Judul: Comparison of Methods for Assessing Soil Fertility Status  on Toposequence Transect in Sandai Subdistrict, Ketapang District, West  Kalimantan
Abstrak: Penilaian status kesuburan tanah penting dalam pengembangan pertanian terutama untuk menghadapi tantangan krisis pangan dan potensi degradasi lahan. Penelitian ini mengkaji status kesuburan tanah pada transek toposekuen di Kecamatan Sandai, Kabupaten Ketapang, Kalimantan Barat. Contoh tanah yang diambil dari kedalaman 0-30 dan 30-60 cm pada tujuh titik pengamatan (TP1, TP2, TP3, TK1, TK2, TK3, dan TK4) kemudian dianalisis kapasitas tukar kation (KTK), kejenuhan basa (KB), P2O5 ekstrak HCl 25%, K2O ekstrak HCl 25%, dan karbon organik (C-organik) serta basa-basa dapat ditukar (Ca, Mg, dan K). Analisis ini didukung dengan Principal Component Analysis (PCA) melalui perangkat lunak statistik R Studio. Penilaian kesuburan tanah didasarkan pada kriteria Five Major Soil Chemical Properties (FMSCP), Basic Cation Saturation Ratio (BCSR) dan Sufficiency Level of Available Nutrients (SLAN). Status kesuburan tanah berdasarkan metode FMSCP berkisar antara sangat rendah (SR) hingga rendah (R). Terdapat variasi yang tinggi pada status kesuburan tanah (defisiensi hingga berlebih) berdasarkan kriteria BCSR dan SLAN, yang memiliki hubungan erat dengan keragaman bahan induk tanah dan kemiringan lereng. Tanah-tanah pada titik pengamatan TP1, TP2, dan TP3 berstatus defisiensi hingga seimbang, sedangkan TK1, TK2, TK3, dan TK4 didominasi oleh status seimbang hingga berlebih pada metode BCSR. Kriteria SLAN nasional mengindikasikan Ca, Mg, dan K tanah berstatus defisiensi. Status defisiensi juga terdapat hanya pada unsur K berdasarkan kriteria SLAN internasional. Hasil penelitian ini merekomendasikan implementasi dari metode penilaian status kesuburan tanah berbasis kriteria FMSCP pada tanah-tanah tropis di Indonesia., Assessment of soil fertility status is important in agricultural development, especially to face the challenges of the food crisis and potential land degradation. This research examines the status of soil fertility on topose sequence transects in Sandai Subdistrict, Ketapang District, West Kalimantan. Soil samples taken from depths of 0-30 and 30-60 cm at seven observation points (TP1, TP2, TP3, TK1, TK2, TK3, and TK4) were then analyzed for cation exchange capacity (CEC), base saturation (BS), P2O5 extract HCl 25%, K2O extract HCl 25%, and organic carbon (C-organics) as well as exchangeable bases (Ca, Mg, and K). This analysis was supported by Principal Component Analysis (PCA) via R Studio statistical software. Soil fertility assessment is based on the Five Major Soil Chemical Properties (FMSCP), Basic Cation Saturation Ratio (BCSR) and Sufficiency Level of Available Nutrients (SLAN) criteria. Soil fertility status based on the FMSCP method ranges from very low (VL) to low (L). There is high variation in soil fertility status (deficient to excessive) based on the BCSR and SLAN criteria, which is closely related to the diversity of soil parent materials and slope. The soils at observation points TP1, TP2, and TP3 have deficiency to balance status, while TK1, TK2, TK3, and TK4 are dominated by balance to excess status using the BCSR method. National SLAN criteria indicate soil Ca, Mg and K have deficiency status. Deficiency status also exists only for element K based on international SLAN criteria. The results of this research recommend the implementation of a soil fertility status assessment method based on FMSCP criteria on tropical soils in Indonesia.
Keyword: BCSR, FMSCP, SLAN, soil fertility, toposequence

Judul: Evaluation of Soil Fertility Status Along the Hydrosequence Transect in North Musi Rawas Regency, South Sumatra using Three Different Methods
Abstrak: Kegiatan evaluasi status kesuburan tanah di Indonesia banyak difokuskan pada metode Five Major Soil Chemical Properties (FMSCP). Pendekatan lain seperti Basic Cation Saturation Ratio (BCSR) dan Sufficiency Level of Available Nutrients (SLAN) masih jarang dilakukan pada tanah-tanah tropika. Penelitian ini dilakukan untuk menilai status kesuburan tanah sepanjang transek hidrosekuen yang melewati tiga kecamatan (Karang Dapo, Rawas Ilir dan Nibung), Kabupaten Musi Rawas Utara, Sumatra Selatan berdasarkan metode FMSCP, BCSR dan SLAN serta menentukan metode standar dalam penilaian status kesuburan tanah pada tujuh titik pengamatan dari dua kedalaman (0-30 dan 30-60 cm) yang mewakili lokasi penelitian dan tanah-tanah tropika pada umumnya. Sifat kimia yang dianalisis diantaranya adalah Kapasitas Tukar Kation (KTK), Kejenuhan Basa (KB), P2O5 ekstrak HCl 25%, K2O ekstrak HCl 25%, C-organik dan basa-basa dapat ditukar (Ca, Mg dan K). Secara umum, hasil penilaian dari ketiga metode di atas mengindikasikan tanah di lokasi penelitian memiliki tingkat kesuburan yang rendah terutama pada kedalaman 0-30 cm. Analisis menggunakan metode BCSR dan SLAN secara berturut-turut menunjukkan kondisi dominan basa-basa dalam tanah di lokasi penelitian berada di bawah rasio ideal dan berada di bawah ambang batas ideal. Penelitian ini menyarankan penggunaan metode FMSCP sebagai metode standar dalam penilaian status kesuburan tanah., Soil fertility status evaluation activities in Indonesia are largely focused on the Five Major Soil Chemical Properties (FMSCP) method. Other approaches such as Basic Cation Saturation Ratio (BCSR) and Sufficiency Level of Available Nutrients (SLAN) are still rarely conducted on tropical soils. This research was conducted to assess the soil fertility status along a hydrosequence transect passing through three districts (Karang Dapo, Rawas Ilir, and Nibung), North Musi Rawas Regency, South Sumatra, based on the FMSCP, BCSR, and SLAN methods, and to determine the standard method in assessing soil fertility status at seven observation points from two depths (0-30 and 30-60 cm) representing the research location and tropical soils in general. The chemical properties analyzed include (Cation Exchange Capacity) CEC, (Base Saturations) BS, P2O5 extract HCl 25%, K2O extract HCl 25%, organic-C and exchangeable bases (Ca, Mg, and K). In general, the assessment results from the three methods above indicate that the soil at the research location has low fertility levels, especially at a depth of 0-30 cm. Analysis using BCSR and SLAN methods success indicates that the dominant base conditions in the soil at the research location are below the ideal ratio and below the ideal threshold. This study suggests the use of the FMSCP method as the standard method in assessing soil fertility status
Keyword: BCSR, FMSCP, hydrosequence, SLAN, soil fertility

Judul: Grup dan Homomorfisma Grup pada Rubik Revenge
Abstrak: Rubik cube is a kind of puzzle game. A player must arrange rubik sides, which have been disordered, back to the position where every side has the same colour. This paper does not focus on the settlement solution, but instead on proving the existence of a group homomorphism between rubik movement group and S96 symmetric permutation group in rubik revenge. Firstly, it has been proved that rubik movement set is a group. Then, it also has been proved that the M set, which contains numeric labels of 1 until 96 in cubinos sides, is S96 symmetric permutation group.
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