Agromet 2020-12-30T09:26:56+07:00 Muh Taufik Open Journal Systems <p>Agromet publishes original research articles or reviews that have not been published elsewhere. The scope of publication includes agricultural meteorology/climatology (the relationships between a wide range of agriculture and meteorology/climatology aspects). Articles related to meteorology/climatology and environment (pollution and atmospheric conditions) may be selectively accepted for publication. This journal is published twice a year by the Indonesian Association of Agricultural Meteorology (PERHIMPI) in collaboration with the Department of Geophysics and Meteorology, Faculty of Mathematics and Natural Sciences, IPB University.<br><br><br><br></p> The Efficiency of Water in Supporting Local Wisdom and Food Sustainability in Subak Sange, Bali Indonesia 2020-08-07T11:49:30+07:00 Ni Made Delly Resiani I Wayan Sunanjaya <p>Subak is local wisdom in Bali that has been practiced for centuries in managing irrigation water. Here we present the uniqueness of Subak to manage water with an example of Subak Sange, Gianyar, Bali. The field activity was carried out from April-September 2019. The research objectives were to analyze: (i) the characteristics of local wisdom in Subak Sange, (ii) the effect of irrigation water frequency on pest and disease outbreaks on tobacco yield, and (iii) the efficiency of water use in chili-tobacco intercropping. We combined several approaches to achieve the objectives, including an interview with farmer, diversity analysis, Romijn method, and revenue cost ratio. The results showed that the harmony of relations between farmers was bound by a belief in three elements socio-agrarian-religious. The excessive irrigation gave more pest and disease outbreaks, as shown in 6-irrigation frequencies. In addition, the occurrence of rotten root outbreaks was the highest (29%). The optimal frequency irrigation for yield of tobacco was 4-times, which produced 11.5 tons of dry chopped tobacco per hectare, and this frequency irrigation was much more efficient water use by 79% than rice plants. Based on revenue cost ratio analysis, the chili-tobacco intercropping with four times irrigation was feasible. The findings indicate that management of irrigation water in Subak Sange is promising to support food sustainability in the region.</p> 2020-08-05T00:00:00+07:00 Copyright (c) 2020 Ni Made Delly Resiani, I Wayan Sunanjaya The Potency of the Rice Crop Index Development through Adjustment of Agroclimate and Water Management Situated in Rainfed Field Gunungkidul 2020-09-09T17:17:58+07:00 Eko Srihartanto Sugeng Widodo <p>One of the strategies to increase the rice self-sufficiency is by improving the rice crop index (IP) in rainfed field areas. This paper aims to obtain the areas for IP development based on agroclimate information on the rainfed fields in Gunungkidul. The methodology of research was based on descriptive analysis, surveys and interviews involving farmers, researchers, agricultural officers, and village officials. We performed field surveys and interviews in 2016 and 2017. The surveys were carried out by identification and verification of the water sources for agriculture, determination of the appropriate water infrastructure, and determination of the areas affected by rice cultivation development. The results showed that the determination of the beginning of planting season could refer the Modern Integrated Planting Calendar (KATAM) and the estimation of the start of the rainy season by the local meteorological office (BMKG). We estimated that as many of 2,111 ha was suitable for IP 200 development, which may raise the potency of rice production to 10,058 tons (increased by 5.10%). On other hand, the IP 300 only covers the rainfed field areas of 687 ha, which has a potential rice production of 3,294 tons (increased by 1.67%). Further identification and verification are needed regarding the potency of water sources. This will determine which types of proper water infrastructure that must be provided for support the development of IP, hence the national rice self-sufficiency.