Pengaruh Kalium dan Varietas Jagung terhadap Eksudat Asam Organik dari Akar, Serapan N, P, dan K Tanaman dan Produksi Brangkasan Jagung (Zea Mays L.)

Pot experiment was aimed to study effect of potassium (K) and variety on organic acid exudates from roots, plant N, P, and K uptakes, and plant dry weight. The experiment was conducted in the green house of Indonesian Soil Research Institute, Bogor using sand culture method. Factorial in Completely Randomized Block Design with three replications was used in this experiment. The first factor was K application, i.e. without K and application of 100 ppm K, and the second one was 10 varieties of maize, i.e. Antasena, Sukmaraga, CIMMIT 3330, Wisanggeni, Bisma, Lamuru, Pioneer-4, Pioneer-7, Pioneer-11, and Pioneer-21. The result showed that application of K significantly increased plant N and K uptakes. Among tested varieties, the N, P, and K uptake, as well as roots and dry weights of CIMMIT 3330 were the lowest, while those variables of Pioneer-7 were the highest. Among organic acid exudates, oxalic acid was the most dominant exudates exerted from roots, it was about 3.15 mg/g roots dry weight (DW) of Wisanggeni compared to 5.93 mg/g roots DW of CIMMIT 3330. Plant age significantly affected the exudates which was in the order of 4 weeks after planting (WAP) > 2 WAP > 6 WAP. Among tested varieties (Antasena, CIMMIT 3330, Wisanggeni, Lamuru, and Pioneer-21), CIMMIT 3330 was the most potential variety to increase availability of soil K in smectitic soils, thus increasing the efficiency of K fertilizer in the soils

Soil P Availability in Neutral and Alkaline Soils

The availability of soil P for plant growth depends on equilibrium reaction between several P forms in the soils, such as soil soluble, labile, non-labile, as well as organic P. The research that aimed to study soil P availability, form, and sorption, as well as soil properties that affect on P availability in neutral and alkaline soils was conducted in Soil Testing Laboratory, Indonesian Soil Research Institute using 91 topsoil samples (0-20 cm) which have pH neutral-alkaline taken from Java. The samplesconsisted of Inceptisols (13 samples), Vertisols (47 samples), and Alfisols (31 samples). Soil properties analyzed were soil pH H2O (1:5), clay content (pipette), organic-C (Kjeldahl), exch. Ca and Mg (NH4OAc 1 N pH=7), exch. Al (KCl 1 N), and P (HCl 25%, Olsen, and Bray I). Soil P fractionation and sorption were determined using Kuo (1996) and Fox and Kamprath (1970) procedures respectively. The result showed that according to HCl 25%, Olsen, and Bray I extractions, the availability of soil P among the soils was in order of Inceptisols > Vertisols > Alfisols. Whereas the soil P forms in tested soils was in order of residual-P > Ca-P > (Fe+Al)-P > organic-P. Buffering capacity, maximum sorption, as well as bonding energy constant of soil P was in order of Inceptisols > Vertisols > Alfisols. Furthermore, soil properties that effected significantly on the variables of soil P availability were soil clay content, organic-C, and exch. Mg in Inceptisols; clay content and organic-C in Vertisols; as well aspH, clay content, and exch. Ca in Alfisols

Residu Jerami Padi Untuk Meningkatkan Produktivitas Tanah Sulfat Masam Berkelanjutan

. Large amount of acid sulfate soil area both actual and potential acid sulfate soil in Indonesia is potential for agriculture development. Soil acidity, low nutrient availability, and iron toxicity are some constrains that often limit plant growth in the soils. Organic matter management is one of the important technologies to increase sustainable acid sulfate soil productivity. This paper discuses the potency of rice straw residues as a source of nutrients and ameliorant that are able to increase sustainable acid sulfate soil productivity. The use of rice straw residue is a very important role in increasing acid sulfate soil productivity because it could be a source of plant nutrients, improve efficiency of P fertilizer, and reduce Fe toxicity. The use of rice straw residues can increase rice production at acid sulfate soil. If the rice straw residue is combined with other component of technologies, such as the use of decomposer of trichoderma, planting rice variety that is resistant to iron toxicity (IR 66 and Margasari), and a the use of biofilter in the inlet canal, the rice production would be higher

Pengaruh Amelioran, Pupuk Dan Sistem Pengelolaan Tanah Sulfat Masam Terhadap Hasil Padi Dan Emisi Metana

. High yield and low methane emission are two goals in wetland management systems. The aim of this study was to evaluate the effects of biochar and compost on methane emission and yield of rice on acid sulphate soils. The research was conducted on acid sulfate soil in South Kalimantan using a split-split plot design. The main plot was two management regimes which were traditional (S1) and intensive (S2) managements. The sub plot was the NPK fertilization, namely: P1 = NPK 100%, and P2 = NPK 75% of the recommended rate of NPK. The recommendations rate of NPK fertilizers was (kg ha-1) 200 urea; 100 SP 36; and 100 KCl. Sub-sub plots were ameliorants: B0 = Without ameliorants, B1= Farmers\u27 practice, B2= Compost (a combination of ‘Straw\u27 Compost 30% + ‘Purun\u27 Compost 30% + ‘Cattle Manure\u27 Compost 40%), and B3 = Biochar of rice husk. The results showed that the highest methane emissions amounted to 30.40 kg ha-1 season-1 was resulted from S2P1B2 treatment, with the production index (yield/methane emission) of 82.8 and grain yield of 2.5 t ha-1. The highest grain yield of 3.4 t ha-1 was shown in the treatment S2P2B2 with the production index of 438.9 and methane emissions of 7.75 kg ha-1 season-1. The highest rice production index of 788.6 was obtained in the treatment without ameliorant and 100% NPK fertilization. This treatment gave grain yield of only 1.95 t ha-1 and the methane emissions of 2.47 kg ha-1 season-1. This research concluded that the objective of high yield is not synchronized with low methane emission and thus treatment S2P2B2 with the highest yield is remommended