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PUPUK DAN PEMUPUKAN Smno.jurstnh.fpub.febr2013. UNSUR HARA. Ada sekitar 14 unsur esensial yg diperoleh tanaman dari tanah Ca dan Mg diberikan ke tanah berbentuk kapur. Unsur hara makro yg paling sering bermasalah adalah N, P, K Ketiga unsur hara ini lazim disebut sebagai UNSUR PUPUK.
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PUPUK DAN PEMUPUKAN Smno.jurstnh.fpub.febr2013
UNSUR HARA Ada sekitar 14 unsur esensial yg diperoleh tanaman dari tanah Ca dan Mg diberikan ke tanah berbentuk kapur. Unsur hara makro yg paling sering bermasalah adalah N, P, K Ketiga unsur hara ini lazim disebut sebagai UNSUR PUPUK KESEIMBANGAN HARA Unsurhara N, P, K biladipakaisecaratepat, akanmampumengendalikan, mengimbangi, mendukungdanmengisisatu-sama-lain, sertaberpengaruhbaikthdunsurharalainnya. Unsurharapupukygdiberikanseyogyanyamerupakantambahanbagiunsurygsudahadadalamtanah, sehinggakeseimbanganharatanahdapatmenunjangpertumbuhantanamanygbaik. TIGA KELOMPOK BAHAN PUPUK TUNGGAL 1. Pembawanitrogen: MISALNYA Urea, ZA 2. Pembawafosfattersedia; misalnya TSP, SP36 3. Pembawakaliumlarutair: misalnyaKCl, ZK
PEMBAWA NITROGEN PupukN adaduakelompok, yaitu: 1. Pupuk ORGANIK 2. Pupuk ANORGANIK PEMBAWA NITROGEN ORGANIK Pupuk organik harus mengalami aminisasi, amonifikasi, dan nitrifikasi sebelum nitrogennya tersedia bagi tanaman. Pupuk organik secara lambat dan berangsur-angsur membebaskan nitrogen sepanjang musim tanaman. Pupuk organik Sumber Persentase N Darah kering Rumah Potong Hewan 8 - 12 Sisa daging RPH 5 -10 (3-13% P2O5) Tepung daging RPH 10-11 (1-5% P2O5) Sisa ikan kering Pengolahan ikan 6 - 10 (4-8% P2O5) Tepung biji kapas Ampas 6-9 (2-3% P2O5; 1-2% K2O) Batang tembakau Sisa 1.5 - 3.5 (4-9% K2O) Tepung tembakau Ampas 5 - 7 (2% P2O5, 1% K2O) Tepung coklat Ampas 3.5 - 4.5 Sekam padi Ampas 1.0 Sumber: Nelson, 1965
PEMBAWA NITROGEN ANORGANIK PertimbanganUmum: PupukN anorganikdapatdibuatdari N2 atmosferdenganteknologisintetik yang semakinmaju. Pupuk Rumus Kimia Persentase Nitrogen Natrium nitrat NaNO3 16 Ammonium sulfat (NH4)2SO4 21 Amonium nitrat NH4NO3 33 Amonium nitrat gamping NH4NO3 dan dolomit 20 Urea CO(NH2)2 42 - 45 Kalsium sianamida CaCN2 22 Amonia cair NH3 cair 82 Larutan amonia NH4OH encer 20-25 Amofos NH4H2PO4 11 (48% P2O5) Diamonium fosfat (NH4)2HPO4 21(53% P2O5)
AMONIA NH3 Gas amoniadibuatdariunsur-unsurnya, Hidrogendan nitrogen: N2 + 3H2 ------------------------ 2 NH3 Penggunaannya: 1. Dg menggunakantekanantinggidapatdicairkanmenjadiamoniacair 2. Dapatdilarutkandlm air menjadi NH4OH 3. Gas amoniadipakaiuntukpembuatanpupuk lain Bagan pembuatan pupuk Nitrogen: + NH3 Am. Nitrat 33% N HNO3 Na2CO3 Na-nitrat 16% N + Batu fosfat Nitrofosfat 12- 20% N +O2 + H2SO4 Am. Sulfat 21% N NH3 + H3PO4 Am. Fosfat 11-21% N + CO2 Urea 45% N +NH4NO3, +Urea, + H2O Larutan N 27-53% N + H2O Larutan amonia 20% N
