Benefits of real-time fertilizer management within 4 years in 2 long-term experiments (IRRI & PHILRICE)

Issue Date

12-2005

Abstract

Long-Term Fertility Experiments (LTFE) began at the International Rice Research Institute (IRRI) in 1964 and at the Philippine Rice Research Institute (PhilRice) in 1968 to assess the effect of intensive double rice cropping on yield, productivity, and sustainability of rice production. The increasing cost of N fertilizer and concern for the environment led to the investigation of real-time N fertilizer management as a strategy for efficient use of fertilizer N. In real-time N management, the color of the rice leaf is monitored at 7- to 10-day intervals using a leaf color chart (LCC), and N is applied whenever leaf color is more yellowish green than the critical value on the LCC. We report the effects of real-time N management on yield, fertilizer use, and sheath blight at both locations from 2001 to 2004. Real-time N management in the dry season (DS) reduced N fertilizer use by 45 to 80% compared to conventional N management with a fixed seasonal N rate of 210 kg N/ha, while achieving comparable or higher yields of 6 to 8 tons/ha. The seasonal rate of 210kg N/ha, which has been used since the early 1990s, was selected to ensure sufficient N to achieve 9 tons/ha, but climate limited attainment of this yield target in nearly all years. Real-time N management in the wet season (WS) resulted in N inputs ranging from 88 to 113% of the conventional N management with fixed seasonal rate of 80 kg N/ha, although similar yields were produced. The agronomic efficiency of N fertilizer with real-time management in the DS was 19 to 49 kg increase in grain/kg N fertilizer while it was 12 to 22 kg/ with conventional N management. In the WS, the agronomic efficiency with real-time management was 18 to 38 kg/kg while it was 12 to 30 kg/kg for the 80 kg N/ha rate. Real-time N fertilizer management can increase N use efficiency and maintain or increase yields. Results of the study support a fertilizer N management practice development for site-specific nutrient management (SSNM) in the Philippines.

Source or Periodical Title

Philippine Journal of Crop Science

ISSN

0115-463x

Volume

30

Issue

3

Page

37-51

Document Type

Article

Frequency

tri-quarterly

Physical Description

tables/graphs/pictures

Language

English

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