The aim of this study was to investigate the biological treatment of synthetic oilfield-produced water in activated sludge in an attempt to remove the organic compounds using endogenous bacteria; we also hope to determine the biokinetic coefficients. The activated sludge was operated with various hydraulic retention times (HRT=20 hours, 12 hours, 8 hours), solid retention times (SRT=25 days, 20 days, 15 days, 10 days), and substrate concentrations (500 mg L -1 to 1,100 mg L -1 ). The endogenous bacterial strains, which were isolated from existing wastewater treatment facilities, were identified as Pseudomonas sp., Enterobacter sp., Bacillus sp1., and Bacillus sp2. It was observed that the highest COD removals were obtained in reactors A (80.7%) and B (82.4%), which had high SRTs (25 days and 20 days) and HRT (20 hours). At shorter SRTs (15 days and 20 days), the concentration of the COD effluent did not comply with the Indonesian regulations for oilfield-produced water quality standards, which means that these SRTs were not recommended as appropriate operational conditions. Furthermore, the results showed that the yield (Y), decay coefficient (kd), maximum specific growth rate (k), and saturation constant (K s ) were 0.533 mg MLVSS mg -1 COD, 0.167 day -1 , 0.985 day -1 , and 255.46 mg COD L -1 , respectively. These biokinetic coefficients (obtained from the Y and K s values) indicated that although the strains of bacteria can grow well in the reactor, they had low affinities to the substrate, which caused the concentration of the COD effluent to be relatively high.

Vetiveria zizanioides was known as vetiver that produces a good quality oil and is also competent in foreign markets. This study aims to determine the effect of manure and ascorbic acid on the growth of vetiver on saline soil by applying the appropriate dose of manure and ascorbic acid for optimal growth. The methodology was done using a randomized block design with three replicates and consisted of 2 factors, i.e., manure level (K) and the ascorbic acid concentration (A). The results suggested an interaction of the manure and ascorbic acid concentration in the plant height, root volume but not found in the number of clumps. The manure displays a significant response to plant height, number of leaves, number of clumps, and root volume. The ascorbic acid response to the growth was obtained to the best response in plant height, a number of leaves, and root volume. The dose of manure and ascorbic acid that increased concentration was suspected to control salinity stress. The manure was thought to be able to provide the organic matter in saline soil because the addition of organic matter holds water and retains nutrients. Besides, ascorbic acid has been a role antioxidant during plant stress.

ABSTRAKKecamatan Hamparan Perak Kabupaten Deli Serdang memiliki luas lahan pertanian ± 11.046 ha atau 48, 9 % dari luas Kecamatan ini, dimana seluas 7.048 ha adalah lahan sawah yang potensial namun belum dimanfaatkan secara optimal. Berdasarkan UU No 41 tahun 2009 bahwa perencanaan pengembangan lahan pertanian pangan berkelanjutan harus berdasarkan pada kriteria kesesuaian lahan yang dapa dilakukan dengan dukungan penelitian. Penelitian ini bertujuan untuk mengevaluasi karakteristik tingkat kesesuaian lahan sawah dan lahan kering di Kecamatan Hamparan Perak Kabupaten Deli Serdang, untuk menganalisis usaha-usaha perbaikan yang perlu dilakukan dalam meningkatkan produktivitas tanaman dan untuk membuat peta kesesuaian lahan aktual dan kesesuaian lahan potensial tanaman padi sawah dan beberapa tanaman lahan kering di Kecamatan Hamparan Perak Kabupaten Deli Serdang. Metode analisisnya adalah dengan metode membandingkan (matching) menurut FAO. pemilihan satuan unit lahan berdasarkan peta tanah yang terdiri dari 12 titik bor dan 6 lobang profil. Hasil penelitian menunjukkan bahwa tingkat kesesuaian lahan untuk tanaman padi sawah (Oryza sativa) adalah cukup sesuai (S2) seluas 14.093, 883 ha dan sesuai marginal (S3) seluas 17.347,141 ha. Untuk tanaman jagung (Zea mays) termasuk cukup sesuai (S2) seluas 19.391, 019 ha dan sesuai marginal (S3) seluas 12.050,005 ha. Untuk tanaman kedelai (Glicine max) termasuk sesuai marginal (S3) seluas 31.441,024 ha. Untuk tanaman ubi kayu (Manihot utilissima) termasuk kelas sesuai marginal (S3) seluas 31.441,024 ha. Untuk tanaman ubi jalar (Ipomea batatas) termasuk kelas sesuai marginal (S3) seluas 31.441,024 ha. Untuk tanaman sawo (Achras zapota) termasuk kelas cukup sesuai (S2) seluas 17.660,583 ha dan kelas sesuai marginal (S3) seluas 13.780,441 ha. Untuk tanaman mangga (Mangifera indica) termasuk kelas sesuai marginal (S3) seluas 31.441,024 ha. Untuk tanaman sukun (Astocarpus astilis) termasuk kelas cukup sesuai (S2) seluas 17.660,58 ha dan kelas sesuai marginal (S3) seluas 13.780,44 ha. Kata Kunci : Evaluasi kesesuaian lahan, tanaman lahan sawah, tanaman lahan kering, Kecamatan Hamparan Perak. PENDAHULUAN Kecamatan Hamparan Perak Kabupaten Deli Serdang berdasarkan analisa Geographical Information System (GIS) memiliki luas 31.441,024 ha. Namun menurut BPS (2015) luas wilayah Kecamatan Hamparan Perak adalah 230,15 km 2 atau 23.015 ha dan Suhedi (2015) mengatakan luas wilayah ini lebih kurang 22.611,57 hektar. Dari luasan tersebut, seluas 7.048 ha adalah lahan sawah dan 3.998 ha adalah lahan kering yang belum dimanfaatkan secara optimal. Luas lahan pertanian potensial di Kecamatan Hamparan Perak ± 11.046 ha atau 48, 9 % dari luas Kecamatan ini.

