Andisol Soil Research Articles

The effect of liquid organic fertilizer and phosphate solubilising bacteria Bacillus sp on potato growth (Solanum tuberosum) in andisol soil

Andisol is a soil type which has very strong characteristic of binding phosphate nutrients, because bound by allophone clay minerals which can retain P up to 97.8%. Therefore, P in the soil not available for plants, while the total P in the soil is high. The availability of P for plants can be done by giving organic material and phosphate solubilising microbes. The aim of study is to determine the effect of using liquid organic fertilizer (LOF) and phosphate solubilising bacteria (PSB) Bacillus sp on potato growth in andisol soil. The design used was a factorial randomized block design with three replications. The treatments are first factor the LOF concentration {0 (control), 40.80 and 120 ml L−1 water} and the second factor the PSB Bacillus sp type {without bacteria (control), Bacillus cereus, Bacillus pseudomycoides and Bacillus amyloliquefaciens}. The results showed that the application of LOF with dose 40-120 ml L−1 water could not increase the potatoes growth compared to control. Application of PSB can increase the height and diameter (1.00 - 6.35%) wet and dry weight (1.57 - 27.28%) of potatoes plants compared to control. The application of 40 ml L−1 water LOF and PSB Bacillus amyloliquefaciens increased the number of potato tillers 41.36% from the control.

Biofertilización con bacterias solubilizadoras de fósforo y hongos micorrízicos arbusculares en el cultivo de la papa

The present investigation evaluated biofertilization alternatives with the use of phosphorus-solubilizing bacteria and arbuscular mycorrhizal fungi, through the commercial products Fosfotic® and Safer Micorrizas®, respectively, in potato crop cv. Superchola, in Andisol soils from Carchi, Ecuador. The experiment was carried out under production conditions in an area of 360 m 2 , subdivided into six plots of 60 m 2 each (5 m wide x 12 m long), where six treatments corresponding to a fertilized control and different phosphorus doses plus inoculation with Fosfotic® and Safer Micorrizas®. The planting distance was 1 m between rows and 0.50 m between plants. Variables were evaluated: stem length, number of sprouted stems, total number of tubers per plant and their classification by size, as well as the total yield and size, in addition to performing an economic analysis of the treatments studied. The best results were obtained with 100 % of the fertilization based on NK+75 % P+Fosfotic®+Safer Micorrizas® and with 100 % of the fertilization based on NK+25 % P+Safer Micorrizas®; which also showed the highest economic benefits. These results demonstrate the feasibility of using these biofertilizers in the Carchi region, Ecuador.

Study of Sorption Kinetics and Sorption-Desorption Models to Assess the Transport Mechanisms of 2,4-Dichlorophenoxyacetic Acid on Volcanic Soils.

The sorption behavior of 2,4-dichlorophenoxyacetic acid (2,4-D) in the abundant agricultural volcanic ash-derived soils (VADS) is not well understood despite being widely used throughout the world, causing effects to the environment and human health. The environmental behavior and risk assessment of groundwater pollution by pesticides can be evaluated through kinetic models. This study evaluated the sorption kinetics and 2,4-D sorption–desorption in ten VADS through batch sorption experiments. Differences in the sorption extent for the fast and slow phases was observed through the model where 2,4-D sorption kinetics was controlled by external mass transfer and intra organic matter diffusion in Andisols ( ≠ 0). We confirmed from the spectroscopic analysis that the carboxylate group directly drives the interaction of 2,4-D on Andisol soil. The MLR model showed that , , and are important soil descriptors in the 2,4-D sorption in VADS. The Freundlich model accurately represented sorption equilibrium data in all cases ( values between 1.1 and 24.1 µg1−1/n mL1/ng−1) with comparatively higher sorption capacity on Andisols, where the highest hysteresis was observed in soils that presented the highest and lowest content ( close to 0).

Potential test of non-symbiotic nitrogen-fixing bacteria in increasing nitrogen in Andisol soil

Nitrogen (N) is one of the elements most needed by plants and widely distributed in nature. Nitrogen fixation can occur symbiotic or non-symbiotic by soil microbes. This research aimed to examine the potential of N-fixing microbes in increasing the availability of N in the soil. This research was conducted at the Soil Biology Laboratory of Faculty of Agriculture, Universitas Sumatera Utara. The results showed that the ability of microbes to increase the availability of N in the soil was varied. The population of N-fixing bacteria increased during 4 weeks of incubation. All bacterial isolates which incubated on Andisol soil were able to increase soil N-total content by around 9.4% -15.6%. The isolate with the most potential to increase soil N-total content was B6 isolate with an increase in total N content by 15.6%.