</p> 2020-09-09T17:14:46+07:00 Copyright (c) 2020 Eko Srihartanto, Sugeng Widodo Analysis of Synoptic Disturbance in Maritime Continent Using Spherical Harmonics Transformation Method 2020-09-28T14:01:54+07:00 Sayful Amri Faiz Rohman Fajary Tri Wahyu Hadi <p>This study aims to modify the idea of WK99-analyzing the existence of signature in wavenumber and frequency spectrum when the analyzed Outgoing Longwave Radiation (OLR) data is associated with a unique phenomenon in Maritime Continent (MC), Borneo vortex (BV). Although BV is often related to easterly equatorial wave disturbances, there was no specific study to examine its behavior in the spectral domain. The purpose of this study is to develop a method to diagnose certain signatures of BV through spectrum analysis of OLR data when BV occurs. In contrast to previous studies, to present the unique phenomenon in MC as a target for diagnostics, spectrum analysis was performed by Spherical Harmonics (SH). This method used trigonometric and associated Legendre functions which present zonal and meridional structure, respectively. Hence, the separation of antisymmetric and symmetric patterns to the equator in this method was considered better than WK99. The results showed that the spectral signatures of BV were characterized by enhancements of westward propagating mixed Rossby gravity (MRG) with zonal wavenumbers of 5-10 and frequencies of 0.12-0.2 cycle per day (cpd) (periods of 5-8 days). Moreover, the spectrum of the wave is getting stronger for longer BV duration.</p> 2020-09-28T11:25:06+07:00 Copyright (c) 2020 Sayful Amri, Faiz Rohman Fajary, Tri Wahyu Hadi The Use of SST Anomaly to Predict Seasonal Rainfall during the Second Planting Period in the Tanoh Abee Irrigation Area, Aceh Besar 2020-09-30T14:17:48+07:00 Ahmad Farhan Yopi Ilhamsyah . Akhyar <p>Irrigation in Tanoh Abee is used for agricultural activities especially during the second planting season during dry season. However, the availability of irrigation water is controlled by total rainfall received. &nbsp;An accurate prediction of rainfall, which traditionally used “keneunong” local wisdom, is urgently required. The objective of the study is to obtain the best predictor of seasonal rainfall based on the Pacific sea surface temperature (SST) anomaly and the monthly lead time of prediction. We employed monthly rainfall from six stations surrounding the study area and combined with principal component analysis to eliminate rainfall autocorrelation. Seasonal rainfall (quarterly average) was calculated from monthly data. The results showed that 1-month lead time strongly correlated to seasonal rainfall in Tanoh Abee (r&lt;-0.7, α=5%) for the second planting period. On other hand, the 2-month and 3-month lead time were useful to predict seasonal rainfall in March-April-May (MAM) only. For April-May-June (AMJ) and May-June-July (MJJ), the correlation between SST anomaly and seasonal rainfall was weak. This finding indicated that the accuracy of prediction decreases with the longer lead time. Based on our analysis, coordinates of 170° E – 175° E; 5° N - 5° S in Niño 4 region have strongly correlated with seasonal rainfall in MAM, AMJ, and MJJ periods. Moreover, further research is necessary to combine any approaches that will improve our prediction skill for another 2- or 3-month lead time.</p> 2020-09-30T14:11:14+07:00 Copyright (c) 2020 Ahmad Farhan, Yopi Ilhamsyah, . Akhyar The Use of Dam Environmental Vulnerability Index (DEVI) for Assessing Vulnerability of Bengawan Solo Watershed, Indonesia 2020-12-14T11:53:12+07:00 RR Mashita Fauzia Hannum I Putu Santikayasa Muh. Taufik <p>Bengawan Solo is the longest river in Java, but current conditions show that its watershed is in a critical condition. Deforestation was very intensive in the last three decades that contributed to degradation of the watershed. Other factor contributing to the degradation is dam construction. However, our knowledge on the impact of dam construction on the environment and its vulnerability is poorly understood. Here, we assessed vulnerability of the watershed based on physical properties such as existing dams, morpho-dynamic activities, and deforested area. The study aims to identify the vulnerability of the Bengawan Solo watershed based on dam environmental vulnerability index (DEVI) approach, and to analyse the dominant variable contributing to DEVI. For calculating DEVI, several data were needed including land cover, rainfall, stream water stage, soil type, stream network, and dams. The results showed that