Nitrogen and Phosphorous Movement Characteristic in Terrace Paddy Field Using Cascade Irrigation System in West Sumatra, Indonesia

West Sumatra is one of Indonesian rice bowl. The landscape of this province dominated by mountainous area with beautiful terrace paddy field lied from the middle slope to the lowland. The most common rice cultivation management in this area is application of cascade irrigation system with blanked amount of chemical fertilizer application. This study intends to figure out, whether this kind of paddy field management sustains and friendly to the environment or not. The results showed that cascade irrigation system created some discrepancies in suspended solid (SS), dissolve organic matter (DOM) and the nutrient movement characteristic a long the slope. The SS and DOM load and discharge strongly influenced by land preparation activities, while total and available nitrogen (N) and phosphorous (P) affected by chemical fertilizer application. In the upper part, the amount of chemical fertilizer seemed sufficient, indicated by negative amount of nutrient balance, while lower terrace show some indication of excess nutrient input. To avoid some demerit of cascade irrigation system, chemical fertilizer application should be base on site specific characteristic and taking into account of natural source contribution.Keywords: Cascade irrigation, chemical fertilizer, nutrient balance, terrace paddy fiel

THE CONTROLLING FACTORS OF SILICON SOLUBILITY IN SOIL SOLUTION

Silika adalah unsur yang menguntungkan bagi tanaman padi, yang dapat mencegah penyakit blast, meningkatkan kekuatan batang, dan mengurangi abiotik stress. Silika (Si) dalam larutan tanah dipengaruhi oleh beberapa faktor, seperti pH, temperatur, bahan organik dan potensial redoks (Eh). Tujuan penelitian adalah untuk mengetahui faktor pengontrol kelarutan Si dalam larutan tanah. Penelitian ini menggunakan silika gel dan tanah Ultisols yang berasal dari Jepang. Pada Penelitian ini diamati pengaruh Ca (kalsium), Mg (magnesium) dan unsur lainnya terhadap kelarutan Si dilakukan di dalam laboratorium. Sepuluh gram sampel tanah dalam tabung plastik ditambah silika gel, Ca dan Mg, selanjutnya ditambah air hingga tergenang dan diinkubasi pada suhu 300C selama 29 hari. Kalsium dan Mg diaplikasikan pada tanah dengan konsentrasi 5, 10, 15 mg Ca L-1 (T2, T3, T4) dan 5, 10, 15 mg Mg L-1 (perlakuan T5, T6, T7). Sebagai kontrol adalah T0 (tanah) dan T1 (tanah + silika gel). Selama inkubasi, konsentrasi Si, Ca, Mg, Fe, dan Mn dalam air permukaan diukur menggunakan ICP spektroskopi pada hari ke 8, 15, dan 29. Hasil analisis tanah awal dikategorikan sedikit asam (pH 5,7) dan konsentrasi Si adalah 267,1 mg SiO2 kg-1. Konsentrasi tersebut termasuk dibawah batas kritis Si tersedia (300 mg SiO2 kg-1). Hasil penelitian menunjukkan bahwa total konsentrasi Ca dan Mg dalam larutan tanah lebih tinggi untuk perlakuan T4 dan T7 dibandingkan perlakuan lainnya. Pada 8 hari pertama inkubasi, pelepasan Si ke dalam larutan tanah lebih tinggi untuk T1 dan T2 dibandingkan dengan perlakuan lain. Kelarutan Si berkorelasi positif dengan Mn, Eh dan berkorelasi negatif dengan pH. Hal ini mengindikasikan bahwa faktor tersebut adalah yang mengontrol pelepasan Si dalam larutan tanah. Pada penelitian ini tidak ditemukan korelasi antara Si dan konsentrasi Ca atau Mg dalam larutan tanah.Silica is a beneficial element for rice plants which can protect from blast disease, increase stem strength, and alleviate abiotic stress. Silicon in soil solution is affected by several factors such as pH, temperature, organic matter, and redox potential (Eh). This study aims to investigate the controlling factor of Si solubility in soil solution. In the present study, Japanese silica gel (JSG) and Ultisols were collected from Japan. In laboratory experiment, the effects of Ca (calcium), Mg (magnesium) and others on solubility of Si (silica) were investigated. Under submerged condition, ten gram of soil with silica gel, Ca and Mg in plastic tube were incubated at 300C for 29 days. Calcium and Mg were applied into soil, at the concentration of 5, 10, 15 mg Ca L-1(T2, T3, T4 respectively) and 5, 10, 15 mg Mg L-1(T5, T6, T7 respectively). There was two controls as a follow T0 (soil) and T1 (soil + silica gel). During incubation, Si, Ca, Mg, Fe, and Mn concentrations in surface water were measured using ICP spectroscopy at day 8, 15, and 29. The results show the soil before treatment was slightly acidic (pH 5.7) and extractable Si concentration was 267.1 mg SiO2 kg-1. It was classified to be below critical level of available Si for rice (300 mg SiO2 kg-1). Total concentration of Ca and Mg in soil solution were highest for treatment T4 and T7, respectively compared with other treatments. On the first 8 days of incubation, Si released into soil solution was higher in T1 and T2 compared to other treatments. The solubility of Si was significantly positive correlated with Mn, Eh, and negatively correlated with pH, that indicated these were the controlling factors of the Si release in soil solution. There was no correlation between Si and Ca or Mg concentration in soil solution

