Suria Darma Tarigan

A review of the ecosystem functions in oil palm plantations, using forests as a reference system.

Oil palm plantations have expanded rapidly in recent decades. This large‐scale land‐use change has had great ecological, economic, and social impacts on both the areas converted to oil palm and their surroundings. However, research on the impacts of oil palm cultivation is scattered and patchy, and no clear overview exists. We address this gap through a systematic and comprehensive literature review of all ecosystem functions in oil palm plantations, including several (genetic, medicinal and ornamental resources, information functions) not included in previous systematic reviews. We compare ecosystem functions in oil palm plantations to those in forests, as the conversion of forest to oil palm is prevalent in the tropics. We find that oil palm plantations generally have reduced ecosystem functioning compared to forests: 11 out of 14 ecosystem functions show a net decrease in level of function. Some functions show decreases with potentially irreversible global impacts (e.g. reductions in gas and climate regulation, habitat and nursery functions, genetic resources, medicinal resources, and information functions). The most serious impacts occur when forest is cleared to establish new plantations, and immediately afterwards, especially on peat soils. To variable degrees, specific plantation management measures can prevent or reduce losses of some ecosystem functions (e.g. avoid illegal land clearing via fire, avoid draining of peat, use of integrated pest management, use of cover crops, mulch, and compost) and we highlight synergistic mitigation measures that can improve multiple ecosystem functions simultaneously. The only ecosystem function which increases in oil palm plantations is, unsurprisingly, the production of marketable goods. Our review highlights numerous research gaps. In particular, there are significant gaps with respect to socio‐cultural information functions. Further, there is a need for more empirical data on the importance of spatial and temporal scales, such as differences among plantations in different environments, of different sizes, and of different ages, as our review has identified examples where ecosystem functions vary spatially and temporally. Finally, more research is needed on developing management practices that can offset the losses of ecosystem functions. Our findings should stimulate research to address the identified gaps, and provide a foundation for more systematic research and discussion on ways to minimize the negative impacts and maximize the positive impacts of oil palm cultivation.

Water scarcity and oil palm expansion: social views and environmental processes

Conversions of natural ecosystems, e.g., from rain forests to managed plantations, result in significant changes in the hydrological cycle including periodic water scarcity. In Indonesia, large areas of forest were lost and extensive oil palm plantations were established over the last decades. We conducted a combined social and environmental study in a region of recent land-use change, the Jambi Province on Sumatra. The objective was to derive complementary lines of arguments to provide balanced insights into environmental perceptions and eco-hydrological processes accompanying land-use change. Interviews with villagers highlighted concerns regarding decreasing water levels in wells during dry periods and increasing fluctuations in stream flow between rainy and dry periods. Periodic water scarcity was found to severely impact livelihoods, which increased social polarization. Sap flux measurements on forest trees and oil palms indicate that oil palm plantations use as much water as forests for transpiration. Eddy covariance analyses of evapotranspiration over oil palm point to substantial additional sources of evaporation in oil palm plantations such as the soil and epiphytes. Stream base flow from a catchment dominated by oil palms was lower than from a catchment dominated by rubber plantations; both showed high peaks after rainfall. An estimate of erosion indicated approximately 30 cm of topsoil loss after forest conversion to both oil palm and rubber plantations. Analyses of climatic variables over the last 20 years and of a standardized precipitation evapotranspiration index for the last century suggested that droughts are recurrent in the area, but have not increased in frequency or intensity. Consequently, we assume that conversions of rain forest ecosystems to oil palm plantations lead to a redistribution of precipitated water by runoff, which leads to the reported periodic water scarcity. Our combined social and environmental approach points to significant and thus far neglected eco-hydrological consequences of oil palm expansion.

