PRINSIP-PRINSIP MANAJEMEN

KESUBURAN TANAH.

Bahan Kajian MK. Manajemen Kesuburan TanahDiarikan soemarno - jursntnhfpub - Sept 2013

PRINSIP-PRINSIP MANAJEMEN KESUBURAN TANAH

1. Tujuan Program MST.2. Concepts of large scale, intermediate and

small scale “precision” farming.3. Soil and plant sampling, testing, and

interpretation.4. Kesuburan tanah dan Manajemen pupuk5. Aplikasi, efisiensi dan manfaat pupuk.

1. Meningkatkan hasil tanaman (pangan dunia)2. Mereduksi biaya per satuan hasil 3. Kualitas produk (not always a factor - fast

growing wood is lower quality than slow-growing wood)

4. Mereduksi gangguan penyakit (can go the other way by making tissues protein-rich and juicy for bugs)

5. Mencegah pencemaran lingkungan (new since the 60's - never used to be considered)

6. Memperbaiki kesehatan dan estetika lingkungan

7. Memperbaiki habitat liar (hunting permits)

SASARAN MANAJEMEN KESUBURAN TANAH

1. Cut the unit cost of production by producing the largest possible crop.

2. Match the crop needs with available nutrient supply.

3. Nitrates, phosphates, and pesticides – the old way

4. Typical crop uptake values (archaic units - lb/acre - multiply by 1.12 to get kg/ha; also note that P as P2O5 and K as K2O)

TUJUAN PRODUSEN

1. Pupuk memperbaiki pertumbuhan tanaman2. Semakin banyak tanaman, semakin banyak

CO2 yang diserap (diambil) dari udara atmosfir

3. Semakin banyak vegetasi penutup muka lahan , semakin sedikit erosi dan pencemaran perairan

Aplikasi pupuk yang bijaksana dapat melindungi lingkungan.

SEKALA PENGELOLAAN LAHANLarge-scale: Treating the entire field as one

management unit. 1. SEDERHANA DAN TEKNOLOGI TEPATGUNA2. Presisi operaisonal relatif rendah.3. Tidak memperhitungkan variabilitas lahan dan

kandungan haranya.4. Memerlukan sedikit instrumentasi dan latihan

teknologi5. Produksi tidak merata dan potensi

pencemartan lingkungan

Medium-scale: Sub-dividing the field into two or more management units requiring different

applications of fertilizer, pesticides, and irrigation.

1. Biasanya dipraktekkan atas dasar intuitif2. Memungkinkan penerapan standar lapangan3. Based on soil types, drainage characteristics,

empirical observation, and ease of boundary delineation

4. Efisiensi lebih baik dan pencemaran lingkungan lebih sedikit

SEKALA MEDIUM.

Small-scale (precision): A system in which infinitesimal land management units occur within

a single field.1. Menggunakan GPS dan mengembangkan

basis-data elektronik untuk tanah dan tanaman2. Memerlukan penerapan beragam teknologi dan

peralatannya3. Lebih praktis untuk komoditi tanaman yang

nilai ekonominya tinggi

SEKALA KECIL.

1. No amount of care in preparation and analysis can overcome poor or inappropriate soil sampling

2. Soils vary continuously with space and depth; you cannot sample all the variability

3. Know your horizons and sample accordingly when possible

4. We often dig a quantitative pit and get horizon depths and then sample with augers thereafter

5. Often sampling plow layer in ag soils; this will NOT work in wildland soils.

.SAMPLING TANAH.

Over-riding guide: Take a sample so that it represents what it is

intended to represent

1. Kedalaman lapisan bajak (traditional ag)2. At 30 cm (~1 ft) increments; alternate 30 cm increments3. Horison tanah untuk sistem yang masih utuh4. Tipe tanah5. Sampel komposit terdiri atas 5-20 sub-sample untuk

setiap sampel analisis6. Hara setiap tahun, status garam setiap tahun.

KEDALAMAN DAN BANYAKNYA CONTOH

Horizontal variation: sample by landscape strata that make sense (land use, soil series, slope, aspect, current

vegetation, etc.)