Assessment Erosion 3D Hazard with USLE and Surfer Tool: A Case Study of Sumani Watershed in West Sumatra Indonesia

Quantitative evaluation of soil erosion rate is an important basic to investigate and improve land use system, which has not been sufficiently conducted in Indonesia.  The Universal Soil Loss Equation (USLE) and Erosion Three Dimension (E3D) in Surfer were used to identify characteristic of dominant erosion factors in Sumani Watershed in West Sumatra, Indonesia using data soil survey and monitoring sediment yield in outlet watershed.  Climatology data from three stations were used to calculate Rainfall erosivity (R) factor. As many as101 sampling sites were used to investigate soil erodibility (K-factor) with physico-chemical laboratory analysis. Digital elevation model (DEM) of Sumani Watershed was used to calculate slope length and Steepness (LS-factor). Landsat TM imagery and field survey were used to determine crop management (C-factor) and conservation practices (P-factor). Calculating soil loss and map of USLE factor were determined by Kriging method in Surfer 9. Sumani Watershed had erosion hazard in criteria as: severe to extreme severe (26.23%), moderate (24.59%) and very low to low (49.18%).  Annual average soil loss for Sumani watershed was 76.70 Mg ha-1 y-1 in 2011. Upland area was designated as having a severe to extreme severe erosion hazard compared to lowland which was designated  as having very less to moderate.  On the other land, soil eroded from upland were deposited in lowland. These results were verified by comparing one year’s sediment yield observation on the outlet of the watershed. Land use (C-factor), rainfall erosivity (R- factor), soil erodibility (K-factor), slope length and steepness (LS-factor) were dominant factors that affected soil erosion. Traditional soil conservation practices were applied by farmer for a long time such as terrace in Sawah.  The USLE model in Surfer was used to identify specific regions susceptible to soil erosion by water and was also applied to identify suitable sites to conduct soil conservation planning in Sumani Watershed.[How to Cite : Aflizar, R Afrizal, T Masunaga. 2013. Assessment Erosion 3D Hazard with USLE and Surfer Tool: A Case Study of Sumani Watershed in West Sumatra Indonesia. J Trop Soils, 18 (1): 81-92. doi: 10.5400/jts.2013.18.1.81][Permalink/DOI: www.dx.doi.org/10.5400/jts.2013.18.1.81

Assessment Erosion 3D Hazard with USLE and Surfer Tool: a Case Study of Sumani Watershed in West Sumatra Indonesia

