Assessment of residual effects of long term use of NPK: b formulation on tobacco yeld and quality in Tabora region
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Date
2011
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Sokoine University of Agriculture
Abstract
The assessment of residual effect of long term use of NPK plus B formulation on tobacco
yield and quality involved soil sampling from four districts; Urambo, Uyui, Tabora and
Sikonge. There were two experiments each one with six treatments: pot experiment at ARI
Tumbi had three replications while field experiment at Ntalikwa village had four
replications. Data collected were; leaf length, green and dry weights grade index and
nutrients concentration in plant leaves. The results showed that; total nitrogen was very
low (0.03 to 0.18%). Phosphorus was low to medium (5.62 to 60.83 mg/kg soil).
Exchangeable potassium was, low to very high (0.06 to 0.81), exchangeable calcium was
very low to high (0.01 to 4.4). The cation exchange capacity (CEC) of the soils was low;
6.4 to medium 23.33 me/100 g soil. Tobacco grown in Isenga soils (sandy soils) and
Kikungu soils (Alfisols) had good performance in T2 (40.5 mg N kg’1 ) while Tobacco
grown in Mbuga soils (Vertisols) had good performance in T3 (recommended rate 300 mg
N kg'1, 238 mg P kg'1, 598 mg K kg'1 and 3 mg B kg'1 soil). The increase in rates of
NPK+B and CAN, Mg, Zn caused death of tobacco in treatments 4, 5 and 6 possibly due to
B toxicity. In the field experiment the current formulation, T3 (NPK + B (10:18:24 +0.1
and 5 g CAN) produced below treatment 4, 5, and 6. Dry weight yield and quality
increased in treatments with higher rates of NPK+ B formulation with Zn and Mg than the
current recommendation. The highest yield was from T6 (2488.12 kg ha’1). Residual
nutrients T1 yielded 1411.89 kg ha’1 of dry leaf of tobacco. In general, low residual
nutrients in Tabora soils need new formulations which include Mg and Zn to improve yield
and quality of tobacco.
Description
Master's Theses
Keywords
Long term use- NPK, Tobacco yeld, Tobacco quality, Tabora region