Isolation of potassium solubilizing bacteria in Andisol soil affected by the eruption of Sinabung

The Sinabung eruption emits smoke and volcanic ash which will decompose into the main soil material and turn into effect the structure of Andisol that will be formed. This study aims to find isolates of potassium solubilizing bacteria in several thicknesses of volcanic ash. The research was conducted at the Laboratory of Soil Biology, Agriculture Faculty, Universitas Sumatera Utara. Potassium solubilizing bacteria was isolated using medium Aleksandrov. The results showed that 7 isolates were found in different thickness, in the soil sample there was 1 isolate (K1), at a thickness of 1 - <2 cm 2 isolates (K2, K3) were found, at a thickness of 2-5 cm there were 2 isolates (K4, K5), and at >5cm there were 2 isolates (K6, K7).

Soil macrofauna diversity in andisol after eight years of Mount Sinabung eruption in Sumatra, Indonesia

Abstract. Sembiring M, Munawaroh H, Mukhlis, Hidayat B, Sabrina T. 2021. Soil macrofauna diversity in andisol after eight years of Mount Sinabung eruption in Sumatra, Indonesia. Biodiversitas 22: 3024-3030. The eruption of Mount Sinabung resulted in volcanic ash covering the soil of various thicknesses. That will affect the population and diversity of macrofauna in it. This research aimed to determine the Andisol soil macrofauna in Karo District with various thicknesses of volcanic ash covering from Mount Sinabung. This research was conducted in May 2019. Plots were placed in four locations, Location I: processed land (0 cm), Location II: Land covered by thin ash (?2 cm), Location III: Land covered by medium ash (2-5 cm), Location IV: Land covered by thick ash (?5 cm). Sampling was conducted by using the Pitfall trap, Monolith squared, and Hand sorting methods. The research results indicated that the thicker the volcanic ash covering the soil surface, it would reduce soil moisture, soil water content, organic C, and soil pH, but on the other hand, increase the soil temperature. A total of 20 species were able to live on the Andisols affected by the eruption of Mount Sinabung.

Pinhole Multistep Centrifuge Outflow Method for Estimating Unsaturated Hydraulic Properties with Small Volume Soil Samples

If soil hydraulic conductivity or water holding capacity could be measured with a small volume of samples, it would benefit international fields where researchers can only carry a limited amount of soils out of particular regions. We performed a pinhole multistep centrifuge outflow method on three types of soil, which included granite decomposed soil (Masa soil), volcanic ash soil (Andisol soil), and alluvial clayey soil (paddy soil). The experiment was conducted using 2 mL and 15 mL centrifuge tubes in which pinholes were created on the top and bottom for air intrusion and outflow, respectively. Water content was measured at 5, 15, and 30 min after applying the centrifuge to examine the equilibrium time. The results showed that pinhole drainage worked well for outflow, and 15 or 30 min was sufficient to obtain data for each step. Compared with equilibrium data, the retention curve was successfully optimized. Although the curve shape was similar, unsaturated hydraulic conductivities deviated largely, which implied that Ks caused convergence issues. When Ks was set as a measured constant, the unsaturated hydraulic properties converged well and gave excellent results. This method can provide soil hydraulic properties of regions where soil sampling is limited and lacks soil data.

The Effect of Adsorbent Composition: Quartz Sand/Andisol Soil/Zeolite/Activated Carbon Against Mn, Fe, BOD, and COD in Citarum River Eater Cleaning Progress

The results of the water quality monitoring by Perum Jasa Tirta II mentioned that water from the Cisanti outlet (upstream of the Citarum River) contained heavy metals that exceed the quality standard threshold. This study aimed to determine the effectiveness of heavy metal absorption with various absorbents, such as quartz sand, andisol soil, zeolite, and activated carbon in the Citarum River, West Java. The method that used in this work was refining silica and synthesized various combinations of quartz sand, andisol soil, zeolite, and activated carbon. The results showed that the composition of quartz sand/andisol soil/zeolite/activated carbon by 20/20/20/40 gave the best performance in the absorption. The studies of Fe, Mn, BOD, and COD revealed that the adsorption-treated water had met the parameters of PERMENKES RI number 32 of 2017. The variations of adsorbent composition did not affect the absorption of Mn and Fe metals content from water taken from the location before the dam and Citarum River 2, as indicated by statistical analysis. Although, for other locations, the variations of adsorbent composition impacted the reduction of Mn, Fe, BOD, and COD contents.

