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The accumulation of microplastics (MPs) in agricultural land may threaten food security and farmers' health, which is of interest. This study examined the implication of MPs contamination/pollution on the chemical properties of an Inceptisol on different slopes in the horticultural production center of Banuhampu Subdistrict, Agam District, West Sumatra Province. The soil samples were determined by purposive random sampling with a quantitative survey method. Sample testing was carried out using a randomized completely block design with five treatments, i.e., 25-45% in forests, and 0-8%, 8-15%, 15-25%, and 25-45% in fields at a depth of 0-20 cm. The Inceptisol contaminated with MPs has the following characteristics: pH = 5.01, EC = 0.09 dS m-1, Eh = 92.97 mV, mineral = 68.81%, OM = 31.19%, CEC = 60.67 cmol(+) kg-1, C = 2.13%, N = 0.81%, P2O5 = 6.46 ppm, K = 0.48, Ca = 1.59 cmol(+) kg-1, Mg = 0.62 cmol(+) kg-1 , and SO4 = 98.98 ppm. The concentration of MPs on the Inceptisol was 438.33 particles kg-1 with filament shape, transparent color, and large size (1-5 mm) were the most commonly found. Polymer types included polyamide 6, polystyrene, and polyethylene. The effect of slope level on the surface change charger of Inceptisols contaminated with MPs was insignificant. However, the effect was significant in OC, total N, K-exch, and available S. The implications of microplastic contamination/pollution did not have a significant relationship with the chemical properties of the soil. However, it has a negative relationship to redox potential (Eh), mineral composition, and Ca-exch.

This study aims to compare the soil quality indexing model by adding and weighting the soil under different land uses and slope positions on the southwest slope of Mount Merapi, Indonesia. Soil sampling was carried out based on a landscape analysis divided into four geomorphological units (slopes): upper, middle, lower and foot slopes. The research design was nested where the soil sample was located (surface soil 0-30 cm). Based on the research results, soil quality indices (SQI) of forest on the upper slopes is very high. SQI of dry fields on the middle, lower and foot slopes is low to medium. SQI of mixed gardens on the middle and lower slopes is low to medium. SQI of snake fruit land on the middle, lower and foot slopes is medium to high. SQI of grassland on the lower slopes is medium to high, and SQI of paddy fields on the foot slopes is medium to high. Weighted soil quality index (SQIw) has a higher correlation (R2 = 0.90) and can predict soil quality better than the adding soil quality index (SQIa) model (R2 = 0.76). Indicators that most influence soil quality are the percentage of sand, total N, C-POM, C-Min, pH, and aggregate stability, that indicators are entirely influenced by organic matter, site-specific management to maintain SQI by maintaining organic matter. The selected indicators in this study can be used to determine the SQI in similar areas.

Edamame soybean (Glycine max (L.) Merr.) cultivation in phosphorus-limited Andisols presents a formidable challenge due to restricted phosphorus availability despite high phosphorus retention. Unlocking the full potential of this crop demands innovative solutions. This study delves into the transformative effects of biochar and phosphorus fertilizer, individually and synergistically, on edamame soybean growth in Andisols. Employing a randomized complete block design, researchers investigate three types of biochar (B0: control, B1: biochar pellets, B2: biochar powder) and four phosphorus fertilizer rates (P0: control, P1: 27 kg ha-1 P2O5, P2: 54 kg ha-1 P2O5, P3: 81 kg ha-1 P2O5). The bamboo-derived biochar was produced using the Kon-tiki method at ±500 °C. The study reveals no significant interaction between biochar and phosphorus fertilizer. Individually, treatments with B1, B2, and phosphorus fertilizers significantly enhance ammonium, nitrate, and phosphorus availability compared to B0 and P0. Biochar-induced modifications improve phosphorus and nitrogen absorption by roots, resulting in increased shoot dry weight and the root/shoot ratio. However, the number of leaves is solely influenced by phosphorus fertilizer treatment. Additionally, both biochar and phosphorus fertilizers contribute to nitrate reductase activity, root volume, an increased number of pods per plant and higher protein content in edamame soybeans. B2 outperforms B1 and high P3 intensifies this effect, improving nutrient uptake and yield. In summary, biochar and phosphorus fertilizers demonstrate significant potential to revolutionize edamame soybean cultivation in phosphorus-limited Andisols, optimizing pod number per plant and enhancing quality with elevated protein content.

The type of vegetation and soil organic matter affect the carbon fraction, nitrogen fraction and soil carbon stocks that contribute to the global carbon cycle. Therefore, the calculation of the composition of the fractions in different land covers is very important as a potential indicator of the effect of land management practices on soil organic carbon dynamics and supports the reduction of carbon dioxide (CO2) and soil carbon storage. This research aimed to determine the composition of the carbon fraction, nitrogen fraction and soil carbon stock in different land cover. There were six types of land cover with vegetations of 10-year-old bamboo, 30-year-old bamboo, 50-year-old bamboo, bulrush, a mixture of brushwood and bulrush, and a mixture of Albizia falcataria and brushwood, each of which was sampled three times. Soil samples were used to determine microbial biomass, particulate organic, humic acid, fulvic acid and soil carbon stock. The six land cover types showed significant differences in all fractions and soil carbon stocks. Fifty-year-old bamboo vegetation has the highest carbon storage of 0.029 g g-1 soil. The stable carbon fraction, in the form of humic acid and fulvic acid, in 50-year-old bamboo vegetation is more excellent than that in other vegetation. This study shows that 50-year-old bamboo vegetation has the potential to sequester carbon and store carbon in forms that decompose slowly, namely humic acid and fulvic acid, in the soil for a longer period.

Nitrogen dynamics in soil produce N2O emissions. To decrease N2O emissions and conserve N, recent studies have focused on chemicals derived from root exudates that inhibit nitrification. However, selective plant breeding could be used to control nitrification activity in soil instead of fertilisers or synthetic nitrification inhibitors. In this study, we investigated the relationship between nitrification rates (NR) and related N dynamics and plant characteristics for 11 maize varieties with varying levels of nitrification inhibition (NI) compared to Brachicaria humidicola (Bh) as the positive control. In a greenhouse experiment, soil concentrations of NI, NR, NH4+-N, and NO3--N and nitrogen uptake by plants were measured. Six maize varieties had a 1.1-1.6 times lower NR than Bh. Low-NR varieties had higher NI and lower root-to-shoot ratios. NI was positively correlated with total N and shoot N content but not with cumulative N2O and NH4+-NO3-. These results show that maize has the capacity to reduce soil nitrification while increasing the total N in the soil and shoot N content in maize.

