Judul: Pengaruh Dosis dan Waktu Pemupukan N terhadap Produktivitas Kedelai dengan Budidaya Jenuh Air pada Lahan Sawah
Abstrak: Penyebab rendahnya produksi dan produktivitas kedelai dalam negeri adalah teknik budidaya yang masih konvensional dan pengelolaannya masih berbiaya tinggi. Teknik budidaya jenuh air merupakan solusi untuk meningkatkan produksi dan produktivitas kedelai, budidaya jenuh air menggunakan olah tanah minimum dengan dosis pupuk yang berimbang dapat menurunkan modal awal petani. Penelitian ini bertujuan mengetahui pengaruh dosis dan waktu pemberian pupuk N terhadap produktivitas kedelai dengan budidaya jenuh air di lahan sawah. Penelitian ini dilakukan pada bulan Agustus hingga November 2020 di Kebun Percobaan Sawah Baru Institut Pertanian Bogor. Penelitian ini menggunakan rancangan kelompok lengkap teracak (RKLT) dua faktor yaitu dosis pupuk N (0 kg N ha-1, 25 kg N ha-1, 50 kg N ha-1, dan 75 kg N ha-1) dan waktu pemberian pupuk N (saat tanam, fase reproduktif, dan saat tanam + fase reproduktif) yang terdiri dari 12 satuan percobaan dan diulang sebanyak 3 kali. Hasil dari penelitian ini yaitu pada perlakuan dosis pupuk 75 kg N ha-1 yang diberikan saat awal tanam merupakan dosis pupuk yang direkomendasikan, perbedaan pemupukan nitrogen tidak memberikan respon signifikan terhadap beberapa parameter pengamatan, akan tetapi pemberian pupuk N saat awal tanam lebih baik jika dibandingkan dengan tanpa pemberian pupuk N., Domestic soybean production and productivity is low and cultivation techniques is conventional and use high costs. Saturated soil culture techniques are a solution to increase soybean production and productivity. Saturated soil culture using minimum tillage with a balanced fertilizer dose can reduce farmers' initial capital. This study aims to determine the effect of dose and time of N fertilizer application on soybean productivity under saturated soil culture in paddy fields. This research was conducted from August to November 2020 at the teaching farm IPB University, Sawah Baru Experimental Station. This study used a two-factor randomized complete group design (RKLT), the dose of N fertilizer (0 kg N ha-1, 25 kg N ha-1, 50 kg N ha-1, and 75 kg N ha-1) and the time of fertilizer application N (during planting, reproductive phase, and during planting + reproductive phase) which consists of 12 experimental units with three replications. The result of this research is that the 75 kg N ha-1 fertilizer dosage given at planting is the recommended dosage for N tertilizer. Differences in nitrogen fertilization did not provide a significant response to several observed parameters, however N fertilization at planting was better than without N fertilizer.
Keyword: Saturated Soil Culture, Rice fields, N fertilization, Productivity

Judul: Growth and Productivity of Soybean with Phosphate Fertilization Dose and Frequency on Saturated Soil Culture in Tidal Swamp
Abstrak: Konsumsi kedelai di Indonesia tahun 2020 mencapai 2,87 juta ton, sedangkan produksi nasional hanya 613.300 ton karena luas lahan kedelai menurun akibat persaingan komoditas dan perubahan lahan pertanian. Lahan pasang surut menjadi alternatif peningkatan areal pertanian menggunakan teknik budidaya jenuh air. Penelitian bertujuan mempelajari dosis dan frekuensi pemupukan P terhadap pertumbuhan dan produktivitas kedelai dengan budidaya jenuh air di lahan pasang surut. Penelitian menggunakan rancangan kelompok lengkap teracak faktorial dengan dua faktor dan tiga ulangan. Faktor pertama adalah dosis pupuk P terdiri atas: 36, 72, dan 108 kg P2O5 ha-1 (180, 360, dan 540 kg Fertiphos ha-1). Faktor kedua adalah frekuensi pemupukan P terdiri atas; pada saat tanam 0 hari setelah tanam (HST), 0 dan 30 HST, dan 0, 30, 60 HST. Perlakuan berbagai dosis pemupukan fosfat berpengaruh nyata terhadap peningkatan tinggi tanaman, jumlah cabang, jumlah daun, luas daun, bobot basah batang, bobot kering batang, bobot kering daun, jumlah polong isi, jumlah polong hampa, bobot biji ubinan, dan produktivitas. Perlakuan berbagai frekuensi pemupukan fosfat berpengaruh nyata terhadap peningkatan tinggi tanaman, jumlah cabang, jumlah bintil akar, jumlah polong isi, dan jumlah polong hampa. Dosis pupuk 108 kg P2O5 dan frekuensi pemupukan fosfat dengan tiga kali pemupkan pada 0, 30, dan 60 HST menjadi kombinasi terbaik untuk peningkatan produksi kedelai. Dosis pupuk 108 kg P2O5 ha-1 menghasilkan produksi kedelai tertinggi sebesar 2,60 ton ha-1., Indonesia's soybean consumption is estimated to reach 2.87 million tons in 2020. Meanwhile, the national production is only 613,300 tons as the soybean area is decreasing due to commodity competition and agricultural land changes. Tidal land is an alternative to increase agricultural area using water-saturated cultivation techniques. The research aimed to study the dose and frequency of P fertilization on the growth and productivity of soybean plants with water-saturated cultivation on tidal land. The study used a factorial randomized complete block design with two factors and three replications. The first factor was the dose of P fertilizer consisting of: 36, 72, and 108 kg P2O5 ha-1 (180, 360, and 540 kg Fertiphos ha-1). The second factor is the frequency of P fertilization consisting of; at planting 0 days after planting (DAP), 0 and 30 DAP, and 0, 30, and 60 DAP. The treatment of various doses of phosphate fertilization had a significant effect on increasing plant height, branch number, leaf number, leaf area, stem fresh weight, stem dry weight, leaf dry weight, number of filled pod number, number of empty pods, seed weight, and productivity. The treatment of various phosphate fertilization frequencies significantly increased plant height, number of branches, number of root nodules, number of filled pods, and number of empty pods. The fertilizer dose of 108 kg P2O5 ha-1 and phosphate fertilization frequency at 0, 30, and 60 DAP the best combination for increasing soybean production. The fertilizer dose of 108 kg P2O5 ha-1 resulted in the highest soybean seed yield as much as 2.60 tons ha-1.
Keyword: Fosfor, Lahan rawa, Varietas Demas 1, Phosphorus, swamplands

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology