Obtaining soil water content and soil workability data using remote sensing technology with passive sensors has some limitations due to cloud cover, cloud shadow, haze and smoke. This study proposes a method for computing soil water content and soil workability over large areas, faster and in near real-time based on Sentinel-1A (SAR) data. Sample data collected from sugarcane plantations in the Kediri and Sidoarjo districts in East Java, Indonesia, were used to develop a mathematical model of the proposed method using multi-polynomial regression. The performance indicators of the model (RMSE, MAPE and accuracy) were calculated with the results of RMSE = 0.213 and 0.250, MAPE = 16.39% and 18.79%, and accuracy = 83.6% and 81.2% for the training and testing models, respectively. The distribution of soil water content and soil workability can be computed and visualized using a spatial map. The future contribution of this work is to develop a decision support system for the selection of appropriate machinery for sugarcane field operations based on the principles of precision agriculture.

Subsurface drainage technology may offer a useful option in improving crop productivity by preventing water-logging in poor drainage paddy fields. The present study compared two paddy fields with and without sheet-pipe type subsurface drainage on land and water productivities in Indonesia. Sheet-pipe typed is perforated plastic sheets with a hole diameter of 2 mm and made from high-density polyethylene. It is commonly installed 30–50 cm below the soil surface and placed horizontally by a machine called a mole drainer, and then the sheets will automatically be a capillary pipe. Two fields were prepared, i.e., the sheet-pipe typed field (SP field) and the non-sheet-pipe typed field (NSP field) with three rice varieties (Situ Bagendit, Inpari 6 Jete, and Inpari 43 Agritan). In both fields, weather parameters and water depth were measured by the automatic weather stations, soil moisture sensors and water level sensors. During one season, the SP field drained approximately 45% more water compared to the NSP field. Thus, it caused increasing in soil aeration and producing a more significant grain yield, particularly for Inpari 43 Agritan. The SP field produced a 5.77 ton/ha grain yield, while the NSP field was 5.09 ton/ha. By producing more grain yield, the SP field was more effective in water use as represented by higher water productivity by 20%. The results indicated that the sheet-pipe type system developed better soil aeration that provides better soil conditions for rice.

Evapotranspirative irrigation is a simple idea in a watering field based on the actual evapotranspiration rate, by operating an automatic floating valve in the inlet without electric power to manage water levels. The current study introduces a model of evapotranspirative irrigation and its application under different water levels. The objectives were (1) to evaluate the performances of evapotranspirative irrigation under various irrigation regimes, and to (2) to observe crop and water productivities of the system of rice intensification (SRI) as affected by different types of irrigation. The experiment was performed during one rice planting season, starting from July to November 2020, with three irrigation regimes, i.e., continuous flooded (CFI), moderate flooded (MFI) and water-saving irrigation (WSI). Good performance of the system was achieved; low root mean square error (RMSE) was indicated between observed water level and the set point in all irrigation regimes. Developing a better drainage system can improve the system. Among the regimes, the WSI regime was most effective in water use. It was able to increase water productivity by up to 14.5% while maintaining the crop yield. In addition, it has the highest water-use efficiency index. The index was 34% and 52% higher than those of the MFI and CFI regimes, respectively. Accordingly, the evapotranspirative irrigation was effective in controlling various water levels, and we recommend the system implemented at the field levels.

The varying condition of climate, soil properties, crop stage, ground water existing in oil palm cultivation require the specific water balance model to perform the precision crop water use. The purposes for this research were to develop oil palm water balance model for calculating the hydrological parameter of oil palm and analysing oil palm water footprint and root water uptake distribution in root zone. The model of oil palm water balance was developed through the following step: oil palm root architecture study, instrument installation and data observation, model development and calibration. The oil palm water balance tool was developed by inputting the data base including climate, soil properties, crop stage, root density and root zone layer as well. The results in the case for 11th year oil palm tree on soil type ultisol in Central Kalimantan during the simulation climate data pointed out that the average root water is 3.46 mm/day and distributed 63% on 2st root zone. From the total water usage and the average production 14.19kg/month, it resulted the 1.053 m3/kg water footprint of FFB (76 % green water and 24% blue water).

