Sediment quality of Tondano Lake, Indonesia has been investigated through measuring the geochemical characteristics such as the content of heavy metals, organic matter and grain size distribution; and also the relationship between heavy metals and organic matter, and between heavy metals and grain size distribution. These could be used as preliminary data for the purpose of evaluating lake condition as a part of freshwater ecosystem. The Tondano sediment had contained some heavy metals such as Cr, Cu, Hg, and Zn; where Cr and Zn, both less than the Sediment Quality Guideline (SQG), but Cu and Hg were well within the SQG. Organic matter content was highest at the northern outlet area, with the lowest amount at the southern inlet area. Grain size distribution was mostly dominated by sandy-loam clay (the highest content was at central lake). This was a result of intensive agricultural activities surrounding the lake, which brought sand grain via rivers from all areas to the central lake. The heavy metal contents were not found to be correlated with the organic matter, nor the grain size distribution (clay content).

Tondano Lake, one of vital natural resources at Minahasa Regency, North Sulawesi, has some functions and some problems, i.e.: sedimentation and lake shallowing. This research was conducted by using water hyacinth (Eichornia crassipes (Malt)) as compost/organic fertilizer and sediment of Tondano Lake as plant media for Packoy growth. This research has aimed to: 1) Test the composition of Tondano Lake sediment, 2) Test the composition of water hyacinth compost, and 3) Measure the growth of Pakcoy toward the given compost as a preliminary research (Pot Experiment). This was conducted: a) sediment sampling at the west part of Tondano Lake, b) sediment and compost analyses at Chemical and Soil Fertility Laboratory of Agriculture Faculty of Unsrat, c) planting Pakcoy in small pots with Group-Randomized Design for nine months in 2016. Results showed that, 1) sediment composition of Tondano Lake as the plant media has tested, 2) compost composition of water hyacinth has tested, and 3) Pakcoy growth toward the given compost as a preliminary research (Pot Experiment) has measured by height of plant, number of leaves, and freshedweight of crops, andso would applicable in further research due to the result of analyses was significantly different. ABSTRAKDanau Tondano merupakan salah satu sumberdaya alam vital di Kabupaten Minahasa Provinsi Sulawesi Utara, memiliki berbagai peruntukkannya dan terdapat berbagai permasalahan, antara lain: sedimentasi dan pendangkalan danau. Penelitian ini dilakukan dengan memanfaatkan tanaman eceng gondok (Eichornia crassipes (Malt)) sebagai kompos/pupuk organik dengan sedimen Danau Tondano sebagai media tanam bagi pertumbuhan tanaman Pakcoy.Penelitian ini bertujuan untuk: 1) Menguji komposisi sedimen Danau Tondano sebagai media tanam, 2) Menguji komposisi kompos dari tanaman eceng gondok, dan 3) Mengukur pertumbuhan tanaman Pakcoy terhadap pemberian kompos sebagai penanaman awal (Percobaan Pot). Penelitian ini dilaksanakan: a) sampling sedimen di bagian barat Danau Tondano, b) analisa sedimen dan kompos di Laboratorium Kimia dan Kesuburan Tanah Fakultas Pertanian Unsrat, c)penanaman tanaman Pakcoy ditanam di pot-pot kecil dengan Rancangan Acak Kelompok selama sembilan bulan di tahun 2016. Hasil penelitian menunjukkan bahwa, 1) komposisi sedimen Danau Tondano sebagai media tanam telah teruji, 2) komposisi kompos dari tanaman eceng gondok telah teruji, and 3) pertumbuhan tanaman Pakcoy terhadap pemberian kompos sebagai penanaman awal (Percobaan Pot) telah terukur melalui tinggi tanaman, jumlah daun dan berat segar tanaman sehingga penelitian ini dapat diaplikasikan lebih lanjut oleh karena hasil analisisnya berbeda nyata.

Research has aimed to: 1)determine the composition of Lake Tondano sediment and organic manure as technology products, 2)apply those products as the effort of local resources management fulfilled the requirements for plant, 3)measure the growth and yield of nut plants toward the given organic manures. This research was conducted on Pot Experimental with application of technology product of Lake Tondano sediment as the mixture of planted media for growth and yield of nut plants (peanut and green pea) by given the organic manures (compost and green manure of water hyacinth, and poultry manure) in the method of Block Random Design. Using the sediment, water hyacinth and poultry manure was focused on this research in order to apply the technology product as the application of science and technology based local policy as the conservation effort to Lake Tondano in North Sulawesi province, Indonesia. Results showed that: 1)nutrient contents of Lake Tondano sediment for N,P,K were medium and C-organic content was very high and pH was neutral, 2)organic manures (compost and green manure of water hyacinth, and poultry manure) has variation and very high ratio of C/N, and the nutrient contents were fulfilled the requirements in using to apply as technology products, 3)given the organic manures on the mixture of Lake Tondano sediment gave significant effect on the growth and yield of nut plants (peanut and green pea), i.e.: variation doses of organic manures (green manure of water hyacinth of 10 ton/ ha + compost of water hyacinth of 10 ton/ ha + poultry manure of 10 ton/ ha) gave highest value on Pot Experiment. Height of plant and number of leaves increased with the extent of variation doses of organic manures. This experiment could be applied in further Field Experiment planning.