kompendium evaluasi kesuburan tanah

Bahan Kajian pada
MK. Manajemen Kesuburan Tanah
EVALUASI
KESUBURAN TANAH
Diasbtraksikan Oleh:
SMNO.jursntnh.fpub. Des2012
PRODUKSI
TANAMAN
Kebutuhan
tanaman
terhadap hara
Kemampuan tanah
menyediakan hara
bagi tanaman
1. Bertumpu pada unsur hara yang tersedia dalam
tanah
2. 2. Penambahan unsur hara melalui pemupukan
dan praktek pengelolaan lainnya
Kemampuan tanah menyediakan
unsur hara sangat beragam dan
berfluktuasi
Teknik Diagnosis/Pendugaan:
1. Identifikasi gejala defisiensi
hara
2. Uji Tanah
3. Analisis jaringan tanaman
TEKNIK
PENDUGAAN
STATUS
KESUBURAN
TANAH
Identifikasi Gejala Defisiensi
Unsur Hara pada tanaman
Analisis jaringan tanaman yg
tumbuh pada tanah
Uji Biologis:
Ukuran tingkat kesuburan tanah
adalah pertumbuhan tanaman
atau mikroorganisme tertentu
UJI TANAH SECARA
KIMIAWI
“Proses diagnosis problematik hara dan
pembuatan rekomendasi pupuk”
Uji
Tanah
UJICOBA
PUPUK
Analisis
Tanaman
Missing
Element
Technique
KOMBINASI
NYA
GEJALA
DEFISIENSI
UNSUR HARA
PADA
TANAMAN
Pertumbuhan tanaman yg tidak normal dapat
disebabkan oleh adanya defisiensi satu atau lebih
unsur hara, gangguan dapat berupa gejala visual yang
spesifik.
Gejala defisiensi hara:
1. Kegagalan pertumbuhan pd saat perkecambahan
2. Pertumbuhan tanaman sangat kerdil
3. Munculnya gejala spesifik pad daun, pd waktu tertentu
4. Internal abnormalities, misalnya penyumbatan jaringan pembuluh
5. Tertundanya kemasakan tanaman
6. Penurunan hasil tanaman
7. Kualitas tanaman: kandungan protein, minyak, pati, daya simpan
8. …..
1.
2.
3.
Gejala defisiensi bersifat relatif, seringkali defisiensi satu unsur hara
bersamaan dengan kelebihan unsur hara lainnya.
Di lapangan tidak mudah membedakan gejala-gejala defisiensi.
Tidak jarang gangguan hama dan penyakit menyerupai gejala defisiensi
unsur hara mikro.
“Situasi dimana tanaman memerlukan tambahan
unsur hara tertentu meskipun belum ada gejala
defisiensi yang spesifik”
Kandungan hara dalam tanaman berada di atas zone
defisiensi, namun masih berada di bawah batas
optimal untuk pertumbuhan dan produksi tanaman
HIDDEN HUNGER
= KELAPARAN
TERSEMBUNYI
Melacak hidden hunger
Optimum fisiologis
Top yield
Hidden hunger
Optimum ekonomis
Field trial
Tissue test
Plant analyses
Feed value
Morfologi
Part analyses
root absorption
Soil tests
Symptoms
dosis pemupukan
air tanah, aerasi, suhu
Hasil analisis tanaman berguna untuk menyusun program pemupukan musim tanam mendatang .
Hasil uji tanah berguna untuk membantu mengeliminir / mengatasi problematik hara musim tanam
sekarang
Kedua cara ini harus digunakan dengan hati-hati, terutama dikaitkan dengan sejarah pengelolaan
tanah pada masa yang lalu
Kekurangan hara dalam tanah diperparah oleh
kondisi cuaca yang abnormal, misalnya
kekeringan tanah atau kelebihan air yg
menggenang, atau suhu tanah yang tdk normal.
PENGARUH
MUSIM
Pengaruh temperatur thd kandungan N-P-K daun tomat
Umur
tanaman
(hari)
36
50
60
110
Dry matter (%)
N
12oC
P
K
N
3.27
4.11
4.62
4.40
0.15
0.37
0.35
0.43
2.12
3.11
1.70
4.95
4.92
4.78
6.05
4.15
20oC
P
0.38
0.44
0.47
0.62
K
4.23
4.40
3.12
4.20
Sumber: Zurbicki, 1960.
Pada kondisi temperatur rendah, tanaman tomat menyerap lebih
sedikit nitrogen, fosfat dan kalium.
PENGARUH
STRESS AIR
TANAH
Stress air tanah mempengaruhi penyerapan unsur
hara oleh tanaman jagung.
Kandungan NPK daun jagung lebih rendah pada
kondisi stress air tanah.
Pemupukan dapat mereduksi efek stress air tanah
Pengaruh pemupukan N-P-K dan stress air tanah thd kadar NPK daun jagung
Dosis pupuk
N
P
K
……… kg/ha …………….
Kadar NPK
No stress days
Maximum stress
………………… % N …...…………….
0
179
78
78
47
47
179
179
0
78
47
47
179
179
39
39
0
93
2.0
2.9
………………… % P …...…………….
0.26
0.32
………………… % K …...…………….
1.1
1.6
Sumber: Voss, 1970.
1.5
2.2
0.12
0.18
0.7
1.2
ANALISIS
TANAMAN
(Plant
Analyses)
Dua macam analisis tanaman yg lazim adalah:
1. Tissue test, biasanya dilakukan pada jaringan
segar tanaman di lapangan
2. Total analyses, dilakukan di laboratorium
Analisis tanaman didasarkan pada premise bahwa: “ Jumlah
unsur hara tertentu dalam tanaman merupakan indikasi dari
ketersediaan unsur hara tersebut dalam tanah”.
Karena kekurangan unsur hara tertentu akan membatasi
pertumbuhan tanaman, maka kemungkinan unsur hara lain
dalam tanaman menunjukkan konsentrasi tinggi.
Tingkat kritis (critical level) unsur hara telah berhasil ditemukan pada berbagai
jenis tanaman.
Tingkat kritis adalah kandungan (content) suatu unsur hara dalam tanaman, di
bawah mana hasil tanaman atau pertumbuhannya menurun di bawah optimum.
Misalnya tingkat kritis P daun jagung pada masa pembungaan adalah 0.3% P.
Ternyata besarnya tingkat kritis ini juga dipengaruhi oleh keseimbangan unsur hara
lain dalam tubuh tanaman
TISSUE TEST
Uji Jaringan
Tanaman
Dalam uji ini digunakan cairan sel dari jaringan
tanaman segar untuk mengetahui jumlah unsur
hara yg masih belum terasimilasi, seperti N, P, K,
Mg dan Mn.
Hasil uji ini dikategorikan menjadi Sangat
Rendah, Rendah, Medium,atau Tinggi
GENERAL METHOD
1. The Purdue Soil and Plant Test Kit: Bagian tanaman dihancurkan
dan diekstraks dengan reagen khusus. Intensitas warna yang
berkembang diabndingkan dengan standar
2. Metode Kertas Saring. Cairan sel dipindahkan ke dalam kertas
saring, kemudian dilakukan uji unsur hara N, P, K dengan
menggunakan reagen tertentu.
Bagian tanaman yang dianalisis
Harus dipilih bagian tanaman yang dapt memberikan indikasi paling baik
terhadap status hara tanaman.
Bagian tanaman yg digunakan untuk Uji
Jaringan Tanaman
Tanaman
Nitrogen
Jagung
Main stem ,
leaf midribs
Leaf midribs near ear
Kedelai
-
Petiole pd bagian atas tnm Petiole
Biji-bijian
Main stem
Kentang dan
Tomat
Main stem,
petiole
Sumber: Ohlrogge, 1962.