Bengawan Solo watershed had moderate to high vulnerability (60%). Moderate level was identified for Madiun and Wonogiri sub-watershed, while high level was in Cepu and Babat sub-watershed. Our findings revealed that morpho-dynamic activities as represented by sediment rate and stream water stage had contributed to the high DEVI value as in Cepu and Babat sub-watershed. Further, influence of dams in this research was not dominant implying that any improvement to the DEVI approach remains research challenges. The improvement of the approach is expected to better identify the impact of dam construction on environment, situated in other regions than Amazon, where it was firstly developed.</p> 2020-12-09T11:40:58+07:00 Copyright (c) 2020 Mashita Fauzia Hannum, I Putu Santikayasa, Muh. Taufik Influence of Land Use and Rainfall on Carbon Stock Dynamics for Oil Palm and Rubber 2020-12-14T11:50:26+07:00 Oktanindita Priambodo Hariyadi Suwarto I Putu Santikayasa <p>The expansion of agricultural commodities including oil palm plantations potentially causes an increase of greenhouse gas emissions by amplifying carbon dioxide (CO<sub>2</sub>) in the atmosphere. In the long term, this amplification will alter climate change. However, oil palm also has the potency to reduce greenhouse gas emissions by absorbing CO<sub>2</sub> through photosynthesis. This study aims to determine the carbon stock that can be absorbed by oil palm and rubber plants, and to determine the relationship of rainfall with carbon stock in oil palm plants. The study used satellite image data based on Landsat and combined with rainfall data from near Perbaungan District, North Sumatra. &nbsp;Three Landsat data (acquisition date: (i) 12 February 2000, (ii) 8 March 2009, and (iii) 11 August 2019) were processed to estimate carbon stock. The procedure for estimating carbon stock was as follows: determining the sample and digitizing the sampling points, converting the digital value of the numbers into the spectral spectrum, calculating the albedo values, calculating the long-wave and short-wave radiations, computing biomass, and the absorbed carbon stock. The results showed that the carbon stock in oil palm was greater than that of rubber plants as oil palm has a greater biomass. The greater the plant biomass, the bigger the carbon stock absorbed. Further, the findings revealed that rainfall in dry season has a contribution to carbon stock in oil palm and rubber. The higher the total rainfall during dry season will increase the absorbed carbon stocks.</p> 2020-12-14T11:43:03+07:00 Copyright (c) 2020 oktanindita priambodo, Hariyadi, Suwarto, I Putu Santikayasa Determinant Factors of Food Farming Vulnerability in Banten Province To Support Climate Change Adaptation 2020-12-30T09:26:56+07:00 Suciantini Woro Estiningtyas Adi Rahman <p>Food crop is one of the most impacted agricultural sectors by climate related disaster. The negative impacts of climate related disaster could be assessed by its vulnerability level that depends on various indicators including exposure, sensitivity, and adaptive capacity. This paper aims to identify the determinant factors that influence the vulnerability of food farming&nbsp; based on the characteristics of land resources, climate and water, and socio-economic factors at the district level in Banten Province, and to develop recommendations on climate adaptation. Identification of the dominant factors, which most contribute to the level of vulnerability, is one of the main considerations to determine the strategy of adaptation. &nbsp;Our results showed that the main determinant factors varied among districts. The most important factors were Oldeman’s climate type (SEI12), the ratio of the number of extension agents to rice field area (ACI3), and the ratio of the number of farmer groups to rice field area (ACI4). SEI12 deals with the climate, whereas ACI3 and ACI4 are related human resources and institutions. Further, although urban area had high exposure and sensitivity as in rural area, but the adaptive capacity for the urban area was still high. Therefore, the level of vulnerability was reduced in urban, but still high in rural area. More efforts are expected to adapt climate related disaster in rural area.</p> 2020-12-29T14:29:26+07:00 Copyright (c) 2020 Suciantini, Woro Estiningtyas, Adi Rahman