PENDUGAAN NUTRIENT BUDGET TAMBAK INTENSIF UDANG, Litopenaeus vannamei

Abstract

Penelitian ini bertujuan untuk mendapatkan nutrient budget tambak intensif udang Litopenaeus vannamei sebagai acuan alokasi input produksi pada tingkat kapasitas asimilasi lingkungan perairan. Pendugaan nutrient budget tambak udang intensif menggunakan pendekatan mass balance, dihitung berdasarkan input nutrien nitrogen - N dan fosfor – P yang berasal dari pakan, benih, pupuk, media probiotik, inflow, dan output nutrien yang ada pada produksi udang, outflow, dan endapan lumpur di dasar tambak. Sampel air, tanah, sedimen, plankton diambil sebelum penebaran dan setiap dua minggu selama pemeliharaan dari tiga petak tambak, masing-masing 5 titik sampel per petak tambak contoh. Analisis nitrogen dan fosfor dilakukan untuk sampel pakan, karkas udang awal dan akhir. Data managemen budi daya meliputi padat penebaran benur 50 ekor m-2, produksi 1.188—1.489 kg/0,25 ha, dan FCR 1,69—2,14; maka total input nutrien tambak udang Litopenaeus vannamei antara 171,9155—179,3778 (176 ± 3,9586) kgN dan 95,2533—99,4180(97,8340 ± 2,3348) kg P. Pakan mendominasi input N sebesar 61,96% ± 0,66%; disusul inflow 30,93% ± 0,70%; pupuk 6,52% ± 0,15%, serta media probiotik dan benur masing-masing <1%. Pola yang sama terjadi pada input phosphorous dengan komposisi 87,75% ± 0,24% dari pakan; 7,73% ± 0,19% pupuk; 4,05% ± 0,25% inflow dan media probiotik < 1%. Total output nitrogen tambak udang vannamei antara 107,1279-110,1438 (108,4957 ± 1,5274) kg N dan 51,6362—63,6576 (56,1292 ± 6,5604) kg P. Komposisi output nitrogen adalah outflow sebanyak 29,82% ± 3,20%; kemudian udang yang dipanen 21,32% ± 1,33%, lumpur atau sludge 10,40% ± 0,81%. Sedangkan komposisi output phosphorous didominasi oleh lumpur 39,03% ± 6,59%; kemudian udang yang dipanen 15,22% ± 0,85% dan outflow 3,09% ± 0,26%. Efisiensi pakan dan air melalui managemen budi daya yang benar menjadi peubah dominan penentu beban limbah tambak udang.This research was aimed to find out nutrient budget on L. vannamei intensive ponds as input allocation reference produce at environmental assimilation capacity level. Nutrient budget assessment was used mass balance approach, calculate based on nutrient input of nitrogen (N) and phosphor (P) from feed, seed, fertilizer, probiotic media, and inflow and nutrient output within pond yield, outflow, and sludge sedimentation at pond bottom. Sampling for water quality, sediment, and plankton was carried out at three ponds and five stations within each pond before stocking and continued fortnightly as long as culture periods. Nitrogen and phosphor analyzed for feed, and shrimp carcass of both of initial stocking and harvest. The data of culture management consist of shrimp yield reached 1,188—1,489 kg/0.25 ha with stocking density of 50 ind/m2 and FCR 1.69—2.14. Total input nutrients within L. vannamei ponds are 171.9155—179.3778 (176 ± 3.9586) kg N and 95.2533—99.4180 (97.8340 ± 2.3348) kg P. Food given domination on N input N with 61.96% ± 0.66% followed by inflow by 30.93% ± 0.70%, fertilizer 6.52% ± 0.15%, and both of probiotic media and seed supply less than1% respectively. There are the same pattern with phosphorous input with following composition 87.75% ± 0.24% from food, 7.73% ± 0.19% fertilizer, 4.05% ± 0.25% inflow and probiotic media less than 1%. Total output nitrogen from L vannamei ponds between 107.1279—110.1438 (108.4957 ± 1.5274) kg N and 51.6362—63.6576 (56.1292 ± 6.5604) kg P. Composition of nitrogen output is dominated by outflow 29.82% ± 3.20%, followed by shrimp harvest 21.32% ±1.33%, and sludge 10.40 ± 0.81%. Meanwhile, composition of phosphorous output dominated by sludge 39.03% ± 6.59%, shrimp harvest 15.22% ± 0.85% and outflow 3.09% ± 0.26%. Both food and water efficiency under good culture management are the mainfactors of waste load from shrimp culture ponds.