XU, FANGSEN, GOLDBACH, HEINER E., BROWN, PATRICK H., BELL, RICHARD W., FUJIWARA, TORU, HUNT, CURTISS D., GOLDBERG, SABINE, SHI, LEI, Rashid, A., Yasin, M., Ali, M. A., Ahmad, Z., and Ullah, R.
Rice (Oryza sativa L.), the world's leading staple food, is grown on 2.3 M ha alluvial, calcareous, low organic matter soils of Pakistan, giving an average paddy yield of 2.000 t ha-1 (GOP 2004). As fertilizer use in rice predominantly pertains to nitrogen (N), and to a lesser extent to phosphorus (P) and zinc (Zn) (Rashid et al. 2000), one major cause of low farm-level productivity compared with much higher potential yields (i.e. 4.00-4.50 t ha-1, M. Akram, personal communication) is inadequate and imbalanced nutrient management [ABSTRACT FROM AUTHOR]