Variasi vertikal:

Perlu diketahui kedalaman

horison, dan sampling tanah pada kedalaman

horison ini

Percent C ----Depth

15 cm A horizon

30cmB horizon

45 cm

60 cm BC horizon

75 cm

90cm C horizon

Percent C ----Depth

A horizon

15 cm E horizon

30cm

45 cm

60 cm Bhs horizon

75 cm

90cm C horizon

Variations in soil analysis due to sampling depth - clear boundaries

Depth % N Core 1 Core 2 Core 3 0.27% 0.16% 0. 29%

0 cm 0.30%

15 cm 0.25%

30 cm 0.05%

45 cm 0.02%

Which core gave the correct value for soil %N? Core 1 is most representative. Sample byhorizon

Lokasi mana yang memberikan %N tanah yang paling tepat? Lokasi 1 paling representatif, Sampel tanah menurut horison

Variasi hasil analisis tanah akibat perbedaan kedalaman sampling tanah. Batas-batas horison tanah jelas

Variations in soil analysis due to sampling depth -diffuse boundaries

Depth % N Core 1 Core 2 Core 3 0.16% 0.08% 0. 23%

0 cm 0.25%

15 cm 0.15%

30 cm 0.05%

45 cm 0.02%

Which core gave the correct value for soil %N? All three did. With core 3, you wouldwant to sample at least one more depth. The point is, you must be consistent withsampling depth

Variasi hasil analisis tanah akibat perbedaan kedalaman sampling tanah. Batas-batas horison difuse (baur)

Lokasi mana yang memberikan %N tanah yang paling tepat? Ketiga lokasi bagus. Di lokasi 3 sampling lebih dari satu

kedalaman

Errors due to variations in horizon thickness

Depth % N Core 1 Core 2 Core 3 0.29% 0.14% 0. 11%

0 cm 0.30%

15 cm 0.15%

30 cm 0.07%

45 cm 0.02%

When this occurs, which is frequently, you must live with it. Pick a modal depth and takelots of samples. It is always best to measure horizon depth at each point and average this,but not always possible.

Kesalahan karena variasi ketebalan horison tanah

Kalau hal ini terjadi, maka harus dilakukan observasi lebih akurat dan detail. Tentukan kedalaman “median” dan ambil banyak contoh tanah. Pada setiap

titik sampel diukur kedalaman horison , dan kalau memungkinkan dirata-rata.

pH, acidity / alkalinity: Electrode in 1:1 or 1:2 soil:water ratio with 0.01M CaCl2. Some people use distilled water – this generally gives a higher pH – why? Al, H+ displacement. Also: review lime requirement.

Garam-garam larut: Saturated paste extract 1:1 or 1:2

Nitrogen: Not reliably precise. Total N, C:N ratio, extractable ammonium and nitrate, N mineralization, resins….None cheap or very quantitative.

UJI TANAH

Phosphorus:

The book says this:• Bray 1: 0.025 M HCl = 0.03 M NH4F (for acidic soils)• Mehlich 1: 0.05 M HCl + 0.025 M H2SO4 (for acidic soils)

• Olsen’s bicarbonate: 0.5 M NaHCO3 at pH 8.5 (for neutral and alkaline soils; assumes all goes to H2CO3 in acidic soils)

• Mehlich 3: 0.2 M acetic acid + 0.25 M ammonium nitrate + 0.015 M NH4F + 0.013 M HNO3 + + 0.001 M EDTA

.UJI P-TANAH

Potassium, Calcium and Magnesium: Exchange with ammonium chloride, potassium chloride or acetate (CEC). No one I know uses

the bicarbonate + DPTA extract mentioned. Total digests are usually not useful except for

research purposes.

Sulfur: SO4

2- is the preferred way, by water, phosphate, LiCl.

Total S not usually useful except for research, but with new CHNS analyzers, it is now easy to

get.

Uji K, Ca, Mg dan S

Boron: Hot water extract. Some people use cold water and works just as well.

