PRINSIP-PRINSIP MANAJEMEN

KESUBURAN TANAH.

Bahan Kajian MK. Manajemen Kesuburan TanahDiarikan soemarno - jursntnhfpub - Sept 2012

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 pupuk

5. 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 tanaman

2. 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 LAHAN

Large-scale: Treating the entire field as one management unit.

1. SEDERHANA DAN TEKNOLOGI TEPATGUNA

2.Presisi operaisonal relatif rendah.

3.Tidak memperhitungkan variabilitas lahan dan kandungan haranya.

4.Memerlukan sedikit instrumentasi dan latihan teknologi

5.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 intuitif

2.Memungkinkan penerapan standar lapangan

3.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 tanaman

2.Memerlukan penerapan beragam teknologi dan peralatannya

3.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.)

Vertical variation:

need to know horizon depths

and keep sampling

constant by depth

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

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

Variations in soil analysis due to soil expansion or contraction

Wet soil

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%

Dry soil

Depth % N Core 1 Core 2 Core 3 0.20% 0.19% 0. 21%

0 cm 0.30%

15 cm 0.07%

30 cm 0.05%

45 cm 0.02%

Samples indicate soil lost N - but did it? On a mass basis, no it did not. The N that wasthere simply compressed in the A horizon

Db = 1.6 g cm-3

Db = 1.1 g cm-3

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.

Effects of Coarse FragmentsSoil A: 55% Coarse FragmentsDepth % N

0 cm 0.30%

15 cm 0.15%

30 cm 0.05%

45 cm 0.02%

Soil B: 3% Coarse fragmentsDepth % N

0 cm 0.20%

15 cm 0.10%

30 cm 0.05%

45 cm 0.02%

Although soil B has 33% lower %N in the top two horizons, it has more nutrient contentbecause there is simply more fine earth fraction (<2mm) per whole soil volume than insoil A. For each square meter of whole soil (soil + rock), soil B has twice as much fineearth fraction (0.97 m3) as soil B (0.45m3)

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

• Vector analysis to assess growth response (weight + concentration) - we will do this in 497/697

• 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.

.

.STATUS KANDUNGAN HARA DALAM TANAMAN

Tujuan: To predict the amount of each nutrient needed for

plant growth.

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 differ4.Masih belum tuntas, terutama untuk kehutanan.

REKOMENDASI PUPUK

KUALITAS PUPUK

1. Fertilizer Grade: Minimum guaranteed percentages of N, P (P2O5), K (K2O)

2. Additional nutrient contents are separately specified

3. Total weight of bag content

4. Manufacturer

5. Sometimes the filler content and salt index are specified

6. 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 banding1. 10-25 cm deep, often anhydrous ammonium2. Penempatan pupuk pada lokasi yang dapat

dijangkau oleh akar tanaman3. Biaya mahal.

•Split Application (multiple applications)1. Aplikasi pupuk dua hingga tiga kali2. Especially useful for N, where available levels

drop to background within 4-12 months3. May backfire if most uptake is early and levels are

low in split at that time 4. Waktunya kritis

TEKNIK APLIKASI UPUPK.

.Pupuk dibenamkan dalam Tanah

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?

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

PEMUPUKAN DAN KETERSEDIAAN HARA ATANAH.

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

• Foliar application1. Bertujuan untuk penyerapan hara

lewat daun2. Seldom used to get all macros into

plants; often used for micros which immobilize in soils

3. May require wetting and/or sticking agents

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