PUPUK NITROGEN AMONIUM SULFAT Banyak digunakan oleh petani di Indoensia Dapat digunakan untuk membuat pupuk majemuk Ion NH4+ dalam kondisi aerobik dapat mengalami nitrifikasi Pada sawah NH4+ bereaksi dengan koloid tanah, shg tdk tercuci Pada tanah alkalis memberikan hasil yang memuaskan Natrium & AMONIUM NITRAT Amonium nitrat mengandung ion NH4+ dan NO3- Pemberiannya sebaiknya dlm bentuk pelet, unt mengurangi sifat higroskopis MUDAH MELEDAK BILA TERJADI KEBAKARAN UREA Reaksi pembuatannya: 2NH3 + CO2 NH2COONH4 NH2CONH2 + H2O
PUPUK FOSFAT SUPERFOSFAT Kandungan fosfatnya 16-21%, dibuat dengan jalan menambahkan asam sulfat kepada batu fosfat. Ca3(PO4)2 + 2H2SO4 Ca(H2PO4)2 + 2CaSO4 + kotoran CaHPO4 Superfosfat biasa ( 20% P2O5) + H2SO4 Pupuk majemuk Batu +H2SO4 or H3PO4 +NH3 NH4-fosfat (20-54% P2O5) Fosfat tanur listrik 54% P2O5 TSP (42-50% P2O5) + HNO3 + NH3 Nitrofosfat (11-35% P2O5)
PUPUK FOSFAT TSP Pupuk Bentuk Kimiawi Kadar P2O5 tersedia (%) Persen P Superfosfat Ca(H2PO4)2 + CaHPO4 15-50 7 - 22 Superfosfat NH4H2PO4 amoniat CaHPO4 Ca3(PO4)2 16-18 (3-4%N) 7 - 8 (NH4)2SO4 Amofos NH4H2PO4 48 (11% N) 21 Amonium-polifosfat (NH4)4P2O7 & lainnya 58-60 (12-15%N) 26-27 Diamonium fosfat (NH4)2HPO4 53 (21% N) 23 Sampah tanur baja (CaO)5.P2O5.SiO2 15-25 7-11 Batu fosfat Fluor atau Klor Apatit 25-30 11 - 13 Ca-metafosfat Ca(PO4)2 62-63 27-28 Asam superfosfat H3PO4 dan H4P2O7 76 33
Klasifikasi Pupuk Fosfat Pupuk fosfat dapat diklasifikasikan berdasarkan ketersediaan fosfatnya. FOSFAT TERSEDIA: Fosfat yang segera dapat diserap tanaman dan merangsang pertumbuhan tanaman KLASIFIKASI PUPUK FOSFAT 1. Larut dalam air Ca(H2PO4)2 NH4 H2PO4 K H2PO4 Fosfat tersedia 2. Larut dlm sitrat: 15% amonium sitrat CaHPO4 atau 2% asam sitrat 3. Tidak larut Tepung tulang Fosfat tidak tersedia Batuan fosfat
PUPUK KALIUM Bahan dasar pupuk kalium adalah hasil tambang garam kalium (klorida dan sulfat) yang terdapat di Jerman, Perancis dan USA. BAHAN PUPUK KALIUM Pupuk Rumus Kimia Persentase Kalium Kalium klorida KCl 48-60 Kalium Sulfat K2SO4 48-50 Kalium-magnesium sulfat K dan Mg sulfat 20-30 (25% MgSO4 ) Kainit KCl sebagian besar 12-16 Kalium Nitrat KNO3 44( 13% N) Abu kayu K2CO3 sebagian besar 3-7 (1-2% P) Abu ampas tebu An-organik 30 Abu sabut kelapa An-organik 30 Sekam padi Organik 2
PUPUK MIKRO Pupuk yang mengandungsatuataulebihunsurharamikro, dalambentuktersediabagitanaman Garam-garam unsur mikro yg lazim untuk pupuk Tembaga sulfat CuSO4 25-35% Cu Tembaga sulfat basa CuSO4. 3Cu(OH)2 13-53% Cu Tembaga karbonat (basa) CuCO3. Cu(OH)2 57 % Cu Seng sulfat ZnSO4 23 - 35% Zn Seng sulfat basa ZnSO4.4 Zn(OH)2 55% Zn Mangan sulfat MnSO4 23 % Mn Mangan sulfat basa MnSO4. MnO 40-49 % Mn Natrium Borat Na2B4O7 34-44% B2O3 Fero sulfat FeSO4 20% Fe Feri sulfat Fe2(SO4)3 17% Fe Natrium molibdat Na2MoO4 37-39% Mo .
