara merata urea dengan asam humat, dan kemudian
dicampur hingga merata. Dosis untuk 100 kg urea menggunakan 1
liter (atau sesuai dengan kebutuhan asam humat).
Rekayasa stabilisasi urea dengan asam humat menghasilkan
urea yang lambat melepaskan nitrogen (slow release), hal ini
diperlukan untuk meminimumkan kehilangan N melalui proses
pencucian dan penguapan.
A recent study on ammonia loss from urea by using acidic
materials such as Humic Acid (HA) has been successful. Besides
reducing ammonia loss, the mixture of urea-HA improves plant
growth and development (American Journal of Applied Sciences,
Nov, 2009).
Amending urea HA can reduce ammonia loss in acid soils by
improving ammonium retention. This may in effect improve urea
N use efficiency as well as reducing environmental pollution in
agriculture (American Journal of Applied Sciences, 5(5):588-591
2009).
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Urea-TSP-MOP-HA mixtures effectively reduced ammonia loss
and retained soil exchangeable ammonium compared to urea
alone. The acidic nature and high CEC of HA aided in reduction
of ammonia loss and retained soil exchangeable ammonium.
However, the addition of HA in the urea-TSP-MOP mixtures was
not beneficial since the mixtures alone without HA able to reduce
NH3 loss and improved NH4 retention. This may be due to K+
contained in the acid that reduce the quantity of H+ in the
mixtures thus increased soil pH.
Urea, TSP and MOP amended with HA or HA and FA
significantly reduced ammonia loss. The outcome of this study
may contribute to the improvement of urea N, P and K use
efficiency as well as reducing environmental pollution. (American
Journal of Environmental Sciences 5 (5): 605-609, 2009).
The use of liquid organic N fertilizer has the ability to reduce
NH3 volatilization in acid soil. The use of both humic and fulvic
acids could be effective in promoting NH4+ retention. Thus, it
can be concluding that, humic substances, in general, have great
ability in controlling NH3 loss and retaining NH4+ in acid soils.
It could be a cheapest, practical and easiest way to control N loss.
The CEC provided by HA, which ranged between 417-583 cmol
kg-1 may have contributed to ammonia loss reduction. The
negative sites due to ionization of carboxylic (COOH) and
phenolic (OH) might have improved NH4+ retention hence
reduction in N loss. These negative charges could develop with
the level of salt and pH, that occurred in soil. More salt will
produce more negative charge in soil. A similar situation will
occur at high pH. Thus, the presence of KOH, as a source of salt,
could enhance HA charges and indirectly reducing the N loss.
(American Journal of Agricultural and Biological Sciences 4 (1):
18-23, 2009).
Purpose of this research was offering basic data for the
production of humic acid slow-release fertilizers. The effects of
NH4+ concentration, equilibrium time and pH value on the
NH4+ adsorption of humic acid extracted from Shanxi brown
coal and its absorptive regularity were studied by ion-exchange
equilibrium method in this paper.
Results showed that with the increase of NH4+ concentration,
adsorption capacity of NH4+ increased. The adsorption of NH4+
on humic acid could be well described by Freundlich equation
and its kinetics adsorption fit Elovich equations best. Under the
condition of pH lower than 7.04, pH increase of medium was of
great advantage of NH4+ adsorption and could improve the
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velocity of adsorption reaction. Under the condition of pH lower
than 4.03, physical adsorption was the dominant. However, under
the condition of 4.03 < pH < 7.04, chemical exchange was
dominant. The adsorption capacity could be increased by 58.03 %
at the optimal condition. On the whole, chemical exchanged
played a more important role on NH4+ adsorpiton. Adsorption
capacity rose markedly in the beginning of the adsorption
process, however, it slowed down later. While suitable ratio of
solid to liquid could increase unit adsorption until the ratio
increased to some extent, then the unit adsorption would
decrease. When the ratio was 0.04 and 0.03, the unit adsorption
reach maximum being 34.9 ,72.2 mg/g, respectively. (Plant
Nutrition and Fertilizer Science. 2005,11(4) : 516-523)
