EVALUATION OF ENVIRONMENTAL LOAD AND COST FROM ORGANIC WASTE UTILIZATION FOR FERTILIZER IN NGAWI REGENCY, INDONESIA

Sustainable agricultural land management is important to maintain the sustainability of rice production. It can be done by extensification and intensification. Intensification can be done by fertilizer utilization. Application of organic fertilizer is necessary to improve the soils, environment and rice yields. This study is aimed to measure organic fertilizer application level in Ngawi, to identify factors affecting organic fertilizer application level, to calculate the mass balance of organic fertilizer and to find out and to describe the best pattern of animal manure and rice straw management from the viewpoint of environmental load and cost to increase the amount of organic fertilizer. This study consisted of two research parts. Both are conducted by questionnaire survey. First part of this study was to investigate the current organic fertilizer application level, factors affecting the utilization of organic fertilizer, and potential amount of organic fertilizer. Analysis used in first study was statistical analysis and mass balance between organic fertilizer supply and demand. Considering manure and rice straw for organic fertilizer, the second part of this study was to propose the best pattern of manure and rice straw management using global warming potential (GWP) and costs analysis. There was 7 patterns of manure and rice straw management. Pattern 1 represented current manure and rice straw management. Pattern 2 and 3 were combination of manure and rice straw, with and without rice straw burning. Pattern 4 and 5 were combination of manure compost and rice straw, with and without rice straw burning. Pattern 6 and 7 were combination of manure-rice straw compost, with and without rice straw burning. Best pattern, then, was analyzed spatially using ArcGis software. This study found that organic fertilizer application level was low (326 kg/ha) compared to government recommendation (2000 kg/ha). However, there was imbalance between production and demand of organic fertilizer. Therefore rice straw was potential to be th source of organic fertilizer. Factors affecting organic fertilizer utilization was formal education, agricultural training, and membership in the farmer group. Current manure and rice straw management (pattern 1) generated 24,491 t CO2-eq of GWP. Costs related with current manure and rice straw management was Rp. 1,970,400. It was found that pattern 2 to 7 could increase the amount of organic fertilizer. From the viewpoint of environmental load, pattern 2 to 7 generated the lower GWP and could reduce GWP by 79 to 87% compared to pattern 1. From the viewpoint of cost, pattern 2 to 7 required larger cost compared to pattern 1. From the viewpoint of spatial, only Mantingan and Gerih district which have adequate amount of manure and rice straw to the application of pattern 5. The residue of manure and rice straw for pattern 5 from Mantingan was 733 t and 1,881 t, and from Gerih was 550 t and 1,883 t. To maintain the application of pattern 5 and sustainability of agricultural land, Ngawi is divided into 2 zone that is zone for intensive rice cultivation (Mantingan, Widodaren, Ngrambe, Kedunggalar, Paron, Geneng, Gerih, and Kwadungan) and zone for intensive animal farming (Sine, Jogorogo, Kendal, Karanganyar, Pitu, Ngawi, Kasreman, Padas, Pangkur, Bringin, and Karangjati).