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Pemberian silikat diketahui dapat meningkatkan aktivitas antioksidan, stabilitas membran sel, dan kandungan klorofil meningkat sehingga dapat mengatasi cekaman panas. Penelitian ini bertujuan untuk mengetahui dosis silikon yang optimum terhadap pertumbuhan dan hasil tanaman gandum yang maksimum di dataran medium. Percobaan dilakukan sejak Maret hingga Agustus 2016 di Kebun Percobaan Fakultas Pertanian Universitas Padjadjaran, Jatinangor, dengan ketinggian tempat yaitu ± 750 m di atas permukaan laut. Rancangan percobaan adalah Rancangan Acak Kelompok, terdiri dari 7 perlakuan dosis pupuk silika yang diulang 3 kali. Perlakuan terdiri dari 0, 50, 100, 150, 200, 250, dan 300 kg ha-1. Perbedaan nilai rata-rata taraf diuji dengan Duncan Multiple Range Test pada taraf nyata 5%. Hasil penelitian menunjukkan bahwa pupuk silika berpengaruh terhadap pertumbuhan dan hasil tanaman dibandingkan tanpa pupuk silika, dilihat dari tinggi tanaman, jumlah anakan, persentase gabah isi, bobot 100 butir, bobot biji, dan kandungan gluten. Dosis pupuk silika yang paling baik bagi pertumbuhan dan hasil adalah 250 kg ha-1. Kata kunci: gandum,silikon, dataran medium

Mikroba pelarut fosfat (MPF) berperan penting dalam mobilisasi fosfor tanah dan selanjutnya memfasilitasi penyerapannya oleh akar tanaman. Penelitian rumah kaca telah dilakukan untuk mengetahui pengaruh mikroba pelarut fosfat dan pupuk P terhadap P tersedia, aktivitas fosfatase, populasi mikroba pelarut fosfat, dan konsentrasi P tanaman serta hasil tanaman padi gogo (Oryza sativa L.) yang ditanam pada Ultisols Jatinangor. Rancangan percobaan yang digunakan adalah Rancangan Acak Kelompok pola faktorial yang terdiri atas dua faktor yaitu jenis inokulan MPF dan dosis pupuk fosfat. Hasil penelitian menunjukkan bahwa tidak terdapat interaksi antara isolat mikroba pelarut fosfat dengan dosis pupuk P terhadap semua parameter penelitian. Namun inokulasi campuran Pseudomonas sp. dan Penicillium sp. mampu meningkatkan aktivitas fosfatase,  konsentrasi P tajuk hingga 19,23 % dan bobot gabah kering giling (GKG) padi gogo hingga 29,03 %. Aplikasi 75 kg P2O5 ha-1 mampu meningkatkan P tersedia hingga 20,66 % dan bobot GKG  hingga 15,23 % dibandingkan kontrol.

Soil is a very complex and dynamic system, consisting of the solid, liquid and gas. The solid parts of soil is made from minerals and organic materials (rough and smooth). Organic materials with smooth from is called humic acid. This product is a result from oxidation polimeritation of compounds like phenol, lignin and proteins from plants also from the metabolism of microorganism in the ground. In general, the composition of organic matter is dominated by humin with large, medium and lower of molecular weight. Humic acid has the composition of elements like carbon (40-80%), nitrogen (2-4%), sulfur (1-2%), phospor (0-0,3%) and also oxygen. Humic acid has unique characteristics compared with fulvic acid and humin. One of the most spesific character is the bonding to interact with metal ions, oxide, hydroxide, minerals, organic, and toxic materials.Key words: Adsorbtion, Characterization, Heavy metals, Humic Acid

Biofertilizer is a biological product that can be used to improve the soil fertility. It is useful in enriching soil with micro-organisms that produces organic nutrients and may also reduce the plant diseases. This experiment investigates the usefulness of biofertilizer which can increase the soil properties. This study was conducted at sugarcane plantation, Purwadadi Subang Bandung. The experiment was arranged in a Randomized Block Design (RBD) with 6 treatments and 4 replications. The treatments were (50; 25) g/treatment Biofertilizer + (¼; ½; ¾; 1) of the recommended dose of NPK and the recommended dose of NPK as a control. The chemical properties (potential K, K sorption, potential P, P sorption, total N and pH) were affected by biofertilizer application, except for N sorption. The best treatment from this product was combination from high level of biofertilizer (50 g) and (1/2 -1) of the recommended dose of NPK. The application of biofertilizer can substitute NPK fertilizer 25%-50% in soil. In general, this product has a good potency especially to increase some of soil chemical properties in a short time with simple application in the field.

No abstract

In recent years, the application of cow manure waste as an adsorbent of heavy metals in water and soil has increased. The analysis of the most effective adsorbents from cow manure as materials that can reduce heavy metals, while being low-cost and easy to produce, is important in the agricultural field. This study investigated adsorbents from cow manure, such as compost, biochar and humic acid, and analyzed the capability of the adsorption mechanisms of Cr, Pb and Cd. The experiments were performed as a function of pH, adsorbent dose, initial metal ion concentration, and contact time. To investigate the mechanism of the adsorption process, the Langmuir and Freundlich models were used. The results showed that the optimum conditions of Cr, Cd and Pb ions were achieved by compost, biochar and humic acid with 83–99% removal. An adsorption isotherm model for compost, biochar and humic acid generally followed the Langmuir and Freundlich models. This study ranks the different forms of cow manure waste in the following order based on their ease of production, high adsorption capacity, and low cost: biochar > compost > humic acid.

Humic and fulvic acids are important materials for the health of the soil. This is related to the capability of humic and fulvic acids as chelating agent for pollutant in soil. The relationship between humic and fulvic acids with that of the soil properties is an important aspect to determine the characteristics of soil. Furthermore, production of humic and fulvic acids is a time-consuming process with several stages. Regarding this problem, the selection of sample size to study humic and fulvic acids is important. The relationship between the soil properties was analysed using the Partial Least Square (PLS) analysis, which is regarded as a solution to solve the analysis of complicated problems by offering a powerful approach. This study aimed to analyse the relationship between humic and fulvic acids, in terms of their mineral and physicochemical properties using the PLS method. The study was carried out in West Java, Indonesia. The results showed that the relationship between the chemical, physical, mineral contents with humic and fulvic acids, affected the negative and positive aspects of the relationship. Humic acids had a weak to good model category (0.269-0.940) with regards to the soil properties, and fulvic acids had a moderate model category (0.495-0.603) against all soil properties. Thus, the PLS method can solve a problem in study relationship between the soil properties with small sample and can help in understanding the soil characteristics in general.