Judul: Pengaruh Pemberian Fosfat Alam Terhadap Perubahan Sifat Kimia Tanah, dan Kadar Hara Pada Tanaman Jagung (Zea mays)
Abstrak: The utilization of acid soil for agriculture faced several obstacles, including P deficient. It is because P ions sorbed by various soil components, such as Fe-Al ions, and Fe-Al hydrous oxides. One of the efforts made to overcome this problem is the use of natural phosphate in acid soils. This study aims to determine the effect of natural phosphate fertilizers in soil chemical properties and nutrients rate in plant of Latosol (Oxyc Dystrudept) Darmaga. Experimental design used in this study was a randomized design with a single factor, named P fertilizer. Source of P fertilizer used in this study is a natural phosphate and SP-36. Treatment dosage of P fertilizer are, control I (0%), control II (N + K), Std 100% (N+K+SP36), RP 50%, RP 100%, RP 150%, RP 200%, (N + K 50%) + RP 50%, and (N + K 50%) + RP 100%. The results showed that the phosphate fertilizer did not significantly affect soil pH, exchangeable-Al, available-P, exchangeable-Ca, and exchangeable-Mg. phosphate fertilizer have significantly affect only in exchangeable-K. Meanwhile, phosphate not significantly affect the rate of Mg, K, Ca, P and N. Rock phosphate’s application significantly affected the growth of maize on 4 week after planting (MST) and 6 MST. Rock phosphate’s application did differ significantly on increasing cob with husk’s weight and cob without husk’s weight. But rock phosphate’s application did not differ significantly on total weight of stover. The highest percent of crop value in treatment who give rock phosphate fertilizer there is in treatment of RP 150% with 158.1%, and the lowest percent of crop value there is in treatment of (N+K 50%) + RP 50% with 98.6%, and lowest in all treatment there in treatment of Control I with 74.7%. From result of crop value can get a conclusion that rock phosphate fertilizer is better than standard fertilizer (SP36).
Keyword: acid soil, maize, phosphate

Judul: Perbandingan Pengaruh Pupuk Fosfohumat dengan Superfosfat terhadap Pertumbuhan dan Produksi Jagung (Zea mays. L) dan Sifat Kimia Latosol Cimulang
Abstrak: In many countries, sustainable agriculture is almost improved and delevoped constantly to increase food availibility. One of the efford is using the fertilizer which derived from nature and modify them to increase the nutrient’s availibity for plants. One of the nature fertilizers is rock phosphate (RP). This study used Fosfohumic fertilizer. Fosfohumic is RP fertilizer that is mixed with humic acid solution. The purpose of this study was to determine the effect of fosfohumic fertilizer on growth and yield of maize and Cimulang latosols chemical properties, as well as its comparison with SP18 fertilizer. The result of the trial showed that P fertilizer significantly affect on the growth of maize. The height of maize of SP18 has the highest value compared to fosfohumic. The height of maize of FH2 is higher than FH0, but it was not significantly different. Fosfohumic fertilizer (FH0, FH1, FH2) application did not significantly affect on other variables such as the weight of the corn cobs and root, and nutrient uptake by plants. Fosfohumic fertilizer application did not significantly affect on the availability of P in soil. The effect of SP18 has the highest number of P availibility and nutrients uptake by plant compared to fosfohumat. The addition of humic acid could increase the growth of root and weight of corn cobs.
Keyword: SP18, fosfohumic, humic acid, rock phosphate

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