PUPUK MAJEMUK PUPUK CAMPURAN = PUPUK MAJEMUK = pupuk yang mengandung lebihdari satu macam unsur hara esensial N, P, K PUPUK LENGKAP = pupuk yang mengandung unsur hara N, P, K PENAMPILAN FISIK PUPUK Umumnya bersifat lepas, sehingga mudah ditabur ke tanah Pupuk tidak mudah menggumpal dan mengeras Cara menghindarkan penggumpalan: 1. Pupuk disimpan dalam kantong kedap air 2. Pupuk dicampur dengan bahan yang dapat menyerap air 3. Membuat pupuk berbentuk pelet PENGARUH PUPUK thd pH TANAH Kebanyakan pupuk majemuk cenderung mengasamkan tanah Pengaruh utama adalah karena NH4+ mengalami nitrifikasi: NH4+ + 2 O2 2H+ + NO3- + H2O
Yield response curve: The curve below describes the crop response to fertilizers application Zone A - Too low fertilizers application which results in nutrient deficiencies and lower yields Zone B - Adequate fertilizers application results in maximum efficiency and the highest profitability. Zone C - Over fertilization where yield is not affected but fertilizers are wasted. Zone D - Excessive fertilizers application which results in decreased yields, toxicities and salinity damages Sumber: www.smart-fertilizer.com/tips-and-info
Careful adjustment of fertilizer application to plant needs and timing for maximum growth benefit.www.kalkaskacounty.net/planninge...0020.asp
Fertilizer application in this manner is called "banding," as opposed to "broadcasting" over entire field. Sumber: cals.arizona.edu/extension/susta...sic.html
FERTILIZER PLACEMENT Potassium fertilizers have been recently used as much as nitrogen and phosphorus fertilizers and therefore much research work has been done concerning their placement. Placement of potassium fertilizer with the seed has appeared to be the most effective method of application provided the rate of application is not greater than the seed can tolerate. Sumber: 159.226.205.16/curriculum/3w/02/...dex.html
Recommended fertilizer application for transplanted Japonica rice with growth duration of 150−155 days. Sumber: www.irri.org/irrc/SSNM/country%2...rice.htm
Site-Specific Nutrient Management (SSNM) • for Manual Transplanted Rice in Jiangsu Province, China • Single Japonica rice: 150−155 days growth duration (from seed to harvest) • SSNM is a plant-based approach for ‘feeding’ a rice crop with nutrients as needed. SSNM includes the following features: • Applying sufficient P and K within 14 days after transplanting (DAT) to meet crop needs. • Applying only a moderate amount of fertilizer N before active tillering. • Applying fertilizer N at tillering and later growth stages based on the needs of the crop for supplemental N as determined with a leaf color chart (LCC). • Applying fertilizer K at panicle initiation based on crop needs. • Using micronutrients based on local recommendations.
