Mwaganicha, Thobias Kinyamagoha2026-02-172026-02-171990https://www.suaire.sua.ac.tz/handle/20.500.14820/7323DissertationPot and field experiments were carried out to investigate the effects of different rates and sources of N in soils with different initial pH on soil chemical properties, tissue nutrient concentration, growth and yield of cotton at the University Farm, Morogoro. Nitrogen rates applied were 0,150 kg N/ha and the N sources were SA, 50, 100 and urea and CAN. The soils used had initial pH values of 4.8, 6. 1 and 6.9 and were designated as strongly acid soil (SAS), moderately acid soil (MAS) and almost neutral soil (ANS), respectively. The experimental design was a split-plot with N rates as N sources as main plot and N source plots. Soil chemical properties assessed were pH, exchange able acidity, Al, bases and Mn. Concentration of N, P, Mn were determined in Ca and leaf tissues at flowering in the pot study and at flowering and boll stages of cotton development in the field experiment. Shoot dry weight, plant heights, number of fruiting branches, number of flowers, number of bolls, number of early maturing bolls, as well as seedcotton yield and one thousand seeds weight were also determined Nitrogen application above the control significantly increased exchangeable acidity and aluminium in the SAS, the effects being mainly due to different rates of SA. Other soil chemical properties in SAS and all measured properties in MAS and ANS were not significantly affected by the rates and sources of N. Nitrogen application significantly increased N concentration in leaf tissues except that of leaf blades at flowering in SAS and in both petioles and leaf blades at boll development stage in ANS. The N concentration at flowering associated with maximum seedcotton yield was 2.0% for petiole N and 4.4% for leaf blades N. While P and Ca concentrations in leaf tissues at flowering were significantly increased due to different rates of CAN, Ca concentration was significantly decreased at 150 kg N/ha applied as SA and urea in the SAS. in leaf tissues at Manganese concentration flowering was significantly increased due to various rates of SA in the SAS, and in leaf blades at flowering and boll stages of cotton development in the ANS. Shoot dry weight, branches, plant heights, number of fruiting number of flowers and number of bolls were significantly increased by N application. Were early maturing bolls not significantly affected by N application. Nitrogen sources did not significantly affect the growth and reproductive characters of cotton, except shoot dry weight in the field experiment at flowering which was significantly increased by SA. Seedcotton yield and one thousand seeds weight were significantly increased by N application, with maximum responses being at 100 kg N/ha. Nitrogen sources had no significant effects on the yield components of cotton in the ANS. Nitrogen concentration in leaf tissues was significantly correlated with shoot dry weight and yield of seedcotton. It was therefore concluded that (i) consideration of N sources was necessary in the SAS but was appearing irrelevant in the MAS and ANS, (ii) the agronomic optimum N rate was close to 100 kg/ha for these soils and (iii) concentration of N in petioles and leaf blades at flowering could be used to assess the N I status of cotton plants with values of 2.0% and 4.1l% respectively, being tentatively suggested as optimum.enNitrogen sourcesNitrogen ratesSoil tissue nutrient concentrationSoil tissue propertiesYieldCottonGossypium hirsutum lSoilsMorogoroThesis