Soil Moisture Characteristics on Several Soil Types

Soil water availability is one of the important factors injluencing plant growth. Soil that can store more water in a longer time can support a better plant growth. This study was aimed to evaluate the dynamics of soil water of four different soils with different characteristics. Four soils classes are clayey textured soils-Red Yellowish Podsolik Jasinga, Clayey textured soils-Latosol Darmaga, . Sandy Textured soil-Regosol Sindang Barang, and highly organic mater content soi/sAndosol Sukamantri. The result showed that at every-suction analyzed, Andosol Sukamantri had consistently highest water content while Regosol Sindang Barang was consistently lowest. Similar tendency wasfoundfor available water capacity. The result also showed that moisture content at Regosol decrease more rapidly than those of the other three soils. The time need to reach likely constant moisture content is variable with soil type; lowest at Regosol Sindangbarang (45 hours after completely saturated and drained) followed by Podsolik Jasinga (73 hours), Latosol darmaga (74 hours) and Andosol Sulcamatri (76 hours).

Land-use change in oil palm dominated tropical landscapes-An agent-based model to explore ecological and socio-economic trade-offs.

Land-use changes have dramatically transformed tropical landscapes. We describe an ecological-economic land-use change model as an integrated, exploratory tool used to analyze how tropical land-use change affects ecological and socio-economic functions. The model analysis seeks to determine what kind of landscape mosaic can improve the ensemble of ecosystem functioning, biodiversity, and economic benefit based on the synergies and trade-offs that we have to account for. More specifically, (1) how do specific ecosystem functions, such as carbon storage, and economic functions, such as household consumption, relate to each other? (2) How do external factors, such as the output prices of crops, affect these relationships? (3) How do these relationships change when production inefficiency differs between smallholder farmers and learning is incorporated? We initialize the ecological-economic model with artificially generated land-use maps parameterized to our study region. The economic sub-model simulates smallholder land-use management decisions based on a profit maximization assumption. Each household determines factor inputs for all household fields and decides on land-use change based on available wealth. The ecological sub-model includes a simple account of carbon sequestration in above-ground and below-ground vegetation. We demonstrate model capabilities with results on household consumption and carbon sequestration from different output price and farming efficiency scenarios. The overall results reveal complex interactions between the economic and ecological spheres. For instance, model scenarios with heterogeneous crop-specific household productivity reveal a comparatively high inertia of land-use change. Our model analysis even shows such an increased temporal stability in landscape composition and carbon stocks of the agricultural area under dynamic price trends. These findings underline the utility of ecological-economic models, such as ours, to act as exploratory tools which can advance our understanding of the mechanisms underlying the trade-offs and synergies of ecological and economic functions in tropical landscapes.

Parameter Sensitivity Test of SWAT Hydrological Model On Two Different Resolutions (Case Study: Sub-Das Cisadane Hulu, West Java)