Liquid organic fertilizer and types of organic mulch toward photosynthesis translocation of green beans (Phaseolus vulgaris L.)

Green bean productivity is closely related to the accumulation of photosynthesis translocation. Organic base matter for fertilizer and mulch provide eco-friendly system to support plant productivity. Liquid organic fertilizer and types of organic mulch serve the optimum condition for growing environment of green beans. This study aimed to determine the concentrations of liquid organic fertilizer and types of organic mulch toward biomass addition in green beans. The experiment was conducted on Andisol soil in Cisalak, Subang West Java from January to March 2018. A factorial randomized block design was used to arrange the first factors (0 ml l−1, 1 ml l−1, 2 ml l−1, and 3 ml l−1 liquid organic fertilizer) and the second factors (without mulch, paddy straw mulch, and reeds mulch). The results obtain no interaction between liquid organic fertilizer and types of organic mulch for number pods per plant, pods weight per plant, dry stover weight, shoot root ratio and harvest index. Liquid organic fertilization in 2 ml and paddy straw mulch, independently, gave the best recommendation to increase green bean productivity.

Surface-applied or incorporated biochar and compost combination improves soil fertility, Chinese cabbage and papaya biomass

Many Hawaiian agricultural soils are acidic with low-nutrient retention; therefore, organic soil amendments are often used to improve soil properties and increase yields. Amendments can be incorporated for annual crops, but perennial orchards need surface application to avoid damaging surface roots. Pot trials compared responses to incorporated (IBC) or surface-applied (SBC) combination of hardwood biochar and chicken manure compost (4% v/v of each amendment) added to an Andisol and Oxisol. Soil pH was increased by 0.4–1.1 units in IBC and by 0.2–0.5 for SBC in the 0–10 cm soil layer. Both SBC and IBC increased soil total N, extractable P, Ca and Mg in the 0–10 cm soil layer. Soil pH, total C and extractable Ca were also higher in the 10–20 cm soil layer for IBC soil, indicating movement and/or leaching of amendments. Chinese cabbage biomass was 18–70% higher in the IBC and 14–47% higher in the SBC than that in the unamended soil, while papaya biomass was 23% and 19% higher in SBC and IBC, respectively. There was a greater response in the more acidic Andisol soil, with larger improvements in soil pH, plant nutrient uptake and root biomass than the Oxisol. Surface application was as effective in increasing plant growth as the incorporated amendment, providing evidence for farm scale assessment. Biochar and compost are recommended for use in tropical soils, and surface application may be beneficial to annual and perennial crops.

Integrated Use of Organic And Inorganic Fertilizers on Maize (Zea Mays L.) Yield and Soil Fertility in Andisols Soil of Sidama, Ethiopia

The study was carried out to determine the influence of organic and inorganic fertilizers on maize yield and soil fertility; to determine economically optimum organic and inorganic fertilizer combinations for maize production. The study was performed in a randomized complete block design consisting of 10 treatments and 3 replications. The treatments were: Control, 100% of R-NP (138 N and 92 P), 100% of vermicompost,100% of conventional compost, 25% R-NP+75% of vermicompost, 50% of R-NP+50% of vermicompost, 75% of R-NP+25% of from vermicompost, 25% of R-NP+75% of conventional compost, 50% of R-NP+50% of conventional-compost, 75% of R-NP+25% of conventional-compost. All rates of vermicompost and conventional compost were applied based on N equivalence. Results indicate that applications of inorganic fertilizers with a combination of organic source fertilizers were increases maize yield and yield components and improve the nutrient status of the soil. The highest maize grain yield (7494.3 kg ha-1) and above-ground biomass yield (18718.0 kg ha-1) were obtained from the applications of 50% recommended NP fertilizer plus 50% vermicompost which is based on the recommended N equivalent respectively. Similarly, we found that a combination of both inorganic and organic fertilizers application also is the best strategy to improve major soil nutrients, maintain soil fertility. The economic analysis revealed that the highest net benefit of (108,872.00 ETB ha-1) was obtained from the application of 50% recommended NP fertilizer plus 50% vermicompost based on the recommended N equivalence. Yet, the lowest yield and net benefit value were attained from the control or unfertilized plot. Therefore, this study suggests that an appropriate proportion of organic fertilizer with inorganic fertilizer not only for higher yield maize production with an assurance of potential economic returns to the small hold farmers but also improve and maintain the soil fertility and should be adopted with similar soil type and agro-ecologies.