Quantitative evaluation of soil erosion rate is an important basic to investigate and improve land use system, which has not been sufficiently conducted in Indonesia.  The Universal Soil Loss Equation (USLE) and Erosion Three Dimension (E3D) in Surfer were used to identify characteristic of dominant erosion factors in Sumani Watershed in West Sumatra, Indonesia using data soil survey and monitoring sediment yield in outlet watershed.  Climatology data from three stations were used to calculate Rainfall erosivity (R) factor. As many as101 sampling sites were used to investigate soil erodibility (K-factor) with physico-chemical laboratory analysis. Digital elevation model (DEM) of Sumani Watershed was used to calculate slope length and Steepness (LS-factor). Landsat TM imagery and field survey were used to determine crop management (C-factor) and conservation practices (P-factor). Calculating soil loss and map of USLE factor were determined by Kriging method in Surfer 9. Sumani Watershed had erosion hazard in criteria as: severe to extreme severe (26.23%), moderate (24.59%) and very low to low (49.18%).  Annual average soil loss for Sumani watershed was 76.70 Mg ha-1 y-1 in 2011. Upland area was designated as having a severe to extreme severe erosion hazard compared to lowland which was designated  as having very less to moderate.  On the other land, soil eroded from upland were deposited in lowland. These results were verified by comparing one year’s sediment yield observation on the outlet of the watershed. Land use (C-factor), rainfall erosivity (R- factor), soil erodibility (K-factor), slope length and steepness (LS-factor) were dominant factors that affected soil erosion. Traditional soil conservation practices were applied by farmer for a long time such as terrace in Sawah.  The USLE model in Surfer was used to identify specific regions susceptible to soil erosion by water and was also applied to identify suitable sites to conduct soil conservation planning in Sumani Watershed.[How to Cite : Aflizar, R Afrizal, T Masunaga. 2013. Assessment Erosion 3D Hazard with USLE and Surfer Tool: A Case Study of Sumani Watershed in West Sumatra Indonesia. J Trop Soils, 18 (1): 81-92. doi: 10.5400/jts.2013.18.1.81][Permalink/DOI: www.dx.doi.org/10.5400/jts.2013.18.1.81

Beneficial Effect of Silicon Application and Intermittent Irrigation on Improving Rice Productivity in Indonesia

It is believed that silicon (Si) application could increase rice production, however studies related to those topics are still limited. The study determined the combination effect of Si application and water management on rice growth and productivity. This study was conducted at the experimental station of Indonesian Agricultural Environment Research Institute, Jakenan, Pati, Central Java at dry season. A split-plot in randomized complete block design with four replications was set. The main plots were different types of irrigation and subplots were Si fertilizer application. Results showed that the application of Si increased plant resistance on blast disease. This current result might be due to the increasing of Si concentration in leaves. IT water management significantly increased the yield compared to CF. IT increased root growth and gave an impact on increasing of plant growth and rice yield. Moreover, IT significantly increased Cu, Mn, and Zn concentration in rice grain. Combination of Si application with IT water management could increase rice plant productivity especially in area with water shortage. Keywords: blast disease, lodging, rice productivity, silicon application, water managementPenggunaan pupuk silika dipercaya dapat meningkatkan produksi padi, tetapi penelitian pengaruh silika pada tanaman padi di Indonesia masih terbatas. Penelitian bertujuan mengetahui pengaruh kombinasi pemberian pupuk silika dan pengelolaan air pada pertumbuhan dan produktivitas tanaman padi. Penelitian yang dilaksanakan di kebun percobaan Balai Penelitian Lingkungan Pertanian, Jakenan, Pati, Jawa Tengah pada musim hujan. Percobaan menggunakan rancangan petak terbagi dengan empat ulangan. Sebagai petak utama adalah perbedaan pengelolaan air sedangkan anak petak adalah perlakuan pupuk silika. Hasil penelitian menunjukkan bahwa pemberian silika meningkatkan ketahanan serangan penyakit blas. Pemberian silika nyata menurunkan serangan blas daun dan leher yang diduga karena adanya peningkatan Si daun. Pengelolaan air berselang (IT) nyata pada meningkatkan hasil dibandingkan pengelolaan air konvensional (CF). Perlakuan IT meningkatkan pertumbuhan akar dan berdampak pada peningkatan pertumbuhan dan hasil padi. Perlakuan IT juga nyata meningkatkan kandungan hara Cu, Mn, dan Zn pada beras. Kombinasi pemberian silika dan pengelolaan air IT meningkatkan produktivitas tanaman padi terutama pada daerah dengan ketersediaan air terbatas. Kata kunci: pemberian silikon, penyakit blas, pengelolaan air, produktivitas padi, reba

The Long-Term Effect of Blanket Phosphorus Fertilizer Application on the Available P Content in Sawah Soils; Comparative Study in Java, Indonesia

