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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.