Effect of soil conditioner enriched with biofertilizers to improve soil fertility and maize (Zea mays L.) growth on andisols Sinabung area

Andisol soil contains a lot of heavy metals Al and Fe, which results in P being unavailable to plants and can cause low soil pH, this will inhibit plant growth. One effort that can be made to increase the availability of nutrients in the soil is by utilizing soil enhancing ingredients enriched with biological fertilizers. The research design used was factorial randomized block design (RBD) consisting of: Factor I: (biological fertilizers) M0 = without application, M1 = Talaromyces pinophilus (Hedgecock), M2 = Azotobacter sp, M3 = Mycorrhizae, M4 = Talaromyces pinophilus + mycorrhizae + Azotobacter sp. Factor II Soil enhancing ingredients, namely P0 = Without Soil Improvement, K1 = Zeolite 50 g, K2 = Humic acid 50 ml, K3 = compost / manure fertilizer for agriculture 50 g. From the results the combination of microbial treatment and soil conditioner can increase nitrogen in the soil by 2-40.81 %, cation exchange capacity by 1.7-44.29 % and P available by 1.3-49.36 %. Soil conditioner combined with biological fertilizers can improve soil quality in general, the best treatment is a combination treatment of T. pinophilus + mycorrhizae + Azotobacter sp. with coffee skin (M4P4).

Effectiveness of Nitrification Inhibition through Addition of Local Litter to Corn Plants in Andisols

Nitrification is the oxidation process of NH4+ to NO3- microbially. The nitrification process can produce compounds in the form of NO3-, N2O, or NO which can cause environmental pollution through water, soil, or air, thus harming living things. The research was conducted to find ways to inhibit or control nitrification effectively and sustainably. The experiment was carried out in a plastic greenhouse located in Plesungan, Karanganyar until the maximum vegetative planting period of corn around May-June using a completely randomized design three replications. Andisols soil media was taken from Tegalrejo Village, Tengaran District, Semarang Regency 07&amp;ordm;25&amp;#39;28.3 &amp;#39;&amp;#39; LS and 110&amp;ordm;31 &amp;#39;35.7 &amp;#39;&amp;#39; BT with an altitude of 760 meters above sea level. There are 5 treatments, one control, four are natural inhibitor treatments in the form of litter addition. The litter used was Gliricidia maculate, Albizzia falcataria, Senna siamea, and Tithonia diversifolia. Statistical analysis showed that treatment just significantly affect NO2- concentrations (potential nitrification), not significantly affect NH4+, NO3- concentrations, and efficiency utilization of N. However, measurement results in the laboratory and field showed that the addition of local litter could inhibit nitrification, which was demonstrated through the efficiency of N utilization. Tithonia diversifolia because it has the highest average N utilization efficiency of 25.79%, 58.71% more efficient than control treatments. Also followed by plant growth results showed that the root&amp;rsquo;s dry weight and canopy&amp;rsquo;s dry weight positively correlated with NH4+ concentrations and efficient utilization of N, also canopy&amp;rsquo;s dry weight negatively correlated with NO2- concentrations (potential nitrification). The highest results occurred in the Tithonia diversifolia treatment.

Antagonistic Activity of Chilean Strains of Pseudomonas protegens Against Fungi Causing Crown and Root Rot of Wheat (Triticum aestivum L.).

