PRINSIP-PRINSIP MANAJEMEN KESUBURAN TANAH. Bahan Kajian MK. Manajemen Kesuburan Tanah

1. PRINSIP-PRINSIP MANAJEMEN KESUBURAN TANAH. Bahan Kajian MK. Manajemen Kesuburan Tanah Diarikan soemarno - jursntnhfpub - Sept 2012

2. PRINSIP-PRINSIP MANAJEMEN KESUBURAN TANAH Tujuan Program MST. Concepts of large scale, intermediate and small scale “precision” farming. Soil and plant sampling, testing, and interpretation. Kesuburan tanah dan Manajemen pupuk Aplikasi, efisiensi dan manfaat pupuk.

3. SASARAN MANAJEMEN KESUBURAN TANAH • Meningkatkan hasil tanaman (pangan dunia) • Mereduksi biaya per satuan hasil • Kualitas produk (not always a factor - fast growing wood is lower quality than slow-growing wood) • Mereduksi gangguan penyakit (can go the other way by making tissues protein-rich and juicy for bugs) • Mencegah pencemaran lingkungan (new since the 60's - never used to be considered) • Memperbaiki kesehatan dan estetika lingkungan • Memperbaiki habitat liar (hunting permits)

4. TUJUAN PRODUSEN Cut the unit cost of production by producing the largest possible crop. Match the crop needs with available nutrient supply. Nitrates, phosphates, and pesticides – the old way 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)

5. Aplikasi pupuk yang bijaksana dapat melindungi lingkungan. Pupuk memperbaiki pertumbuhan tanaman Semakin banyak tanaman, semakin banyak CO2 yang diserap (diambil) dari udara atmosfir Semakin banyak vegetasi penutup muka lahan , semakin sedikit erosi dan pencemaran perairan

6. SEKALA PENGELOLAAN LAHAN Large-scale: Treating the entire field as one management unit. SEDERHANA DAN TEKNOLOGI TEPATGUNA Presisioperaisonalrelatifrendah. Tidakmemperhitungkanvariabilitaslahandankandunganharanya. Memerlukansedikitinstrumentasidanlatihanteknologi Produksitidakmeratadanpotensipencemartanlingkungan

7. SEKALA MEDIUM. Medium-scale: Sub-dividing the field into two or more management units requiring different applications of fertilizer, pesticides, and irrigation. Biasanyadipraktekkanatasdasarintuitif Memungkinkanpenerapanstandarlapangan Based on soil types, drainage characteristics, empirical observation, and ease of boundary delineation Efisiensilebihbaikdanpencemaranlingkunganlebihsedikit

8. SEKALA KECIL. Small-scale (precision): A system in which infinitesimal land management units occur within a single field. Menggunakan GPS danmengembangkan basis-data elektronikuntuktanahdantanaman Memerlukanpenerapanberagamteknologidanperalatannya Lebihpraktisuntukkomodititanaman yang nilaiekonominyatinggi

9. .SAMPLING TANAH. • No amount of care in preparation and analysis can overcome poor or inappropriate soil sampling • Soils vary continuously with space and depth; you cannot sample all the variability • Know your horizons and sample accordingly when possible • We often dig a quantitative pit and get horizon depths and then sample with augers thereafter • Often sampling plow layer in ag soils; this will NOT work in wildland soils.

10. KEDALAMAN DAN BANYAKNYA CONTOH Over-riding guide: Take a sample so that it represents what it is intended to represent Kedalamanlapisanbajak (traditional ag) At 30 cm (~1 ft) increments; alternate 30 cm increments Horisontanahuntuksistem yang masihutuh Tipetanah Sampelkompositterdiriatas 5-20 sub-sample untuksetiapsampelanalisis Hara setiaptahun, status garamsetiaptahun.

11. Horizontal variation: sample by landscape strata that make sense (land use, soil series, slope, aspect, current vegetation, etc.)

12. Vertical variation: need to know horizon depths and keep sampling constant by depth

18. UJI TANAH 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.

19. .UJI P-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

20. Uji K, Ca, Mg dan S 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: SO42- 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.