Fosfor
Jaringan daun di dekat
pusat tanaman
Petiole pd bagian –
bawah tnm
Kalium
Blade tissue,
midrib near ear
Sama dg Fosfor
Petiole
TIME OF
TESTING
1. Tingkat kemasakan sangat penting dalam uji
jaringan tanaman.
2. Umumnya tanaman semusim mengalami perubahan
status hara selama masa pertumbuhannya
3. Umumnya periode kritis terjadi pada fase
pembungaan atau antara pembungaan hingga awal
pembuahan. Selama periode ini penggunaan unsur
hara pada tingkat maksimum.
4. Kandungan nitrat biasanya lebih tinggi pd pagi hari,
sehingga uji jaringan tdk boleh pagi-pagi.
Beberapa hal penting:
1. Hal yg ideal adalah mengikuti serapan hara selama musim pertumbuhan dg jalan
uji lapangan sebanyak lima atau enam kali. Biasanya kandungan hara lebih
tinggi pada awal musim pertumbuhan
2. Kebutuhan tanaman paling besar biasanya terjadi pd saat masa pembungaan
dan awal pembentukan buah dan biji
3. Pembandingan tanaman di lapangan sangat berguna. Uji tanaman dari daerah
defisien dibandingkan dg tanaman dari daerah normal
4. Ragam tanaman, jumlah sampel 10 - 15 tanaman
USE OF
TISSUE TEST
&
PLANT
ANALYSES
1. Membantu menentukan kemampuan tanah
untuk menyediakan unsur hara.
Hasil uji
jaringan ini dipadukan dengan hasil uji tanah
dan sejarah pengelolaan lahan.
2. Membantu mengidentifikasi gejala defisiensi
3. Membantu menentukan pengaruh pemupukan thd suplai hara dlm
tanaman. Hal ini sangat penting untuk mengukur pengaruh pupuk
meskipun tidak ada respon hasil. Dalam banyak kasus, hara ppuk tidak
dapat diserap tanaman karena penempatannya keliru, cuaca kering,
pencucian, fiksasi oleh tanah, atau aerasi buruk
4. Mengkaji hubungan antara status hara tanaman dengan penampilan
tanaman
5. Survei daerah yang luas
6. Menarik partisipasi banyak orang.
INPERPRETASI
TISSUE TEST
&
PLANT
ANALYSES
Interpretasi hasil uji dan analisis tanaman harus
dikaitkan dengan proses fisiologi tanaman.
Beberapa faktor penting yang harus
dipertimbangkan adalah:
1.
2.
3.
4.
Performance dan vigor tanaman secara umum
Kandungan unsur hara lainnya dalam tanaman
Adanya gangguan hama dan penyakit
Kondisi tanah, seperti aerasi yg buruk, kemasaman tanah, suhu
tanah
5. Kondisi air tanah, stress air , genangan air
6. Kondisi klimatik
7. Waktu dalam seharian: pagi, siang, sore, malam.
1. Umumnya kalau pada awal pertumbuhannya tanaman mempunyai kandungan
N,P, atau K yang rendah hingga medium, maka hasil tanaman akan di bawah
optimum
2. Pada saat pembungaan hasil uji medium hingga tinggi dianggap cukup untuk
kebanyakan tanama n
TOTAL
ANALYSES
Analisis Total dilakukan pada sluruh tanaman atau bagianbagian tanaman.
Bahan tanaman dikeringkan, dihaluskan dan diabukan.
Bahan abu tanaman kemudian diekstraks dengan reagen
kimia.
1. Kalau kadar K daun bagian bawah lebih rendah dari kadar K daun bagian atas,
maka tanaman defisiensi kalium.
2. Peningkatan hasil dg peningkatan kadar hara
3. Keseimbangan hara
4. Time of sampling: Kadar hara tanaman menurun mulai dari awal hingga akhir
masa pertumbuhannya
5. Crop Logging: Penggunaan analisis tanaman dalam operasi produksi tanaman
6. A-Value Technique: Teknik Analisis Radio-kimiawi
Pemupukan N menurunkan kadar P dan K tanaman tebu umur 10 bulan
Dosis pupuk N (lb/A)
Nitrogen (ppm)
0
300
Sumber: Burr, 1960.
229
463
Internode 8-10 :
Fosfor (ppm)
131
57
Kalium (ppm)
1160
340
Hasil tanaman jagung (Y)
Hasil tanaman jagung (Y)
Y = 1.20 + 31.88 X
r = 0.96
(Hanway, 1962)
at tasseling
(Loue, 1963)
Kadar K daun jagung (X)
Kadar N daun jagung (X)
Kadar Ca atau Mg daun jagung (Y)
Kadar K petiole
Dosis pupuk K = 400 kg/ha
200
(Loue, 1963)
Mg
Ca
100
0
(Tyler et al., 1960)
Kadar K daun jagung (X)
Umur tanaman kentang
BIOLOGICAL
TESTS
FIELD TEST.
Percobaan lapangan melibatkan berbagai perlakuan
pemupukan pada sebidang lahan. Biasanya digunakan
Rancangan Percobaan tertentu
Ukuran petakan contoh tgt jenis tanaman dan jatak
tanamnya
STRIP TESTS ON FARMERS FIELDS
Sepetak lahan petani diperlakukan dengan “pemupukan” yang
direkomendasikan berdasarkan hasil uji tanah dan/atau analisis tanaman.
LABORATORY & GREENHOUSE TESTS
1. Mitscherlich Pot Culture
2. Neubauer Seedling Method
3. Sunflower Pot Culture technique for Boron
METODE MIKROBIOLOGIS
1. Sackett & Stewart Technique
2. Aspergillus Niger
3. Mehlich Cunninghamella-Plaque Method for Phosphorus
Ketersediaan dan keseimbangan hara dalam tanah
SAMPLING:
Tanah &
Tanaman
Interpretasi
&
Rekomendasi
Analisis
Laboratorium
Korelasi antara
hasil analisis &
respon
tanaman
Contoh Tanah representatif :
1. Terdiri 10-20 subsample dari zone perakaran: 0-20 cm
2. Sebidang lahan yg seragam slope, drainage, warna, dan sejarah
pemupukannya
3. Area non-representatif: fence row, manure pile
4. Informasi pelengkap: petani, nomor lapangan, tanaman, praktek
pemupukan
5. Waktu sampling
6. Sampel komposit: 500 g, ditumbuk, diayak 2 mm
TUJUAN
UJI TANAH
1. Untuk mempertahankan status
kesuburan sebidang lahan
2. Untuk meramalkan / menduga respon kapur dan
pupuk yg menguntungkan
3. Untuk mendapatkan landasan bagi rekomendasi
jumlah kapur dan pupuk
4. Untuk mengevaluasi status kesuburan tanah di suatu wilayah
SOIL TEST
LEVEL
Sumber Unsur Hara
Tanah
Pupuk
Tinggi
Tanah
Pupuk
Medium
Tanah
Pupuk
Rendah
Tanah
Pupuk
Sgt Rendah
Tanah
Pupuk
Sgt Tinggi
Unsur hara yg
tersedia dari dlm
tanah
Unsur hara yg diperlukan dari pupuk
SAMPLING THE SOIL
UJI TANAH
1.
2.
3.
4.
Contoh tanah harus dapat mewakili kondisi daerah / lahan
Seringkali digunakan contoh tanah komposit
Peralatan sampling tanah
Area sampling: satu contoh mewakili liasan lahan tertentu
DEPTH OF SAMPLING
1. Untuk tanah-tanah pertanian, kedalaman sampling 15 - 30 cm
2. Kedalaman ini biasanya merupakan lapisan olah tanah
3. Untuk keperluan deskripsi profil tanah, sampling dilakukan untuk setiap
horison tanah
TIME OF SAMPLING
1. Sampling dapat dilakukan setiap saat asalkan kondisi tanah
memungkinkan
2. Rekomendasi umum adalah melakukan uji tanah setiap tiga tahun
3. Sampling tanah dapat dilakukan pada saat tanaman sedang tumbuh
ANALYZING THE SOILS
1. Kation: NH4+, K+, Ca++, Mg++
2. Fosfor
3. Unsur mikro
4. N dan Bahan organik
5. Kemasaman tanah dan kebutuhan kapur
6. Belerang
7. Sifat Fisika Tanah
8. …...
Hasil uji tanah harus dikalibrasikan dengan respon
tanaman thd penambahan unsur hara (pupuk) .
Respon tanaman dapat diperoleh dari percobaan
lapangan atau rumah kaca.
Indeks kesuburan tanah = “relative sufficiency” yg
dinyatakan sbg persentase dari jumlah yang diperlukan
untuk mencapai hasil maksimum
KALIBRASI UJI
TANAH
Indeks Kesuburan (%)
Sangt Rendah
Rendah
Medium
0 - 50
60-70
80-100
Tinggi
Sngt Tinggi
Ekstrem Tinggi
Tingkat kritis = Indeks kesuburan 75 %
Peluang respon pupuk
S. Rdh
Rndh
Medium
Tingkat kesuburan tanah
Tinggi
Indeks Kesuburan (%)
Sgt Tinggi
110 - 200
210 - 400
> 410
INTERPRETASI
SOIL TEST
Masalah penting dalam menginterpretasikan hasil uji
tanah adalah kaitannya dengan “pemupukan” yang
diperlukan.
Beberapa faktor yg harus diperhatikan adalah:
1. Karakteristik tanah
2. Hasil yang diharapkan
3. Tindakan pengelolaan
4. Kondisi agroklimat
Konsep hasil relatif (% hasil) didasarkan atas idea bahwa hasil yang diharapkan
(yg dinyatakan sebagai persentasi hasil maksimum) diduga dari hasil uji tanah
P dan K.
Sejumlah pupuk perlu ditambahkan untuk mencapai hasil tanaman hingga 95%
hasil maksimum.
Kelemahan konsep ini adalah kalau ada efek interaksi antar unsur hara.
Hasil Penelitian Barber (dari Purdue University) disajikan berikut:
Populasi tanaman jagung dan respon pupuk
Populasi jagung (tnm/A)
15.700
24.500
Sumber: Barber, 19…
Respon jagung (bu/A) thd pemupukan :
Dosis 100 lb P2O5
Dosis 200 lb K2O
2
21
22
39
REKOMENDASI
PUPUK
1. Interpretasi hasil uji tanah melibatkan evaluasi ekonomi
terhadap hubungan antara nilai uji tanah dengan respon pupuk.
2. Potensial respon pupuk dipengaruhi oleh faktor-faktor tanah,
agroklimat, dan pengelolaan oleh petani
3. Rekomendasi pemupukan nitrogen sangat dipengaruhi oleh
tanaman musim sebelumnya dan sasaran hasil
4. Untuk sistem komersial, sasarannya adalah mempertahankan
hara tanah pd tingkat untuk melestarikan “top profit” per
hektar lahan. Unsur hara tdk boleh menjadi faktor pembatas
selama pertumbuhan tanaman.
Hasil tanaman
D
C
B
A
Dosis pupuk
Respon hasil thd pemupulan
tgt pd potensial hasil tanaman
A: terendah; D: tertinggi
1. BUILDUP / Basic Treatment
TIPE REKOMENDASI
Pemupukan bersifat korektif, untuk meningkatkan ketersediaan
hara tanah hingga taraf yang diperlukan
Uji tanah harus dilakukan setiap 2 - 3 tahun untuk memperbaiki
dosis pupuk untuk mengganti kehilangan karena dipanen, erosi,
pencucian dan fiksasi.
2. ANNUAL APPLICATION
Pupuk P dan K ditambahkan kepada setiap tanaman dalam rotasi untuk
mempertahankan hasil uji tanah
3. ROTATION.
a.
b.
c.
d.
e.
Beberapa faktor yg harus diperhatikan:
Pemupukan dilakukan sebelum tanaman yg paling responsif & profitable
Row-application pupuk P untuk jagung
Forage-crop menyerap banyak K, perlu pemupukan setiap tahun
Kedelai punya respon lebih baik thd kesuburan tanah yg tinggi daripada pemupukan
langsung
Dalam sistem pergiliran tanaman dlm setahun, pemupukan dilakukan pd tanaman yg
paling responsif
4. REPLACEMENT SYSTEM
Dosis pupuk ditentukan berdasarkan jumlah hara yang diambil tanaman untuk menghasilkan tingkathasil tertentu. Beberapa faktor yg harus diperhatikan adalah:
a. Kemampuan tanah menyediakan unsur hara, termasuk kemampuan fiksasi hara
b. Tingkat kecukupan hara dalam tanah
c. Kandungan hara dalam hasil panen
d. Kemampuan tanaman menyerap hara tanah.
1. Metode ini didasarkan pada gagasan bahwa tanaman dapat memanfaatkan
sejumlah tertentu unsur hara yg terkandung dlm tanah, pupuk dan rabuk.
2. Kalau jumlah hara yang diperlukan untuk mencapai hasil tertentu dapat diketahui,
maka jumlah tambahan pupuk dan rabuk dapat dihitung
3. Rekomendasi pupuk dipengaruhi oleh: sistem rotasi, tindakan pengelolaan, analisis
tanah, dan tanaman yang akan ditanam
4. Contoh untuk tanaman jagung sbb:
Estimasi persentase ketersediaan N, P, K dari tiga sumber:
Sumber
Persentase yg diperoleh selama satu musim:
Nitrogen
Fosfor
Kalium
Tanah (available)
Rabuk (total)
Pupuk (available)
40
30
60
Sumber: Berger, 1954.
40
30
30
40
50
50
BEBERAPA
PRINSIP
PENTING
Praktek pengapuran dan pemupukan yang tepat sangat
tergantung pada kebutuhan tanaman, agroklimat,
karakteristik tanah dan metode analisis defisiensi dlm tanah
Pendekatan diagnostik dalam uji tanah dan analisis tanaman
lebih utama untuk tindakan pencegahan
Gejala defisiensi merupakan sarana yang sangat bermanfaat di daerah
/ lahan yang baru dilakukan pemupukan.
Di daerah yang telah dikelola secara intensif, interpretasi gejala
defisiensi sangat sulit karena adanya komplikasi dari berbagai faktor
HIDDEN HUNGER merupakan bahaya tersembunyi, tetapi uji
tanah & tanaman yang hati-hati dapat membantu menghindari
bahaya ini
Tanaman mengintegrasikan semua faktor lingkungan tumbuhnya ke dalam
kehidupannya, uji tanah dapat menjadi sangat bermanfaat. Analisis jaringan
tanaman yg sedang tumbuh di lapangan sangat berguna, namun harus
diinterpretasikan secara hati-hati.