This study investigates the impact of boron fertilizer on physiological activities of cocoa trees, specifically focusing on boron content, nitrogen content, nitrate reductase activity, chlorophyll content, and photosynthesis rate in cocoa plant leaves. This research was arranged in a randomized complete block design with two treatment factors, which were the type of boron fertilizer application (soil and foliar fertilizer), and the dose of boron fertilizer (1.5, 3, 4.5, and 6 g plant−1 with 0 g plant−1 as a control). Data were then analyzed for variance differences (ANOVA) with α = 5%, followed by the Tukey test, and contrast orthogonal for comparing treated and control plants. The results showed that the dose of boron fertilizer and the type of fertilizer application used have a significant effect on the physiological activity of the cocoa plant. The dose of boron with soil application affects physiological activity in a linear pattern where each additional dose of boron will increase the activity of nitrate reductase, chlorophyll content, and photosynthetic rate. The dose of boron with foliar application affects physiological activity in a quadratic pattern, where the dose of boron in the range of 3 g plant−1 is the optimum dose that gives maximum results on nitrate reductase activity, chlorophyll content, and photosynthetic rate in the cocoa leaves. Therefore, it is considered that the application of boron fertilizer at a dose of 3 g plants−1 with the foliar application is more efficient in increasing physiological activity compared to the dose of boron with soil application.

Biji kakao merupakan bahan utama pembuatan berbagai produk makanan, minuman dan obat obatan, hal tersebut menyebabkan permintaan kakao terus meningkat. Namun demikian peningkatan kebutuhan tersebut tidak diimbangi dengan peningkatan produksi di tingkat produsen. Indonesia sebagai salah satu produsen terbesar kakao dunia justru mengalami penurunan produksi dan kualitas akibatnya volume eksport terus mengalami penyusutan. Salah satu penyebab rendahnya produksi dan kualitas biji adalah kesuburan tanah. tanaman kakao merupakan tanaman yang sangat peka terhadap ketersediaan unsur hara. Berdasarkan hal tersebut maka tujuan dari penelitian ini adalah untuk mengetahui pengaruh status kesuburan tanah terhadap produksi dan kualitas biji beberapa klon kakao. Penelitian ini dilaksanakan pada Bulan June 2017 sampai bulan Oktober 2018 bertempat Di kebun kakao milik PT Pagilaran Unit Segayung Utara yang berlokasi di Desa Simbangjati, Tulis Kabupaten Batang Jawa Tengah. Penelitian dirancang menggunakan rancangan tersarang (Nested Design) dengan tiga klon (RCC 70, RCC 71 dan KKM 22) bersarang pada dua Status kesuburan tanah. Status kesuburan tanah didasarkan pada level ketersediaan unsur hara N,P,K dan B. Paramemeter yang diamati adalah karakteristik tanah, karakter fisiologis yang meliputi kadar klorofil daun, Laju fotosintesis, kandungan CO2 daun, kandungan H2O daun, Laju transpirasi dan Lebar bukaan Stomata, Komponen hasil meliputi berat biji perbuah, jumlah biji perbuah, berat biji perpohon, jumlah buah perpohon dan produksi per hektar. Serta komponen kualitas yang meliputi kadar lemak, kadar protein dan bean count. Hasil menunjukkan bahwa status kesuburan tanah tinggi memperlihatkan kadar klorofil, laju fosintesis , kadar CO2 dan H2O daun lebih tinggi yang menyebabkan produksi dan mutu biji (bean count dan kadar lemak) lebih tinggi.

One of the indicators of land productivity assessment is soil fertility. The causes of infertile soil have been widely reported. This study aimed to evaluate soil fertility using the Soil Fertility Capability Classification (SFCC) approach and to determine the relationship between soil morphological and physiochemical properties and soil fertility. The research was conducted in North Galela Sub-district, North Halmahera Regency. The research framework began with the interpretation of thematic maps, surveys, field observations, and the making of soil fertility evaluation maps. Soil sampling was carried out based on the stratified random sampling method and supported by laboratory measurements according to USDA international standards. The research result showed that the research area had 14 soil fertility statuses. The fertility classes having the most significant limiting factor were loamy texture (Ø15% rock outcrop, moderate salinity (0.2-0,4 mS cm-1), Na saturation >15%, and a rather steep slope (14%) with Lithic Eutrudepts type. Both of these classes have a top layer texture, and the bottom layer contains clay

Biochar quality is influenced by the type of its raw material and pyrolysis temperature. Nevertheless, the quality criteria of biochar as a nutrient carrier remain unanswered. This study aimed to find the chemical properties, micromorphology, and optimum pyrolysis temperature from various agricultural wastes to obtain good biochar as a nutrient carrier. This experiment was conducted at three level temperatures: 400, 500, and 600°C, and the raw materials were coconut shells, oil palm shells, and corn stalks. The chemical and physical properties of biochar were: pH-H2O, OC, CEC, total N, P, K, Mg, Ca, and Na, ash, functional groups, amorphous carbon, morphology, and SSA. The results show that the coconut shells and oil palm shells biochars contained high levels of N-total and the chain-C aromatic, and the pore structure was solid and regular. Corn stalks biochar containing ash is high, and C-aromatic is low and fragile. Increased temperature of pyrolysis produced well-crystallized minerals. It is concluded that 500°C is the optimum temperature for oil palm shells pyrolysis resulting in biochar with the highest C-aromatic structure and arrangement of pores which are strong, regular and uniform, and high stability, but the nutrient content was low.