The Scientific Basis for Making Fertilizer Recommendations Yield response as influenced by soil test level and soil test recommendation approach. (Hergert, 1997)
KONSEP KESUBURAN TANAMAN Tigamacampendekatantentangrekomendasipemupukantelahdikembangkanolehparaahli. These have developed slowly, but became important during the 1950s and 1960s when soil testing research was conducted. Because our research database is limited, general principles are developed so that decisions can be made in areas where all the desired information is not known. Since agricultural production always includes unknowns, crop fertilization recommendations are based on interpretation of data and experience. Reasonable scientists have come to different conclusions on what these general fertility principles are. Some of the differences are due to geographic location; some are due to the specific nutrient in question; and other differences are due to the value placed on the many possible objectives.
Tigakonseptentangharatanaman : Pendekatankoreksidefisiensihara,Pendekatanpemeliharaan, Pendekatanpanenhara. Pendekataninisemuamenjelaskanbahwa: 1) Ujitanahhanyamengukursebagiandarijumlahsuatuhara yang adadalamtanah. 2) Tidakmungkindapatmengukurberapajumlahhara yang akanmudah-tersediaabagitanaman. This means that a soil test value is an index of the soil’s fertility status, not a quantitative measure of the total amount of nutrient in the soil or its availability. 3) Para penelititerdahulumenjelaskanbahwatingkatketersediaanharadisuatu area diukurdengankisaran “rendahhinggatinggi”. Rekomendasiawaliniditujukanuntukdiaplikasikanatasdasarkonsisilapangan.
PENDEKATAN KOREKSI DEFISIENSI HARA The deficiency correction concept states that a nutrient should be applied only if there is a reasonable expectation of a crop response. The idea of a limiting factor resulted . Ujitanahdikembangkanuntukdapatmendeteksikapansuatuharamembatasikehidupantanamanpadasuatulahan. Research is conducted to determine crop yields at different soil test levels for a given nutrient (correlation). The next step determines how much fertilizer is required for optimum yields at different soil test levels (calibration).
This approach requires the most intensive research because the soil test needs to be responsive to changes in soil levels and correlated with crop response. Duapertanyaanpenting yang harusdijawabadalah: 1) Apakahtanamanakanresponterhadappemupukan2) Berapabanyakpupuk yang diperlukan? In addition, the soil test should be broadly applicable to various crops and across geographic regions. The database should be large enough that a probability statement can be made with each fertilizer recommendation. For example, “When soil tests for phosphorus are at 10 ppm(Metode Bray and Kurtz ), there is a 0-20 percent probability of a yield response to applied phosphorus.”
The advantage of this method is that the only fertilizers applied will be those that increase yields, and these will be applied at optimum rates. Metodeinidisebut “MEMUPUK TANAMAN,” tujuannyaadalahmencapairespontanaman. Metodeinidianggaplayaksecaraekonomidansesuaisecaraekologis. The deficiency correction approach to fertilizing the crop only recommends fertilizer to the point of economic optimum yield. Experience has shown that fertilizer recommendations to correct deficiencies increase the soil test level for most non-mobile nutrients.
“Hasilmaksimumekonomis” adalahhasil-tanamandimanapetanimendapatkankeuntunganmaksimumdaripupuk yang diaplikasikannya. If a farmer applies less fertilizer than this, he will save money on his fertilizer bill, but the money lost from decreased yields will be larger than the money he saved on fertilizer. If a farmer applies more fertilizer than needed to reach the economic yield, he may increase his yield somewhat, but his fertilizer costs will increase more than the increase in crop value. Peningkatanhasil x Hargajagung> jumlahpupuk x Biayapupuk
PENDEKATAN PEMELIHARAAN The maintenance approach sets a soil test level goal , and recommends fertilizer to build the soil to the specific nutrient level that has been determined to be ideal. This approach uses soil test levels, as does the deficiency correction approach, to determine when to fertilize. Soil tests for this approach still have to be correlated, as with the deficiency correction approach. The difference is that emphasis is placed on maintaining the soil fertility level at or above the point of the economic maximum yield. Pendekataninijugadisebut “MEMUPUK TANAH,” since emphasis is placed on achieving a specific nutrient level in the soil. Those who recommend this approach have interpreted the research data to conclude that this approach benefits the producer over time. BIASANYA, PENDEKATAN PEMELIHARAAN inimenggunakannilaiujitanah yang lebihtinggidibandingkandengannilai-kritis yang digunakanolehpendekatankoreksidefisiensihara.