BEBERAPA
PRINSIP
PENTING
Kalau unsur hara ditambahkan melalui pemupukan,
kandungan hara dalam tanaman akan meningkat. Dalam
kaitan ini penting untuk ditentukan suatu titik (kadar
hara tanaman) dimana tidak terjadi lagi peningkatan hasil
ekonomis tanaman
Analisis tanaman sangat penting untuk mengetahui / menganalisis
problematik unsur hara mikro di suatu area lahan.
Keseimbangan di antara unsur hara dalam tubuh tanaman sama pentingnya
dengan jumlah aktual masing-masing hara tsb. Misalnya hubungan di antara
Ca-Mg-K-NH4 ; Mn-Fe-Zn-P
Prinsip uji tanah adalah mencari nilai yg dapat digunakan untuk
menduga jumlah unsur hara yang diperlukan untuk menambah
ketersediaan dalam tanah. Hasil uji tanah ini harus dikalibrasikan
dengan percobaan pemupukan di lapangan dan rumah kaca. Harus
diingat bahwa kesuburan tanah hanyalah salah satu faktor yg
mempengaruhi produksi tanaman
Ciri-ciri fisika tanah menjadi semakin penting kalau kondisinya telah
mendekati “top profitable yield”; namun perlu diidentifikasi lebih lanjut
ciri-ciri fisika mana yang “cocok” dan mana yang tidak cocok.
BEBERAPA
PRINSIP
PENTING
Rekomendasi yang disusun untuk mendapatkan
hasil yang lebih tinggi seyogyanya ditujukan pada: to
maintain foil fertility at a level for top profit yields.
Ada empat macam pendekatan dalam menusun rekomendasi:
1. Build-up dengan dosis pemupukan yang tinggi
2. Annual application, pemupukan setiap musim tanaman dlm sistem rotasinya
3. Rotational fertilization
4. Replacement, mengganti unsur hara yang dipanen
Pemupukan tanaman dimaksudkan untuk mensuplai unsur
hara yang ketersediaannya dalam tanah tidak mencukupi
kebutuhan tanaman untuk menghasilkan maximum net return.
Hasil atau nilai hasil
Tingkat pengelolaan yg baik
Tingkat pengelolaan rata-rata
Biaya pupuk
A
B
Dosis pupuk
MODEL EVALUASI KESUBURAN TANAH DAN REKOMENDASI
PEMUPUKAN
1. Pendekatan yang Digunakan
2. Gejala Defisiensi Unsur Hara
3. Kelaparan Tersembunyi
4. Analisis Jaringan Tanaman
5. Uji Biologis
6. Uji Tanah
Diunduh dari: smno fpub ……….. 6/10/2012
UJI TANAH = SOIL TESTING
1. Uji tanah merupakan metode kimiawi untuk mengestimasi kemampuan
tanah mensuplai unsur hara.
2. Uji tanah secara kimiawi dapat menentukan dugaan kebutuhan hara sebelum
tanaman ditanam.
3. Uji tanah mengukur sebagian dari total suplai hara dalam tanah.
4. Untuk dapat menggunakan hasil evaluasi ini untuk menduga kebutuhan unsur hara
suatu tanaman maka harus dikalibrasikan dengan percobaan pemupukan di
lapangan dan di rumah kaca.
Diunduh dari: ……….. 6/10/2012
UJI TANAH = SOIL TESTING
Tujuan Uji Tanah
1. Untuk mempertahankan status kesuburan tanah di suatu bidang lahan.
2. Untuk memperkirakan peluang respon yang menguntungkan terhadap
kapur dan pupuk.
3. Untuk memberikan landasan bagi rekomendasi dosis kapur dan pupuk.
4. Untuk mengevaluasi status kesuburan tanah di suatu wilayah.
Diunduh dari: ……….. 6/10/2012
UJI TANAH = SOIL TESTING
Tujuan uji tanah adalah untuk mendapatkan "suatu nilai" yang akan
membantu meramalkan jumlah unsur hara yang diperlukan untuk
menunjang suplai unsur hara dalam tanah.
Misalnya, tanah yang menunjukkan nilai uji tanah "tinggi" tidak akan
memerlukan banyak tambahan pupuk.
Diunduh dari: ……….. 6/10/2012
UJI TANAH = SOIL TESTING
Keterkaitan antara hasil uji tanah dengan rekomendasi dosis
pupuk (Tisdale dan Nelson, 1975)
Hasil Uji
Tanah
Proporsi sumber unsur hara tanah pada berbagai nilai uji
tanah
Sagt Tinggi
TANAH
Tinggi
TANAH
Medium
Rendah
Sngt Rendah
PUPUK
PUPUK
TANAH
PUPUK
TANAH
PUPUK
TANAH
PUPUK
Unsur hara
dari tanah
Unsur Hara dari Pupuk
Diunduh dari: ……….. 6/10/2012
UJI TANAH = SOIL TESTING
PENGAMBILAN CONTOH TANAH
Salah satu aspek yang sangat penting dari uji tanah adalah cara mendapatkan contoh tanah
yang dapat mewakili daerah yang diuji.
Biasanya contoh tanah komposit sebanyak 500-1000 g diambil dari suatu bidang lahan.
Dengan demikian prosedur pengambilan contoh tanah harus benar-benar diikuti.
Analisis kmiawi di laboratorium menggunakan contoh tanah. Kalau contoh tanah yang diambil
tidak mewakili kondisi lapangan maka hasil rekomendasinya juga akan keliru.
Pada umumnya kesalahan sampling tanah di lapangan lebih besar dibandingkan dengan
kesalahan di laboratorium.
Diunduh dari: ……….. 6/10/2012
UJI TANAH = SOIL TESTING
Menganalisis Contoh Tanah
Suatu uji tanah secara kimiawi harus dirancang untuk memungkinkan perkiraan jumlah unsur hara yang
berhubungan dengan fraksi pertukaran kation, fraksi yang mengikat fosfat, dan dalam kondisi tertentu diharapkan
juga mampu memperkirakan unsur hara yang berhubungan dengan dekomposisi bahan organik.
Beberapa macam larutan pengekstraks telah banyak digunakan dalam rangka untuk mengkorelasikan hasil uji
tanah dengan pertumbuhan tanaman.
Menurut Bray (1948), tingkat kehandalan metode ekstraksi tanah ditentukan oleh tiga
hal, yaitu
1.
2.
3.
harus mampu mengekstraks semua atau sebagian bentuk unsur hara
tersedia dalam tanah yang cirinya berbeda-beda,
prosedur ekstraksinya harus cepat dan akurat,
jumlah unsur hara yang terkestraks harus berkorelasi dengan pertumbuhan
dan respon tanaman terhadap unsur hara yang terkait pada berbagai
kondisi.
Diunduh dari: ……….. 6/10/2012
UJI TANAH = SOIL TESTING
Larutan pengekstraks P-tanah, mulai dari air, alkalin, hingga asam-asam lemah yang dicampur dengan asam-asam
yang relatif kuat dan ammonium fluorida telah banyak digunakan untuk ekstraksi fosfat.
Korelasi antara hasil uji P-tanah dengan fraksi P-anorganik dalam tanah dari Bangladesh.
Uji tanah
Pengekstraks
Ca-P
Al-P
Fe-P
Olsen
0.5M NaHCO3 pH = 8.5
0.55
0.62
0.78*
Truog
0.002N H2SO4 pH = 3
0.90*
0.59
0.09
North Car.