Phosphorous (P) is strongly adsorbed by soil components, such as soil organic matter and soil amorphous minerals in Andisols, which have been identified as an influential factor in adsorption and release of soil P. The aim of this study was to characterize the pattern of soil P adsorption and release in both organic and conventional vegetable farming systems in Merbabu Mountain area, Indonesia. Soil samples were collected from soil layers (0 cm to 20 cm and 20 cm to 40 cm) in organic and conventional farming systems. The result showed that the highest adsorption rate was found in organic farming systems at a depth of 20 cm to 40 cm. The lowest adsorption rate was found in conventional farming systems with low input of organic matter at a depth of 20 cm to 40 cm. A higher rate of P release was also found in organic farming systems with a low input of organic matter. It can be concluded that vegetable soils in organic farming systems are not only highly capable of adsorbing P but also capable of releasing P rapidly.

The nitrogen use efficiency (NUE) of maize is usually below 60%. Considering future food supply and climate change, selective breeding of maize with high nitrogen (N)-efficient varieties, covering genetic diversities, is an effective strategy for identifying specific elements for controlling NUE and productivity per arable farming unit while reducing environmental damage. This study evaluated the yield and nitrous oxide (N2O) emission of 30 maize varieties under two different N doses of 57.5 kg N ha−1 (N1, N-sufficient) and 173 kg N ha−1 (N3, N-high) applied in two equal splits on 2 and 4 weeks after germination (WAG). Then, the tested maize varieties were categorized into four groups based on the grain yield and cumulative N2O, that is, efficient-efficient (EE) under both N1 and N3, high-N efficient (HNE) under N3 only, low-N efficient (LNE) under N1 only, and nonefficient-nonefficient (NN) under neither N1 nor N3. Maize yield was significantly positively correlated with shoot biomass, N-accumulation, and kernel-number under N1 and with N2O-flux at 5 WAG, NH4+, shoot biomass, and all of yield components under N3, whereas cumulative N2O showed a significant positive correlation with NO3− under N3 only and with N2O flux at 3 WAG under both N levels. The EE generally showed higher grain yield, yield components, N-accumulation, dry matter accumulation, root volume, and NH4+ in soil and lower cumulative N2O and NO3− in soil relative to NN maize varieties. The EE variety groups of maize can be a feasible strategy for increasing N fertilizer efficiency without reducing maize production as well as decrease the negative impact of N lost in agricultural system.

Appropriate weeds control is needed against weeds constraints in field, especially the organic field. With the appropriate management, weeding would benefit the organic field not only in reducing weeds but also in increasing nitrogen (N) availability in organic rice fields. This research aims to observe soil available N changes affected by weeding frequencies in organic paddy fields. Treatments applied were five weeding frequencies (WF) such as 0 WF, 2 WF, 4 WF, 6 WF, and 8 WF, to study the effect of various weeding frequencies on soil total N and available N ( NH4+ and NO3–) in the organic rice field. The soil in the conventional field was analyzed as a comparison to organic field soil. The results showed that soil C and N contents are similar in all treatments. Meanwhile, 6 WF performed the highest soil NH4+ among organic plots (10.36 mg N kg–1) and 8 WF enhanced soil NO3– to the highest average among all plots (10.12 mg N kg–1). The treatment of 6 WF and 8 WF also maintain the increase of soil NH4+ to 51 days after transplanting (DAT), meanwhile 0 WF, 2 WF, and 4 WF decreased after 40 DAT. Water samples from fields inlet-outlet and river showed that NH4+ content found in water sample was higher than NO3–. We concluded that the more frequencies of weeding applied to organic fields potentially preserved soil inorganic N longer, which is very important in supporting rice growth.

Potato self-sufficiency in Indonesia faces three main problems: rising air temperatures, limited availability of low-temperature land suitable for potato cultivation, and lack of high-temperature tolerant potato varieties. Therefore, it is necessary to identify the tolerance of potato variety to high-temperature. This research was conducted in two locations: the optimum temperature location and the high-temperature location, using nine varieties, are Agria, Andina, Amabile, Cingkariang, Granola L, Granola K, Margahayu, Olympus, and Tedjo-MZ. The study design uses a split plot with three replications. Differences in temperature as the main plot and varieties as subplots. Parameters observed were air temperature, growth, and yield of potato tubers. The analysis carried out were the Stress Sensitivity Index (SSI), Stress Tolerance Index (STI), Yield Stability Index (YSI), and Cluster Analysis. The results showed that there were no tolerant to high-temperature varieties. Based on the STI, only Olympus was a medium tolerant of high temperatures. Based on the Stress Sensitivity Index (SSI), four varieties are moderately susceptible to high temperatures (Olympus, Andina, Cingkariang, and Margahayu). The YSI analysis shows the same results as the SSI. The cluster analysis results showed harmony between the results of the stress index analysis and cluster analysis. Nine varieties had a high similarity (87.3%), meaning that all varieties had the same characteristics and less tolerance to high temperatures. Olympus was the more tolerant variety to high temperatures, followed by Andina, Cingkariang, and Margahayu. The four varieties consider promising potato lines in high-temperature areas.

The expansive ability of soil causes a series of problems in various sectors. The dominance of smectite clay minerals significantly affects expansive ability because they have an unstable interlayer structure. Cation intercalation and calcination is a treatment method that can increase the stability of the clay interlayer structure. This research investigated the effects of intercalation cations and calcination treatment on the swelling ability and cracking properties in the clay from vertisols; the cations used for intercalation were aluminum and iron. The intercalation tested doses were based on the equivalent weight of 0x, 0.5x, and 1x cation exchange capacity (CEC) clay value. The calcination treatments used were 200°C, 300°C, and no calcination. Each treatment interaction was repeated three times. Parameters observed were the total area, average crack width, average lump area, total number of lumps, moisture content, swelling volume, and pH after treatment. The results showed that each treatment had a significant effect. Clay with an Al intercalation dose of 1x CEC without calcination treatment had the highest total area after drying, which was 41.035 cm2; the lowest average crack width was 0.153 cm, and the smallest swelling volume was 3.6 cm3. In contrast, the clay without intercalation and calcination treatments had a swelling volume up to 10 cm3 on the 7th day. The clay with an Al intercalation dose of 1x CEC with 200°C calcination exhibited the best results in reducing the expansive clay ability and can be used as a guideline for further testing to reduce the soil’s expansive ability.