SERAPAN N –PUPUK TANAMAN TEBU
G. J. C. Gava; P. C. O. Trivelin; A. C. Vitti and M. W. Oliveira. 2003.
Recovery of nitrogen (15N) from urea and cane trash by sugar cane
ratoon (Saccharum spp.). Rev. Bras. Ciênc. Solo vol. 27 no. 4
Viçosa July/Aug. 2003
An experiment was carried out to evaluate how mineralized nitrogen from
cane trash and urea nitrogen applied to the soil is utilized by sugarcane
ratoon. The field experiment was carried out from October 1997 to August
1998 on a Paleudalf soil in Piracicaba, State of São Paulo, Brazil. Four
treatments were established: (T1) application of a vinasse and urea mixture
over the whole soil area covered with cane trash-15N (crop residue); (T2)
application of a vinasse and urea-15N mixture over the entire soil area
covered with cane trash (crop residue); (T3) application of a vinasse and
urea-15N mixture over the whole area without cane trash; (T4) urea-15N
buried in furrows on either side of the cane rows, with previous application
of vinasse on the soil without cane trash. The experiment was installed in a
randomized block design with four replications. Components of crop
productivity; accumulation of nitrogen in the aerial part of the sugar cane
ratoon; and the crop's use of 15N nitrogen of urea and of mineralized cane
trash were evaluated for each treatment. The plant development occurred
in a 315 day cycle and was similar in both conditions, with and without cane
trash. Ten-16 % of the total nitrogen accumulated in shots of sugarcane
ratoon came from the fertilizer and an average of 4 % was absorbed from
the mineralized N of cane trash. Mean efficiency of the utilization of urea
nitrogen by sugarcane ratoon was 17 %, with no difference among
treatments, and that of the cane trash 8 %. Cane trash nitrogen was
available to the plant towards the late crop cycle.
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SERAPAN N, P, K TANAMAN TEBU
Rakkiyappan, P.; S. Thangavelu, K. V. Bhagyalakshmi and R. Radhamani.
2007. Uptake of nitrogen, phosphorus and potassium by some
promising mid late maturing sugarcane clones. Sugar Tech. Volume 9,
Number 1, 23-27, DOI: 10.1007/BF02956909
A field experiment was conducted at the ECC farm of Sugarcane Breeding
Institute, Coimbatore during 1999–2000 to evaluate promising mid late
maturing sugarcane clones for nutrient use efficiency. Twelve clones
including three standards were planted in a clay soil (Typic Haplustert).
Nitrogen, phosphorus and potassium contents were estimated in dry leaves,
green tops and stem on dry weight basis and their uptake in different parts
was calculated. Total nutrient uptake and uptake per tonne of cane were
also computed. Significant clonal variations in N, P and K uptake by various
plant parts viz., dry leaves, green tops and stem, total uptake in above
ground parts and uptake per tonne of cane (physiological use efficiency).
Total N uptake ranged from 88.55 kg/ha in CoTl 93116 to 148.52 kg/ha in Co
7219. The lowest uptake of 0.88 kg N per tonne of cane was recorded in Co
86032 and the highest uptake of 1.47 kg/tonne of cane was registered in Co
93018. Clones identified for better N use efficiency were Co 94011, Co
94015 and CoTl 93116. Total P uptake by above ground parts ranged from
34.95 kg/ha in CoTl 93116 to 57.97 kg/ha in Co 7219. The uptake of
phosphorus per tonne of cane ranged from 0.34 kg in Co 94012 to 0.56 in Co
93018 with a mean of 0.48 kg. Clones Co 94012, Co 94016, Co 94015, Co
94009 and CoTl 93116 were identified for better P use efficiency. The total K
uptake in above ground parts varied from 108.55 kg/ha (CoTl 93116) to
305.98 kg/ha (Co 7219) with a mean of 210.25 kg/ha. The K uptake per
tonne of cane ranged from 1.44 kg in CoTl 93116 to 2.91 kg in Co 7219 with
a mean of 2.09 kg. Clones identified for better potassium use efficiency were
CoTl 93116, Co 93018 and Co 94012. Co 86032 was found superior among
the standards in nutrient use efficiency.
PEMUPUKAN N DAN SUPLAI AIR TANAMAN TEBU
OBREZA, T.A.; D.L.ANDERSON; D.J. PITTS. 1998. Water and nitrogen
management of sugarcane grown on sandy, high-water-table soil. Soil
Science Society of America journal. 1998, vol. 62, no4, pp. 992-999.