In order to evaluate the effects of long-term phosphorus fertilizer application on the sawah soils, a comparative study was conducted in Java Island as a pioneer of Green Revolution (GR) technology application in Indonesia. Soil samples taken in 1970 by Kawaguchi and Kyuma were compared with new sample taken from the same site or the sites close to 1970 in 2003. The results showed that available phosphorus (P) sharply increased during the study period. The average content of available P in topsoil layer changed from 10.5±11.6 mg kg-1 P in 1970 to 19.6±22.4 mg kg-1 P in 2003, or increased by 118%. Long-term application of 125 kg super-phosphate [Ca(H2PO4)2] per hectares per cropping season as P fertilizers was also affected the profile distribution of available P in whole sites studied, especially in Vertisols. The land management differences between seedfarms planted with rice in monoculture systems whole study period and non-seedfarms cultivated rice and upland crops in some rotation patterns found affected the changing rate of available P in the soils. During the period of 1970-2003, average content of available P in seedfarms changed from 15.7±16.2 mg kg-1 P to 31.1±29.1 mg kg-1 P, while in non-seedfarm from 6.9±8.7 mg kg-1 P to 11.5±8.2 mg kg-1 P in 1970 and 2003, respectively. The great variation on the changing rate of available P observed in this study indicated that general chemical fertilizers recommendation in Indonesia was caused excess P input in some sites, but insufficient in others. To avoid the adverse effect of P fertilizer application in the future, recommendation of P should be based on the site characteristic and taking into account of natural resources contribution

Characteristics and Stocks of Soil Nutrient under Various Land Use Types in a Super Wet Tropical Rain Forest Padang, West Sumatra

In order to clarify the characteristics and stocks of soil nutrient under various land use types in a super wet tropical rain forest in Padang, West Sumatera, an investigation of the nutrient characteristics of the several samples of soils under different land use such as cacao plantation (CP), cinnamon plantation (CMP), mixed garden (MG), and primary forest (PF) in Gadut Mountain, Padang, West Sumatra was conducted. The soil nutrient characteristics varied among the different land use types. The range of nutrient characteristics under four land use type were 4.60 – 7.01% and 0.4 – 0.60% for total carbon and total nitrogen and were 9.80 – 24.59, 0.68 – 2.07 and 0.30 – 0.8 cmol (+) kg-1 for Ca, Mg and K, respectively. The highest content of soil nutrient status was found under MG, while the lowest soil nutrient status found at PF. This result indicated that the MG with various vegetation types might contribute in enriching the organic matter in soil. The soil nutrient content such as TN, exchangeable Ca, Mg and K tended to decrease with soil depth of each land use type. However, the sodium (Na) content in soil tended to increase within the soil depth. These were presumably due to evaporation of Na at surface soil within the study area was low. These study results showed that spatially the nutrient properties of soil were closely related to the land use type and management practices. It was suggested that the nutrient characteristics of soils under various land use types in a super wet tropical rain forest region, in Gadut Mountain, Padang West Sumatra were significantly affected by the land use types and land coverage

3D Agro-ecological Land Use Planning Using Surfer Tool for Sustainable Land Management in Sumani Watershed, West Sumatra Indonesia

Estimation of soil erosion 3D (E3D) provides basic information that can help manage agricultural areas sustainably, which has not been sufficiently conducted in Indonesia. Sumani watershed is main rice production area in West Sumatra which has experienced environmental problem such as soil erosion and production problem in recent years. 3D Agro-ecological land use planning based on soil erosion 3D hazard and economic feasibility analyses consist of production cost and prize data for each crop. Using a kriging method in Surfer tool program, have been developed data base from topographic map, Landsat TM image, climatic data and soil psychochemical properties. Using these data, the Universal Soil Loss Equation was used for spatial map of soil erosion 3D and proposed a 3D agro-ecological land use planning for sustainable land management in Sumani watershed. A 3D Agro-ecological land use planning was planned under which the land use type would not cause more than tolerable soil erosion (TER) and would be economically feasible. The study revealed that the annual average soil erosion from Sumani watershed was approximately 76.70 Mg ha-1yr-1 in 2011 where more than 100 Mg ha-1yr-1 was found on the cultivated sloping lands at agricultural field, which constitutes large portion of soil erosion in the watershed. Modification of land use with high CP values to one with lower CP values such as erosion control practices by reforestation, combination of mixed garden+beef+chicken (MBC), terrace (TBC) or contour cropping+beef+chicken (CBC) and sawah+buffalo+chicken (SBC) could reduce soil erosion rate by 83.2%, from 76.70 to 12.9 Mg ha-1 yr-1, with an increase in total profit from agricultural production of about 9.2% in whole Sumani watershed