Pendekataninidigunakandibeberapalaboratorium. Beberapa Lab. Ujitanahmembedakanrekomendasinyamenjadiduabagian, yaitu (1) rekomendasipupuk, dan (2) rekomendasi “membangun- build”. The “build” recommendation is designed to speed the increase in soil test level to the chosen optimum value. Whether it applies to soils of a given region must be tested to confirm its validity in terms of crop response and farm profitability.
A specific example of the maintenance idea is the nutrient balance concept. This concept states that for optimum crop growth there is a “best ratio” of basic cations (positively charged ions) and a best total base saturation for a given soil. There has been little information published that confirms that a best cation saturation ratio really exists for all soils or that it should vary from one soil to another. Konsepkeseimbangan Ca-Mg-K denganmenerapkankonseprasiountukmembuatrekomendasipemupukandianggaptidak valid.
Konsep “keseimbangan” dikembangkandarihasil-hasilpenelitianpadatanah-tanah yang kejenuhankationnyasnagatberagam. A “best ratio” for the cation composition of the cation exchange capacity (CEC) was proposed — 65 percent calcium, 10 percent magnesium, 5 percent potassium, and 20 percent hydrogen. Later work by Graham in Missouri (1959) suggested that the percentages of calcium, magnesium and potassium be 75, 10 and 2.5, but could vary around these values. The saturation ranges were: 65-85 percent calcium, 6-12 percent magnesium, and 1-5 percent potassium. Variasikomposisikationdidalambatas-bataskisaraninitidakakanbanyakmempengaruhihasiltanaman.
While the idea of keeping a soil in “balance” is appealing, it should not be taken so far as to demand remedial treatment in most cases. Kalausetiapharatidakada yang menjadifaktorpembatas, dantidakadakelebihanhara yang ekstrim, makahubunganrelatifdiantaraharamasihdapatdianggaplayak.
PENDEKATAN PANEN HARA A third approach to fertilizer recommendations still widely used is nutrient removal. Before the advent of soil testing, the nutrient removal approach to crop fertilization was the best science had to offer. Early agricultural scientists realized that crops obtained their nutrition from the soil and, to maintain good production, nutrients had to be returned to the soil. This was accomplished through crop residues, wood ashes, and manures. As a simple guideline to adding fertilizers, the nutrient removal approach is a major advance over not considering crop nutrition at all. “Mengembalikanketanahapasaja yang dipanen” secarateoritisdapatmenjagaproduktivitasdanmenghindaridegradasitanah.
PENDEKATAN PANEN HARA The disadvantage of this approach is that it does not account for the soil’s ability to supply many essential nutrients. Nutrient removal does not recognize that not all nutrients are used at 100 percent efficiency. A producer may under- or over-fertilize by following the nutrient removal approach. Pendekatanpemupukan yang paling menguntungkanharusmemperhatikanbiaya input usahatanidandampaklingkungan.. Rekomendasipemupukandneganbertumbpupadapendekatanpanenharabiasanyamengabaikankeduahalini. In addition, a strict adherence to the nutrient removal approach makes soil testing unnecessary, since nutrients are added based on what is harvested.
