Download - INDEKS P TANAH. Phosphorus Index for Oregon & Washington Steve Campbell USDA - Natural Resources Conservation Service Portland, Oregon Dan Sullivan Oregon

INDEKS P TANAH

Phosphorus Index for Oregon & Washington

Steve CampbellUSDA - Natural Resources Conservation Service

Portland, Oregon

Dan SullivanOregon State University

Corvallis, Oregon

SUMBER: https://prod.nrcs.usda.gov/Internet/FSE.../nrcs142p2_041108.ppt

Tujuan dan Konsep Indeks-P

1. Indeks P adalah alat-bantu untuk “assess the potential for phosphorus transport from a field to surface waters”.

2. Indeks P didasarkan pada “soil properties, field characteristics, and management practices”.


NUTRIENT ENRICHMENT CAN LEAD TO EXCESS ALGAE GROWTH

Why is there a concern about phosphorus transport to surface waters?


Dampak Eutrofikasi terhadap Kualitas Air

1. Mengganggu kualitas air untuk perikanan, rekreasi, industri, dan air-minum.

2. Beberapa jenis blue-green algae membentuk senyawa yg bersifat toksik bagi hewan dan manusia.

3. Oxygen depletion during decay of aquatic plants.

4. Increases in pH can cause an increase in ammonia concentrations, which can be harmful to fish.


Management P : “Then” dan “Now”

Then PROBLEM:

Soils “fix” P in insoluble forms, limiting crop yields

Now PROBLEM:

Soils have a finite P sorption capacity. As we load a site with P, soluble P concentrations increase in runoff.


Then FACT:

We can control P loss from agricultural sites by reducing soil erosion losses

Now FACT:

Enough P to cause eutrophication can occur because dissolved P can move in runoff, without soil erosion



Then FACT:

Phosphorus does not move through the soil

Now FACT:

P can move through soil and reach surface water via tile drains



Proses Transport P

In: Sharpley et al., 1999; ARS-149


Sejarah Konsep Indeks P

• Developed by Lemunyon and Gilbert, USDA-SCS in 1993 (Journal of Production Agriculture 6:4)

• Adopted by NRCS - Oregon in 1994 using the national model

• Revision to the 1994 version in 2000 to reflect Pacific Northwest conditions.


Proses revisi Indeks P di Oregon dan Washington

Dikembangkan oleh Komite yang beranggotakan dari: –Kantor Konservasi sumberdaya alam– Universitas Negeri Oregon–Washington State University– Industri Pertanian


Faktor-faktor dalam Indeks P di Oregon dan Washington

Faktor-faktor Transport P1. Potensi erosi tanah2. Kelas Runoff3. Bahanya banjir4. Distance to perennial surface water /

buffer width5. Drainage bawah-permukaan


Faktor Sumber:

1. Nilai Uji P-tanah

2. Dosis aplikasi pupuk P : commercial and organic forms

3. Metode dan waktu aplikasi pupuk P


Faktor-faktor dalam Indeks P di Oregon dan Washington

Each P Index factor is assigned a weight based on its relative effect on P transport

Transport Factor Weight

Soil erosion (sheet and rill) 1.50

Soil erosion from sprinklerirrigation

0.75

Runoff Class 1.00

Flooding Hazard 0.75

Distance to surface water /buffer width

0.75

Subsurface drainage 0.50


Each P Index factor is assigned a weight based on its relative effect on P transport

Source Factor Weight

Soil Test P (ppm) 1.00

Commercial P FertilizerApplicaton Rate (lb/ac)

0.75

Commercial P FertilizerApplication Method

0.50

Organic P Source ApplicationRate (lb/ac)

1.00

Organic P Source ApplicationMethod

1.00


Each P Index factor is assigned a P Loss Rating with corresponding points

P LossRating

Points

None 0Low 1

Medium 2High 4

Very High 8+


Faktor erosi tanah (sheet & rill) predicted by the

Revised Universal Soil Loss Equation (RUSLE)

Erosion Rate(tons/acre/year)

P LossRating

Points x Weight(1.5)

< 1 None 0

1 – 3 Low 1.5

4 – 6 Medium 3.0

7 – 15 High 6.0

> 15 Very High 12.0


P Index Runoff Class Factor

• Faktor ini didasarkan pada:– Soil Hydrologic Group - considers water

infiltration rate, depth to seasonal high water table, and depth to impermeable layers.

–Kemiringan lahan - the steeper the slope, the higher the potential for P transport.


Runoff Class Factor

Runoff ClassP Loss Rating


Negligible None 0

Very Low or Low Low 1

Medium Medium 2

High High 4

Very High Very High 8


Flooding Hazard Factor - from soil surveys or local information

Flooding Frequency

P LossRating


None or very rare None 0

Rare Low 0.75

Occasional Medium 1.5

Frequent High 3.0

Very Frequent Very High 6.0


Faktor jarak thd perairan / Lebar penyangga

Distance to water / buffer widthP IndexRating

Points xWeight(0.75)

> 500 ft. or buffer > 30 ft. wide None 0

300 – 500 ft. or buffer 20-30 ft. wide Low 0.75

200 – 299 ft. or buffer 10-19 ft. wide Medium 1.5

100 – 199 ft. and buffer < 10 ft. wide High 3.0

< 100 ft. and no buffer Very High 6.0


Uji P-tanah : Agronomic & Environmental Interpretations

In: Sharpley et al., 1999; ARS-149


Faktor uji tanah untuk P

Soil Test P –ppm (Bray P1)

P Loss Rating


< 40 None 0

50 Low 1

60 Medium 2

80 High 4

> 120 Very High 8 +

P Index Points = (Soil Test P - 40) / 10


Neraca Hara : Rumput hijauan Biosolids fertilization,

agronomic rate to supply 160 lb available N per acre

0

50

100

150

200

250

300

350

400

450

Nu

trie

nts

, lb

/acre

Nitrogen Phosphorus Potassium

Applied Nutrients

Removed Nutrients


P Application Rate Factor

P2O5

ApplicationRate (lb/ac)

P LossRating

Organic PPoints x Weight

(1.0)

Commercial PPoints x Weight

(0.75)

None applied None 0 0

50 Low 1 0.75

100 Medium 2 1.5

200 High 4 3.0

400 + Very High 8 + 6.0 +

P Index Points = (lb/ac P2O5) / 50


Faktor Metode Aplikasi P

1. Berdasarkan pada bagaimana dan waktu aplikasipupuk P ke tanah

2. Is the P source injected, incorporated with tillage, or surface applied ?

3. What time of year is the P source applied ?


Faktor Metode Aplikasi P

Organic P Application MethodP LossRating

Points xWeight (1.0)

None Applied None 0

Injected > 2 inches deep orincorporated Mar. – Sept.

Low 1

Incorporated Oct. – Feb. orsurface applied Mar. – Aug.

Medium 2

Surface applied Sept. – Oct. High 4

Surface applied Nov. – Feb.VeryHigh

8


Potential for P Transport

Source Factors

Soil Erosion

Runoff

Surface & Subsurface

Soil Test P

Rate of P applied

fertilizer or manure

Method & timing of P application

P Index Class

low, medium, high,

very high

PhosphorusIndex

Adapted from SERA-IEG 17, No. 389


In Sharpley et al., 1999; ARS-149

Indeks P mengidentifikasi daerah-daerah yang berpotensi tinggi untuk transport P

Indeks Phosphorus


P Index Site Vulnerability ClassesTotal Rating Value –

Sum of WeightedTransport and Source

Factors

P Transport SiteVulnerability Class

< 13.0 Low

13.0 – 25.0 Medium

25.1- 50.0 High

> 50.0 Very High


Ringkasan

1. The Phosphorus Index is a planning tool to assess the potential for phosphorus transport from a field to surface waters.

2. Users of the P Index may include conservation planners, extension specialists, other agricultural professionals, and land managers.


Download - INDEKS P TANAH. Phosphorus Index for Oregon & Washington Steve Campbell USDA - Natural Resources Conservation Service Portland, Oregon Dan Sullivan Oregon

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