Abstract Landslides are the second biggest natural disasters in Indonesia, occurring mostly in volcanic area with thick and clay rich soils. Examining the changes of land surface and soil morphology brought about by a particular landslide is usually the first step required for vegetative rehabilitation. Most examinations to date, however, have been based on general characters rather than on soil morphology, including physical and chemical characteristics of the soil, which are usually locally specific. This study investigates the morphological characteristics of soil in a landslide-prone slope region of Sumbing Volcano, in Central Java Province of Indonesia. The field investigations are conducted at three landslides sites. It starts with interpreting small format areal-photographs which have been geo-corrected, followed by the delineation of landslide zones (i.e. crowns, main scarps, heads, bodies and toes) based on morphological analysis of the landslide sites. Finally, identification of morphological, physical and chemical characteristics of the soil in each of the landslide zones are conducted in the field, along with laboratory tests. The results demonstrate that soil morphology is unique for each of the landslide zones. The characters of the undisturbed soil, as indicated by well-defined genetic horizons, are found in the crown zones. Outcrop of high clay content soil material layers are seen in the main scarp zones. Meanwhile pedoturbation processes are evident in the zone of bodies and toes, suggesting that the soil is prone for erosion. If natural erosions in these zones are not controlled and/or unmitigated, the situation will trigger landslide reactivations. We suggest that in studying landslide, one also considers the characters of soil morphology, as this additional information provides a more complete understanding of both land surface morphology and soil morphology to inform landslide vegetative rehabilitation.

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.

The need of nitrogen (N), phosphate (P) and potassium (K) nutrient in oil palm nursery are usually fulfilled with synthetic chemical fertilizers such as NPK fertilizer. The application of NPK fertilizer can cause the soil to become hard due to the accumulation of the residue left on the ground. Cow manure is able to substitute NPK fertilizer based on the chemical status of the soil. This study aimed at analyzing the effect of NPK fertilizer substitution with cow manure on the growth of oil palm seedlings in the pre-nurseries and main nurseries. The experiment was conducted from February to September 2018 in the Banguntapan research and experimental field, Faculty of Agriculture, Universitas Gadjah Mada. The experiment applied the Randomized Complete Block Design (RCBD) with one factor and six blocks as replications. The factors were subtitution using the replacement series method with five levels of doses, 100% NPK, 75% NPK + 25% cow manure, 50% NPK + 50% cow manure, 25% NPK + 75% cow manure and 100% cow manure. The observed parameter variables were root lenght, root area, hump diameter, leaf area, the number of leaves, plant height and plant dry matter. The use of 25% NPK substitute with 75% organic material was the best result in increasing the growth performance of oil palm seddlings in pre-nursery and main nursery.

The low yield of rice in thick peat can be overcome by provisioning complete nutrients. Various efforts have been made to increase the productivity of Indonesian peatlands, one of which is by adding salted fish waste and cow manure. This research was carried out on a plastic house scale from October 2017 to January 15, 2018, in Pelalawan District, Pelalawan Regency, Riau. This research was arranged in a Completely Randomized Design (CRD), consisting of eight treatments, namely L0 = Control, L1 = 1.5 ton.ha-1 of fish waste, L2 = 2.25 ton.ha-1 of fish waste, L3 = 7 tons/ha of cow manure, L4 = 15 ton.ha-1 of cow manure, L5 = 1.5 ton.ha-1 of fish waste + 7 ton.ha-1 of cow manure, L6 = 1.5 ton.ha-1 of fish waste + 15 ton.ha-1 of cow manure, L7 = 2. 25 ton.ha-1 of fish waste + 7 ton.ha-1 of cow manure, and L8 = 2.25 ton.ha-1 of fish waste + 15 ton.ha-1 of cow manure. The results showed that the application of cow manure and salted fish waste could increase soil pH, total NPK, and NPK uptake. The application of 2.25 tons/ha of fish waste and 15 tons/ha of cow manure resulted the best results in soil pH, total NPK, and NPK uptake, therefore it is recommended for the cultivation of lowland rice on peat soil.

Farming in peatland can produce a commodity well if it follows the right planting calendar. Microclimate conditions in the peatland cannot yet be measured in real-time within a shorter time interval. Pelalawan, a region where most of its farmers use peatland for oil palm cultivation, need guidance on applying the best method of oil palm cultivation, which is possible to improve. This study aims to apply a telemetric based (field monitoring system) real-time climatic data application to monitor the agricultural field (peatland). Climate data and weather – soil sensors were set up in Pelalawan village from August 18 to November 16, 2018. Besides, the advancement of planting calendar determination method is also done for peatland farming with a climatic water balance analysis. The change in peatland farming has been successfully observed and measured. The changes in the climatic environment can be observed continuously within a time interval of 30 minutes. Sun radiation data show a significant fluctuation shift from day to day. It also occurs for rainfall, temperature and humidity data. Climatic data fluctuation can be monitored directly and continuously with a Field Monitoring System (FMS) application. Water balance for paddy and corn is obtained based on Plant Water Need and Effective Rain. The recommended schedule according to water balance analysis (surplus and deficit) is paddy 1 – corn – paddy 2.

Methane (CH4) emission from paddy rice fields is a global concern; however, engineering plant spacing can decrease CH4 emission. Due to this, field research was conducted to measure CH4 emissions from rice fields planted using jarwo 2:1 spacing, which has a 25 × 12.5 cm and 50 cm for the plant-free area (PFA), compared to tegel, which has a spacing of 25 × 25 cm. Each field was treated with organic fertilizer (mixture of cow manure and neem compost in a ratio of 1:1) with one of four doses: 0, 3, 6 and 9 tons/ha. The results showed that chemical properties such as soluble-Fe, soil organic matter (SOM), soil acidity (pH), and redox potential (Eh) were significantly correlated with CH4 emissions (0.52***, 0.47**, 0.36*, and -0.27* respectively). Jarwo 2:1 had lower CH4 emissions than tegel on all doses of fertilizer. The most efficient dose of fertilizer was 3 tons/ha applied jarwo 2:1 because it was able to produce rice up to 12 tons/ha with CH4 emissions of only 34 kg/ha/season, while CH4 emissions in tegel was 39 kg/ha/season. It is concluded that jarwo 2:1 with 3 tons/ha organic fertilizers can be recommended to farmers because it produces lower CH4 emissions and higher rice yield.