It was crucial to acquire soil CO₂ flux data from a bare peatland site in Kampar Peninsula, Riau Province, Indonesia so as to evaluate the carbon budget of the site in which water is managed, drained, and utilized for acacia plantation. CO₂ flux was continuously measured from July 2012 to February 2013 using an automatic soil CO₂ flux measurement system. In this study, the factors affecting carbon emission were analyzed and tested for indirect CO₂ flux estimation, and the results showed that CO₂ flux varied with weather, water, and soil-related variables, and where there was rainfall, soil temperature and soil moisture both played an important role. CO₂ flux was modeled using an artificial neural network (ANN) approach with inputs of soil moisture, temperature, and electrical conductivity (EC) as proxy variables. Based on the measurements, the total carbon dioxide (CO₂) emission during the measurement period from July 2012 to June 2013 was 52.25 t ha⁻¹. Total CO₂ emission in 2012 was estimated as 54.86 t ha⁻¹ using the ANN model. Furthermore, the results generated by the model showed that levels of CO₂ flux declined as the temperature decreased, and soil moisture increased toward soil water saturation.

Beban limbah cair industri kertas meningkat seiring dengan peningkatan produksi kertas di Indonesia. Konsentrasi COD berkisar antara 8.300–45.384 mg/L O2 dan TSS sebesar 41.000 mg/L. Salah satu upaya untuk mengurangi beban COD dan TSS di dalam limbah cair industri kertas adalah dengan memanfaatkan proses lumpur aktif. Penelitian ini difokuskan pada pengaruh proses sedimentasi di dalam unit lumpur aktif untuk mereduksi COD dan TSS. Penelitian ini juga mencakup analisis dua tipe pengendapan, yaitu pengendapan partikel diskrit dan pengendapan flok. Tujuan utama penelitian ini untuk mengestimasi nilai hydraulic loading rate dan solid loading rate serta rekomendasi dimensi unit sedimentasi lumpur aktif. Penelitian ini meliputi kegiatan monitoring kinerja proses dengan tiga variasi waktu detensi (HRT). Beberapa variabel yang diperhatikan untuk mencapai tujuan penelitian ini, antara lain kecepatan pengendapan bebas (v), percepatan gravitasi (g), massa jenis partikel (ρs), massa jenis fluida (ρ), diameter partikel (d), dan koefisien penarikan atau drag coefficient (Cd). Pengukuran reduksi COD mengacu pada SNI 6989.2:2009 dan pengukuran reduksi TS mengacu pada SNI 06-6989.26-2005. Penelitian ini menunjukkan bahwa kecepatan pengendapan discrete particle settling tergantung pada karakteristik satuan partikel berdasarkan diameter partikel. Kecepatan pengendapan flocculant settling tergantung pada pengaruh interaksi partikel dalam pembentukan flok atau gumpalan beberapa entitas partikel. Jika ditinjau dari nilai umur lumpur (SLR), HRT 8 jam dan HRT 12 jam menunjukkan kondisi under loaded pada unit sedimentasi. Sementara itu, nilai HLR dan SLR pada HRT 6 jam telah memenuhi rentang kriteria desain lumpur aktif. Dengan demikian, desain terbaik untuk unit sedimentasi sekunder lumpur aktif, yaitu HRT 6 jam dengan HLR sebesar 42,16 m3/m2hari, SLR sebesar 102,45 kg/m2hari dan rata-rata reduksi padatan total mencapai 89,26%.ABSTRACTThe influence of paper production affect simultenously to the increase of pulp and paper wastewater in Indonesia. The COD concentration ranged from 8,300–45,384 mg/L O2 and TSS was 41,000 mg/L. Reducing COD and TSS concentrations in the paper industry wastewater is to utilize by using activated sludge processes. This research was focused on the effect of sedimentation process in activated sludge to reduce COD and TSS. This research also included the analysis of two types of deposition, namely discrete particle settling and floc settling. Main objective this research was directed at determining the value of the hydraulic loading rate and solid loading rate as well as recommendations for the dimensions of the activated sludge sedimentation unit. This research included monitoring of process performance with three variations of detention time (HRT). There were several variables that are considered to achieve the objectives of this study, including free deposition velocity (v), acceleration due to gravity (g), particle density (ρs), fluid density (ρ), particle diameter (d), and drag coefficient. coefficient (Cd). The COD and TS reduction measurement refered to SNI 6989.2:2009 and SNI 06-6989.26-2005, respectively. This study showed that the speed of discrete particle settling depends on the characteristics of the particle unit as seen from the particle diameter. The deposition rate of flocculant settling depends on the effect of particle interactions in the formation of flocs or agglomerates of several particle entities. When viewed from the SLR value obtained, the 8-hour HRT and 12-hour HRT indicated that the sedimentation unit was in an under-loaded condition. Meanwhile, the HLR and SLR values at HRT 6 hours complied the activated sludge design criteria. Thus, the best design for the activated sludge secondary sedimentation unit was HRT 6 hours with an HLR of 42,16 m3/m2day, an SLR of 102,45 kg/m2day and an average total solids reduction of 89,26%.