Seed treatments with antagonistic bacteria could reduce the severity of crown and root rot diseases in wheat crops. The objective of this study was to evaluate the potential antagonistic activity of a bacterial consortium of three Chilean strains of Pseudomonas protegens against the wheat crown and root rot pathogens Gaeumannomyces graminis var. tritici, Rhizoctonia cerealis, and Fusarium culmorum. Two field experiments were carried out on artificially infested soil during two consecutive seasons (2016–2017 and 2017–2018) in an Andisol soil of southern Chile. Control treatments (not inoculated with fungi) were also included. Each treatment included a seed treatment of spring wheat cv. Pantera-INIA with and without the bacterial consortium. Both phytosanitary damage (incidence and severity) and agronomic components were evaluated. Bacterial populations with the phlD+ gene in the wheat plant rhizosphere during anthesis state (Z6) were also quantified. In both seasons, infection severity decreased by an average of 16.8% in seeds treated with P. protegens consortium, while yield components such as spikes m−1 and number of grains per spike increased. The use of antagonistic bacteria resulted in a total yield increase only during the first experimental season (P < 0.05). In general, accumulated rainfall influenced the antagonistic effect of the consortium of P. protegens strains, accounting for the differences observed between the two seasons. The results suggest that this P. protegens consortium applied on seeds can promote plant growth and protect wheat crops against crown and root rot pathogens in Southern Chile under field conditions.

Effect of humic acid on the growth and yield of two maize (Zea mays L.) cultivars on andisol

One way to improve maize (Zea mays L.) production is through land extension using Andisol land. However, andisol soil has phosphate (P) fixation problem due to the high amorphous material. Hence, the use of organic material in the form of humic acid that has greater affinity to amorphous minerals is recommended to solve the problem. This research was conducted in February-May 2017 at Tri Dharma field of Faculty of Agriculture, Gadjah Mada University. The Andisol land used has a low available P category from Datar, West Java and Wonosobo, Central Java. This research was arranged in a Randomized Complete Block Design (RCBD), consisting of 2 factors. The first factor was maize cultivar (Bisi-2 and Pioneer-35). The second factor was the doses of humic acid, consisting of control treatment (without fertilizer and humic acid), NPK without humic acid, and NPK + humic acid at 5%, 10%, and 15%. The percentage of humic acid given, based on the amount of NPK 16:16:16 fertilizer, was 350 kg ha-1. Fertilization was applied 3 times 100 kg ha-1 on 1 WAP, 150 kg ha-1 at 3 WAP and 100 kg ha-1 at 7 WAP. The results is, humic acid treatment had the same effect with NPK fertilization treatment only and control on P available Andisol soil. Humic acid, also has the same effect with NPK fertilizer treatment in increasing the yield component of 100 seeds weight, dry weight of seeds, harvest index, length of cobs and productivity.

Place exposure pattern toward landslide disaster due to heavy rainfall in Probolinggo District, East Java

Landslide is the third largest disaster occurred in Indonesia, including in Probolinggo District. Analyzing the place exposure patterns toward landslide disaster due to heavy rainfall, which triggering the landslide in Probolinggo District is the purpose of this study. Daily rainfall data in 1990–2015 were used to obtain the frequency of heavy rainfall regions (> 50 mm/day, > 100 mm/three days and > 150mm/five days) using the interpolation method based on Thiessen Polygon. The potential landslide region was obtained by using SINMAP models, which was verified by the landslide location data from 2015 to 2016. Descriptive spatial analysis using the overlay technique showed that 50.30 % (85,358 Ha) area in Probolinggo District has the potential of the landslide, especially in Sub District Krucil, Andisol Soil region, the slopes of 15–40 % region, and the rainfall of 1500–2000 mm/year region. The place exposure patterns toward landslide disaster due to heavy rainfall in Probolinggo district is in the region which has the higher potential of landslides, and heavy rainfall frequency, the level of place exposure to landslides disaster due to heavy rainfall will be higher.

Isolation of non-symbiotic Nitrogen-fixing bacteria on andisol land affected by Sinabung eruption

Andisol soils affected by the eruption of Mount Sinabung have different levels of ash thickness, each thickness has a different microbial activity and nutrient status. The aim of this research was to find non-symbiotic nitrogen-fixing bacteria isolates in several volcanic ash thicknesses. This research was conducted at the Soil Biology Laboratory, Faculty of Agriculture, University of Sumatera Utara. Isolation of non-symbiotic nitrogen-fixing bacteria was carried out using a nitrogen-free growth medium, Jensen medium. The results indicated that 7 bacterial isolates were able to grow on nitrogen-free medium, these isolates had different shapes (B1- B7). In the land which is not covered with ash there are 2 isolates, in the soil covered in thin ash (<2 cm) there are 2 isolates, in the soil covered in medium ash (2-5 cm) there are 2 isolates and in the soil covered in thick ash (> 5 cm) there are 1 bacterial isolate.