Vetiver root is a commodity that is tolerant enough to be planted in salty soils with a certain level of salinity. One approach to increase oxidative stress tolerance that will increase the enzyme substrate at the cellular level is ascorbic acid. The purpose of this study was to increase students' knowledge about how the response of vetiver seed (Vetiveria zizanioides) growth in salt soils to ascorbic acid through practical field learning in plant physiology courses. This research was conducted using a factorial randomized block design (RBD), the first factor was the salinity (S), namely S0: 0 dsm-1 and S1: 4 dsm-1. The second factor was ascorbic acid (A), namely A0: without treatment, A1: 50 ppm, A2: 100 ppm and A3: 150 ppm. There were 8 treatment combinations that were repeated 3 times resulting in 24 experimental units. The parameters observed were plant height, number of leaves and number of stomata. In this study, ascorbic acid had a significant effect on plant height, number of leaves and number of stomata. Saline soil had a significant effect on the number of stomata parameters. No interactions for all parameters were observed.

Vetiver (Vetiveria zizanioides L.) plants are able to protect the soil from erosion and are tolerant of salinity stress. However, at high salinity levels, vetiver plants show a decreasing growth. The application of gibberelin is expected to increase the growth of vetiver in salinity stress conditions. The purpose of this study was to evaluate the growth responsiveness and production of vetiver the application of gibberelin under salinity stress conditions. This research was conducted in the green house of the Faculty of Agiculture, Universitas Sumatera Utara, Medan. This study used a non-factorial completely randomized design, namely the salinity stress (S) which consisted of 3 levels, each treatment was repeated 3 times, so that 9 treatment combinations were obtained: the concentration of gibberelin was 0 (no treatment), 50 ppm and 100 ppm.

Salinity is one of the problems in agricultural land in the world, including in Indonesia. Vetiver is quite tolerant of planting in saline soils at a certain level of salinity, but vetiver growth is inhibited at high salinity levels. The purpose of this study was to evaluate the effect of gibberellin in saline soils on the growth and production of vetiver (Vetiveria Zizanioides L.). This research was conducted in the greenhouse of the Faculty of Agriculture, Universitas Sumatra Utara, Medan. This study used a non-factorial completely randomized design, It was salinity stress (S) which consisted of 3 factors: Gibberellin concentrations of 0 (without treatment), 50 ppm, and 100 ppm. The results of this study indicate that giving Gibberellins in salinity stress conditions has a significant effect on the observed variables of plant height, specific leaf area, and cuticle thickness.

In order to alleviate the deleterious effects of salinity, different types of phytohormones have been used. Among them, GA3 has been the main focus of some plant scientists. This study aimed to evaluate the effect of gibberellic acid and salinity on growth and production of roselle (Hibiscus sabdariffa L). This research was conducted in a greenhouse of Agriculture Faculty, University of Sumatera Utara, Medan. The study used utterly randomized design with two factors. The first factor was gibberellic acids. They were gibberellic acid (5 mg L-1) and no gibberellic acid. The second factor was salinity. They were 0 dsm-1 and 4-5 dsm-1. The interaction between gibberellic acid and salinity acid indicated a significant effect on the percentage of germination, chlorophyll a and b and beta-carotene. The application of giberellic acid helped in the tolerance of plants to salinity. Thus, application of GA3 become essential to improve overall productivity in salinity.

This research to the characteristics of the land suitability of coconut plantations in the Secanggang District. This research also analyzes the improvement efforts that need to be done in increasing the productivity of coconut plants and make maps of actual land suitability and potential land suitability of coconut plants in Secanggang District. As well as providing recommendations for fertilization on coconut plantations. This research was conducted using a survey method consisting of four stages of activity, namely preparation, main survey, soil analysis and data processing. It can be seen from the results of this study that the potential land suitability of coconut in Secanggang District is S3 f and n (marginally according to nutrient retention factors and nutrient availability) in the Village of Kepala Sungai, Tanjung Ibus, Karang Gading, Perkotaan and Telaga Jernih. S3 f (marginally according to nutrient retention factor) in Karang Anyar, Kebun Kelapa, Secanggang, Selotong, Pantai Gading, and Teluk Village. S2 w, f and n (enough according to the limiting factors of water availability, nutrient retention and nutrient availability) exist in Sei Ular and Hinai Kiri villages. The with improvement efforts to the limiting factor of nutrient retention by adding organic matter, the limiting factor of low nutrient availability is by fertilizing. After an effort has been made to evaluate the suitability of coconut land to S2 w with the limiting factor of water availability, namely rainfall, which is the main limiting factor in assessing land suitability because land improvements cannot be made.