0.025N H2SO4+0.05N HCl
0.88*
0.65*
0.06
HCl
Bray 1
0.3 N HCl
0.03 +0.025N HCl
0.95*
0.72*
0.70*
0.73*
0.23
0.46
Bray 2
0.3 N NH4F+0.025N HCl
0.78*
0.74*
0.38
Schoefield
Morgan
EDTA
0.01M CaCl2
NaOAc + HOAc
0.02N Na2-EDTA
0.06
0.79*
0.77*
0.05
0.56
0.95*
0.03
0.18
0.41
Sumber: Ahmed dan Islam (1975) Dalam Sanchez, 1976.
UJI TANAH = SOIL TESTING
Metode uji tanah, faktor-faktor tanah yang mempengaruhi interpretasinya, dan kisaran
kritis unsur mikro.
Unsur
hara
B
Cu
Faktor yang berpengaruh
Esensial
Tekstur; pH
Fe
Probable
Kapur
B.O.
pH; Kapur
Mn
pH
Mo
Zn
pH
pH;
kapur
B.O.
Fe, P, S
P
Metode Ekstraksi
Kisaran tingkat
H2O panas
Fe NH4C2H3O2 (pH 4.8)
0.5 M EDTA
0.43N HNO3
Biologis
NH4C2H3O2(pH 4.8)
DTPA+CaCl2(pH7.3)
0.05N HCl+0.025N H2SO4
0.1N H3PO4 dan 3N NH4H2PO4
Hydroquinone+ NH4C2H3O2
H2O
(NH4)2C2O4 pH=3.3
0.1N HCl
Dithizone+NH4C2H3O2
EDTA+(NH4)2CO3
DTPA+CaCl2 pH 7.3
kritis (ppm)
0.1-0.70
0.20
0.75
3-4.00
2-3.00
2.00
2.5-4.5
5-9
15-20
25-65
2
0.04 – 0.2
1-7.5
0.3-2.3
1.4-3.0
0.5-1.0
Sumber: Sanchez, 1976.
UJI TANAH = SOIL TESTING
Korelasi dan Kalibrasi Uji Tanah
Aspek-aspek yang sulit dalam proses evaluasi kesuburan tanah adalah korelasi, interpretasi dan rekomendasi,
karena melibatkan fenomena yang rumit.
Nilai uji tanah itu sendiri belum mampu memberikan banyak informasi, ia hanya merupakan nilai empiris yang bisa
atau tidak-bisa mencerminkan ketersediaan unsur hara.
Nilai ini akan menjadi lebih bermakna kalau mempunyai korelasi yang baik dengan respon tanaman.
Kajian korelasi seperti ini biasanya dilakukan pada dua tingkat, yaitu tingkat kajian di rumah kaca yang melibatkan
berbagai kondisi tanah, dan kajian lapangan yang lebih definit dengan melibatkan lokasi (lapangan) yang dipilih
secara hati-hati.
Diunduh dari: ……….. 6/10/2012
UJI TANAH = SOIL TESTING
Tujuan pokok dari kajian korelasi di rumah kaca adalah untuk membandingkan berbagai
metode ekstraksi dan menentukan tingkat kritis "tentatif".
Sedangkan kajian lapangan bertujuan untuk menetapkan tingkat kritis yang "definit" untuk
suatu metode ekstraksi yang terpilih.
Pada hakekatnya hasil uji tanah dikalibrasikan dengan respon tanaman terhadap
pemupukan di lapangan.
Respons pertumbuhan dan hasil tanaman dari berbagai dosis pupuk dapat dihubungkan
dengan jumlah unsur hara yang tersedia dalam tanah.
Diunduh dari: ……….. 6/10/2012
UJI TANAH = SOIL TESTING
Apabila hasil tanaman berkorelasi dengan suatu peubah tertentu,
misalnya P-tersedia dalam tanah, maka hal ini berarti bahwa Ptersedia tersebut merupakan faktor pembatas yang lebih penting
dibandingkan ppeubah-peubah lainnya yang tidak dikendalikan
dalam suatu kajian korelasi .
Diunduh dari: ……….. 6/10/2012
UJI TANAH = SOIL TESTING
Hasil penelitian Hauser (1973) tentang korelasi hasil analisis P-tanah dengan
respon kapas:
Hasil analisis P-tanah dikelompokkan menjadi tiga kategori, yaitu rendah,
medium dan tinggi.
Dosis rekomendasi didasarkan pertimbangan jumlah pupuk yang diperlukan
untuk menaikkan nilai analisis P-tanah menjadi kategori "tinggi".
Respon hasil kapas, kg/ha
RENDAH
Hasil analisis tanah, ppm P
SEDANG
TINGGI
UJI TANAH = SOIL TESTING
Cate dan Nelson (1965) mengemukakan suatu metode plotting
hasil relatif (persen dari hasil maksimum) sebagai fungsi dari
nilai-nilai analisis tanah.
Diagram pencar titik-titik dibagi menjadi empat kuadran oleh
garis vertikal dan horisontal.
Kedua garis ini digeser-geser sedemikian rupa sehingga
banyaknya titik-titik yang berada pada kuadran kiri bawah
dan kanan atas mencapai maksimum, dan titik-titik yang
berada pada kuadran kiri atas dan kanan bawah mencapai
minimum.
Diunduh dari: ……….. 6/10/2012
An overview of fertilizer-P recommendations in Europe: soil testing, calibration and
fertilizer recommendations
L. Jordan-Meille , G. H. Rubæk , P. A. I. Ehlert , V. Genot , G. Hofman , K. Goulding , J. Recknagel , G. Provolo , P.
Barraclough
Soil Use and Management. Volume 28, Issue 4, pages 419–435, December 2012
The procedure for applying phosphorus (P) fertilizer to soil can be divided into three consecutive steps: (i)
Measurement of soil-P availability, (ii) calibration of the soil-P fertility level and (iii) estimation of the
recommended P dose. Information on each of these steps was obtained for 18 European countries and
regions with the aim of comparing P fertilizer recommendation systems at the European scale.
We collected information on P fertilizer recommendations through conventional or grey literature, and
personal contacts with researchers, laboratories and advisory services. We found much variation between
countries for each of the three steps: There are more than 10 soil-P tests currently in use, apparent
contradictions in the interpretation of soil-P test values and more than 3-fold differences in the P fertilizer
recommendations for similar soil-crop situations.
This last result was confirmed by conducting a simple experimental inter-laboratory comparison. Moreover,
soil properties (pH, clay content) and crop species characteristics (P responsiveness) are used in some
countries in the calibration and recommendation steps, but in different ways. However, there are also
common characteristics: soil-P availability is determined in all countries by extraction with chemical
reagents and the calibration of the soil-P test values, and the fertilizer recommendations are based on the
results from empirical field trials. Moreover, the fertilizer recommendations are nearly all based on the
amount of P exported in the crops. As long as rational scientific and theoretical backgrounds are lacking,
there is no point in trying to synchronize the different chemical methods used. We therefore call for a
mechanistic approach in which the processes involved in plant P nutrition are truly reproduced by a single
standard method or simulated by sorption-desorption models.
Diunduh dari: onlinelibrary.wiley.com › ... › Vol 28 Issue 4 ……….. 6/12/2012
Soil Testing to Predict Phosphorus Leaching
Rory O. Maguire and J. Thomas Sims
JEQ. Vol. 31 2002 No. 5, p. 1601-1609
Subsurface pathways can play an important role in agricultural phosphorus (P) losses that can
decrease surface water quality.
This study evaluated agronomic and environmental soil tests for predicting P losses in water leaching
from undisturbed soils. Intact soil columns were collected for five soil types that had a wide range in
soil test P.
