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The main constraint in the extensification of maize on the dry land of acid soil is the low availability of P in soil. This study aimed to determine the effect and the optimal dose of humic acid on the growth and yield of maize on acid soil. This research was conducted from February to May 2017 at Tri Dharma Field Laboratory, Faculty of Agriculture, Gadjah Mada University. Acid soil with low P availability used was from sub-district Cigudeg and Jasinga, West Java. The research was arranged in Randomized Complete Block Design (RCBD) with 2 factors. The first factor was maize cultivar, namely Bisi 2 and Pioneer 35. The second factor was the rate of humic acid and NPK fertilizer, consisting of 0 kg.ha-1 (without) NPK and 0% (without) humic acid, NPK + 0% (without) humic acid, NPK + 5% humic acid, NPK + 10% humic acid, and NPK + 15% humic acid. NPK fertilizer applied was NPK 16:16:16 at a dose of 350 kg.ha-1. The results showed that humic acid application on acid soil increased C-humic content in the soil, soil P availability, total dry weight of the plant, and kernel dry weight at harvest (15 weeks after planting). The increase in soil P availability did not improve the plant growth but increased the accumulation of plant biomass. The application of humic acid at 15% (52.5 kg.ha-1) combined with NPK fertilizer on acid soil significantly increased total dry weight of plant and kernel dry weight up to 13.14% and 21.81%, respectively, thus, it is recommended for maize cultivation on acid soil.

Kedelai (Glycine max) merupakan salah satu tanaman pangan yang dibudidayakan. Kebutuhan kedelai yang selalu meningkat setiap tahun mendorong usaha peningkatan terhadap produksi kedelai. Upaya peningkatan produksi dapat dilakukan dengan menggunakan pupuk hayati dan memanfaatkan lahan yang kurang produktif di Indonesia. Pupuk hayati yang digunakan mengandung isolat Bradyrhizobium japonicum sebagai penambat nitrogen dan Aeromonas salmonicida sebagai pelarut fosfat. Isolat yang terdapat dalam pupuk hayati diharapkan dapat membantu pertumbuhan kedelai di tanah asam dengan menyediakan unsur nitrogen dan fosfat. Penelitian ini bertujuan untuk mengetahui pengaruh pemberian pupuk hayati yang terdiri atas B. japonicum (BJ 11 wt) dan A. salmonicida pada penanaman kedelai di tanah asam. Tanaman percobaan dibuat dalam empat kelompok, yaitu dengan inokulasi Isolat BJ 11 (wt), PP, BJ 11 ditambah dengan PP, dan tanpa inokulasi (kontrol). Hasil penelitian menunjukkan bahwa aplikasi B. japonicum dan A. salmonicida cenderung dapat meningkatkan laju pertumbuhan tanaman, jumlah daun, dan bobot kering akar. Kata Kunci: Bradyrhizobium japonicum, Aeromonas salmonicid, Tanah Masam dan Kedelai Soybean (Glycine max) is one of cultivated food crops. Since the need of soybean is always increased every year, it needs some efforts to improve soybean production. One of the steps can be done is by using biofertilizer in a less productive land such as acid soil. Biofertilizer that used in this study consist of Bradyrhizobium japonicum as nitrogen fixation and Aeromonas salmonicida as phosphate solubilizer bacteria (PP). Isolates contained in the biological fertilizer is expected to help the growth of soybean in acid soils by providing elements of nitrogen and phosphate. The aim of this research was to know the effect of using biofertilizer consisted of B. japonicum (BJ 11 wt) and A. salmonicida (PP) to soybean growth in acid soils. The experiment was arranged with four group treatments that were inoculation with BJ 11 (wt), PP, BJ 11 plus PP, and without inoculation (as control). The results showed that the application of B. japonicum and A. salmonicida as inoculant mixture tend to increase plant growth, leaf number, and dry root weight. Keywords: Bradyrhizobium japonicum, Aeromonas salmonicid, Acid Soil and Soybean

Characteristic of Ultisol in PT. Great Giant Pineapple is very acidic soil and low of macro and micro nutrient content. This condition can be solved by liming so pineapple plant can growth optimally. There are many material of lime with different shape and size. The purpose of this study was to analyze calcium source with the right doses that can increase pH, provide nutrient available and decrease any toxic elements. This study used a completely randomized design with 18 treatments. The treatment included D0, C0, T0 (control), dolomite with 1, 2, 3, 4 and 5 t ha-1 doses (D1, D2, D3, D4, D5), Granular Calcite with doses of 100, 200, 300, 400, and 500 kg ha-1 (C1, C2, C3, C4, C5) and Suspension of Calcite with doses of 75, 100, 125, 150, 175 L ha-1 (T1, T2, T3, T4, T5). The results showed that application of calcium sources had significant effect on soil pH, Al saturation, Fe available, exchangeable-Ca, exchangeable-Mg, CEC, Base Saturation, available-P, total-N, and exchangeable-K in several time of observations. Application of 5 t dolomite ha-1 increased soil pH, and decreased Al saturation and available-Fe, and it also increased Ca and Mg contents. However, application of dolomite had no significant effects on N, available-P and exchangeable-K at several time of observations. The initial growth parameter was not significantly affected by application of dolomite.

Bumi Nabung district consists of 6 villages with a total area of 7,810 ha which are divided into 251 ha of rain fed rice lands, 4,908 ha of dry land, 1,317 ha of lowland, 1,158 ha of yards and 176 ha of others. Rumbia district consists of 14 villages which has a total area of 22,696 ha of land consisting of 2,728 ha of yards, 17,358 ha of dry land, 326 rainfed paddy field, 839 ha of swamp land, 1,470 ha of lowland and 4,232 ha of others. Bumi Nabung and Rumbia districts have a low soil fertility potential that is reflected by the lowof soil pH, CEC, total N, available P, and high level of exchangeable Al and Al saturation. The results assessment based on the physical and chemical characteristics showed that Bumi Nabung district have 5 villages on suitable class S-2 (North Bumi Nabung, East Bumi Nabung, Bumi Nabung Ilir, South Bumi Nabung, and Sri Kencono) and one village New Bumi Nabung has less suitable class S-3. In the Rumbia District, there were 14 villages belonged to suitable class (S-2), namely Reno Basuki, Rekso Binangun, Teluk Dalam Ilir, Rukti Basuki, Restu Baru, Restu Buana, Bina Karya Buana, Bina Karya Putra, Bina Karya Jaya, Bina Karya Utama, Bina Karya Sakti, Joharan, Rantau Jaya Ilir and Rantau Jaya Baru. Bumi Nabung and Rumbia districts have the potential fertility and land suitability for extensification and development of soybean crops. The main technology components to support this program are the use of ameliorant (dolomite and zeolite), the application of organic fertilizers (manure and compost) and inorganic fertilizers (NPK).