The Effect of Varieties on Growth and Yield of Chili (Capsicum annum L.) in Andisol Soil Aceh Besar

This research aims to determine the effect of varieties on the growth and yield of chili plants on the Andisol soil. This research was carried out at Lon Baroh, Lembah Seulawah District Aceh Besar, greenhouse and laboratory of plant physiology, Faculty of Agriculture of Syiah Kuala University, Darussalam, Banda Aceh from November to March 2019. The analysis of data used in this study was Randomized Block Design – non Factorial with 3 replications. There are 2 series of this research, Serie A and Series B. Serie A is used to collect data on growth and yield of chili plants and Serie B is used to collect data on mycorrhizal infection. The factors observed in this research were varieties. Varieties used are Lado F1 and Perintis. The result of this research showed varieties of chili plants highly significant take effect on plant height 15, 30 and 45 DAP, stem diameter 30 and 40 DAP, productive branch numbers, plant fresh weight, plant dry weight, fruit weight, fruit length, fruit number and yield potential and significantly affect on stem diameter 45 DAP, root fresh weight, and root dry weight. The best growth and yield of chili plants is found in Lado F1 varieties.

The effect of mychorrizal dose interactions with varieties on growth and yield of chili (Capsicum annum L.) in andisol soil Bener Meriah

This study aims to determine the interaction of mycorrhizal doses and varieties on the growth and yield of chili plants in Andisol soil. This research was conducted in Blang Kucak Village, Wih Pesam District, Bener Meriah Regency, Green House and Laboratory of Plant Physiology, Faculty of Agriculture, Syiah Kuala Darussalam University, Banda Aceh from January to May 2019. Analysis of the data used in this study was Randomized Block Design, with 3 x 2 factorial pattern with 3 replications. There are 2 series in this experiment namely Series A and Series B, series A is used for data collection of growth and yield of chili plants, while series B is used for data collection of mycorrhizal colonization. The factors observed in this study were mixed mycorrhizal bio-fertilizers and varieties. The dose of mycorrhizal bio-fertilizer used was control (without mycorrhizal), 5 g plant−1 and 10 g plant−1 and the varieties used were varieties of PM-999 and Perintis. The results showed a very significant interaction between mycorrhizal doses and varieties on the parameters of the number of productive branches, besides that there were significant interactions on plant height at 45 DAP, fruit weight, fruit length, number of fruits and yield potential (tons ha−1). The best combination was found in the treatment of doses of 10 g mycorrhizal plants−1 and Perintis varieties.

Determination of the Best Potassium Extraction Method for Tomato (Solanum lycopersicum L.) on Andisols

Penetapan rekomendasi dosis kalium (K) berdasarkan uji tanah untuk tanaman tomat pada tanah Andisol belum banyak dikaji di Indonesia. Penelitian diawali dengan pembuatan status hara K tanah di Kebun Percobaan IPB Pasirsarongge Cianjur dilanjutkan dengan uji korelasi di rumah plastik PKHT IPB Tajur Bogor pada Desember 2015 sampai Mei 2016. Tujuan penelitian adalah menetapkan metode ekstraksi K terbaik bagi tanaman tomat di tanah Andisol. Status K tanah dibuat dengan larutan kalium sulfat (K2SO4) sebesar 0, ¼X, ½X, ¾X, dan X dimana X adalah 413.4 kg K ha-1 sebagai dosis K maksimum yang ditambahkan untuk mencapai kadar K maksimum dalam larutan tanah. Larutan K2SO4 disiram merata pada bedengan tanah dan diinkubasi selama 4 bulan. Ekstraksi K tanah menggunakan 5 metode yaitu: Bray 1 (HCl 5N), HCl 25%, Morgan Wolf (NaC2H3O2.3H2O), Mechlich (HCl 0.05N + H2SO4 0.025N) dan NH4OAc (NH4OAc, pH 7). Hasil penelitian menunjukkan adanya perbedaan respon tinggi tanaman, bobot kering biomas, kandungan K tanaman terhadap tingkat status hara K tanah. Pola respon kuadratik ditunjukkan pada tinggi tanaman umur 6 dan 7 minggu setelah tanam, dan bobot kering total. Metode ekstraksi K Andisols terbaik untuk tomat adalah NH4OAc dengan nilai koefisien korelasi (r): 0.75.&#x0D; Kata kunci: biomas, K2SO4, metode ekstraksi, NH4Oac, status K