Zn, Fe, Mn, Cu: Many trials on this using 0.1 M HCl, Coca-Cola (carbonic acid + sugar), chelates like DPTA

Mo, Ni: Totals, resins, chelates

Soil tests are changing – resins are coming into play now and must be checked against older methods. Also, total analysis may become easier now, as for example CHNS analysis.

Uji Unsur Hara Mikro

Leibigs Law of the Minimum: Growth is limited by the essential nutrient present

in the lowest relative amount.

Thus, the plant is the ultimate judge. However -1. In annual crops, plant analysis may be too

late (already grown)2. In forests and range, plant analysis is not too

late (growth goes on for years)3. Plant analysis is generally more sensitive

than soil analysis.

Uji tanah vs. Analisis Tanaman

1. Not generally favored by ag people because it is "too late“ and doubles the analytical expense

2. Sangat disenangi oleh pakar kehutanan karena dianggap lebih sensitif - tanaman merupakan “arbiter” akhir

3. Analisis total tanaman : digunakan untuk riset-riset pertanian dan kehutanan

4. Analisis daun, sering digunakan dalam pendugaan status hara / nutrisi tanaman

5. Analisis kering oven (65oC)6. Analisis Total - nilai-nilai ambang atau nilai

kritis.

ANALISIS TANAMAN

.BATAS AMBANG HARA DALAM TGANAMAN

• Analisis vektor untuk menduga respon pertumbuhan (Bobot + Konsentrasi)

• DRIS (diagnosis recommendation integrated system)

• Kisaran kritis hara tanaman• Gejala defisiensi visual• Mobile nutrients like N, S, P, Mg, K symptoms

appear on older tissues because of translocation

• Unsur hara Imobil seperti Cu, Mn, Ca, Fe ; gejala defisinesinya muncul pada jaringan muda.

.

UNSUR HARA TANAMAN

Unsur Hara TanamanBagaimana tanaman memperoleh dan menggunakan hara?

1. Mengapa unsur hara itu penting?

2. Apa saja unsur hara esensial itu?• Sistem klasifikasi hara

3. Unsur hara dalam tanah• Ketersediaan hara• Penjerapan oleh partikel tanah• Efek pH tanah

4. Akar dan penyerapan hara• Struktur Akar• Zone penyerapan

4. Mycorrhizae5. Nitrogen – unsur hara yang biasanya membatasi tanaman

Mengapa unsur hara itu penting?

In most natural soils, the availability of mineral nutrients limits plant growth and primary

productivity.

Nutrient limitation is an important selective pressure and plants exhibit many special traits related to the need to acquire and use mineral

nutrients efficiently.

Apa saja unsur hara esensial?

Hara Makro - present in relatively high concentrations in plant tissues.

N, K, P, Ca, Mg,S, Si Nitrogen is most commonly limiting to productivity of natural and managed soils. Phosphorus is next most limiting, and is most limiting in some tropical soils.

Hara mikro - present in very low concentrations in plant tissues.

Ada 17 unsur hara esensial yang dibutuhkan tanaman

Apa definisi unsur hara “essensial”?1. In its absence the plant cannot complete a

normal life cycle2. The element is part of an essential

molecule (macromolecule, metabolite) inside the plant

Most elements fall into both categories above (e.g., structural vs. enzyme cofactor)

These 17 elements are classified as 9 hara makro (present at > 10 mmol / kg

dry wt.) 8 hara mikro (< 10 mmol / kg dry wt.)

Uanru hara mikro dengan konsentrasi sangat rendah

ppm

Very low concentrations, but still essentialbecause of specialized roles in metabolism

I. Hara Tanaman

Hara Makro / Mikro Hydroponics allowed us to see what was needed The necessary nutrients are those the plant can

not grow with out Dua Kategori:

1. Hara Makro (C, O, H, N, S, P, K, Ca, Mg) Majority of the time used for the main

organic compounds 2. Hara Mikro (Cl, Fe, B, Mn, Zn, Cu, Mo, Ni)

Mostly cofactors for particular enzymes (Fe -> Cytochromes

Soils particles are generally negatively charged and so bind

positively charged nutrient ions (cations). KTK atau CEC: Kemampuan tanah mengikat kation.