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.

Applying volcanic ash as planting media has to cope with several constrains: it quickly became sediment and hardened when exposed to water. One of the efforts to improve its physical condition is by utilizing biochar, which is one of amendment materials that can improve the soil quality. This study used vertical column container made from PVC to enable vertical plant arrangement. Volcanic ash requires additional nutrient intake from organic fertilizer such as urban waste compost. The objective of this study was to identify the proper dose combination of volcanic ash, biochar, urban waste compost fertilizer and column population per m2 to sustain the growth of curly lettuce in vertical cropping system, as well as the water use efficiency. This study was designed by using the Completely Randomized Design (CRD) Factorial with three factors. The first, second and third factors consisted of Biochar M1, M2 and M3 (25; 33; and 50 %), compost fertilizer doses of K1, K2, and K3 (25; 33; and 50 %), and column density of P1, P2 and P3 (4 columns/m2, 3 columns/m2 and 2 columns/m2), respectively. The total combination was 3 x 3 x 3 and each was repeated 3 times. Resulted data of this study consisted of growth and crops and analyzed by using the Analysis of Variance and continued with the HSD Tukey 5% Test (Honest significant deference). The water use efficiency (g/kg) can be formulated as the production of dry material per total water during the cultivation season (g/kg). Results of this study showed the highest fresh consumption result was obtained from treatment M3K3 in 556 g/column (comparison of volcanic ash, charcoal husk and compost = 25 : 25 : 50 %) and the best water-use efficiency was 2.30 g/kg.

Vegetation recovery is essential in land restoration after the eruption of Mount Merapi in 2010. Vegetation is a source of organic material that produces root exudate containing organic acids. These acids accelerate the dissolution process of volcanic material so that it affects the soil characteristics. This study was conducted to analyze the effect of four types of perennial plants on soil chemical and physical characteristics. The soil samples were taken on the area planted with cinnamon, albizia, bamboo, and acacia, at depths of 0 – 10 cm, 10 – 20 cm, 20 – 30 cm, 30 – 40 cm, and 40 – 50cm. The soil chemical analysis carried out included pH H2O, pH KCl, pH NaF, C-organic, Humic acid and Fulvic acid, cation exchange capacity, Ca, Mg, K, Na, available P, base saturation, and particle size distribution. The results show that pH H2O, pH KCl, C-organic, humic acid and fulvic acid, CEC, K, Na, Ca, Mg, available P, base saturation, and particle size distribution were significantly affected by vegetation type. Meanwhile, the pH of NaF was not significantly influenced by vegetation type. Cinnamon is a plant that gives the strongest influence in the improvement of soil chemical-physical properties compared to the other three types of vegetation. Therefore cinnamon is quite prospective plant to be developed for post-eruption land reclamation.

Humic acids containing carboxyl and hydroxyl groups that have the ability to cover the P adsorption site in Typic Hapludults. Molybdate has similarity behaviour with phosphate in theacid soils. Research aim was to study the effects of molybdate and humic acid to the kinetics of phosphate adsorption in Typic Hapludults of Cigudeg, Bogor. Important of kinetics is to get accuration of materials transport, to control influence on anion mobility, that the assessment is needed for the efficient application of Mo and P. Aplication humic acid and molybdate as competitor anion of phosphate was conducted with combination of humic acid and Mo concentration as double anions. Many models describe the kinetics for the adsorption of phosphate by soils i.e. zero order, first order, second order, and Elovich. As ststistically, there was not interaction of humic acid and molybdate on P adsorption. Application of humic acid with rate of 100 mg.L-1 was not effective decrease P adsorption in Typic Hapludults. It was due to the pH of the adsorption system that get near to its pKa of carboxyl gruop about 5. Meanwhile aplication 2 and 5 mmol.L-1 of molybdate significantly decrease of P adsorption. The second order kinetics models apropriate to the adsorptionof P in the Typic Hapludults of Cigudeg, with determination coefficients value (R2) of 0.999-1 and standard error value (SE) of 0.001–0.011.The results suggest that the molybdate as competitor anion affected the kinetics for the adsorption of phosphate due to the charge of molybdate.

The great eruptions of Mount Merapi in 2010 have drawn a great deal of attention from both national and international media.The month-long eruptions killed more than 200 people, displaced over 100,000 residents, killed over 1,000 livestock and destroyed over 1,000 hectares of productive farming fields. Incidentally, agriculture is one of the livelihood sectors that suffered heavily. Further, it impacted farmers the most as they depend on farming activities as their main source of livelihood. After, the eruption, land management became based on material type and condition of the land.. Principles of land management involve the provision of appropriate environmental needs of plants, the availability of moisture, nutrients, colloidal holding nutrients, and aeration. In short, they entail the technical aspects of recovery after the eruption of plants based on the conditions of the land. Also included are crop diversification (intercropping cultivation, crops rotation, mixed farming, etc) and intensification of yard (horticulture crops, hedge rows); as well as reinforcing of core and source of cattle nutrition, for example gliricedea; fast growing and producing crops are needed but those that need high capital / major costs for planting and care are not required. Furthermore, the concept of post-eruption land arrangements needs to be formulated based on the configuration of the land which is mainly related to local circumstances such as topography, hydrology, meteorology, and natural drainage systems.

