DAMPAK PELADANGAN HORTIKULTURA TERHADAP TAHANA FOSFOR DI ANDISOL KARANG ANYAR

MISERI ROESLAN AFANY, IR.MP., Prof. Dr. Ir. KPH Tejoyuwono Notohadikusumo; Dr.Ir. Syamsul Arifin Siradz, MSc.

2015 | Disertasi | S3 Ilmu Tanah

Penelitian ini bertujuan untuk mengaji dampak peladangan hortikultura terhadap tahana fosfor serta faktor kimia dan mineralogi terkait di Andisol Hutan Pinus. Objek penelitian adalah untuk mencirikan status P di Andisol asli hutan dan mengevaluasi dampak peladangan hortikultura terhadap: (i) P-Total dan P-Potensial (ekstrak HCl 25%). (ii) P tersedia (iii) fraksi P organik dan anorganik (iv) Retensi-P Blakemore (v) sifat sifat kimia dan mineralogi tanah tahana P. Pengukuran sifat sifat kimia tanah terkait tahana P meliputi: pH H20, DHL, COrganik, kation tertukar Ca, Mg, K, Na. Analisis mineralogi mencakup pH NaF, Al and Fe–humus (Al dan Fe ekstrak Pyrofosfat), Al and Fe amorfus (Al dan Fe ekstrak oksalat), Allophane+Imogolit (Si ekstrak oksalat), Al dan Fe kristalin bebas (Al dan Fe ekstrak - Dithionat sitrat ). Untuk mewakili daerah telitian, sampel di ambil di lima lokasi hutan dan ladang hortikultura yang berdampingan dengan cakupan area Kalisoro, Blumbang, Banaran, Tambak Reja dan Tlogo Dlingo. Sampel diambil pada hutan pinus, ladang dengan penanaman hortikultur <15 tahun dan > 15 tahun masing-masing lima titik sampel top soil dan sub soil. Secara umum peladangan memberikan dampak menguntungkan terhadap tahana hara fosfor pada Andisol yakni terjadinya peningkatan P total tanah, P larut asam (Ppotensal), P tersedia, P anorganik (Ca-P), di ikuti meningkatnya mineralisasi P organik asli serta penurunan jerapan atau retensi P Blakemore . Dampak menguntungkan juga terjadi pada sifat sifat kimia tanah terkait tahana-P diantaranya adalah peningkatan pH H2O, peningkatan daya hantar listrik (DHL), peningkatan kation kation basa tertukar serta terjadinya mineralisasi bahan organik asli tanah secara berangsur sejalan dengan lamanya kegiatan peladangan. Dari segi mineralogi tanah peladangan meningkatkan pH NaF, Al dan Fe amorf, Al dan Fe kristalin bebas sebaliknya Al dan Fe-humus menurun sejalan penurunan bahan organik. Di sisi lain kadar Alofan+imogolit cenderung menurun pada beberapa lokasi pengamatan akibat peladangan. Dalam kaitannnya dengan faktor faktor yang berpengaruh terhadap Tahana P, korelasi positif terjadi antara P tersedia dengan kandungan P total, P larut HCl 25%, Ca- P, dan pH H2O, sebaliknya berkorelasi negatif dengan retensi P, kadar alofan+imogolit, pH Na-F, Al/Fe humus dan Al/Fe amorfus. Jerapan P berkorelasi positif dengan pH Na- F, kadar Alofan, Al dan Fe-humus serta Fe dan Al amorf sebaliknya berkorelasi negatif dengan pH H2O, Ca-P dan C-organik. Kandungan Ca-P berkorelasi positif dengan kadar Ca tertukar dan pH H2O. Korelasi juga terjadi diantara sifat sifat kimia dan atau antar mineralogi tanah. Korelasi positif terjadi antara pH H2O tanah dengan jumlah kation basa tertukar sebaliknya dengan kadar bahan organik, sedang pH NaF berkorelasi positif dengan Alofan+imogolit. Kadar Alofan+Imogolit berkorelasi positif dengan pH H2O dan berkorelasi negatif dengan kadar C-organik. Perubahan tahana P, sifat kimia dan mineralogi dipengaruhi oleh aktivitas petani serta perubahan iklim mikro tanah akibat peladangan, diantaranya adalah perubahan vegetasi dan pengolahan tanah, pemberian pupuk kandang hewan secara malar (continue) dalam jangka panjang disamping pemupukan superfosfat.

This research aimed to study the impact of horticulture cultivated on phosphorus status and related chemical & mineralogical properties in Pine Forest Andisol. Objectives this research were to characterized P status of native Andisols, soil chemical and and mineralogical properties and evaluate the impact of continuous horticulture cultivated of pine forest on (i) Total soil-P and P-extract HCl 25% (ii) soil-available P (iii) organic and in organic P fraction (iv) P-retention Blakemore (v) some soils chemical and mineralogical properties that related with them The soil chemical analysis includes measurement of pH H20, EC, organic-C, exchangeable cations Ca, Mg, K, Na. While mineralogical analysis were pH NaF, Al and Fe–humus (Pyrophosphate-extractable Al/Fe), Al and Fe amorphous (Oxalate–extractable Al/Fe), Allophane (Oxalate-extractable Si), Free Al and Fe crystalline (Dithionate citrate – extractable Al/Fe). For representative area of researched, sample was taken for 5 locations pine forest and horticulture cultivated that is cover Kalisoro, Blumbang, Banaran, Tambak Rejo and Tlogodlingo with continues horticultural cultivated for <15 years and > 15 years (Intensive cultivated). Each of 5 location was taken 5 samples top soils and sub soils except for Intensive cultivated only top soils. In general, activity cultivated in Andisols enhance beneficial impact on phosphorus status, This positive impact were increasing in soil total-P, Mineralization organic-P as well as decreasing organic-C , acid solution-P, Available- P, Inorganic Ca-P. Long term horticultural cultivated reduced fixation of P as well as retention-P Blakemore analysis. Cultivated in generally have beneficial impact on chemical properties as increasing pHH2O, electric conductivity (EC), exchangeable cations Ca++, Mg++, Na+ and K+ while native organic-C decreased gradually as well as increasing years of cultivated. Horticultural cultivated so impact on change soils-mineralogical properties i.e. pH NaF, Al/Fe amorphous, free Al/Fe crystalline in general increase for five locations observed by continues cultivated. In opposites Al/Fe-humus decreased induce by organic C decreases after long term cultivated, allophane content tend to decreases after long continues cultivated. There were positively correlated between available-P with total P, Ca-P and pH H2O, but negatively correlation with P-retention, Allophane content, pH NaF, Al/Fe-humus and Al/Fe-amorphous respectively. Positively correlation occurs between P-retention with pHNaF, Allophane content, Al/Fe-humus complex, Al/Fe-amorphous but negatively correlation with pH H2O and organic-C. Positively correlation between Ca-P with cation Ca content and pH H2O. Positively correlation between soil chemical and or mineralogical properties according to pH H2O and sum of exchangeable bases cations and negative correlation between pH and C-organic contents. Positively correlation between pH NaF with Al/Fe–Amorphous, Al/Fe-humus and allophane. Positively correlation between allophane content and pH H2O and negative with organic-C content as anti allophanic agent Change in P status, soil chemical and mineralogical properties as affected by farmer activity and change in soil micro climate. Farmer activity according soil tillage and changed cropping, long term continue application of livestock manure like cows dung or another as well as fertilizing super phosphate for horticultural crop

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