NH4+, NO3

-, Cl-, PO4-2, SO4

-2

pH tanah mempengaruhi ketersediaan hara dalam tanah.

AKARMempunyai

permukaan yang luas untuk

penyerapan hara

Bulu Akar = Root hairs

Bulu akar = Root hairs

Fig. 5.7

Zone Penyerapan hara:

Konsentrasi hara menurun karena diserrap akar

Zone ini di sekitar akar tanaman

Akar-akar halus dan bulu akar

menyerap hara dari tanah.

Hifa mikoriza

membantu penyerapan hara

oleh akar.

Akar tanaman dan penyerap[an hara dari tanah

Clayparticle

Root hair

H+

K+

K+

K+K+

K+

K+

K+

K+

Pertukaran Kation antara bulu akar tanaman dengan partikel liat tanah

Mikoriza VAM (Vesicular Arbuscular Mycorrhiza)

Di dalam akar tanaman• Intercellular mycelium• Intracellular arbuscule

• tree-like haustorium• Vesicle with reserves

Di luar akar• Spores (multinucleate)• Hyphae

• thick runners• filamentous hyphae

Membentuk jaring-jaring hifa yang sangat ekstensif

Bakteri fiksasi NitrogenGenus: Rhizobium

N2 NH4

Supply of electrons

Fig. 38.07

Penyerapan ion hara

Outside cell (positive)

Net positive charge

Net negativechargeInside cell

(negative)

Proton pumps establish an electrochemical gradient.

Penyerapan hara secara aktif

Kation memasuki bulu akar melalui saluran atau Karier

Anion memasuki bulu akar melalui ko-transporter.

Konsep Kadar Kritis Hara tanaman

Above critical concentration, there is no net benefit (e.g., yield increase) if more nutrient is supplied

Below critical concentration, nutrient level limits growth!

Not shown on diagram: all elements eventually become toxic at very high concentrations

Analisis jaringan tanaman menunjukkan defisiensi hara

Gejala defisiensi muncul kalau hara esensial tidak ada (tidak cukup)

Essential because of their metabolic functions

Characteristic deficiency symptoms shown because of these roles

Typical deficiency responses are Chlorosis: yellowing; precursor to Necrosis: tissue death

Expressed when a supply of an essential metabolite becomes limiting in the environment

Element concentrations are limiting for growth when they are below the critical concentraion This is the concentration of

nutrient in the tissue just below the level giving maximum growth

Kurangnya hara akan berpengaruh negatif terhadap pertumbuhan tanaman

Plant responses to limiting nutrients usually very visible: affects yield/growth!

Again, chlorosis and necrosis of leaves is typical Sometimes straightforward relationship

e.g., in chlorosis (lack of green color), N: chlorophyll component Mg: cofactor in chlorophyll synthesis

Ctrl - P- Ca

- N - Fe

Tujuan: Menduga jumlah hara yang dibutuhkan untuk

pertumbuhan tanaman.

1. Berdasarkan sejarah lahan dan pertanaman2. Berdasarkan pada produksi yang jelek atau

perhitungan estimasi serapan hara atanaman.3. Based on plant or soil analysis; different labs

use different standards so recommendations may differ

4. Masih belum tuntas, terutama untuk kehutanan.

REKOMENDASI PUPUK

KUALITAS PUPUK

1. Grade Pupuk: Jaminan persentase minimum hara N, P (P2O5), K (K2O)

2. Additional nutrient contents are separately specified

3. Total weight of bag content4. Manufacturer 5. Sometimes the filler content and salt index

are specified6. Beberapa material dapat memebntuk asam.

Note that the three numbers on the bag are N, P as P2O5, and K as K2O or sometimes KCl

• Note that fertilizers do not actually contain P2O5 or K2O

This is an artifact of very old methods of analysis where these nutrients were measured by combustion and ended up as oxides which needed to be weighed.

• See the calculations on p. 334, 335, and 336; we will go over these in detail in class

PERHITUNGAN PUPUK

• Starter: with the seed, low amounts• Broadcast: spread evenly over the land (lowest

efficiency) • Tidak dekat akr tanaman, dapat memberi

makan gulma• Fiksasi P dalam tanah• Mengapa dilakukan?