A study that was aimed to determine the influence of long of land use and cropping systems on soil fertility and yield of cassava conducted at centre of cassava in Sukadana Subdistrict, East Lampung. Survey was conducted to characterize soil fertility due to the long of landuse and cassava cropping system from February to September 2014. Treatments of cropping system and long of land use observed involving: (1) Cassava monoculture for more than 30 years, (2) Cassava monoculture for 10- 30 years, (3) Cassava monoculture for less than 10 years, (4) Intercropping cassava and maize, (5) Intercropping cassava and groundnut, (6) Crop rotation of cassava and maize, and (7) Crop rotation of cassava and groundnut. The results showed that concentration of all macro nutrients of cassava monoculture for more than 30 years was lower than cassava monoculture for less than 10 years including the decrease of 11% of soil pH, 49% of total N , 66% of organic C, 57% of available P, 64% of K, 70% of Ca, 55% of Mg and 37% of CEC. Intercropping or crop rotation of cassava with legume or non-legume increased the soil pH, organic C, total N, K, Ca and Mg and decreased exchangeable Al. The changes in soil chemical and physical properties due to different cropping system affected the yield of cassava. The highest yield of cassava was obtained by crop rotation of cassava and maize, while the lowest was monoculture for more than 30 years. Cassava monoculture grown for 10-30 years or more than 30 years had low soil fertility so that the yield of cassava was also low. The yield of cassava in the rotation system was higher than the intercropping

Different weeding frequencies (WFs)―0WF, 2WF, 4WF, 6WF, and 8WF―were adopted in an organic rice field to investigate their influence on weed types, rice and weed biomass, rice tiller and weed number, N concentration, and N uptake. The study field was located in Tsuruoka, Yamagata, Japan. Rice (cv. Sasanishiki) was planted from May to September 2019, and all weeding events were carried out until 49 days after transplantation (DAT) using a rotary weeder. Rice and weed samples were collected at 60, 88, and 110 DAT. Echinochloa crus-galli (E. crus-galli), Schoenoplectus juncoides, and Monochoria vaginalis (Burm. f.) were the most commonly found weeds. High weed diversity was observed at both 6WF and 8WF, E. crus-galli was the dominant weed at 0WF. Compared to 0WF, 2WF displayed a significantly decreased weed biomass. However, at 8WF, the weed biomass was reduced by 79.0%, the rice biomass was increased by 277%, and the rice tiller number was almost three times higher than that at 0WF and 110 DAT. Compared to 0WF, a significantly increased rice N uptake was observed at 4WF, and rice N uptakes achieved at 6WF and 8WF were two and four times higher than those at 0WF, respectively. Higher weeding frequencies provide notable benefits in suppressing weeds and supporting rice growth, especially in N uptake competition with weeds.

The objective of this study was to determine the changes in the basic soil chemical properties including pH, electrical conductivity (EC), available phosphorus (P), dissolved organic carbon (DOC) and inorganic Nitrogen (NH4+ -N and NO3- -N) after approximately 15-40 years land use change from rice paddy field to orchard, wetland and upland in northeast Japan. Five land use change fields were investigated, including, forest, rice paddy, orchard, wetland and upland near Kumagai shrine, Shonai-machi, Yamagata, Japan. Soil samples were collected from surface layer (0-15 cm) and subsurface layer (15-30 cm) in October 2015. Soil chemical properties of pH, EC, available P, DOC and inorganic N (NH4+ -N and NO3- -N) were analyzed on air-dried samples. The pH increased significantly in the upland after 15 years conversion from rice paddy in both layers, with other land use changes only increasing pH in subsurface layer. EC significantly decreased in the surface layer of orchard and upland fields and in subsurface layers of all the converted fields. Available P significantly decreased in the converted fields, except in the upland subsurface layer. DOC amounts were not significantly different after land use changes from paddy fields. The NH4+ -N decreased significantly only in the surface layer of upland, while NO3- -N increased significantly only in the surface layer of wetland. Significant changes in soil properties were observed after 15 years conversion to upland and 40 years conversion to orchard and wetland from former rice paddy field in this study.

A study was conducted to establish the indirect effects of nitrogen (N) and silicon (Si) on the growth and development of Spodoptera litura on soybean. A full-factorial experiment was arranged in 4x2 factors: first factor was nitrogen with varied doses of 0, 25, 50, and 100 kg/ha; second factor was silicon at 0 and 200 g/m2. The results demonstrated that the application of N and Si indirectly affected the growth and development of S. litura including leaves consumed, weight of larvae, weight of pupal, fecundity and survivorship. In addition, combination of nitrogen and silicon also affected the growth and development of soybean as evidenced by the decreased absorption of Si by soybean following the application of N, while the application of Si combined with high nitrogen doses decreased the absorption of Si. It was also observed that the effect of N was not significant on the growth and development of S. litura. The application of Si with the high N doses, however, decreased the growth and development of S. litura. It is, therefore, concluded that the mechanism of relationship between N and Si on S. litura could not be explained only by quantifying the absorption value of N and Si.

A study that was aimed to determine the effect of organic matter from groundnut and maize biomass on the availability of N and C labile fraction was conducted in laboratory and glasshouse, Iletry, Malang. Research used randomized block design with three replications. The first factor was land use : (1). Soil from land cultivated by cassava crops for less than 10 years, and (2). Soil from land cultivated by cassava crops for more than 30 years. The second factor was type of organic matter: (1). Groundnut biomass, (2). Maize biomass, (3). Groundnut-maize biomass, with a ratio of 1:1, (4). Groundnut – maize biomass, with a ratio of 2:1, (5). Groundnut – maize biomass, with a ratio of 1:2, and (6). Without organic matter. The results showed that application of groundnut and maize biomass were affect the N and C labile fraction. Application of groundnut + maize biomass increases N and C labile fraction more 40% than without biomass as well as the landuse of planted with cassava less than 10 years was 20 % higher N and C labile fractions than the land that has been planted with cassava more than 30 years. This research showed that analysis of N or C labile fraction is more sensitif than analysis of N total or C organic. It indicates that analysis of labile fractions can be used to analyze of N and C availability in the soil, beside of N total and C organic analysis

Vertisol is a soil that has neutral to slightly alkaline pH. Zinc availability decreases with increasing pH. The existence of symptoms micronutrients scarcity, especially zinc, also caused by the use of highly yielding seeds with unbalanced fertilization. In addition, Zn uptake by plants is sustainability process which resulted in a decrease in nutrient levels of Zn in the root zone. The aim of the research was to determine the optimum Zn formula that can be added to the NPK compound fertilizer and to determine the effectiveness of the fertilizer on the growth and yield of rice. The experiment was arranged by completely randomized block design with 10 treatments and 3 replicates of each treatment. NPK compound fertilizer dose was given 300kg / ha. The result of this study showed that the compound fertilizer NPK + Zn had no effect on plant height, number of tillers and weight of the plant. The additional dose compound of 2% Zn to the dose of compound fertilizer NPK + Zn did not increase the yield. There was a tendency NPK treatment +0.75% Zn deliver the highest results. NPK compound fertilizer application + Zn significantly increased the uptake of Zn.