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Little information exists regarding water and N fertilizer management for
sugarcane (Saccharum spp.) production on Florida's high-water-table sandy
soils. We hypothesized that sugar yield and N-use efficiency would be
affected by water table depth and N fertilizer application timing. Sugarcane
(cv. CP 72-1210) was grown in >1-ha plots for three seasons on Basinger
sand (siliceous, hyperthermic Spodic Psammaquent) to determine the
effects of water table depth (0.46 vs. 0.57 m), N fertilization frequency (13
vs. 7 split applications for 3 yr, at 224 kg N ha-1 yr-1), and Mg fertilizer rate
(0 vs. 60 kg Mg ha-1 yr-1) on cane and sugar yields. Annual mean high- and
low-water-table differences were 0.13, 0.11, and 0.10 m, resulting in a 0.2 to
1.4 J kg-1 difference in soil water matric potential at middle of the root zone,
and a 0.02 to 0.11 m3 m-3 difference in soil water concentration in the top
0.30 m. Three-year mean yields for low vs. high water table were 73.7 vs.
67.9 t sugarcane ha-1 and 9.23 vs. 8.51 t sugar ha-1. High vs. low N
fertilization frequency yielded 75.0 vs. 66.5 t sugarcane ha-1 and 9.41 vs.
8.33 t sugar ha-1. There were no water level x N fertilization frequency
interactions. Where mean Mehlich 1 extractable Mg was 25 mg kg-1, Mg
fertilization did not affect yield, suggesting that this Mg level should be
classified in the unresponsive (high) range. Although increasing N
fertilization frequency increases the fertilization program cost, its use is
justified by increased sugar yield.
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PEMUPUKAN N TANAMAN TEBU PADA TANAH LIAT
(Increasing N application had detrimental effects on sugarcane juice
quality, but the magnitude of the effects were small compared to
increasing cane growth responses, therefore sugar yield continued to
increase as N application increased.)
SUGARCANE RESPONSES TO N FERTILIZER APPLICATION ON CLAY SOILS.
Robert Wiedenfeld. Texas Agricultural Experiment Station , Texas A&M
University Research and Extension Center Weslaco, TX 78596. BWiedenfeld@tamu.edu
Sugarcane fertilization practices have been developed for the Rio
Grande Valley of Texas based on numerous studies; however, few have been
conducted on clay soils. Nitrogen has been found to be the primary nutrient
needed, and responses to N fertilization have been limited in the plant-cane
11
crop and increase incrementally in succeeding ratoons to its highest level in
the second and following ratoons. This study was conducted to evaluate the
effect of rate and timing of N fertilizer application on sugarcane growth, and
to determine optimum fertilization practices for sugarcane yield on clay
soils. As in previous studies, responses to N application did not occur in the
plant cane crop, but were observed in the first through third ratoons.
Increasing rate of N application improved stalk population, stalk growth
rate, leaf area index, cane yield and sugar yield. Early N application resulted
in depletion of available N before full growth potential had been reached,
possibly to microbial immobilization or leaching. Late fertilizer application
caused a loss of early growth, an effect that was mostly, but not entirely,
compensated for by later growth. Soil NO3--N levels varied little even
though yield responses to N fertilization indicated that there were some
dramatic differences in soil N availability and residual levels. Increasing N
application had detrimental effects on sugarcane juice quality, but the
magnitude of the effects were small compared to increasing cane growth
responses, therefore sugar yield continued to increase as N application
increased. Early fertilizer application resulted in lower sugar yield due to
lower cane yield, while late fertilizer application resulted in lower sugar
yields due to lower juice quality rather than any loss in growth. Nitrogen
fertilizer application to sugarcane on clay soils in subtropical South Texas is
not required on plant cane crops, and should be at least at or above the
level of 224 kg ha-1 used in this study in ratoon crops. Timing of a single
application should be in March or April, or split into 2-3 applications on clay
soils.
PEMUPUKAN N DAN AKUMULASI SUKROSE TANAMAN TEBU
(Increasing N supply decreased the sucrose concentration in dry
millable stalks, this effect was relatively small compared to the large
positive effect of N supply on stalk biomass).
Muchow, R.C.; M.J. Robertson, A.W. Wood, B.A. Keating. 1996. Effect of
nitrogen on the time-course of sucrose accumulation in sugarcane. Field Crops
Research. Volume 47, Issues 2–3, August 1996, Pages 143–153
Sugarcane is harvested commercially at ages varying from 9 to 36
months. Since high N supply can decrease the sucrose concentration in fresh
millable stalks and consequently decrease the commercial value of the
stalks, the opportunity exists to manipulate N supply (both from fertiliser
and that mineralised from soil organic matter) to maximise economic return
at different times of harvest. Accordingly, this study describes how N supply
the time-course of sucrose accumulation in sugarcane and determines yield
12
both on a dry weight basis (as commonly analysed by crop physiologists) and
on a fresh weight basis (which is how cane is paid for commercially). Data on
crop N uptake and its efficiency of utilisation are also presented.