This research was completed using mixed qualitative and quantitative methods. Field surveys were executed in sugar cane plantation throughout South Sulawesi Indonesia. Land suitability analyses were performed using a parametric approach with Storie’s index equation followed up with correlation analysis using the Pearson correlation. Results revealed that the period for sugarcane crop growth in the humid tropic relatively dry regions of South Sulawesi Indonesia lasted for the months of November to July. The land suitability for sugar cane in the research location was moderately suitable (S2c) and marginally suitable (S3c, S3s, S3s,f and S3c,w) with limiting factors such as relative humidity during crop maturation phase, the duration of sunlight, soil depth, soil texture, soil pH and soil drainage. Land suitability index at the research location ranged from 25.2 to 55.0; sugar cane yields ranged from 30.3 to 62.0 Mg ha year. Pearson correlation coefficient (r) between LSI with cane and sugar productivity were 0.81 and 0.84 respectively, signifying the strength of the correlation between the two values. This also indicates that land suitability index can be estimating the potential crop yield in the humid tropicsthat relatively dry climate regions.Field experiment with a split plot design has been carried out in order to assess the growth characteristics and yields, and effectiveness of MVA upland rice which were given potassium fertilizer in two growing seasons. MVA inoculation consisted of three treatments (without MVA, Glomus sp. and Gigaspora sp.) while potassium fertilizer consisted of five levels (0, 12.5, 25, 37.5, and 50 kg ha-1 K). The results showed that plant growth variable which was inoculated by MVA at any levels of K fertilizer was higher in the dry season than that in the wet season, whereas the opposite occurred for net assimilation rate. Potassium content of leaf tissue, shoot/root ratio, and grain weight per hill was determined and mutually dependent on genus MVA, dosages of K fertilizer, and growing season. Harvest index and grain dry weight per hill were influenced by the growing season and the genus MVA but the effect did not depend on each other. At all dosages of K fertilizer and any MVA genera, Gigaspora sp. inoculation was better than that of Glomus sp. Dry weight of grains per hill was affected by the contribution of grain content per hill, weight of 1000 grains and number of productive seedlings per hill. The optimum dosage of K fertilizer in the dry season was 32.4 kg ha-1 K with grain yield 3.12 Mg ha-1 for inoculation of Gigaspora sp., whereas the optimum dosage in the wet season was 34.2 kg ha-1 K for the treatment Glomus sp. inoculation with Gigaspora sp. in the wet season did not reach dosages of optimum K fertilizer. Keywords: Harvest index, MVA, potassium fertilizer, upland rice [ How to Cite : Natawijaya D. 2012. Increasing Growth and Yield of Upland Rice by Application of Vesicular Arbuscular Mycorrhizae and Potassium Fertilizer. J Trop Soils 17 (1): 53-60. doi: 10.5400/jts.2012.17.1.53] [ Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.1.53 ]This study aimed to examine Organonitrofos Plus fertilizer (OP) on sweet corn (Zea mays Saccharata L.) and its effect on changes in soil chemical properties of Ultisols. Organonitrofos Plus fertilizer is an enhancement of Organonitrofos fertilizer enriched with microbes at the beginning of the manufacturing process. Research was conducted in the greenhouse of Integrated Agricultural Laboratory of Lampung University. Treatment applied was a factorial of 4 t 2 t 3 with three replications in a randomized block design. The first factor was the dose of OP fertilizer (0, 10, 20, 30 Mg ha-1), the second factor was the dose of inorganic fertilizers (without inorganic fertilizers, and with inorganic fertilizers, namely Urea 0.44, 0.28 SP-36 and KCl 0.16 Mg ha-1), and the third factor was the dose of biochar (0, 10, 20 Mg ha-1). By a single OP fertilizers, inorganic fertilizers, and the interaction between the OP and the inorganic fertilizers increased the weight of dry stover, cob length, cob diameter, cob with husk and cob without husk of corn. OP fertilizers which are applied in Ultisols can improve soil fertility and increase corn production so that OP fertilizer can lessen the use of inorganic fertilizer and can be used as a substitute for inorganic fertilizer. RAE values were highest in treatment of O4K2B2 (30 Mg OP ha-1, with inorganic fertilizer, 10 Mg biochar ha-1) that was equal to 181%, followed by O2K2B3 (10 Mg OP ha-1, with inorganic fertilizer, 20 Mg biochar ha-1 ) with the difference in RAE value of 0.5%.[How to Cite: Dermiyati, SDn Utomo,n KF Hidayat, J Lumbanraja, S Triyono, H Ismono, NEn Ratna, NT Putri dan R Taisa. 2016. Pengujian Pupuk Organonitrofos Plus pada Jagung Manis (Zea mays Saccharata. L) dan Perubahan Sifat Kimia Tanah Ultisols. J Trop Soils 21: 9-17 Doi: 10. 10.5400/jts.2016.21.1.9][Permalink/DOI: www.dx.doi.org/10. 10.5400/jts.2016.21.1.9]Coco rind is a waste that if not used can cause environmental problem around the plantation. One way to utilize cocoa rind is by making it into compost which can be used as organic fertilizer. Different planting distance will affect on the number of plant population per unit area and will indirectly affect the absorption of nutrients, water and other growth factors. The purpose of this study was to determine the effect of the utilization of compost from cacao rind waste on the growth of Saccarum edule Hasskarl plant with different planting distance. The design used was to factor randomized block design with 2 replications, then there are 18 treatment combinations. In this research, the first factor of cacao rind composts comparison with cow manure consisted of three levels, they are: P1 = 50 kg; 10 kg; P2 =50 kg: 30 kg; P3 = 50 kg: 50. While the second factor uses the planting distance which consisted of three levels, they are: J1= 100 cm X 150 cm; J2= 100 cm X 100 cm; J3= 100 cm X 50 cm. Based on the research results, it shows that the best treatment of cocoa rind compost and cow manure, which affects on the number of buds is treatment P3 on 5 WAP, while the best used for the plants’ height is P2 on 3 WAP, and the best used for the leaves’ length is treatment P2 on 2 to 4 WAP.

