Long term trends and short term fluctuations in farmers' fertilizer use in irrigated rice
1998
Moya, P.F. | Pabale, D.L. | Tiongco, M. | Dawe, D. (International Rice Research Inst. P.O. Box 933, Manila (Philippines))
A socio-economic monitoring survey included 36 sample farmers from 1987-93 to document input use, farming practices and production in irrigated rice systems of Laguna [Philippines]. Special emphasis was given to seasonal changes in farmers' fertilizer management practices with respect to quantity and type of fertilizer applied, number of timing of application, variation in farm prices of fertilizer, and rice productivity. Similar data from a periodical loop survey (1966-94) of rice farmers in Laguna was also used to analyze long term trends in fertilizer use and rice productivity. The number of timing of fertilizer application varied widely across farmers ranging from 1 to 5 in the DS [dry season] and 1 to 4 in the WS [wet season]. The timing of application fluctuated from 1-45 DAT from the 1st application, 11-70 days for the 2nd application and 30-91 days for the 3rd application. The number of fertilizer applications showed a declining trends from 1987-93, in contrast to the increasing trend for the quantity of fertilizer used. Nitrogen fertilizer was increased from 77 kg/ha in WS 1987 to 92 kg/ha in WS 1992. Similar trends occurred for P and K fertilizer. As expected, farmers, applied higher amounts of fertilizer for the DS, with applications increasing from 99 kg/ha in 1989 to 120 kg/ha in 1993. Surprisingly, fertilizer use and management also varied substantially across time for individual farmers and the paper investigated the size and nature of these fluctuations. In addition, the effects of quantity of fertilizer use, timing and frequency of application on rice yield were also analyzed in the study
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