INDEKS P TANAH

Phosphorus Index for Oregon & Washington Steve Campbell USDA - Natural Resources Conservation Service Portland, Oregon Dan Sullivan Oregon State University Corvallis, Oregon SUMBER:

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”. SUMBER:

NUTRIENT ENRICHMENT CAN LEAD TO EXCESS ALGAE GROWTH Why is there a concern about phosphorus transport to surface waters? SUMBER:

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. SUMBER:

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. SUMBER:

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 SUMBER: Management P : “Then” dan “Now”

Then FACT: Phosphorus does not move through the soil Now FACT: P can move through soil and reach surface water via tile drains SUMBER: Management P : “Then” dan “Now”

Proses Transport P In: Sharpley et al., 1999; ARS-149 SUMBER:

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. SUMBER:

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 SUMBER:

Faktor-faktor dalam Indeks P di Oregon dan Washington Faktor-faktor Transport P 1.Potensi erosi tanah 2.Kelas Runoff 3.Bahanya banjir 4.Distance to perennial surface water / buffer width 5.Drainage bawah-permukaan SUMBER:

Faktor Sumber: 1.Nilai Uji P-tanah 2.Dosis aplikasi pupuk P : commercial and organic forms 3.Metode dan waktu aplikasi pupuk P SUMBER: 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 SUMBER:

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

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

Faktor erosi tanah (sheet & rill) predicted by the Revised Universal Soil Loss Equation (RUSLE) SUMBER:

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. SUMBER:

Runoff Class Factor SUMBER:

Flooding Hazard Factor - from soil surveys or local information Flooding Hazard Factor - from soil surveys or local information SUMBER:

Faktor jarak thd perairan / Lebar penyangga SUMBER:

Uji P-tanah : Agronomic & Environmental Interpretations In: Sharpley et al., 1999; ARS-149 SUMBER:

Faktor uji tanah untuk P P Index Points = (Soil Test P - 40) / 10 SUMBER:

Neraca Hara : Rumput hijauan Biosolids fertilization, agronomic rate to supply 160 lb available N per acre Applied Nutrients Removed Nutrients SUMBER:

P Application Rate Factor P Application Rate Factor P Index Points = (lb/ac P 2 O 5 ) / 50 SUMBER:

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 ? SUMBER:

Faktor Metode Aplikasi P SUMBER:

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 Phosphorus Index Adapted from SERA-IEG 17, No. 389 SUMBER:

In Sharpley et al., 1999; ARS-149 Indeks P mengidentifikasi daerah-daerah yang berpotensi tinggi untuk transport P Indeks Phosphorus SUMBER:

P Index Site Vulnerability Classes SUMBER:

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. SUMBER: