Kepadatan Bakteri Total dan Azotobacter SP di Rizosfer Selada (Lactuca Sativa L.) Setelah Aplikasi Kasing dan Pupuk NPK

Organic matter and inorganic fertilizer application are important to maintain the existence of potential microbes in the rhizosphere and maintain the soil quality. A greenhouse experiment has been carried out to determine the effect of vermicompost and NPK fertilizer on total bacterial and Azotobacter population in rhizosphere and yield of lettuce (Lactuca sativa L.) grown in soil order of Inceptisols. The experimental design was a factorial randomized complete block design with three replicates were tested three doses of vermicompost (7.5, 15 and 22.5 t ha-1) and four doses of inorganic fertilizers; NPK (300; 450; 600 and 750 kg ha-1). The results showed that there was no significant interaction between vermicompost and NPK fertilizer on either total bacterial or Azotobacter population, as well as on fresh weight of lettuce. Both vermicompost and NPK fertilizer did not affect the biological parameters. However, the application of 750 kg/ha NPK fertilizer can increased lettuce weight up to 24% compared to that of control. This study suggested that in the relatively poor soil nutrients, lettuce growth was depend on inorganic fertilizers

Populasi Bakteri dan Jamur Serta Pertumbuhan Tanaman Teh (Camellia Sinensis L.) pada Dua Jenis Media Tanam Setelah Inokulasi Azotobacter

Substituting a part of soil on tea Camellia Sinensis (L.) O. Kuntze) nurseries by using organic matter could minimize the remove fertile soil from nature. Biofertilizing are a way to improve the biological quality of soil and subsequently tea seedling quality. The aim of the research was to determine the effect of planting media composition and biofertilizer doses on total fungal and bacterial population on planting media; as well as tea seedlings growth. The experiment was conducted using a randomized block design consisting of 9 treatments and 4 replications, each replication consisted of three plants. The treatment consisted of soil without biofertilizer (control), soil + 5% biofertilizer, soil + 10% biofertilizer, cocopeat without biofertilizer, cocopeat + 5% biofertilizer, cocopeat + 10% biofertilizer, filter cake without biofertilizer, filter cake + 5% biofertilizer, and filter cake + 10% biofertilizer. Biofertilizer used in this experiment were Azotobacter vinelandii and Azotobacter chroococcum that was mixed with growing media before planting. Result of the experiment showed that planting media affect microbial populations differently. The population of total bacteria, total fungi and Azotobacter sp. in the filter cake media with 10% biofertilizer was significantly higher than those of other growing media. However, Azotobacter biofertilizer had no effect on seedling growth of tea (Camellia Sinensis (L.) O. Kuntze) clones Gambung-

Populasi Bakteri Pelarut Fosfat, P-Potensial dan Hasil Jagung yang Dipengaruhi oleh Aplikasi MPF pada Ultisols Jatinangor

Ultisol is low fertility soil and as low available P due to P fixation by Al and Fe. The phosphate solubilizing microbes (PSM) is the microbial group that enable realease fixed-P to soil solution and be absorbed by plant. This research was aimed to determine the effects of PSM biofertilizer and phosphate fertilizer dosage combination on soil potential P, total phosphate solubilizing bacteria (PSB) population and yield of maize (Zea mays L.) grown in Ultisols. This research used a Randomized Block Design that consist of nine treatments with three replications. The treatments were 100 kg ha-1 of SP-36 fertilizer, 50 kg ha-1 of PSM biofertilizer, SP-36 fertilizer (50 kg ha-1 and 100 kg ha-1) with PSM biofertilizer (25 kg ha-1, 50 kg ha-1 and 75 kg ha-1) repectively. The result showed that the combination of PSM and phosphate fertilizer dosage had significantly effect on PSB total population and maize yield, but did not not on potential P. This experiment suggested that SP-36 fertilizer with 50 kg ha-1 dosage and PSM biofertilizer with 50 kg ha-1 dosage is the best combination

Perubahan Kadar N Tersedia dan Populasi Azotobacter di Rizosfer Sorgum (Sorghum Bicolor L.) yang Ditanam di Dua Ordo Tanah dengan Inokulasi Azotobacter SP.

Bioagumentation by used of nonsimbiotic N­2 fixing Azotobacter is a way to enhance soil N availability in sustainable Agricultural land. A green house experiment has been done to verify effect of Azotobacter sp. inoculation in two soil order, Inceptisols and Entisols, on NH4+danNO3- content , N uptake as well as Azotobacter population in rhizosphere soil of sorghum (Sorghum bicolor L.). Experiment was set up in Randomized Block Design with eight treatments and three replicates, sorghum was maintained in green house until maximum vegetative phase. Resuls showed that Azotobacter sp. AS4 was more enable to increase the availability of soil N rather than isolate AS3. Bacterial bioaugmentation with Azotobacter sp. AS4 on Inceptisols increased more NO3-, Azotobacter sp. population in soil rhizosphere and shoot height of sorghum genotype 2.24

Azotobacter Chroococcum dan Pembenah Tanah untuk Menurunkan Serapan Kadmium oleh Tanaman Padi (Oryza Sativa L.)

Heavy metal contamination in paddy field which came from industry nearby and agricultural input. Increased level of toxic heavy metal cadmium will threat rice production and quality. Bioremediation by used of rhizosphere bacteria is an easy, cheap and effective method to control toxic metal uptake. Pot experiment has been done to study the change in cadmium uptake after biofertilizer Azotobacter chroococcum inoculation and some soil ameliorant. Expirement has been carried out in factorial completely randomized block design with A. chroococcum and ameliorant as treatments. Either Azotobacter inoculation or soil ameliorant didn't change soil acidity, the soil still neutral. Rhizosphere of paddy received biochar, hay compost and biochar and inoculated with 108 cfu mL-1 Azotobacter was colonized by more Azotobacter compared to uninoculated one. All plant treated with Azotobacter has higher nitrogen uptake but lower cadmium uptake. This experiment suggested that biofertilizer Azotobacter has a significant role to decrease cadmium uptake by padi, an important food crop

Mercury Contamination in Soil, Tailing and Plants on Agricultural Fields Near Closed Gold Mine in Buru Island, Maluku

Agricultural productivity in Buru Island, Maluku is threatened by tailings which are generated from formerly gold mine in Botak Mountain in Wamsait Village. Gold that extracted by using mercury was carried out in mining area as well agricultural field. High content of mercury in tailings and agricultural field pose a serious problem of food production and quality; and further endangers human health. The purpose of this research was to determine the contaminant level of mercury in tailing, soil and its accumulation in edible part of some food crops. Soil, tailing and plant samples for Hg testing were taken by purposive method based on mining activities in Waelata, Waeapo and Namlea sub district. Six soil samples had been analyzed for their chemical properties. Total mercury levels in tailings and plants were measured by Atomic Adsorption Spectrophotometer. This study showed that agricultural field where tailings were deposited contained Hg above the threshold but agricultural area which is far from hot spot did not. Most edible parts of food crops accumulated mercury more than Indonesian threshold for mercury content in food. This evidence explained that tailings deposited on the surface of agricultural field had an impact on soil quality and crop quality. Tailing accumulated on soil will decreased soil quality since naturally soil fertility in agricultural field in Buru is low