1. Cara yang praktis - pastures, etc.2. Build up stocks in low-fertility soils3. Mudak dan murah4. Cara terbaik menambahkan pupuk

kepada tanaman yang telah mulai tumbuh

TEKNIK-TEKNIK APLIKASI PUPUK

Deep banding ; Dibenamkan ke tanah1. Kedalaman 10-25 cm, misalnya pupuk anhydrous

ammonium2. Penempatan pupuk pada lokasi yang dapat

dijangkau oleh akar tanaman3. Biaya mahal.

• Split Application (Aplikasi ganda, tidak sekaligus)1. Aplikasi pupuk dua hingga tiga kali2. Terutama pupuk N, kandungan hara tersedia

dalam tanah akan kembali seperti semula dalam waktu 4-12 bulan

3. Menyesuaikan dnegan irama penyerpaan hara tanaman

4. Waktunya kritis

TEKNIK APLIKASI UPUPK.

Mar Apr May June July Aug Sept Oct Nov Aplikasi ganda vs Tunggal. Kapan puncak penyerapan hara terjadi?

Soil NH4 + NO3

Single fertilization

Split application

.KAPAN APLIKASI PUPUK?

Aplikasi pupuk

sekaligusAplikasi pupuk

dua-kali

NH4 + NO3 dalam tanah

Sumbangan N-tersedia dalam tanah (dari pupuk) sudah habis pada Juli-Agustus

Sumbangan N-tersedia dalam

tanah (dari pupuk) masih ada hingga Nopember

PEMUPUKAN DAN KETERSEDIAAN HARA ATANAH.Recall that fertilization with P, K, Mg, and other nutrients can (but may not) keep soil available levels elevated for a very long time whereas this never happens with N N ( juga dapat terjadi pada P) Soil Avail Dapat terjadi pada P; juga berlaku bagi K, Ca, Mg Nutr 1 2 3 4 6 7 8 9 10 11 12 13 Years Tahun

Hara ter-

sedia dalam tanah

Pemupukan P, K,Mg dan hara lainnya dapat menjaga ketersediaan hara tanah dalam jangka panjang, tetapi tidak

demikian halnya dnegan nitrogen

N tersedia dalam tanah mudah

hilang

1. Side dressing: setelah tanaman tumbuh2. Point Injector fertilization: using a rod to

make a hole, put fertilizer deep near plant.3. Dollop or tree tablet principle. 4. Fertigation: pupuk ditambahkan bersama

dengan air irigasi: 1. Tidak sama dnegan aplikasi daun.2. Obviously require irrigation equipment;

not normal for forests or range soils3. Sangat efisien4. Biayanya mahal

.TEKNOLOGI APLIKASI PUPUK

• Aplikasi pupuk melalui daun (Foliar application)

1. Bertujuan untuk penyerapan hara lewat daun

2. Seringkali dilakukan untuk mensuplai unsur mikro, kalau diberikan melalui tanah akan mengalami imobilisasi hara

3. Memerlukan bahan pembasah dan bahan perekat

4. Respon tanaman cepat

APLIKASI PUPUK DUAN

1. Didefinisikan sebagai persentase pupuk yang secara aktual digunakan oleh tanaman; atau diukur dalam bentuk hasil tanaman dan keuntungan

2. Generally 30-70% for N, 5-30% for P, 50-80% for K in crops, according to the book (sounds high)

3. Generally 5-40% for N, P, and K in trees, counting only what is in trees at any one time

4. However, trees recycle nutrients, and forest floor contents can be re-used

5. Tidak mudah menilai dalam persentase.

.EFISIENSI PUPUK

• Mengapa efisiensi pupuk relatif rendah?

1. Imobilisasi oleh mikroba tanah2. "Fixation“ P dalam tanah3. Jenis hara keliru4. Waktu aplikasi pupuk tidak tepat5. Dosis pupuk tidak tepat6. Too low feeds microbes, which are

most efficient competitors7. Too high in the case of N causes

nitrate leaching losses

.EFISIENSI PUPUK