Judul: Peat Water Table, Nutrient Dynamics and Leaf Nutrient  Status in Oil Palm (Elaeis guineensis Jacq.) Plantations
Abstrak: Indonesia merupakan penghasil minyak sawit terbesar di dunia, dimana Provinsi Riau, khususnya Kabupaten Siak, menjadi kontributor utama. Penelitian dilakukan pada perkebunan kelapa sawit di Kabupaten Siak yang memiliki iklim hutan hujan tropis dengan kelembaban tinggi. Jenis tanah di daerah ini merupakan lahan gambut dengan kematangan hemik. Curah hujan mempengaruhi tinggi muka air dan volume air gambut, dimana akan mempengaruhi dinamika hara daun dan gambut, sehingga mempengaruhi perkembangan vegetatif dan produksi tanaman. Untuk mengetahui pengaruh tinggi muka air, dilakukan penelitian pada lokasi gambut dengan rancangan percobaan purposive sampling, dengan 3 blok ulangan, dimana setiap blok terdiri dari 5 plot, dengan 6 sampel tanaman di setiap plot. Penelitian dimulai dari Februari 2023 - Maret 2024. Hasil penelitian menunjukkan bahwa interval tinggi muka air 40 - 50 cm dan volume air 70 - 85 ml 100 ml-1 merupakan yang optimum dalam penyerapan hara daun P, K, Cu, Zn, dan B, dan kadar klorofil daun. Kadar klorofil daun pada interval 0,040 - 0,045 mg cm-2 merupakan yang optimum dalam penyerapan hara daun P, K, Cu, Zn, dan B, serta bobot tandan, sedangkan bobot kering daun dipengaruhi oleh kadar hara daun Cu, Zn, dan B pada interval yang optimum. Metode diagnosis and recommendation integrated system (DRIS) merupakan alternatif dalam menghitung kadar hara daun yang mendekati standar hara daun., Indonesia is the largest producer of palm oil in the world, where Riau Province, especially Siak Regency, is the main contributor. The research was conducted on oil palm plantations in Siak Regency which has a tropical rainforest climate with high humidity. The soil type in this area is peatland with hemic maturity. Rainfall affects the water level and volume of peat water, which will affect the nutrient dynamics of leaves and peat, thus affecting vegetative development and plant production. To determine the effect of water level height, a study was conducted on peat locations with a purposive sampling experiment design, with 3 replicate blocks, where each block consisted of 5 plots, with 6 plant samples in each plot. The research started from February 2023 - March 2024. The results showed that the water table interval of 40 - 50 cm and water volume of 70 - 85 ml 100 ml-1 were optimal in the absorption of leaf nutrients P, K, Cu, Zn, and B, and leaf chlorophyll levels. The level of leaf chlorophyll at the interval of 0,040 - 0,045 mg cm-2 was optimal in the absorption of leaf nutrients P, K, Cu, Zn, and B, as well as the weight of the bunch, while the dry weight of the leaves was affected by the nutrient levels of Cu, Zn, and B at the optimal interval. The diagnosis and recommendation integrated system (DRIS) method is an alternative in calculating leaf nutrient levels that are close to the leaf nutrient standard.
Keyword: pemupukan, bobot isi, porositas, klorofil daun, DRIS

Judul: Evaluation of B, P, and S Nutrients on Oil Palm Crop (Elaeis guineensis Jacq.)
Abstrak: Kebutuhan terhadap produk kelapa sawit akan terus meningkat karena selain untuk pangan dan industri, juga untuk biodiesel. Kecukupan unsur hara boron, fosfor, dan sulfur berpengaruh terhadap produktivitas kelapa sawit yang dapat diketahui dengan melakukan analisis tanaman. Metode pengabuan basah dan pengabuan kering merupakan dua metode yang umum digunakan untuk analisis tanaman kelapa sawit. Oleh karena itu, penelitian ini bertujuan untuk membandingkan dua metode analisis berdasarkan pengabuan kering dan pengabuan basah dengan korelasi berpasangan sederhana dan mengetahui status kadar hara B, P, dan S pada daun tanaman kelapa sawit. Hasil analisis kadar hara B, P, dan S antara kedua metode berkorelasi positif nyata dengan nilai r berturut-turut 0.2389, 0.6442, dan 0.4753 (r-tabel = 0.2227; n = 76). Metode pengabuan basah menghasilkan rataan kadar hara B dan S yang lebih tinggi dibandingkan metode pengabuan kering. Sebaliknya untuk hara P, metode pengabuan kering menghasilkan rataan kadar hara yang lebih tinggi dibandingkan metode pengabuan basah. Status hara P dan S relatif sama untuk kedua metode dengan status optimum untuk P dan defisien untuk S. Sedangkan untuk hara B status kadar hara berdasarkan kedua metode menunjukkan kelas yang berbeda yaitu agak optimum untuk pengabuan kering dan optimum untuk pengabuan basah., The need for palm oil products is always increased because in addition to food and industry, it is also for biodiesel. The adequacy of nutrient elements boron, phosphorus, and sulfur affect the productivity of palm oil, can be determined by plant analysis. Wet ashing and dry ashing methods are two methods commonly used for oil palm crop analysis. Therefore, this study aims to compare two analytical methods based on dry ashing and wet ashing with simple pair correlations and determine the status of B, P, and S nutrient levels in oil palm leaves. The results of the analysis of nutrient levels B, P, and S between the two methods were significantly positively correlated with the r value, consecutive 0.2389, 0.6442, and 0.4753 (r = 0.2227; n = 76). The wet ashing method produced higher average of B and S nutrients than the dry ashing method. On the other hand for P nutrients, the dry ashing method produced higher average of nutrients than the wet ashing method. P and S nutrient status were relatively the same for both methods where P status was optimum and S deficiency. As for B nutrient, the nutrient content status based on the two methods showed differently, slightly optimum for dry ashing and optimum for wet ashing.
Keyword: Dry ashing, Plant analysis, Wet ashing

Judul: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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