The columns were leached with deionized water, the leachate analyzed for dissolved reactive
phosphorus (DRP), and the soils analyzed for water-soluble phosphorus (WSP), 0.01 M CaCl2 P
(CaCl2–P), iron-strip phosphorus (FeO-P), and Mehlich-1 and Mehlich-3 extractable P, Al, and Fe.
The Mehlich-3 P saturation ratio (M3-PSR) was calculated as the molar ratio of Mehlich-3
extractable P/[Al + Fe].
Leachate DRP was frequently above concentrations associated with eutrophication. For the
relationship between DRP in leachate and all of the soil tests used, a change point was determined,
below which leachate DRP increased slowly per unit increase in soil test P, and above which leachate
DRP increased rapidly. Environmental soil tests (WSP, CaCl2–P, and FeO-P) were slightly better at
predicting leachate DRP than agronomic soil tests (Mehlich-1 P, Mehlich-3 P, and the M3-PSR),
although the M3-PSR was as good as the environmental soil tests if two outliers were omitted.
Our results support the development of Mehlich-3 P and M3-PSR categories for profitable
agriculture and environmental protection; however, to most accurately characterize the risk of P loss
from soil to water by leaching, soil P testing must be fully integrated with other site properties and P
management practices.
Diunduh dari: https://www.agronomy.org/publications/jeq/abstracts/31/5/1601……….. 6/12/2012
. Effective Factors on Adoption of Soil Testing for Farm Fertilizer Nutrition in Shahreza
Township of Esfihan Province, Iran
Saeid Fe`li , Nooshin Bondarian, Mosayeb Baghaei and Arezoo Mirzaei
Research Journal of Soil and Water Management . 2010 . Vol. 1 Issue: 2. Page No.: 38-44
Soil testing is a general soil productivity evaluation program that helps farmers
touse chemical fertilizers wisely.
The purpose of this study was to investigate the effective factors on adoption of
soil testing for fertilizing farms.
The research instrument was astructural questionnaire with close ended questions
which confirmed its validity andreliability. The target population included all
farmers in the Shahreza township of Esfihan Province (N = 9,825). Among of
them, 215 persons were chosen by using the Cochran formula through stratified
sampling as the statistical sample and finally 195 questionnaires were analyzed
(n = 195).
There was a significant difference between the personal, farming and educational
characteristics of adopters and non-adopters of soil testing. The result of
discriminate analysis showed that knowledge about soil sampling principles, the
amount of extensional contacts about soil testing and educational level were
identified as the most discriminative factors (74.40% of population) affecting the
adoption of soil testing.
Diunduh dari: http://www.medwelljournals.com/abstract/?doi=rjswm.2010.38.44……….. 6/12/2012
I GUSTI MADE SUBIKSA, SUPIYANDI SABIHAM.
JURNAL TANAH DAN IKLIM NO. 30/2009
. Soil testing calibration is a process to provide meaning of soil test value in term of crops response.
Research on soil testing calibration for corn has been carried out on Typic Hapludox Cigudeg.
The objectives were: 1) to determine critical point of soil test value of K, 2) to determine the application
rate of K fertilizer recommendation.
The split plot design was used with consisted five rate of K fertilization on three K soil status as the
main plots. There were four K soil test methods assessed to determine the critical point value for corn. K
availability was classified into three categories namely low, medium, and high class.
The results revealed that critical value of four soil testing methods for low, medium, and high
respectively were : HCl 25% (<14, 14-29, and >29 mg 100 g-1), NH4OAc pH 7(<84 ppm, 84-220 ppm,
and >220 ppm), Morgan (<70 ppm, 70-180 ppm, and >180 ppm), and Mechlich I (<54 ppm, 54-135
ppm, and >135 ppm). K fertilization significantly affected to corn plant height in the low soil K status
until the rate of 60 kg K ha-1 (116 kg KCl ha-1). Dry biomass significantly increased due to K
fertilization on low, medium as well as high soil K status. K fertilization also improved corn grain
production. The ears of corn could not develop without K fertilization. This was an evidence that K
nutrient has an important role in enzyme activity and assimilate translocation. Even with low rate of K
fertilization, corn has succeeded to form ears and kernels. In the low soil K status, K fertilization sharply
increased dry grain, but in the medium soil K status the curve was gentler. Whereas in the high soil K
status, K fertilization did not significantly affect the dry grain yield. The recommended application rate
of K fertilization
for corn on Typic Hapludox Cigudeg with low K status was 89 kg K ha-1 and in the medium status was
53 kg K ha-1. Whereas in the high soil K status, no K fertilization was needed.
Diunduh dari: http://124.81.86.163/ojs/index.php/jti/article/view/221 ……….. 6/12/2012
Soil testing and plant analysis in Australia.
Peverill, K.I.
Australian Journal of Experimental Agriculture. [1993, 33(8):963-971]
During the past 3-4 decades, there has been a modest growth in the demand for soil amd
plant testing services in Australia. Such development reflects an increasing awareness by
farmers that there are tangible benefits from the regular use of soil and plant analysis.
Concomitant with these changes, there has been an increasing breadth and sophistication in
the range of available services, instrumental advances that permit more rapid analytical
throughput, evolution of computer management systems (including computer-generated
reports), and a general decrease in reporting time to primary producers.
These developments have not always been matched with adequate quality control and
uniformity in sampling, analysis, interpretation, and fertiliser advice procedures. There is
need for further research and method development leading to the introduction of universal
reagents or ion exchange resin extractions, or new test procedures into laboratory routines,
to enhance laboratory capacities and turnaround times or to improve interpretation skills.
Advances in decision support software are also required in order to refine fertiliser advice to
primary producers. The challenge for the future is the standardisation of procedures and
maintenance of adequate quality control by the various agencies offering soil and plant
testing services. The Australian Soil and Plant Analysis Council (ASPAC) will play a pivotal
role in this process.
Diunduh dari: http://europepmc.org/abstract/AGR/IND20452684……….. 6/12/2012
Soil Health and Sustainable Crop Production: Adoption and Awareness of Soil Testing.
Asthana A, Kumar Sushil
Journal of Sustainable Agriculture. [2008, 32(2):303-320]
Maintenance of proper soil fertility, through application of a balanced mix of
various nutrients, is important for maintaining sustainable crop production levels.
Soil testing is a crucial step in this direction.
This paper describes soil testing as a multi-dimensional concept comprising
seven aspects. Awareness of these factors among farmers is computed, examined,
and statistically analyzed using survey data collected from three categories of
farmers--small, medium and large--in four districts of the Uttar Pradesh state in
India.
The impact of a World Bank-aided project--Diversified Agriculture Support
Project--is also assessed in terms of dissemination of soil testing knowledge.
Results indicate that project interventions had a significant and variable soil
impact on farmers awareness of and likelihood of adopting soil testing in four
districts.
The findings have implications for policy-makers and researchers who are
interested in improving the production and productivity of crops in developing
economies.
Diunduh dari: http://europepmc.org/abstract/AGR/IND44094634……….. 26/12/2012
Correlation of Plant Tissue Tests of Corn, Deficiency Symptoms, and Soil Analyses
on the Jordan Fertility Plots
B. N. Driskell and A. C. Richer
SSSAJ. Vol. 16 No. 3, p. 270-270. July, 1952
Nitrogen. — An excellent correlation at the 0.1% level of significance was found between
tissue tests and visual deficiency symptoms on tiers 1 and 2; however, no correlation was
found between the tissue tests and potential nitrification of the soil or visual deficiency
symptoms and potential nitrification of the soil.
Phosphorus. — Highly significant correlations were found in all instances, namely,
between (1) soil tests and tissue tests, (2) soil tests and deficiency symptoms, and (3)
tissue tests and deficiency symptoms.