There was a trade-off between maximising sucrose yield and sucrose
concentration in fresh millable stalks with different N supply and this varied
with time of harvest. Sucrose concentration in fresh millable stalks,
particularly during early growth, was maximised by low N supply. The lower
sucrose concentration (on a fresh weight basis) with high N supply could be
largely explained by a decrease in stalk dry matter content. Most of the
variation in stalk sucrose yield could be explained by variation in stalk
biomass irrespective of N supply. Whilst increasing N supply decreased the
sucrose concentration in dry millable stalks, this effect was relatively small
compared to the large positive effect of N supply on stalk biomass. It is
concluded that N has a marked effect on stalk dry matter content, and
hence a greater effect on the commercial measures (yield and sucrose
concentration of fresh millable stalks) of sugarcane production than on the
physiological measures (stalk biomass and sucrose concentration on a dry
weight basis) of crop performance.
STATUS N TANAMAN TEBU
The biomass/N ratio varied with cultivar and crop class, and increased with
crop age.
Wood, A.W. ; R.C. Muchow, M.J. Robertson. 1996. Growth of sugarcane under
high input conditions in tropical Australia. III. Accumulation, partitioning and
use of nitrogen. Field Crops Research. Volume 48, Issues 2–3, October 1996,
Pages 223–233.
Leaf nitrogen (g N m−2 leaf) is an important determinant of crop
radiation-use efficiency. It is not known to what extent sugarcane can
maintain high leaf N over its long growth duration. This study analyses the
accumulation of N in two contrasting cultivars of sugarcane (Q117, Q138)
under plant and ratoon crop conditions, and the partitioning of N to the
various plant components, including the leaf. The crops were grown for 15
months under irrigated conditions in the same season and received 34.4 g N
m−2 as fertiliser over the first 100–120 days of the season. Higher early N
accumulation by the ratoon crop was associated with higher early biomass
production. However, maximum N accumulation was unrelated to maximum
biomass accumulation, with the plant crop (25.9 g N m−2) accumulating more
than the ratoon crop (21.3 g N m−2), which resulted in widely varying values
for biomass/N ratio. N accumulation ceased later in the plant (200 days)
than in the ratoon (150 days) crop, and this occurred 100–140 days before
13
maximum biomass. More work is needed to determine if this is due to
exhaustion of soil N supply, reduced root activity, or a lowered crop N
requirement. Leaf N was maintained above 1.2 g N m−2 for 300 days of the
450 day season. Decline in leaf N below 1.2 g N m−2 at the end of the season
was associated with loss in leaf and total crop N accumulation, and
apparently unrelated to the timing of cessation in biomass accumulation.
Throughout the season, leaf N was higher in the plant than the ratoon crop
(averaged over cultivars), and Q117 versus Q138 (averaged over crop
classes), however these differences could not explain crop-class differences
in RUE. Cultivar differences in leaf N were due to higher N accumulation
because specific leaf area and partitioning of biomass and N to leaf were
unaffected by crop class or cultivar. The biomass/N ratio varied with cultivar
and crop class, and increased with crop age.
14
PEMUPUKAN N, STATUS N TANAMAN DAN HASIL GULA
INMAN-BAMBER, N. G.. 1984. THE EFFECTS OF NITROGENOUS FERTILIZER ON
SUGARCANE VARIETIES AND VARIETAL DIFFERENCES IN THIRD LEAF NUTRIENT
CONTENT. Proceedings of The South African Sugar Technologists' Association June 1984. South African Sugar Association Experiment Station, Mount
Edgecombe.
Pengaruh dosis pupuk N terhadap hasil tebu (relative terhadap hasil pada
pemupukan 150 kg N/ha) tiga varietas pada ratun ke tiga.
15
Pengaruh pemupukan N terhadap kadar sucrose tanaman tebu umur 12
bulan (persentase dari kadar sucrose tanaman tebu pada perlakuan dosis
pupuk N tertinggi)
Pengaruh pemupukan nitrogen pada hasil sucrose tebu tiga varietas yang
dipanen pada ratun ke empat (A) dan ratun ke tiga (B) (relatif terhadap
hasil sucrose tebu dengan perlakuan dosis pupuk tertinggi).