Industri gula Indonesia berada di bawah tekanan untuk meminimalkan kehilangan nutrisi off-farm dan mengurangi seluruh biaya produksi. Saprodi pupuk menyerap biaya produksi 65% dari total biaya. Salah satu upaya yang dapat dilakukan adalah penerapan rekomendasi pupuk spesifik berdasarkan analisis tanah. Penelitian ini bertujuan untuk mengelompokkan petak Status Hara N Total, P-Tersedia, K-Tertukar dan cluster rekomendasi pemupukan tanaman tebu (Saccharum officinarum Linn.) di kebun Unit Usaha PG. Djatiroto, Lumajang melalui pemetaan. Analisis dilakukan terhadap 48 sampel, dengan 1 sampel mewakili petak 6,25 ha. Pengelompokan petak berdasarkan peubah konsentrasi N Total, P-Tersedia, K-Tertukar dilakukan dengan metode Hierarchical cluster Analysis dan Sistem Informasi Geografis (GIS) mulai dari bulan Januari sampai Mei 2014. Hasil analisis mendapatkan 5 kelompok area rekomendasi pemupukan. Satu kelompok (cluster 3) yang terdiri dari satu petak dengan rekomendasi 160 kg N/ha, 90 kg P2O5/ha,145 kg K2O/ha; cluster 1 yang terdiri dari 29 petak dengan rekomendasi 160 kg N/ha, 90 kg P2O5/ha, 175 kg K2O/ha; cluster 2 yang terdiri dari 7 petak dengan rekomendasi 120 kg N/ha, 90 kg P2O5/ha, 175 kg K2O/ha, cluster 4 yang terdiri dari 23 petak dengan rekomendasi 160 kg N/ha, 135 kg P2O5/ha, 175 kg K2O/ha; cluster 5 yang terdiri dari 6 petak dengan rekomendasi 120 kg N/ha, 135 kg P2O5/ha, 175 kg K2O/ha.

ABSTRAK Pupuk organik perlu didekomposisi oleh mikroba dan memerlukan lingkungan yang sesuai agar cepat matang sempurna dan tidak memberikan dampak negatif pada aspek sosial, estetika maupun kesehatan pada makluk hidup dan lingkungan. Dekomposisi bahan pupuk organik dilakukan dengan menggunakan kotoran sapi, dengan 2 perlakuan mikroba (tanpa dan dengan mikroba starter) dan 3 variasi waktu, yaitu 0, 6 dan 24 jam setelah diberi mikroba starter. Analisis meliputi uji fisik bahan pupuk yang meliputi pH, warna, aroma, lengas, dan DHL, uji mikroba patogen (Eschericia. coli dan Salmonella) pada pupuk, pengujian kandungan hara pupuk total (C, N, P, K, Ca, Mg, Na, S, Cd, Cr, B, Fe, Cu, Zn) dan Ntersedia (NH4 dan NO3), serta analisis emisi gas amonia (NH3), oksigen (O2), karbon monoksida (CO), karbon dioksida (CO2), metana (CH4), NOx, NO, dan SO2. Mikroba starter mengandung mikrobia dan unsur hara yang sangat diperlukan dalam proses dekomposisi bahan organik. Pupuk kandang sapi setelah aplikasi mikroba starter masih mengandung E. coli dan Salmonella sp. yang cenderung menurun seiring dengan lama waktu inkubasi. Terjadi dinamika kandungan unsur-unsur hara seperti P, K, Mg, Fe dan Cu serta logam berat Cr selama proses inkubasi baik pada pupuk kandang ayam maupun sapi. Dengan perlakuan mikroba starter, bagian senyawa sulfur dari bahan organik banyak yang terombak menjadi gas SO2 yang relatif tidak berbau, dan sebaliknya H2S serta senyawa reduktif sulfida lainnya menjadi terhambat pembentukannya. Perombakan dengan mikroba starter sebaiknya diupayakan dalam suasana aerobik atau dengan suasana lembab tetapi tidak sampai anaerobik sehingga kehadiran senyawa H2S dan senyawa sulfur reduktif lainnya dapat dikurangi atau tidak terbentuk. Hasil penelitian ini menunjukkkan pentingnya penggunaan mikroba starter optimal dan benar untuk memperbaiki kandungan nutrisi dan kualitas pupuk kandang. ABSTRACT Process of decomposition of organic fertilizer relies on the microbial decomposer population and requires a condusive environment. Those two factors influence on the rate of organic material decomposition and limites the negative impact of this organic fertilizer on the aspect of social, ethic, and health of living organism. Cow dung was used as the material for decomposition of organic fertilizer. Two treatments were applied: with or without microbial decomposer (microbial starter) followed by incubation in the dark condition under room temperature. The cow dung was sampled in 0, 6, and 24 hours after microbial starter application.The cow dung pH, color, smell, water content, and electrical conductivity were analyzed. Furthermore, microbial pathogen (Eschericia coli and Salmonella), cow dung total nutrition (C,N,P,K,Ca,Mg,Na,S,Cd,Cr,B,Fe,Cu,Zn), and available N (NH4 dan NO3) were also determined. Amonia emision (NH3), oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), NOx, NO, and SO2were analyzed as well. The result showed that microbial starter contained of important microbial for the process of cow dung decomposition. Application of microbial starter in cow dung reduced E. coli dan Salmonella sp. by the length of incubation time.Variation of nutrition, i.a. P, K, Mg, Fe, Cu, and heavy metal, i.a. Cr was found during incubation, both in chicken and cow manure.Application of microbial starter reduced sulfur in organic matter to be SO2 without smell, and inhibited H2S production. Decomposition by application of microbial starter should be conducted in aerob condition to reduce H2S production. This research implied that application of microbial starter is crucially important in improving manure nutrition and quality.