Analisis Respon Hidrologi terhadap Penerapan Teknik Konservasi Tanah di Sub DAS Lengkong menggunakan Model SWAT

Salah satu penyebab banjir dan erosi adalah kondisi biofisik di bagian hulu Daerah Aliran Sungai (DAS) yang sudah tidak dapat mendukung fungsi hidrologis DAS. Perlu dilakukan upaya-upaya penerapan teknik konservasi tanah yang tepat untuk memperbaiki fungsi hidrologis DAS tersebut. Penelitian ini bertujuan untuk: (1) menganalisis respon hidrologi berdasarkan kondisi biofisik DAS pada tingkat analisis skala meso, dan (2) menganalisis respon hidrologi berdasarkan penerapan skenario teknik konservasi tanah. Wilayah kajian untuk penelitian adalah di sub DAS Lengkong yang terletak di bagian hulu DAS Cisadane seluas 1,788 ha. Penelitian ini dilakukan dengan menggunakan pemodelan hidrologi Soil and Water Assessment Tool (SWAT). Hasil analisis respon hidrologi terhadap penerapan skenario konservasi tanah menunjukkan Koefisien Regim Sungai sebesar 149.71 untuk skenario 1 (penanaman tanaman strip) dan 2 (penanaman pohon mengikuti kontur), sebesar 149.80 untuk skenario 3 (pembuatan teras), sebesar 150.25 untuk skenario 4 (gabungan skenario 1 dan 2), dan sebesar 149.31 untuk skenario 5 (gabungan skenario 1, 2 dan 3). Berdasarkan nisbah erosi potensial dengan erosi yang dapat ditoleransi, diperoleh indeks bahaya erosi untuk skenario 1 sebesar 2.63 (sedang), skenario 2 sebesar 2.57 (sedang), skenario 3 sebesar 0.60 (rendah), skenario 4 sebesar 2.45 (sedang), dan skenario 5 sebesar 0.44 (rendah). Penerapan teknik konservasi tanah yang mengkombinasikan penanaman pohon mengikuti kontur dan penanaman tanaman strip dengan pembuatan teras secara bersamaan, merupakan teknik konservasi tanah yang terbaik untuk memperbaiki respon hidrologi DAS, sehingga dapat direkomendasikan untuk diterapkan di sub DAS Lengkong pada khususnya, dan di DAS Cisadane bagian hulu pada umumnya.

Impact of Land Use Change and Land Management on Irrigation Water Supply in Northern Java Coast

