Response of maize and rice to applied zinc in some benchmark soils of Morogoro rural district
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Date
1992
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Publisher
Sokoine University of Agriculture
Abstract
A study was undertaken to evaluate the response of maize and rice to Morogoro District. applied Zn in benchmark soils of Thirteen bulk soil samples were collected from the benchmark sites. Zinc from these soils was extracted with four commonly used namely 0.005M DTPA (pH 7.3), EDTA-(NH4)2CO3 HC1, and 0.05N HC1 + 0.25N H2SO4. Response of maize and rice Zn extractants (pH 8.6), 0. IN in these assessed in two glasshouse experiments. viz: soils was Three rates of Zn 0, 2.5 or 5 mg/kg soil were applied. These treatments received recommended levels of N, P and K. Field experiments were also conducted sites, two for rice and nine for maize. At eleven Zinc rates of 0, 5, 10 or 15 kg Zn/ha applied together with were recommended rates of N, P and K.. Zinc application significantly increased dry matter yield of plants. Of the four extractants tested, DTPA was found most suitable for assessing available Zn ppm. in the soils. The critical level for this extractant was 1.95 edta-(nh4)2co3 came second. The other two did not give significant correlations with plant uptake. Critical level of Zn for maize in these soils were established at 1.95, 1.3, (NH4)2CO3), 3.0 and 0.1 0.5 ppm by 0.005M DTPA, IM EDTA N HC1 and 0.05 HC1 + 0.25 N H2SO4, respectively. The critical Zn level in maize shoots was estimated to be 17 ppm. On the basis of the critical level established out of 43 samples analyses to gauge the Zn status 65% of these soils tested levels. Were deficient and 35% had adequate Zn Field experiments with rice confirmed the need for Zn application in Dakawa 2 where grain yield increased by 653% after Zn supplementation. A rate of 10 kg Zn/ha is tentatively recommended for use in this soil. Field experiments with maize gave inconclusive results because of moisture stress which dominated prior to the tasselling stage. Therefore additional experiments are recommended.
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Dissertation
Keywords
Maize, Rice applied zinc, Benchmark soils, Morogoro rural district