Agronomy Journal 94:1393-1399 (2002)
© 2002 American Society of Agronomy
PRODUCTION PAPER
Rice Response to Phosphorus Fertilizer Application Rate
and Timing on Alkaline Soils in Arkansas
Nathan A. Slaton*,a, Charles E. Wilson, Jr.b, Richard J. Normanc, Sixte Ntamatungirob
and Donna L. Frizzelld
a Dep. of Crop, Soil, and Environmental Sciences, University of Arkansas, 1366 West Altheimer Drive,
Fayetteville, AR 72704
b Rice Research and Extension Center, University of Arkansas, P.O. Box 351, Stuttgart, AR 72160
c Dep. of Crop, Soil, and Environmental Sciences, University of Arkansas 115 Plant Sci. Bldg., Fayetteville, AR
72701
d Southeast Research and Extension Center, University of Arkansas, P.O. Box 3508, Monticello, AR 71656
* Corresponding author (nslaton@uark.edu)
Received for publication December 14, 2001. Phosphorus deficiency of rice (Oryza sativa L.) in
Arkansas occurs almost exclusively on alkaline silt loam soils. Phosphorus-deficient rice has
been observed where P fertilizer was applied near the time of seeding, which suggests that
fertilizer P is rapidly converted to a form not available to flooded rice on alkaline soils. The
primary objective of this study was to evaluate rice response to P fertilizer applied at different
times. Field studies were established in six commercial rice fields. Three rates of P (9.8, 19.6,
and 39.1 kg P ha-1) were applied at four different times during the growing season including
preemergence (PRE), preflood (PF), 5 to 10 d postflood (POF), or at midseason (MS) and
compared with an untreated control. Significant grain yield increases were measured at two of
the six locations. Grain yields were maximized by application of 19.6 kg P ha-1 at the two highly
responsive sites with yield increases of 24 to 41%. Application of P fertilizer PRE, PF, and POF
were superior to MS applications, which were not different from the control. Phosphorus
concentration in harvested grain was not affected by time or rate of P fertilizer application. The
average grain P content represented 56 to 75% of the total P in the aboveground portion of rice
at physiological maturity. Broadcast applications of P fertilizer to the soil surface between
seeding and active tillering were equally effective at increasing rice yields and optimizing P
uptake on the P deficient soils.
Abbreviations: MS, midseason • PF, preflood • POF, postflood • PRE, preemergence
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