FUNGSI PRODUKSI Fungsi Produksi = Hubungan teknis antara faktor produksi (input) dengan hasil produksinya (output). Metode Produksi = Proses Produksi = Aktivitas = kombinasi faktor-faktor produksi yang dibutuhkan untuk memproduksi satu satuan produk Modal (dianggap tetap) M2 P2 Fungsi Produksi yg sebanding (fixed proportion) M1 P1 M3 P3 Tk2 Tk1 Tk3 Tenaga kerja (dianggap variabel)
ISOKUAN : ISO QUANTITIES Fungsi produksi tidak sebanding (variable proportions). ISOKUAN = Kurva yang menggambarkan berbagai kombinasi faktor produksi yang menghasilkan volume produksi yang sama Pupuk PA A C Q = Q1: Kuantitas Prod. PB B Q = Qo TKA TKB Tenaga Kerja
FUNGSI PRODUKSI: Q = f (TK, P) Q Q B D A C Fase ekonomis Fase ekonomis TKA TKB PC Pd TK variabel, Ptetap Pvariabel, TK tetap Titik-titik A, B, C dan D = inflection points Produk Marjinal = dQ / dTK atau dQ/dM Law of deminishing returns Titik B = batas ekstensif penggunaan tenaga kerja
Produktivitas faktor produksi: Produksi rata-rata per satuan faktor produksi. Q/TK = f (1, M/TK) ….. produksi rata-rata per satuan TK Q/M = f (1, TK/M) ….. produksi rata-rata per satuan M Q B QR R P O TKP TKR TKB TK/M PRODUKSI RATA-RATA
HUBUNGAN PRODUKSI TOTAL, PROD. MARJINAL & PROD. RATA-RATA Fungsi produksi : Q = f (TK, Pk) Produksi rata-rata: Q/TK = f (TK, Pk) / TK Produksi marjinal: Q/ TK Q B Q = f (TK, Pk) R PRTK 0 TKA TKR PM TK
ISOKUAN Kurva indiferensi ……….… Lereng ISOKUAN mencerminkan laju substitusi teknis marjinal, hubungan antara faktor produksi TK dan Pk bersifat teknis Pk Fungsi produksi: Q = f(TK1 Pk) PkA A Isokuan: Qo = f(TK1 Pk) Pk TK Q = Qo 0 TKA TK
TEKNOLOGI, MODAL & FUNGSI PRODUKSI Q Kenaikanproduktivitaskarenapenambahan modal Q = F(TK, M1) Q = F(TK, M0) M1 > Mo 0 TK
EKONOMI PUPUK Petani melakukan usahataninya bertujuan mendapatkan keuntungan yang sebesar-besarnya per satuan luas lahan yang digarapnya ……….. Profit maximizing The farmer realize that : “he must spend money to make money” This is certainly true of expenditures for: “lime, fertilizer, and manure” • Use of fertilizers is an index of the use of modern agricultural methods • Faktor lain yg berpengaruh: • Water control • Seedbed • Cultivar • Date and rate of seeding • Stand of population • Fertilizer placement • Cultivation • Weed, insect and disease • Harvesting practices
EKONOMI PUPUK DAN KAPUR YIELD LEVEL & UNIT COST OF PRODUCTION • Biaya produksi: • Biaya tetap (fixed cost): jumlah biaya yang harus dikeluarkan tidak tergantung pada tinggi-rendahnya hasil tanaman • Biaya tidak tetap (variable cost): biaya yang dikeluarkan tergantung pada tinggi-rendahnya hasil, misalnya biaya pupuk, pestisida, dan panen hasil • Pengaruh pupuk dapat dilihat dari: • Meningkatkan total hasil tanaman • Menurunkan biaya per unit produksi, per ton hasil tanaman
EKONOMI PUPUK DAN KAPUR Pengaruh pupuk N-P-K terhadap hasil jagung dan keuntungan usahatani jagung. Usahatani Jagung 0-0-0 67-22-22 134-45-45 270-90-90 …………. Kg/ha ………………………. Hasil jagung (kw/ha) 48 70 85 98 Gross income per ha $188 274 336 390 Operating cost 56 69 82 111 Othe cash cost 25 25 25 25 Fixed cost 88 88 88 88 Interest cost of land 82 82 82 82 Total cost 251 264 277 306 Cost per q 5.3 3.8 3.3 3.4 Return to land, labor -63 +10 +59 +84 Source:
