Widyatmani Sih Dewi

PENGARUH DOSIS INOKULUM AZOLLA DAN PUPUK FOSFAT ALAM TERHADAP KETERSEDIAAN P DAN HASIL PADI DI ALFISOL

Produksi padi di Indonesia masih belum mampu menutupi kebutuhan nasional. Rendahnya produktivitas ini salah satunya disebabkan oleh penurunan tingkat kesuburan tanah. Salah satu cara untuk meningkatkan kandungan fosfat didalam tanah adalah dengan memberikan pupuk fosfat alam dan juga inokulum azolla. Penelitian ini dilakukan untuk mengetahui dosis yang tepat dari inokulum azolla dan fosfat alam untuk meningkatkan ketersediaan fosfat dan meningkatkan hasil tanaman padi pada tanah alfisol. Penelitian ini menggunakan metode RAL faktorial dengan dua faktor pembanding perlakuan pupuk kandang dan pupuk N,P,K. Analisis data hasil pengamatan menggunakan analisis ragam pada taraf 5% dan apabila terdapat pengaruh beda nyata dilanjutkan dengan uji DMRT taraf 5% untuk membandingkan antar perlakuan. Hasil penelitian menunjukan bahwa perlakuan pemberian inokulum azolla dan fosfat alam dapat meningkatkan ketersediaan fosfat pada tanah alfisol dan mampu meningkatkan hasil padi. Pada parameter P tersedia hasil tertinggi menunjukan pada perlakuan azolla 2,5 ton/ha tanpa fosfat alam dan azolla 5 ton/ha fosfat alam 350 kg/ha yaitu 10,81 ppm. Selain itu pemberian inokulum azolla dan fosfat alam memberikan peningkatan terhadap kadar KTK, bahan organik, N total dalam tanah dan pH tanah.

Penyusunan Model Pengelolaan Kualitas Tanah Sawah di Kecamatan Jatipuro Kabupaten Karanganyar

Title : Paddy Soil Quality Management Modeling in District of Jatipuro, Karanganyar Regency. The intensive paddy soil management were known caused the soil degradation, thus the proper paddy soil quality management was needed to maintain the sustainability of soil function. The aim of the research was built a model that can be used as the reference of paddy soil quality management in district of Jatipuro, Karanganyar regency. The research was executed on October 2008 until February 2009. The research was descriptive explorative, carried out by collecting secondary data for model building and getting sample based on random sampling method at paddy soil in each Soil Map Unit (SMU), laboratory analysis for each selected soil quality indicator, and field observation for model validation. The results showed that the builded model: SQi = 0,414 + 0,363 pH, can be used as the reference of paddy soil quality management in district of Jatipuro. Based on the model then the recommendation of paddy soil quality management could be determined, through increasing pH by submerged the soil and delay the rice planting about 2 weeks after flooding. Keywords: model, paddy soil quality, district of Jatipuro

Study on The Potency of Soil Microbes Isolated from Andisols of Dieng, Central Java, as S-Oxidizing Biofertilizer Inoculant

The problem of nutrient deficiences tend to increase, including sulfur deficiency. The use of high purity NPK fertilizers stimulate sulfur deficiency in agricultural land. This problem can be corrected by the use of elemental sulfur accompanied with S-oxidizing biofertilizer. The study aimed to evaluate the potential of sulfur oxidizing microbial isolated from Andisols of Dieng Central Java as S-oxidizing inoculant. Andisols Dieng naturally contains high sulfur that allegedly inhabited many sulfur-oxidizing microbials. The research consisted of two experiments, each arranged in completely randomized design (CRD). Each experiment consist of two factors namely the kind of microbial isolated from Andisols Dieng and incubation time. The first experiment used Czapekdox+elemental sulfur medium, while the second experiment used vermicompost as medium. The observed variables include soluble-S, bacterial density, biomass of fungi and medium pH. One isolate of bacteria (I1)and three isolates of fungi (F1, F2 and F3) taken from Andisol of Dieng showing their ability to oxidize sulfur in Czapek-dok agar medium. They were used as isolates in the experiment. The result of the first experiment showed that the oxidized sulfur increased with the length of incubation time as indicated by the increase of soluble-S, bacterial cell density or fungi biomass in the medium followed by the decrease of pH. The second experiment showed that the population of bacteria or fungi isolates and soluble-S of vermicompost were increased collaterally with incubation time. The fungi isolate of F2 have the highest potency as inoculant of Soxidizing biofertilizer as shown by it ability to survive, grows and oxidize S both in Czapek-dox+elemental sulfur liquid medium as well as in vermicompost medium.