Phosphorus (P) often becomes limiting factor for plants growth. Phosphorus geochemistry in peatland soil is associated with the presence of peat layer and groundwater level fluctuations. The research was conducted to study the role of peat layer and groundwater level fluctuations on P concentration in peatland. The research was conducted on deep, moderate and shallow peat with sulphidic material as substratum, peaty acid sulphate soil, and potential acid sulphate soil. While P concentration was observed in wet season, in transition from wet to dry season, and in dry season. Soil samples were collected by using peat borer according to interlayer and soil horizon. The results showed that peat layer might act as the main source of P in peatland with sulphidic material substratum. The upper peat layer on sulphidic material caused by groundwater level fluctuations had no directly effect on P concentration in the peat layers. Increased of P concentration in the lowest sulphidic layer might relate to redox reaction of iron in the sulphidic layer and precipitation process. Phosphorus concentration in peatland with sulphidic material as substratum was not influenced by peat thickness. However, depletion or disappearance of peat layer decreased P concentration in soil solution. Disappearance of peat layer means loss of a natural source of P for peatland with sulphidic material as substratum, therefore peat layer must be kept in order to maintain of peatlands.

Much of peatland in Indonesia has sulphidic materials as substratum. Soil acidity and metal elements in peatland may originate from the sulphidic materials which occur underneath of the peat layer. Peat soil buffering capacity and chelating ability of the peat materials regulate the soil acidity and metal solubility in the peatland. The study was aimed to examine the influence of peat thickness and land hydrological conditions on the concentrations of exchangeable aluminium (Al) and hidrogen (H) in the peatland. The study was carried out on peaty acid sulphate soil, deep peat, moderate peat and shallow peat. Exchangeable Al and H were observed in the wet season, transition from wet to dry season and dry season. The results showed that exchangeables of Al and H were mainly originated from sulphidic material which were occured underneath of the peat layer. Peat layer had an important role on the solubility of Al and H in the peatland. Peat thickness had influence on exchangeable-Al and H, 50 cm of the peat thickness (shallow peat) was the critical for peat function to reduce the Al and H solubility in the peatland. Hydrological condition factor did not influence on the solubility of Al and H.

Low phosphorus (P) availability and high iron (Fe) concentration are the dominant characteristics of acid sulphatesoils (ASS). Optimum agricultural management practices are required to leach the excess Fe2+ and to prevent orminimize loss of P from the soil in order to obtain conditions favorable for rice growth. The aim of this experimentwas to study the effect of organic matter (OM) application in the form of rice straw (RS) on leaching of Fe and lossof P in an acid sulphate soil. The experiment was conducted in the glasshouse consisting of three treatment factorsutilizing the completely randomized design with three replications. The first factor was soil condition consisting ofcontinuous application of RS and without RS during the past five years. The second factor was application of freshRS consisting of fresh RS application and without fresh RS application, whereas the third factor was P applicationconsisting of three rates of SP-36 fertilizer (0.5, 1.0 and 1.5 times of the recommended rate). The results showedthat RS application was effective in preventing P loss from the soil at 6 weeks after planting (WAP) and decreasedthe pH of leachate at all observations time but it increased Fe2+ concentration in leachate (0.07-0.42% Fe2+ in thesoil were leached or 2-5 folds higher than without RS application).

The research aimed to study the effect of peat thickness and humification stage of the peat material on Fe solubility at the peatlands with sulfidic material as substratum. The research was conducted at three conditionals of ombrogen peatlands ie ; deep, moderate and shallow peat. Soil samples were collected by using peat borer according to interlayer (the border layer of peat and mineral layer) and conditional of soil horizons. The sample point depth were (cm) G.s2 : 25, G.s1 : 50, Int.s : 70, M.s1 : 90 and M.s2 : 100 for shallow peat, G.m2 : 47, G.m1 : 100, Int.m : 120 and M.m1 : 135 for moderate peat and G.d3 : 50, G.d2 : 150, G.d1 : 200, Int.d : 220 and M.d1 : 235 for deep peat respectively. The results showed that most of Fe on the tested soils was found in organic forms. The peat layers above the sulfidic material decreased the Fe2+ solubility at peatlands. Fe2+ concentration in peat layer decreased with its increasing distance from sulfidic material. There was any other processes beside complexation and chelation of Fe2+ by humic material and its processes was reduction of Fe3+ and this conditions was reflected in redox potential values (Eh).

Peat soils naturally have hydrophilic or water-loving character with highly capable of exchanging the cations and cycling the nutrients from the vegetations. This water-loving character is altered to water-repellent character in hydrophobic peat soils. This research was aimed to observe deeply the functional bunch carrier of hydrophobic and hydrophilic peat soils as shown by FTIR spectra in relation with inherent chemical and physical properties of the soils. Five peat soils consisted of two native and artificial hydrophobic peat soils and one sample of hydrophilic peat soils were studied. Artificial hydrophobic peat soils were yielded by oven-drying the native hydrophobic peat soils at 50 oC for 10 hours. FTIR spectra can distinguish the functional bunch carrier of hydrophobic and hydrophilic peat soils. FTIR spectra of hydrophobic peat soils showed degradation of hydrophilic bunch carrier (¾OH and ¾COOH) and increase of the hydrophobic bunch carrier (tying aromatic from esther and ether). Chemical analysis of the hydrophobic peat soils also indicated the decrease of ¾OH and ¾COOH content, decrease of CEC , soil total acidity and soil moisture content.

The objective of this research was to investigate the effect of application of organic matter from rice straw (RS) on phosphate and Fe2+ solubility in the acid sulphate soils. The research was conducted in the glass house consisting of the three treatment factors using the completely randomized design with three replication. The first factor was soil condition : continuous application of RS and without application of RS during the last 5 years. The second factor was fresh application of RS ; with application and without application, whereas the third factor was phosphate application consisting 3 rates of SP – 36 fertilizers (0.5; 1,0 and 1.5 of application dossage). The result showed the three factors interaction had a significant influence on soil pH at 2 weeks after planting, whilst interaction between RS application and soil condition had a significant influence on soil pH, available phosphate at 4, 6 and 8 weeks after planting. The interaction between RS application and phosphate fertilizers rate had a significant influence on soil pH 4 weeks after planting, and on available phosphate at 8 weeks after planting. The main effect of RS application was significant on exchangeable Fe and soil pH at all observations periods.