Vol 17, No 3 (2010): Desember

 Laju pembasahan dan tingkat pembasahan disamping bahan organik dipercaya mempengaruhi proses awal terjadinya koalesen agregat tanah yang dapat meningkatkan kekuatan tanah. Penelitian ini dirancang untuk memisahkan kedua pengaruh itu sehingga dapat dilakukan perbaikan pengelolaan yang dapat dievaluasi dalam rangka meningkatkan efisiensinya yaitu apakah pengelolaan harus berfokus pada perbaikan teknik irigasi atau meningkatkan bahan organik, atau keduanya. Polivinil alkohol (PVA) yang merupakan salah satu senyawa kimia yang dapat meningkatkan stabilitas agregat diberikan secara terkontrol dengan menggunakan sprayer terhadap agregat tanah berdiameter 0,5-2 mm. Sampel tanah bertekstur kasar dan halus ditempatkan dalam ring dan laju pembasahan air (1, 10 dan 100 mm/jam) menggunakan sistem tetesan yang dikontrol oleh pompa peristaltik. Sampel tanah kemudian dibasahi hingga mendekati jenuh atau hisapan 10 kPa selama 24 jam, kemudian didrainase dengan menggunakan plat tekanan pada hisapan 100 kPa. Pengukuran tahanan penetrometer diukur dengan menggunakan penetrometer kerucut berdiameter 2 mm, sedangkan kekuatan tarik diukur dengan alat uji tidak langsung Brazilian. Tahanan penetrometer lebih rendah pada sampel tanah yang mendapat perlakuan PVA sebelum pembasahan dan pada sampel tanah yang yang mendapat hisapan lebih tinggi (10 kPa) setelah pembasahan awal. Pengaruh tersebut semakin menonjol pada tanah bertekstur kasar. Pada kedua jenis tekstur tanah, kekuatan tarik meningkat dengan semakin tingginya laju pembasahan dan tingkat pembasahan (lebih besar pada kondisi hampir jenuh). Laju pembasahan cenderung lebih penting dalam mendorong proses terjadinya koalesen agregat dari pada tingkat pembasahan.

The study was conducted to evaluate effects of varied concentrations of methanol extract of lemon grass, Andropogon nardus L. (10.5%, 9.5%, 8.5%, 7,5%, 6.5%, and 0% as control) on mortality and feeding activity of the third-instars of P.xylostella larvae. It was used a randomized complete design with three replicates. The results showed that the leaf extract of Andropogon nardus at 8.5 % was the best treatment as it could caused high mortality of P. xylostella (66.67 %) and it was able to deter the feeding activity up to 82.66 %. The data suggested that extracts of Andropogon nardus contains toxic oil and feeding activity repellant.

This research was conducted on February to May 2009 in Jonooge village, Biromaru sub district Sigi regency Central Sulawesi province. A 3x3 factorial experiment in a randomized block design was used. The first factor was nitrogen fertilizer 200 kg N/ha applied at different times and rates: single application at sowing (W1), 1/3 rate at sowing and 2/3 rate at 15 d after sowing (W2), 1/3 rate at sowing and 2/3 at 30 d after sowing (W3), and 1/3 rate at sowing and 2/3 at 45 d after sowing (W4). The second factor was thickness of mulch: 3 cm (J1), 5 cm (J2) and 7 cm (J3). The research results showed that there was no interaction effect between nitrogen fertilizer applications and mulch thickness. Better plant height (164.78 cm), weight of 10 corncobs (2.43 kg), girth (7.70 cm), number of kernel rows, and corncob length (18.3 cm) was found in treatment W3 than the other nitrogen fertilizer treatments. Mulch added at 7 cm thickness resulted in larger sugar content (26.55%), plant height (166.94 cm), and weight of 10 corncobs than the other mulch treatment.