This research was completed using mixed qualitative and quantitative methods. Field surveys were executed in sugar cane plantation throughout South Sulawesi Indonesia. Land suitability analyses were performed using a parametric approach with Storie’s index equation followed up with correlation analysis using the Pearson correlation. Results revealed that the period for sugarcane crop growth in the humid tropic relatively dry regions of South Sulawesi Indonesia lasted for the months of November to July. The land suitability for sugar cane in the research location was moderately suitable (S2c) and marginally suitable (S3c, S3s, S3s,f and S3c,w) with limiting factors such as relative humidity during crop maturation phase, the duration of sunlight, soil depth, soil texture, soil pH and soil drainage. Land suitability index at the research location ranged from 25.2 to 55.0; sugar cane yields ranged from 30.3 to 62.0 Mg ha year. Pearson correlation coefficient (r) between LSI with cane and sugar productivity were 0.81 and 0.84 respectively, signifying the strength of the correlation between the two values. This also indicates that land suitability index can be estimating the potential crop yield in the humid tropicsthat relatively dry climate regions.Field experiment with a split plot design has been carried out in order to assess the growth characteristics and yields, and effectiveness of MVA upland rice which were given potassium fertilizer in two growing seasons. MVA inoculation consisted of three treatments (without MVA, Glomus sp. and Gigaspora sp.) while potassium fertilizer consisted of five levels (0, 12.5, 25, 37.5, and 50 kg ha-1 K). The results showed that plant growth variable which was inoculated by MVA at any levels of K fertilizer was higher in the dry season than that in the wet season, whereas the opposite occurred for net assimilation rate. Potassium content of leaf tissue, shoot/root ratio, and grain weight per hill was determined and mutually dependent on genus MVA, dosages of K fertilizer, and growing season. Harvest index and grain dry weight per hill were influenced by the growing season and the genus MVA but the effect did not depend on each other. At all dosages of K fertilizer and any MVA genera, Gigaspora sp. inoculation was better than that of Glomus sp. Dry weight of grains per hill was affected by the contribution of grain content per hill, weight of 1000 grains and number of productive seedlings per hill. The optimum dosage of K fertilizer in the dry season was 32.4 kg ha-1 K with grain yield 3.12 Mg ha-1 for inoculation of Gigaspora sp., whereas the optimum dosage in the wet season was 34.2 kg ha-1 K for the treatment Glomus sp. inoculation with Gigaspora sp. in the wet season did not reach dosages of optimum K fertilizer. Keywords: Harvest index, MVA, potassium fertilizer, upland rice [ How to Cite : Natawijaya D. 2012. Increasing Growth and Yield of Upland Rice by Application of Vesicular Arbuscular Mycorrhizae and Potassium Fertilizer. J Trop Soils 17 (1): 53-60. doi: 10.5400/jts.2012.17.1.53] [ Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.1.53 ]This study aimed to examine Organonitrofos Plus fertilizer (OP) on sweet corn (Zea mays Saccharata L.) and its effect on changes in soil chemical properties of Ultisols. Organonitrofos Plus fertilizer is an enhancement of Organonitrofos fertilizer enriched with microbes at the beginning of the manufacturing process. Research was conducted in the greenhouse of Integrated Agricultural Laboratory of Lampung University. Treatment applied was a factorial of 4 t 2 t 3 with three replications in a randomized block design. The first factor was the dose of OP fertilizer (0, 10, 20, 30 Mg ha-1), the second factor was the dose of inorganic fertilizers (without inorganic fertilizers, and with inorganic fertilizers, namely Urea 0.44, 0.28 SP-36 and KCl 0.16 Mg ha-1), and the third factor was the dose of biochar (0, 10, 20 Mg ha-1). By a single OP fertilizers, inorganic fertilizers, and the interaction between the OP and the inorganic fertilizers increased the weight of dry stover, cob length, cob diameter, cob with husk and cob without husk of corn. OP fertilizers which are applied in Ultisols can improve soil fertility and increase corn production so that OP fertilizer can lessen the use of inorganic fertilizer and can be used as a substitute for inorganic fertilizer. RAE values were highest in treatment of O4K2B2 (30 Mg OP ha-1, with inorganic fertilizer, 10 Mg biochar ha-1) that was equal to 181%, followed by O2K2B3 (10 Mg OP ha-1, with inorganic fertilizer, 20 Mg biochar ha-1 ) with the difference in RAE value of 0.5%.[How to Cite: Dermiyati, SDn Utomo,n KF Hidayat, J Lumbanraja, S Triyono, H Ismono, NEn Ratna, NT Putri dan R Taisa. 2016. Pengujian Pupuk Organonitrofos Plus pada Jagung Manis (Zea mays Saccharata. L) dan Perubahan Sifat Kimia Tanah Ultisols. J Trop Soils 21: 9-17 Doi: 10. 10.5400/jts.2016.21.1.9][Permalink/DOI: www.dx.doi.org/10. 10.5400/jts.2016.21.1.9]Coco rind is a waste that if not used can cause environmental problem around the plantation. One way to utilize cocoa rind is by making it into compost which can be used as organic fertilizer. Different planting distance will affect on the number of plant population per unit area and will indirectly affect the absorption of nutrients, water and other growth factors. The purpose of this study was to determine the effect of the utilization of compost from cacao rind waste on the growth of Saccarum edule Hasskarl plant with different planting distance. The design used was to factor randomized block design with 2 replications, then there are 18 treatment combinations. In this research, the first factor of cacao rind composts comparison with cow manure consisted of three levels, they are: P1 = 50 kg; 10 kg; P2 =50 kg: 30 kg; P3 = 50 kg: 50. While the second factor uses the planting distance which consisted of three levels, they are: J1= 100 cm X 150 cm; J2= 100 cm X 100 cm; J3= 100 cm X 50 cm. Based on the research results, it shows that the best treatment of cocoa rind compost and cow manure, which affects on the number of buds is treatment P3 on 5 WAP, while the best used for the plants’ height is P2 on 3 WAP, and the best used for the leaves’ length is treatment P2 on 2 to 4 WAP.

