Ladiyani R. Widowati, Dedi Nursyamsi, Sri Rochayati, Mufrizal Sarwani
Increasing food demand in a growing population country such as Indonesia needs much effort to improve food crop productivity. This can be reached by increasing cropping intensity and providing sufficient fertilizer. The proper fertilizer management should be follow. However, in Indonesia, farmers prefer to apply nitrogen fertilizer (i.e urea) rather than other nutrient fertilizers such as P and K, due to quick and high respond of N application to the plant. As the result, inefficiency of N fertilizer used has widely reported. Case study in Kediri-East Java has reported that most of farmers used to apply urea about 400 to 500 kg ha-1 and 600 kg ha-1for lowland rice and maize, respectively. Another study in Wonosobo-Central Java showed that farmers apply around 800 to 1000 kg ha-1 for potato. Inspite of low efficiency N fertilizer use, an excess of N fertilizer application causes environmental pollution. According to the Directorate General of Food Crops (2010), N fertilizer consumption in form of urea has reached 6.69 million tons. Several studies have reported the impact of excessive use of N fertilizer to the environment. The excessive use of N fertilizer in farming system may result in N toxicity in drinking water as well as N2O emission, leaching, run off, erosion, and N imbalance. This information should be used as a base to control and regulate the fertilizer use in agricultural system. Indonesian Ministry of Agriculture launched a decree of a site specific fertilizer recommendation for lowland rice in 2007 called Peraturan Menteri Pertanian No. 40/Permentan/OT.140/04/2007. This regulation should be implemented not only by farmers and extension workers but also by regional and local governments. Several studies showed that a site specific balanced fertilization significantly increased fertilizer use efficiency and rice yield. In addition, Indonesian Soil Research Institute (ISRI) has developed a paddy soil test kit (PUTS) and an upland soil test kit (PUTK) for better fertilizer recommendation. Indonesia has also adopted the technologies developed by IRRI (LCC=Leaf Color Chart) and by IPNI (SSNM=Site Specific Nutrient Management) to increase the efficiency use of N fertilizer. In general, the N management technology, such as the application of slow release urea, the introduction of N fixing microorganism, organic matter and water management, has been utilized. However, it still could not reduce the occurance of N loss through surface run off and downward movement (leaching) as well as erosion. The soil conservation practiced in upland soil through the management of organic materials (hedgerow, alley cropping, cover crop) may improve soil organic carbon and soil moisture. This practice may decrease a soil erosion problem. The losses of N through several processes mentioned above could not be avoided. Hence, the improving of N fertilizer efficiency in agriculture land has not been successful yet. Therefore, soil care and fertility management (especially N Fertilizer) are required to sustain agricultural land in Indonesia. In addition, to improve food crop productivity, the government through Indonesian Agency for Agricultural Research and Development (IAARD) focuses on the national program of integrated nutrient management based on a balanced nutrient.
Keyword: nitrogen, efficiency, loss, technology
Paper published in Proc. of Int. Seminar on Increased Agricultural Nitrogen Circulation in Asia: Technological Challenge to Mitigate Agricultural N Emissions. Taipei, Taiwan, Sep. 27‐28, 2011