The research was aimed at analyzing the growth and nutrition value of elephant grass under different cutting interval times. The research was carried out at the experimental garden of BPTP Gowa, Pa Bentengan Village, Bajeng Sub-district, Gowa Regency, South Sulawesi Province from May 2007 to March 2008. The research utilized a random block design, with 4 treatment levels, i.e.: (1) a four-week cutting interval, (2) a six-week cutting interval, (3) an eight-week cutting interval, (4) a ten-week cutting interval. Each treatment was repeated 3 times, so that 12 treatment units were obtained. The research results showed that the four-week cutting interval produced the best growth and production components such as increased plant height (cm day-1), leaf number (leaf day-1), poll number (poll day-1), wet and dried weight (ton ha-1year-1) The analysis of nutrition value indicated that the 4 week-cutting interval yielded higher water level and crude protein, but lower crude fat and fiber.

The purpose of this study was to determine the population density of parasitical nematodes on tomatoes. This research used a purposive sampling survey in jonooge and Sidera villages Sigi Biromaru sub district Donggala regency. The research results showed that the nematode population density in jonooge village was 71.00 JI/10 g roots and 63.33 JI/100 g soil whereas in sidera village 43.00 JI/10 g roots and 38.00 JI/100 g soil.

The objective of this research was to identify entomopathogenic fungi associated with green leafhopper (Nephotetix virescens) and to determine its virulence toward N. viresnes mortality. The indicators of pathogenicity were symptoms, time of symptom appeared, and mortality of green leafhopper after inoculation of the entomopathogenic fungi. The research was conducted in three phases. The first phase was collecting green leafhopper infected by entomopathogenic fungi in the field. The second phase was isolation, inoculation, and re-isolation of entomopathogenic fungi from the infected green leafhopper (wereng). The third was pathogenicity assay conducted in the Laboratory of Plant Pest and Disease, Faculty of Agriculture, Tadulako University. The research was conducted for four months from February to May 2010. Five isolates of entomopathogenic fungi were collected in Donggala Regency: Metharizium sp., Asperigillus sp., Beauveria sp., Cladosporium sp. and Fusarium sp. Two isolates were found potential as entomopathogenic fungi: Metarhizium sp. and Beauveria sp. Mortality of nimpha green leafhopper (wereng hijau) caused by both fungi were 80.75%, and 80.25% respectively.

This research aimed to identify: (1) the efficiency level of input production (land area size, seed number, fertilizer and labors) of hybrid corn farm, and (2) the income of hybrid corn farm. The research population samples of 35 peoples were hybrid corn farmers in Bobo, Bunga and Berdikari villages taken using a random sampling method. Data was analyzed using the Cobb-Douglass production function, production input efficiency and income analysis. The results of this research showed that all variables observed significantly influenced the hybrid corn production, except labors which was relatively inefficient. The income of the hybrid corn farm was IDR 3,806,414. 19/ha/planting season.

The policy objective for cacao agribusiness development in the province of Central Sulawesi was directed toward the improvement of production, farm income and employment. In fact, there numerous cases such as scarcity and high prices of inputs, and farmer’s limited capital have become obstacles in these efforts,. The objective of this study was to evaluate the effect of P2WK project upon income of the cacao farm and its respected income distribution. The results of this study indicated that the P2WK project had affected upon income improvement through better land use, fertilizer, pesticide and the use of non-household labor, but then it was followed by disproportionate distribution of their income.

This study aimed to identify the risk of household wetland rice farm production in impenso and non impenso regions in Central Sulawesi Province. Respondent samples of 250 farmers were randomly chosen. Data collected through interviews and field note records. The research result showed that coefficient of variance of the rice farm in the impenso region was higher than in the non impenso region suggesting that the risk of the first region was larger than the later.

This research aimed to identify the use efficiency of production factors and the income level of wetland rice farm at Masani Village of Poso Pesisir Sub district of Poso Regency. This Location was purposively determined. Respondents were determined using a simple random sampling method. The number of samples was 63 people taken from population of 167 people. The CobbDouglas production function was used to analyze the use efficiency of wetland rice farm production factors and the level of income was descriptively analyzed. Results of the research showed that (1) factors such as farm area size, seed, fertilizer and labor were not efficiently used in the wetland rice farm at Masani Village of Poso Pesisir Sub district, so increasing these factors are required to reach maximal production and income, and (2) the income of the wetland rice farmers at Masani Village of Poso Pesisir Sub district can be divided into three levels included low income equal to 30.16%, medium 38.10%, and high 31.74%.