Potassium. — All correlation coefficients were significant at the 0.1% level between
exchangeable soil potassium and tissue tests, exchangeable soil potassium and deficiency
symptoms, and tissue tests and deficiency symptoms.
Magnesium. — The correlation coefficients between exchangeable magnesium and tissue
tests on the limed tier were not significant at the 5% level but were significant on the acid
tier. Significance at either the 1% or the 0.1% level was found between exchangeable soil
magnesium versus deficiency symptoms and tissue tests versus deficiency symptoms.
Good correlations were obtained in most instances between soil tests, tissue tests, and
deficiency symptoms, but no one test is always conclusive.
Diunduh dari: https://www.soils.org/publications/sssaj/abstracts/16/3/SS0160030270a……….. 6/10/2012
The Relationship Between Soil Tests for Available Nitrogen and Nitrogen Uptake by Various
Irrigated Crops in the Western States
W. F. Spencer, A. J. MacKenzie and F. G. Viets.
SSSAJ. Vol. 30 No. 4, p. 480-485. July, 1966
Soil tests for available N were evaluated by determining the relationship between N uptake from a
non-N fertilized plot, as a direct measure of the amount of N available to a crop, and available N as
measured by various laboratory methods. Field experiments were conducted with four irrigated
crops, corn (Zea mays), sugar beets (Beta vulgaris L.), sorghum (Sorghum vulgare), and cotton
(Gossypium hirsutum) on neutral to calcareous soils in California, Nebraska, or Washington. Initial
nitrate N, nitrifiable N released on incubation for 2- and 4-week periods, and total N in soil samples
from 0- to 6- and 6- to 12-inch depths were combined to give 14 measures of available N for
correlation with N uptake.
Highly significant correlations were obtained between N uptake from no-N plots and all soil test
values, with the exception of NO3-N released on incubation for 4 weeks. Nitrogen uptake by corn
was most highly correlated with initial NO3-N, 6–12 inches; initial NO3-N plus N released on
incubation for 2 weeks; and total N, 0–12 inches. The coefficient of determination for these
relationships indicated that variations in soil test values were associated with approximately 50% of
the variation in N uptake from no-N plots. Combining the effects of initial NO3-N and total N in a
multiple-regression analyses slightly improved the prediction of N uptake by corn and sugar beets
growing in Nebraska.
With cotton growing on desert soils low in organic matter, initial NO3-N, 0–12 inches, was most
highly correlated with N uptake, and combining the effect of initial NO3-N and total N did not
improve the prediction of N uptake.
Diunduh dari: https://www.soils.org/publications/sssaj/abstracts/30/4/SS0300040480……….. 6/10/2012
A Soil Test for Nitrogen Availability to Corn
F. R. Magdoff, D. Ross and J. Amadon
SSSAJ. Vol. 48 No. 6, p. 1301-1304. Nov, 1984
A soil test for N availability to corn (Zea mays L.), NO-3- to 30cm when plants are 15 to 30 cm tall, was
evaluated on a wide range of soils at 33 locations in Vermont and one in New York state. The NO -3-N
present at the time of sampling is a result of an integration of all the soil and weather factors that have
influenced the availability of N prior to the time for sidedress fertilizer application.
There was a typical response relationship between soil test NO-3-N and corn silage yield on plots that
only received limited amounts of starter N fertilizer at planting. The Cate-Nelson procedure for NO-3-N
vs relative yield (yield without sidedress N/yield with sidedress N) indicated that there was a greater
probability of response to N fertilizer when NO-3-N was less than 36 kg ha−1 than at higher soil test
values.
The currently used N fertilizer recommendation procedure is based on estimates derived from cropping
history, yield goal, soil type, and manure management information provided by farmers. Compared with
the current method of estimating N fertilizer needs, recommendations based on the NO -3-N soil test call
for much less N fertilizer application and are more accurate in separating sites with varying response
probabilities.
As a routine laboratory procedure, the proposed test has numerous advantages over other N availability
procedures. However, special procedures are needed, including rapid soil treatment after sampling (to
eliminate N transformations), sampling the soil at a different time than for the usual soil test, and a
rapid sample turnaround time in the laboratory.
Diunduh dari: https://www.soils.org/publications/sssaj/abstracts/48/6/SS0480061301……….. 6/10/2012
Relationships Between Soil Test Phosphorus, Soluble Phosphorus, and Phosphorus
Saturation in Delaware Soils
Maria C. Pautler and J. Thomas Sims.
SSSAJ. 2000. Vol. 64 No. 2, p. 765-773 . Mar, 2000
Methods to identify agricultural soils that contribute to nonpoint-source pollution of surface waters
by P are of increasing importance, particularly in areas with high animal densities (animal units per
hectare of cropland). Our objective was to determine the relationship between agronomic soil test P
(STP = Mehlich 1) and other soil P tests proposed to measure the potential for P loss by erosion,
runoff, and leaching.
We compared STP with soluble P, P in the “fast desorbing pool” (strip P), and soil P saturation for
127 soils (122 from Delaware and five from the Netherlands). Soil test P was significantly correlated
with total P ( r = 0.57***, significant at the 0.001 level ), soluble P ( r = 0.71*** ), strip P ( r =
0.84*** ), and oxalate-extractable P ( P ox ; r = 0.84*** ) Strip P was a better predictor of soluble P
than STP (r2 = 0.76*** )
The ratio of strip P/Pox (the percentage of reversibly sorbed P in the fast desorbing pool) increased as
P sorption capacity, estimated from oxalate-extractable Al and Fe (Alox + Feox), decreased.
We also determined the degree of P saturation (DPS) using three methods: Langmuir P sorption
isotherms; oxalate extractions of P, Al, and Fe; and STP plus a single-point P sorption index (PSI).
Soluble P, STP, and desorbable P increased for DPS values >30%, similar to upper DPS limits in the
Netherlands and Belgium.
Soils rated agronomically excessive in STP (>50 mg kg−1) had higher ratios of soluble P, strip P, and
Pox to total P than those in agronomically optimum or lower categories.
Diunduh dari: https://www.soils.org/publications/sssaj/abstracts/64/2/765……….. 6/10/2012
VAN RAIJ, B. et al.
Soil testing applied to estimate corn responses to fertilization.
Bragantia [online]. 1981, vol.40, n.1, pp. 57-75. ISSN 0006-8705.
In this paper some of the criteria that have been used in the State of São Paulo in
soil test interpretation were studied, correlating soil test parameters with corn
response to applied nitrogen, phosphorus or potassium in 25 field experiments.
Exchangeable potassium and phosphorus soluble in 0.05N H2SO, correlated well
with responses of the crop to the applied nutrients. Nitrogen responses could not
be correlated to soil test values.
Response curves and fertilizer efficiencies are presented for nitrogen, phosphorus
and potassium. For the two last nutrients, the average curves are given for very
low, low, medium and high soil test values.
Diunduh dari: http://www.scielo.br/scielo.php?pid=S0006-87051981000100006&script=sci_abstract ………..
A soil test for nitrogen availability in the northeastern United States
Frederick R. Magdoff, William E. Jokela, Richard H. Fox & Gary F. Griffin.
