Soil samples from three (3) mapping units in Mvumi and four (4) mapping units in Mbogo Komtonga representing two irrigation schemes in Kilosa and Mvomero Districts in eastern Tanzania were collected and analyzed for different mineral elements. Using zigzag sampling techniques, 9 composite samples with three replicates were collected at depth 0 -30 cm from the delineated pedogeomorphic units at a radius of 20 m around the soil pits. Soil samples from each soil type were bulked, thoroughly mixed, sub sampled to obtain a representative composite sample, packed and sent to Mlingano National Soil Service laboratory (NSS), Tanga, Tanzania for the determination of physical chemical fertility indicators. The data showed overall significant (P ≤ 0.05) difference in fertility status in the selected irrigation schemes. The pH of top soils in Mvumi and Mbogo -Komtonga irrigation schemes ranged from 4.4 to 6.3. These were rated as extremely and/or strongly acid to slightly acid. Of the total area studied in Mvumi and Mbogo Komtonga irrigation schemes, 25.5 % is slightly acid, 40.2 % is medium acid, 31.0 % is extremely acid and 3.3 % extremely acid. Similarly, results of organic carbon (OC) determination from the top soil (0 -30 cm) samples ranged from 26.6 g kg -1 to 51.8 g kg -1 . This corresponds to 45.7 g kg -1 to 89.0 g kg -1 SOM in both irrigation schemes. The data showed that % OC in all irrigation schemes was very high in 92.2 % and high in 7.8 % of the surveyed areas. The results show that the top soils of all the surveyed areas in Mvumi and Mbogo -Komtonga irrigation schemes had N in the range of 1.2 to 3.8 mg kg -1 , 48.7 % had N below the critical limits whereas 51.3 % were above the same. Available P in both schemes range from 0.68 -6.53 mg kg -1 . Based on the generally accepted threshold P level, all the observed P values in Mvumi and Mbogo -Komtonga respectively were considered to be below the critical range. Cation exchange capacity values in most topsoil in Mvumi and Mbogo -Komtonga irrigation schemes were rated as medium or high to very high. These values range between 27.0 -54.6 cmol (+) kg -1 and were rated as medium in 25.5 %, high in 35.3 % and very high in 39.2 % of the total surveyed areas. Exchangeable Ca in the topsoil of Mvumi and Mbogo -Komtonga irrigation schemes ranged from 3.99 -31.3 cmol (+) kg-1 . These were rated as medium in 0.96 %, high in 34.3 % and very high in 70.2 %. Based on the critical limits, MV -Pa3 in Mvumi is likely to be deficient of Ca 2+ for most crops as it lies below the proposed critical limits. Exchangeable Mg 2+ in the irrigation schemes range from 0.28 -5.07 cmol (+) kg -1 , rated as high to very high. These data suggests that all the MUs except for MV -Pa3 in Mvumi and Mbogo -Komtonga have sufficient Mg 2+ supplies for crop growth. Potassium in Mvumi and Mbogo -Komtonga irrigation schemes, range from 0.61 -2.97 cmol (+) kg -1 . These were rated as medium in 64.3 % to very high in 35.7 % of the total area. The data shows that in Mvumi K is unlikely to respond similar to...

Pedogeomorphological categorization of selected soil profiles developed on alluvial deposits in Mbogo - Komtonga traditional irrigation scheme, Mvomero District in Morogoro Region, was carried out during February 2017. Using standard grids, pedogeomorphic approach and standard manuals, detailed soil survey was conducted which enabled delineation of soil mapping units from which the representative profiles were identified, described and sampled. Eighteen samples were collected at a depth of 0–30 cm and from each horizon of the selected soil Master pits and analyzed for physico – chemical characterization. Based on FAO soil survey system of classification, the representative profiles were classified as Eutric Fluvisols and/or Eutric Cambisols. The pedon was deep to moderately deep, well to moderately well drained, with brownish black clay top soils or dull yellowish brown soil colors with sub soils stratified with fS, C, CL and SCL. Top soil pH was strongly to medium acid to medium or slightly acid sub soils. OC showed no decline in soil quality. N was very low to low, P and K levels were medium to low or very low; CEC was high to very high in all the profiles. Ca2+ and Mg2+ in the top soils were high to very high and very low or low to medium in the sub soils. Na+ was rated as low to medium in the top soils of all profiles and low to very low in the sub soils. Base saturation was > 50% and was rated as high. Topsoil Bd and total porosity were ideal to medium. AWC was medium and water storage capacity (AWSC) was good and sufficient for paddy production and other upland crops. These results suggest that where the soil parameters were low to very low as for N, P and SOM should be included in the overall soil fertility management program. Soil reaction may be regulated during irrigation development by provision of sufficient drainage, discharge and flood control structures and minimum application of lime if required.

Aims: To investigate the status of microelements in the selected expanding rice production project irrigation schemes in Unguja and Pemba Islands, Zanzibar Study Design: Standard grid soil survey Place and Duration of Study: Unguja and Pemba Isles Zanzibar during October and December, 2017. Methodology: Detailed soil survey at a scale of 1:10,000 was conducted using pedogeomorphic approach from which composite soil samples were collected at a depth of 0 -30 cm. Each mapping unit had a representative profile around which soil samples were collected at a radius of 20 -30 m for microelements investigation. Results: Results showed that the status of micronutrients (Fe, Zn and Mn) in the selected irrigation schemes varied (P ≤ 0.05) with schemes and their respective mapping units, although in some cases, variations were not significant (P ≤ 0.05). In Unguja and Pemba irrigation schemes, there

A survey was undertaken to assess the soil chemical properties and fertility status in selected irrigation schemes in Unguja and Pemba Isles in October, 2017 during the short rainy seasons. These schemes include Dobi, Kwalempona, Machigini and Ole in Pemba and Bandamaji, Kibonde Mzungu, Koani, Mchangani and Mtwango in Unguja. Soil sampling was done after the soils were grouped into similar pedons following pedogeomorphic approach whereby fifteen and ten mapping units were delineated in Pemba and Unguja respectively. Using zigzag sampling techniques, nineteen composite samples were collected in quadruplicate at a depth of 0 -30 cm from the delineated pedogeomorphic units at a radius of 20 m around the soil pits. Soil samples were bulked, thoroughly mixed, sub sampled to obtain a representative sample, packed and sent to NSS laboratory for analysis. The results showed significant difference in fertility status in the selected irrigation schemes. The pH was rated as neutral to strongly acid and or very strongly acid. Of the 25 surveyed mapping units (MUs), 47% were rated as medium acid, 26% as strongly acid, 11% as slightly acid and neutral and 5% as very strongly acid. Per cent OC was high in 21%, medium in 63% and low in 16%. In Machigini irrigation scheme, a third of the MUs was rated as having high % OC compared with the two thirds with medium values. Nitrogen was very low in 89% and low in 11% of the surveyed MUs. Whereas that all the surveyed MUs had N below the threshold value (< 2 g kg -1 ), 84% had low P and 16% has medium levels of available P. CEC values were rated as medium in 32%, high in 16% and very high in 53% of the MUs surveyed. The C:N ratio suggested that SOM was of poor quality in 89% and moderate in 11% of MUs and all the MUs had C/N ratio outside the suggested range. Nutrient balance shows that Ca/Mg ratio in 58% of the MUs was optimal for most crops and 42% was non-optimal. In conclusion, the soil fertility status and overall information from this study could be used in project irrigation design and fertilizer management studies to establish nutrient and drainage requirements for rice and other crops grown in these areas.