Methods for Delineating Degraded Land at Citarum Watershed, West Java, Indonesia

This research was completed using mixed qualitative and quantitative methods. Field surveys were executed in sugar cane plantation throughout South Sulawesi Indonesia. Land suitability analyses were performed using a parametric approach with Storie’s index equation followed up with correlation analysis using the Pearson correlation. Results revealed that the period for sugarcane crop growth in the humid tropic relatively dry regions of South Sulawesi Indonesia lasted for the months of November to July. The land suitability for sugar cane in the research location was moderately suitable (S2c) and marginally suitable (S3c, S3s, S3s,f and S3c,w) with limiting factors such as relative humidity during crop maturation phase, the duration of sunlight, soil depth, soil texture, soil pH and soil drainage. Land suitability index at the research location ranged from 25.2 to 55.0; sugar cane yields ranged from 30.3 to 62.0 Mg ha year. Pearson correlation coefficient (r) between LSI with cane and sugar productivity were 0.81 and 0.84 respectively, signifying the strength of the correlation between the two values. This also indicates that land suitability index can be estimating the potential crop yield in the humid tropicsthat relatively dry climate regions.Field experiment with a split plot design has been carried out in order to assess the growth characteristics and yields, and effectiveness of MVA upland rice which were given potassium fertilizer in two growing seasons. MVA inoculation consisted of three treatments (without MVA, Glomus sp. and Gigaspora sp.) while potassium fertilizer consisted of five levels (0, 12.5, 25, 37.5, and 50 kg ha-1 K). The results showed that plant growth variable which was inoculated by MVA at any levels of K fertilizer was higher in the dry season than that in the wet season, whereas the opposite occurred for net assimilation rate. Potassium content of leaf tissue, shoot/root ratio, and grain weight per hill was determined and mutually dependent on genus MVA, dosages of K fertilizer, and growing season. Harvest index and grain dry weight per hill were influenced by the growing season and the genus MVA but the effect did not depend on each other. At all dosages of K fertilizer and any MVA genera, Gigaspora sp. inoculation was better than that of Glomus sp. Dry weight of grains per hill was affected by the contribution of grain content per hill, weight of 1000 grains and number of productive seedlings per hill. The optimum dosage of K fertilizer in the dry season was 32.4 kg ha-1 K with grain yield 3.12 Mg ha-1 for inoculation of Gigaspora sp., whereas the optimum dosage in the wet season was 34.2 kg ha-1 K for the treatment Glomus sp. inoculation with Gigaspora sp. in the wet season did not reach dosages of optimum K fertilizer. Keywords: Harvest index, MVA, potassium fertilizer, upland rice [ How to Cite : Natawijaya D. 2012. Increasing Growth and Yield of Upland Rice by Application of Vesicular Arbuscular Mycorrhizae and Potassium Fertilizer. J Trop Soils 17 (1): 53-60. doi: 10.5400/jts.2012.17.1.53] [ Permalink/DOI: www.dx.doi.org/10.5400/jts.2012.17.1.53 ]This study aimed to examine Organonitrofos Plus fertilizer (OP) on sweet corn (Zea mays Saccharata L.) and its effect on changes in soil chemical properties of Ultisols. Organonitrofos Plus fertilizer is an enhancement of Organonitrofos fertilizer enriched with microbes at the beginning of the manufacturing process. Research was conducted in the greenhouse of Integrated Agricultural Laboratory of Lampung University. Treatment applied was a factorial of 4 t 2 t 3 with three replications in a randomized block design. The first factor was the dose of OP fertilizer (0, 10, 20, 30 Mg ha-1), the second factor was the dose of inorganic fertilizers (without inorganic fertilizers, and with inorganic fertilizers, namely Urea 0.44, 0.28 SP-36 and KCl 0.16 Mg ha-1), and the third factor was the dose of biochar (0, 10, 20 Mg ha-1). By a single OP fertilizers, inorganic fertilizers, and the interaction between the OP and the inorganic fertilizers increased the weight of dry stover, cob length, cob diameter, cob with husk and cob without husk of corn. OP fertilizers which are applied in Ultisols can improve soil fertility and increase corn production so that OP fertilizer can lessen the use of inorganic fertilizer and can be used as a substitute for inorganic fertilizer. RAE values were highest in treatment of O4K2B2 (30 Mg OP ha-1, with inorganic fertilizer, 10 Mg biochar ha-1) that was equal to 181%, followed by O2K2B3 (10 Mg OP ha-1, with inorganic fertilizer, 20 Mg biochar ha-1 ) with the difference in RAE value of 0.5%.[How to Cite: Dermiyati, SDn Utomo,n KF Hidayat, J Lumbanraja, S Triyono, H Ismono, NEn Ratna, NT Putri dan R Taisa. 2016. Pengujian Pupuk Organonitrofos Plus pada Jagung Manis (Zea mays Saccharata. L) dan Perubahan Sifat Kimia Tanah Ultisols. J Trop Soils 21: 9-17 Doi: 10. 10.5400/jts.2016.21.1.9][Permalink/DOI: www.dx.doi.org/10. 10.5400/jts.2016.21.1.9]Coco rind is a waste that if not used can cause environmental problem around the plantation. One way to utilize cocoa rind is by making it into compost which can be used as organic fertilizer. Different planting distance will affect on the number of plant population per unit area and will indirectly affect the absorption of nutrients, water and other growth factors. The purpose of this study was to determine the effect of the utilization of compost from cacao rind waste on the growth of Saccarum edule Hasskarl plant with different planting distance. The design used was to factor randomized block design with 2 replications, then there are 18 treatment combinations. In this research, the first factor of cacao rind composts comparison with cow manure consisted of three levels, they are: P1 = 50 kg; 10 kg; P2 =50 kg: 30 kg; P3 = 50 kg: 50. While the second factor uses the planting distance which consisted of three levels, they are: J1= 100 cm X 150 cm; J2= 100 cm X 100 cm; J3= 100 cm X 50 cm. Based on the research results, it shows that the best treatment of cocoa rind compost and cow manure, which affects on the number of buds is treatment P3 on 5 WAP, while the best used for the plants’ height is P2 on 3 WAP, and the best used for the leaves’ length is treatment P2 on 2 to 4 WAP.