Communications in Soil Science and Plant Analysis . Volume 21, Issue 13-16, 1990
Special Issue: Soil Testing and Plant Analysis. pages 1103-1115
. A soil test for nitrogen availabilty to corn (Zea mays, L) has gained wide acceptance in the northeast region
of the United States. The test involves sampling the surface 30 cm of soil during the early part of the growing
season. The N03‐N present at that time is correlated with the probability of obtaining a yield increase by
using sidedress nitrogen fertilizer. The test has been evaluated in 272 yr‐site N response experiments in
Vermont, Pennsylvania, Connecticut, New York, and New Hampshire. The various states in the region that
are now offering a N soil test (Vermont, Pennsylvania, Connecticut, and Maine) have different methods of
making recommendations based on soil‐test levels. However, 20 to 30 mg NO3‐N/kg soil is about the critical
range above which there is a low probability of obtaining yield increases due to sidedress fertilizer N.
Therefore, no additional N fertilizer is recommended.
A major problem, which is slowing widespread utilization of this test is that the soil must be sampled at a
different time of the year than the routine soil tests which are usually sampled in either the fall or prior to the
growing season in the spring. Other critical issues include the deeper sampling and rapid drying needed as
well as the rapid turnaround time required to get the samples to the laboratory, through the laboratory, and
back to the farmer.
There is only a limited “window”; of time available between soil sampling and the period for timely fertilizer
N sidedressing. Various states are using different innovative programs to help introduce farmers to the test
and to speed total turnaround time.
Diunduh dari: http://www.tandfonline.com/doi/abs/10.1080/00103629009368293……….. 6/10/2012
Correlation of Soil Tests for Available Phosphorus and Potassium with Crop Yield
Responses to Fertilization
O. H. Long and L. F. Seatz
SSSAJ. Vol. 17 No. 3, p. 258-262. July, 1953
Separate yield responses to applied P and K were correlated with soil tests for these elements on 72
experiments with corn, 18 with cotton, 35 with small grains, 28 with legume hays and 11 with permanent
pastures. Sodium perchlorate in N/10 perchloric acid was the extracting agent.
Results are presented in graphic form showing soil-test values for P and K plotted against crop yields
obtained without P or K expressed as percent of yields where phosphate or potash was applied.
Two methods of approach are used in showing the degree of correlation. One method is concerned with
“prediction accuracy” at only the lower values of soil P or K. The other method is concerned with the
regression curves and correlation coefficients for the experiments as a whole.
Responses of corn to phosphorus fertilization on loess-derived soils correlated least satisfactorily with the
soil test where a predicted yield response was obtained in only 17% of the tests. Permanent pastures showed
the best correlation; all experiments were on soils low in phosphate and responded to applications of P. The
prediction accuracies obtained with other crops were as follows: corn, on limestone-derived soils, 64%;
cotton, 54%; small grains, 70%; and legume hays, 63%.
Responses of cotton to potassium fertilization indicated the best correlation with the soil test, the prediction
accuracy being 60%. The prediction accuracies obtained with the other crops were: corn, 44%; small grains,
47%; legume hays, 33%; and permanent pastures, 57%.
The correlation coefficient (r) was not significant with respect to P on any crop; it was significant with
respect to K only on corn.
Diunduh dari: https://www.soils.org/publications/sssaj/abstracts/17/3/SS0170030258 ……….. 6/10/2012
The role of soil testing and plant analysis in sustainable agriculture
Mike Brusko.
Communications in Soil Science and Plant Analysis
Volume 23, Issue 17-20, 1992 . Special Issue: Soil Testing and Plant Analysis in the Global Community.
pages 2097-2101
Sustainable agriculture aims to develop food and fiber production systems that
benefit farmers and society both economically and environmentally.
A key step toward that goal is helping farmers simultaneously use and improve the
fundamental resources they have on their farms, such as air, water, soil, sunlight,
labor, and capital.
The more “tools”; farmers have for achieving that goal, the better they'll be able to
meet their own and society's needs.
Proper, timely soil testing and plant analysis can be very valuable tools, provided
they are coupled with fertilizer recommendations based on realistic yield goals,
appropriate credits for organic sources of plant nutrients, and field‐proven crop
response trials.
Diunduh dari: http://www.tandfonline.com/doi/abs/10.1080/00103629209368727……….. 6/10/2012
Agricultural BMPs for phosphorus reduction in south Florida.
Izuno, F. T.; Bottcher, A. B.; Coale, F. J.; Sanchez, C. A.; Jones, D. B.
Trans-ASAE v.38(3): p.735-744 (1995 May- 1995 June)
Four sets of eight or twelve 0.7 ha plots, designed for soil and hydraulic uniformity, were used to
screen potential "Best Management Practices" (BMPs) for reducing total phosphorus (TP)
concentrations and loadings in the Everglades Agricultural Area (EAA) of south Florida. The four
production systems and their alternatives (treatments) studied were: (1) sugarcane (interspecific
hybrids of Saccharum sp.) versus drained fallow plots; (2) fast versus slow drainage rates for
sugarcane; (3) rice (Oryza sativa L.) in rotation following radishes to serve as a P filter crop versus
traditional flooding fallow; and (4) banding phosphorus (P) fertilizer at 50% of the soil-test
recommendation rate for cabbage (Brassica oleracea L.) versus full-rate broadcast applications.
The study showed that there were no differences in P concentrations in drainage water between
sugarcane and drained fallow fields. Annual P loading to the plots in rainfall and irrigation water
(0.63 kg TP ha-1) exceeded the P loading of drainage waters (0.52 kg TP ha-1 for sugarcane and 0.59
kg TP ha-1 for drained fallow plots). Slow drained sugarcane plots exhibited significantly higher TP
concentrations than the fast drained plots. However, TP loads were significantly higher (0.97 kg ha1) for fast drained plots than for the slow drained plots (0.67 kg ha-1). Rice as a P filter crop
following radishes reduced TP concentrations and loadings. Finally, banding P fertilizer at a reduced
rate for cabbage reduced TP concentrations compared to those for broadcasted P at the full
recommended level. Total phosphorus loadings in drainage water were 1.17 kg ha-1 for banded and
1.38 kg ha-1 for broadcast treatments. A total of 1.30 kg TP ha-1 entered the plots. heavy
fertilization. This indicates that the EAA system is currently a net assimilator of P.
Diunduh dari: http://www.nal.usda.gov/afsic/AFSIC_pubs/qb9612.htm……….. 6/10/2012
Chlorophyll meter estimates leaf area-based nitrogen concentration
of rice.
Peng, S.; Laza, M. R. C.; Garcia, F. V.; Cassman, K. G. Commun-soil-sci-plant-anal
v.26(5/6): p.927-935 (1995)
The chlorophyll meter (SPAD-502) can be used to diagnose the nitrogen (N) status of rice
(Oryza sativa L) plants to determine the need for fertilizer-N topdressing. However,
accurate estimation of leaf N concentration on a dry weight basis (Ndw) by SPAD
requires the adjustment of SPAD values for specific leaf weight (SLW).
The objective of this study was to determine if SPAD estimates of leaf N concentration on
a leaf area basis (Na) without correcting for SLW. SPAD values were measured from
different genotypes at various growth stages with the chlorophyll meter.
Leaf N concentration was determined by micro-Kjeldahl procedure and expressed based
on dry weight and leaf area. Specific leaf weight was calculated as the ratio of leaf dry
weight to leaf area. At each growth stage, SPAD estimated Na better than Ndw, especially
at the middle and later growth stages. When data for all stages were pooled, SPAD values
also correlated with Na better than with Ndw (r value of 0.81 versus 0.43).
This finding was also true across 80 genotypes. For estimation of Na by SPAD, therefore,
no adjustment of SPAD values for SLW is needed.
Diunduh dari: http://www.nal.usda.gov/afsic/AFSIC_pubs/qb9612.htm ……….. 6/10/2012