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<p>The oil palm empty fruit bunches are solid waste produced from the processing of oil palms which have a large amount of potential to be used as compost and are expected to improve the physical, biological and chemical properties of the subsoil. This study aimed to evaluate the best combination between oil palm empty fruit bunches compost and rice husk charcoal on soil chemical properties in tomato. This research was conducted in Sona Village, Labuhanbatu Regency on December 2019-March 2020. Analysis of soil chemical properties was conducted at the Socfindo Seed Production and Laboratories (SSPL) Laboratory of PT. Socfin Indonesia. The study was conducted with a factorial randomized block design with 2 factors. The first factor was the application of oil palm empty bunches which consists of no oil palm empty bunches (control), 0.5 kg/polybag, 0.7 kg/polybag and 1 kg/polybag. The second factor was the application of rice husk charcoal which consists of non-husk charcoal (control), consisting of 0.2 kg/polybag and 0.4 kg/polybag. Data that had a significant effect after analysis of variance continued with DMRT at the level of α = 5%. The results showed that application of oil palm empty fruit bunches (0.7 kg/polybag) significantly increased pH and C-organic. Application of rice husk charcoal (0.2 kg/polybag) significantly increased C-organic and P-available.</p>

This study was aimed to elucidate the effect of the application of urea fertilizer and goat manure on some soil chemical properties and yield of a green mustard plant (Bressicca juncea L). This study was conducted with a randomized block design consisting of two factors. The first factor was the application of goat manure (K) consisting of three levels, i.e. (K1) 1 t goat manure ha -1 , (K2) 1.5 t goat manure ha -1 , and (K3) 2 t goat manure ha -1 . The second factor was the application of urea fertilizer consisting of two dose levels, i.e. (U1 75 kg) urea fertilizer ha -1 , and (U2) 100 kg urea fertilizer ha -1 . The measured parameters were soil organic-C content, soil total N content, and fresh weight of the green mustard plant. Results of the study showed that the combination of 2 t goat manure ha -1 and 100 kg urea fertilizer ha -1 was the best treatment that significantly affected soil organic-C content, soil total N, soil C/N r atio, and yield of fresh weight of the mustard green plant.

This study aimed to determine the effect of rice straw compost and rice husk ash on some chemical properties of an Ultisol soil under sweet corn plant. This study was conducted at the Labuhan Batu Rantau Prapat University Campus Land and at the PT. Socfindo Laboratory. The design used in this study was a factorial randomized design consisting of two factors with two replications. The first factor was application of rice husk ash with four dose levels (g 5 kg -1 of soil), i.e. P0 (0), P1 (10), P2 (20), and P3 (30). The second factor was the application of rice straw compost with four dose levels (g 5 kg -1 of soil), i.e. J0 (0), J1 (25), and J2 (50), J3 (75). Results of this study indicated that the application of rice straw compost significantly increased soil organic-C and available P contents, as well as plant height, plant dry weight, N and P uptake by plant. The treatments, however, did not significantly increase soil pH and total-N content. The application of rice husk ash significantly increased soil organic-C content and N uptake by plant, but it did not significantly increase pH, available P content, and total N content of the soil.

The current blended learning method, which mixes online and traditional classroom instruction, is appropriate for the epidemic. According to various research studies, blended learning benefits students by allowing them to study independently without regard for location or time constraints. This article explores and describes the use of the blended learning paradigm during a pandemic using a meta-analysis technique. The objective is to determine the effect of blended learning on learning outcomes; according to the conclusions of a research released in 2021 based on ten published articles, employing the blended learning approach greatly improved learning outcomes during the pandemic, with an effect size value of 1.21. However, the outcomes of this study suggest that publication bias exists as a result of an unbalanced distribution of effect sizes.

Multimedia that you can interact with is an important part of learning. Multimedia can be used as a learning tool to improve the quality of learning. Learning media can be used to try out different ways to teach and learn. Interactive media made for Android helps students learn more. Using this material makes a big difference in how well students learn. The goal of this study is to find out how students feel about using interactive multimedia based on Android in Biology classes at Senior High Schools after COVID-19. This study was done with 60 students from Mts Ar Royan Aek Nabara Labuhanbatu. They all filled out a questionnaire. Students were sent a questionnaire to gather information, and the results were looked at. According to the perception findings, 67 percent of students have used interactive multimedia based on Android, 69 percent of teachers use audiovisual tools to teach ideas, and 78 percent of respondents prefer to use interactive multimedia. This shows that using Android-based interactive multimedia apps could improve the quality and effectiveness of biology education during the COVID-19 epidemic.

Anthropogenic activities that tend to be exploitative in the mangrove ecosystem of Belawan are thought to have an impact on the biota associated with the ecosystem. One of the impacts is thought to be implied by mantis shrimp Cloridopsis scorpio (Latreile, 1828). The reproductive biology of the shrimp is the main object that needs to be studied in relation to the impacts. This study aims to determine the distribution of gonad maturity stage, gonad somatic index, and the length of the first mature of C. scorpio in the Mangrove Ecosystem of Belawan, North Sumatera. The research was conducted on March to May 2019 with a biweekly sampling period. The purposive random sampling was applied to choose three sampling stations in the research location. Mantis shrimp samples were caught using shrimp trawl. The result showed that the gonad maturity stage of males and females were dominated by Stage I. The gonad somatic index (GSI) range of males were 7.00-10.93 and female were 7.40-11.15. The GSI value of C. scorpio is closely related to its gonad maturity development. The length of the first mature (L50) of males were 205.50±10.65 mmBL and females were 186.0±10.48 mmBL.Keywords: Cloridopsis scorpio, Gonad maturity stage, Gonad somatic indeks, Length of the first mature ABSTRAKAktivitas antropogenik yang cenderung eksploitatif di kawasan ekosistem mangrove Belawan diduga telah berdampak terhadap biota-biota yang berasosiasi dengan ekosistem tersebut. Salah satu dampaknya dialami oleh udang mantis Cloridopsis scorpio (Latreile, 1828). Aspek reproduksi C. scorpio menjadi salah satu objek yang perlu dikaji berkaitan dengan dampak tersebut. Penelitian ini bertujuan untuk menganalisis sebaran tingkat kematangan gonad (TKG), indeks kematangan gonad (IKG), dan ukuran pertama kali matang gonad (L50) dari C. scorpio di ekosistem mangrove Belawan, Sumatera Utara. Penelitian dilakukan pada bulan Maret sampai Mei 2019 dengan periode pengambilan sampel dua mingguan. Metode purposive random sampling digunakan untuk menentukan tiga stasiun pengambilan sampel di lokasi penelitian. Sampel C. scorpio ditangkap menggunakan pukat udang. Hasil penelitian menunjukkan distribusi TKG C. scorpio jantan dan betina didominasi oleh TKG I. Nilai IKG C. scorpio jantan berkisar antara 7,00-10,93 dan C. scorpio betina berkisar antara 7,40-11,15. Nilai IKG C. scorpio berkaitan dengan tahap perkembangan gonadnya. C. scorpio jantan mengalami pertama kali matang gonad (L50) pada ukuran 205,50±10,65 mmBL dan C. scorpio betina pada ukuran 186,00±10,48 mmBL.Kata kunci: Cloridopsis scorpio, TKG, IKG, Ukuran pertama kali matang gonad

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