EKONOMI PUPUK DAN KAPUR Level of Farm-Management: Bgm kemampuan petani dalam mengelola usahataninya: Merencanakan, menjadwal, melaksanakan dan mengendalikan kegiatannya Peningkatan hasil atau nilai hasil Superior management Average management Fertilizer cost A B Dosis pupuk With superior farm management, ………… ……………higher rates of fertilizer can be profitably used
EKONOMI PUPUK DAN KAPUR Level of Farm-Management: Bgm kemampuan petani dalam mengelola usahataninya: Merencanakan, menjadwal, melaksanakan dan mengendalikan kegiatannya Peningkatan hasil atau nilai hasil all controllable growth factors adequate R1 Q1, R2 Some controllable growth factors inadequate Q2 Q R Dosis pupuk A higher yield is obtained when all controllable growth factors are adequate ………
EKONOMI PUPUK DAN KAPUR Unit Production Cost: Biaya Produksi Satuan Average Superior Farm Management FM Yield, q per ha 90 150 Fertilizer cost 8.30 23.20 Irrigation cost 8.00 8.00 Total cost 76.80 102.20 Cost per q 0.85 0.68 Profit per ha 13.20 47.80 Profit per q 0.15 0.32 Usahatani jagung irigasi
EKONOMI PUPUK DAN KAPUR Level of management on returns from farming Level of Management: Current Good Superior Yield, bu per acre 20.0 34.0 50.0 Price per unit 2.00 2.00 2.00 Value per acre 40.00 68.00 100.00 Cost per acre 41.98 53.72 55.75 Cost per unit 2.10 1.56 1.11 Return over cash -1.98 14.28 44.25 Usahatani kedelai
RETURNS PER RUPIAH SPENT ON FERTILIZER. Effect of rate of nitrogen on net return per added Rp invested Nitrogen rate Added input Net return per added Rp kg/ha kg N/ha invested 20 20 7.25 40 20 5.75 60 20 5.00 80 20 3.87 100 20 2.38 120 20 1.63 140 20 0.88 160 20 0.50 180 20 0.12 200 20 -0.62
PROFIT per LAND-AREA. Petani umumnya akan berupaya melakukan pemupukan untuk mencapai keuntungan (profit) yang setinggi-tingginya per hektar lahannya. Maximum profit tercapai kalau tambahan hasil sama dengan biaya tambahan terakhir dosis pupuk yang diberikan ( Δhasil / Δpupuk). Aspek ekonomi dari respon hasil jagung terhadap dosis pupuk nitrogen Dosis N Yield Marginal Marginal Marginal Return Gross profit per ha kg/ha kw/ha Yield Co ……. (harga jagung Rp 1/ ku) ……….. 20 8 8 2.4 3.33 5.60 40 15 7 2.4 2.92 10.20 60 21 6 2.4 2.50 13.80 80 26 5 2.4 2.08 16.40 100 30 4 2.4 1.67 18.00 120 32 2 2.4 0.83 17.60 Catatan: Harga pupuk N sebesar Rp 0.12 per kg
What are the most profitable rates of plant nutrients?. Beberapa faktor yang berpengaruh: 1. The expected increase in yield from each increment 2. The level of management 3. The price of fertilizer 4. The price the farmer expects to receive for his crops 5. Additional harvesting and marketing costs 6. Residual effects 7. Levels of other nutrients in the soil or fertilizer
Expected increase in yield from each incement of fertilizer. Hasil per ha HA HB Lokasi A Lokasi B HE Lokasi E HC Lokasi C HD Lokasi D N Dosis pupuk N