KAJIAN PENGARUH SITU TERHADAP RESPON HIDROLOGI DI DAS PESANGGRAHAN MENGGUNAKAN MODEL HEC-HMS

Pesanggrahan river with total extent of watershed about 13,384 ha is one of rivers flowing through Jakarta City that causes flood problem every years. Many effort has been done to reduce flood problem, among others is to build reservoir in watershed, but the effectiveness of reservoir is still questionable. A research aimed to analyze gap of reservoir capacity changes and its influence on hydrological response and to arrange the scenario of reservoir capacity change to improve hydrological response in Pesanggrahan Watershed was done using HEC-HMS Model. Reservoir capacity change scenarios applied to the actual rainfall condition and designed rainfall condition with a certain recurrence interval. The scenarios consist of: reservoir with the exsisting condition (scenario 1), increase depth of reservoir to 5 meters (scenario 2) and build 6 reservoirs on Pesanggrahan watershed (scenario 3). The model was calibrated using daily discharge data from the date of January 10th to April 30th 2009. Model calibration result shows that model is quite accurate to predict peak discharge in Pesanggrahan Watershed with Nash-Sutcliffe efficiency value = 0.9817 and R2 =0.975. Simulation results showed that the reservoir is effective in decreasing its local effect to peak discharge (reservoir area). The presence of reservoir with existing condition reduce only 6.38 % of the peak run off in outlet Kebon jeruk, whereas building of 6 reservoir will reduce 24.6 % of the peak run off in outlet Kebon jeruk. Keywords : HEC-HMS Model, peak discharge, Reservoir capacity change