21. Uji Unsur Hara Mikro 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.

22. Uji tanah vs. Analisis Tanaman • 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 - • In annual crops, plant analysis may be too late (already grown) • In forests and range, plant analysis is not too late (growth goes on for years) • Plant analysis is generally more sensitive than soil analysis.

23. ANALISIS TANAMAN • Not generally favored by ag people because it is "too late“ and doubles the analytical expense • Sangat disenangi oleh pakar kehutanan karena dianggap lebih sensitif - tanaman merupakan “arbiter” akhir • Analisis total tanaman : digunakan untuk riset-riset pertanian dan kehutanan • Analisis daun, sering digunakan dalam pendugaan status hara / nutrisi tanaman • Analisis kering oven (65oC) • Analisis Total - nilai-nilai ambang atau nilai kritis.

24. .BATAS AMBANG HARA DALAM TGANAMAN

25. . • 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.

26. .STATUS KANDUNGAN HARA DALAM TANAMAN

27. REKOMENDASI PUPUK • Tujuan: • To predict the amount of each nutrient needed for plant growth. • Berdasarkansejarahlahandanpertanaman • Berdasarkanpadaproduksi yang jelekatauperhitunganestimasiserapanharaatanaman. • Based on plant or soil analysis; different labs use different standards so recommendations may differ • Masihbelumtuntas, terutamauntukkehutanan.

28. KUALITAS PUPUK Fertilizer Grade: Minimum guaranteed percentages of N, P (P2O5), K (K2O) Additional nutrient contents are separately specified Total weight of bag content Manufacturer Sometimes the filler content and salt index are specified Beberapa material dapat memebntuk asam.

29. PERHITUNGAN PUPUK • 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

30. TEKNIK-TEKNIK APLIKASI 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? • Cara yang praktis - pastures, etc. • Build up stocks in low-fertility soils • Mudak dan murah • Cara terbaik menambahkan pupuk kepada tanaman yang telah mulai tumbuh

31. TEKNIK APLIKASI UPUPK. • Deep banding • 10-25 cm deep, often anhydrous ammonium • Penempatanpupukpadalokasi yang dapatdijangkauolehakartanaman • Biayamahal. • Split Application (multiple applications) • Aplikasipupukduahinggatiga kali • Especially useful for N, where available levels drop to background within 4-12 months • May backfire if most uptake is early and levels are low in split at that time • Waktunyakritis

32. .Pupuk dibenamkan dalam Tanah

33. .KAPAN APLIKASI PUPUK?

34. PEMUPUKAN DAN KETERSEDIAAN HARA ATANAH.

35. .TEKNOLOGI APLIKASI PUPUK • Side dressing: setelah tanaman tumbuh • Point Injector fertilization: using a rod to make a hole, put fertilizer deep near plant. • Dollopor tree tablet principle. • Fertigation: pupuk ditambahkan bersama dengan air irigasi: • Tidak sama dnegan aplikasi daun. • Obviously require irrigation equipment; not normal for forests or range soils • Sangat efisien • Biayanya mahal

36. APLIKASI PUPUK DUAN • Foliar application • Bertujuan untuk penyerapan hara lewat daun • Seldom used to get all macros into plants; often used for micros which immobilize in soils • May require wetting and/or sticking agents • Respon tanaman cepat

37. .EFISIENSI PUPUK Didefinisikan sebagai persentase pupuk yang secara aktual digunakan oleh tanaman; atau diukur dalam bentuk hasil tanaman dan keuntungan Generally 30-70% for N, 5-30% for P, 50-80% for K in crops, according to the book (sounds high) Generally 5-40% for N, P, and K in trees, counting only what is in trees at any one time However, trees recycle nutrients, and forest floor contents can be re-used Tidak mudah menilai dalam persentase.

38. .EFISIENSI PUPUK • Mengapaefisiensipupukrelatifrendah? • Imobilisasiolehmikrobatanah • "Fixation“ P dalamtanah • Jenisharakeliru • Waktuaplikasipupuktidaktepat • Dosispupuktidaktepat • Too low feeds microbes, which are most efficient competitors • Too high in the case of N causes nitrate leaching losses