Identification and correction of some micronutrient constraints in a volcanic soil from Mpangala village, Makete district for optimization of maize yields.
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Date
2003
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Sokoine University of Agriculture
Abstract
A study was conducted in field and glasshouse conditions to identify and correct
some micronutrient constraints in Mpangala volcanic soil for optimization of maize
yields. The study involved routine soil analysis, pot experiments and a field
experiment. Soil analysis revealed the level of Cu to be 0.14 mg kg*1, which was
ranked as deficient; Zn was 0.86 mg kg' (marginal) and boron was 0.52 mg kg"1
(medium). In the first pot experiment, P and N were applied at constant rates of 160
mg kg'1 and 240 mg kg'1, respectively. However in one treatment a higher rate of 320
mg P kg-1 was applied in order to test whether a higher rate of P was still required in
Mpangala soil. Boron was applied at rates of 0 and 2 mg-kg'1, Cu at rates of 0 and 5
mg kg'1 and Zn at rates of 0 and 10 mg kg-1. The results indicated that a combination
of Cu, N and P increased yields dramatically. Moreover the treatment that received
the high P rate of 320 mg kg'1 together with N, B, Cu and Zn fertilizers had
significantly (p = 0.05) higher DM yield than the Cu treatment. Analyses of plant
leaves showed very low concentrations of Cu followed by Zn. However, Zn did not
increase DM yield significantly. It was concluded that Zn may be the next limiting
nutrient after Cu. A second pot experiment was conducted to estimate the optimum
rate of Cu. Nitrogen and P were applied at constant rates of 240 and 320 mg kg",
respectively, and Cu at rates of 0, 5, 7.5, 10, 15 or 20 mg Cu kg'1. The experiment
indicated the rate of 20 mg Cu kg'1 to be optimum in Mpangala soil. In the field
experiment, significantly (p = 0.05) higher grain yield of 5.84 ton ha'1 was obtained
when 2.5 kg Cu ha-1 was applied. The results in this study revealed that Cu was the
most limiting micronutrient in Mpangala soil, followed by Zn. Zinc may need to be
added in addition to Cu, after one harvesting cycle, in order to provide proper
nutrition to the maize crop in the long run. Higher rates of N and P may still be
beneficial, especially if Cu and Zn are optimized.
Description
Dissertation
Keywords
Soil moisture, Soil texture, Parent material, Boron