Boron Fertilization of Rice
David Dunn and Sarah Jones
In this two year study, a location at the Missouri Rice Research Farm that tested low in soil boron (0.19 ppm average) was used to conduct this evaluation. Kaybonnett rice was drill seeded at a rate of 75 lb/a. Weeds were controlled with propanil applications, at 3 lb./acre when the grass had 2-3 leaves and then reapplied approximately 14 days later, shortly before flood establishment (Stam 3+3 program). No insect control was necessary. In this study four Boron application rates, .25, .50, .75, and 1.0 lb B/a, were compared to an untreated check. Two application methods, preplant soil applied and preflood (first tiller) foliar spray, were evaluated for each boron rate. Soil samples were collected prior to flooding from each plot receiving preplant boron.
These soil samples were tested for plant available boron. Each plot was mechanically harvested and the yield recorded.
All boron applications increased rice yields over the untreated check (Table 1). In 1999, the foliar applications produced higher yields than soil applied boron. The average for all four boron treatments in an application type was also greater in the foliar in the first year of the project. In 2000, the soil application for the same rate of fertilizer was greater. The same is also true for the 2000 average for the four treatments. The two year average, however, showed the soil applications produced greater yields for the same boron application rate. The 0.5 lb B/a for both soil and foliar applications (170bu/acre) showed the greatest increase compared to the untreated check (145 bu/acre)
Table 1. Average rough rice yields for boron
treatments in 1999 and 2000 for the rice variety
Kaybonnett.
lb. B/a Application Average rough rice
type yields (bu/a)
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1999 2000 Mean
0 146 144 145
0.25 Soil 150 165 158
0.5 Soil 151 189 170
0.75 Soil 150 173 162
1.0 Soil 147 185 166
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Average Soil 150 178 164
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0.25 Foliar 151 169 160
0.5 Foliar 160 180 170
0.75 Foliar 149 157 153
1.0 Foliar 151 154 153
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average Foliar 153 165 159
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Soil applications of boron increased plant available soil test levels (Table 2). The magnitude of this increase was not consistent with the application rate.
Table 2. Average soil test B levels for
preplant soil applied treatments.
lb B/a Application Soil Test B in ppm
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1999 2000 Mean
0 0.17 0.21 0.19
0.25 Soil 0.24 0.30 0.27
0.5 Soil 0.43 0.33 0.38
0.75 Soil 0.37 0.42 0.40
1.0 Soil 0.49 0.54 0.52
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