16
EFISIENSI PEMUPUKAN N TANAMAN TEBU
(The substantial benefits may be derived from variety specific N fertiliser
recommendations for sugarcane, rather than a single recommendation)
SCHUMANN, A.W.; J.H. MEYER and S. NAIR. 1998. EVIDENCE FOR DIFFERENT
NITROGEN USE EFFlClENClES OF SELECTED SUGARCANE VARIETIES. South
African Sugar Association Experiment Station, Private Bag X02, Mount
Edgecombe, 4300. Proc. S. Afr. Sug. Technol. Ass. (1998) 72.
There is increasing interest in improving the nitrogen (N) use efficiency of
cultivated crops, due to the high cost of synthetic N fertiliser. Since existing
differences in N use efficiency between sugarcane varieties could be
exploited to improve N fertilisation, a hydroponic pot experiment was
conducted to test the performance of seven commercial South African
varieties (NCo376, N12, N14, N16, N19, N24, N25) at three N concentrations
(30, 60, 90 mg NL). At the first N increment, significant varietal differences in
internal N use efficiency (g sucrose / g accumulated N) were recorded in the
ratoon cane. High N use efficiencies for N12 and N19 were 65 and 63%
respectively, above the 'reference' variety NCo-376. In contrast, N14 was
19% less efficient than NCo376, which is in agreement with results from field
trials. These data suggest that substantial benefits may be derived from
variety specific N fertiliser recommendations for sugarcane, rather than a
single recommendation based on NCo376. Based on field trial data, fertiliser
recommendations for N14 have recently been increased by 30 kg N/ha. The
hydroponic technique should be useful for initial screening of the many
commercial and new sugarcane varieties before final field testing and
amendments to fertiliser recommendations.
17
Pengaruh dosis pupuk N terhadap kadar N daun beberapa varietas tebu.
Pengaruh dosis pupuk N terhadap total biomasa akar beberapa varietas
tebu.
18
Pengaruh pemupukan N terhadap rendemen beberapa varietas tebu.
Hubungan antara panen biomasa tebu (shoot) dengan serapan N beberapa
varietas tebu sebagai akibat dari pemupukan N. A = tebu yang respon
efisien. B= tebu yang tidak respon. C = tebu yang respon tidak efisien.
19
Hubungan antara hasil sucrose tebu dengan serapan N beberapa varietas
tebu sebagai akibat dari pemupukan N. A = tebu yang respon efisien. B=
tebu yang tidak respon. C = tebu yang respon tidak efisien.
----------------
20
BAHAN BACAAN
Gava, G.J.C., P.C.O. Trivelin, A.C. Vitti, and M.W. Oliveira. 2003. Recovery of
nitrogen (N-15) from urea and cane trash by sugarcane ratoon
(Saccharum spp.). R. Bras. Ci. Solo. 27:621-630.
Muchovej, R.M., and P.R. Newman. 2004. Nitrogen fertilization of sugarcane
on a sandy soil: I. Yield and leaf nutrient composition. J. Amer. Soc.
Sugar Cane Technol. 24:210-224.
Muchovej, R.M. and P. R. Newman. 2004. NITROGEN FERTILIZATION OF
SUGARCANE ON A SANDY SOIL: II. SOIL AND GROUNDWATER
ANALYSES. Journal American Society Sugar Cane Technologists, Vol.
24, 2004.
Muchow, R.C.; M.J. Robertson, A.W. Wood, B.A. Keating. 1996. Effect of
nitrogen on the time-course of sucrose accumulation in sugarcane.
Field Crops Research. Volume 47, Issues 2–3, August 1996, Pages
143–153
Rakkiyappan, P.; S. Thangavelu, K. V. Bhagyalakshmi and R. Radhamani.
2007. Uptake of nitrogen, phosphorus and potassium by some
promising mid late maturing sugarcane clones. Sugar Tech. Volume
9, Number 1, 23-27, DOI: 10.1007/BF02956909
Rice, R.W., R.A. Gilbert, and R.S. Lentini. 2002. Nutritional Requirements for
Florida Sugarcane. Florida Coop. Ext. Ser., UF/IFAS, Doc. SS-ARG228. Univ. of Fla.,Inst. Food Agric. Sci., Gainesville.
Wood, A.W. ; R.C. Muchow, M.J. Robertson. 1996. Growth of sugarcane
under high input conditions in tropical Australia. III. Accumulation,
partitioning and use of nitrogen. Field Crops Research. Volume 48,
Issues 2–3, October 1996, Pages 223–233.