Department of Soil and Geological Sciences

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Pedological and edaphological properties of the soils of two soil associations in the Morogoro area, Tanzania
(Trop. Agric. (Trinidad), 1982) Moberg, J. P.; Msanya, B. M.; Kilasara, M.
Pedological and edaphological properties of two soil associations forming a continuum from the Uluguru \mountain ranges to the Mindu mountain in the Morogoro area, Tanzania, have been investigated. The general /eatures of the area, including climate, geology and vegetation are discussed as is the movement of soluble salts on the slopes and its effects on soil composition. The investigation shows that there is a close connection between the three soil forming factors, climate, parent material, and relief and the mineral composition of the soils and their edaphological properties. This means that a thorough understanding of the soil forming factors and the soil development processes provides a key to land use evaluation of an area like this, where soil data often are lacking.
Classification of soil profiles from alluvial plains of greece (thessaly and pelopennesos) according to the USDA and FAO soil taxonomy systems
(Sokoine University of Agriculture, 1986) Ala Loannis
Fifty profiles are studied for reclassification according to the USDA Soil Taxonomy System, The data come from soil surveys and investigations carried out since 1977 by the Institute of Soil Classification and Mapping of Larissa and by the Agriculture Faculty of Athens. According to the USDA Soil Taconomy Stystem (1975) the studied profiles are classified in five orders i.e. Mollisols, Entisols, Vertisols, Inceptisols and Alfisols, 7 suborders, 7 great groups, 20 subgroups. In the FAO-Unesco system they fall among the Gleysols, Fluvisols, Regosols, Luvisols, Vertisols, Cambisols and among 15 subunits. There were not sufficient data for the classification purposes and this as well for the chemical analyses (base saturation, cation exchange capacity, extractable cations, sulfidic material, C/N ratio, sometimes organic matter content and amorphous material) as for the particle size analysis (fine sand, fine clay), the physical analyses (bulk density, water retension capacity, n-value, Cole), the mineralogical analyses (clay mineralogy, amorphous minerals, weatherable minirals of 20-200 micron size) and the field observa tions (designation of organic matter, rubbed, dry and moist colour, colour, quantity and size of mottles, depth of cracking pattern, presence of pyroclas tic material, presence of ground water table, orientation, vegetation). Finally many of the chemical analysis should be considered as not accurate
Tableland soil of North-Eastern Brazil:characterization, genesis and classification
(State University of Ghent, 1986) Barrera, Daniel
The coastal low level tablelands of the State of Alagoas are located in the north-eastern region of Brazil between 8° 25' and 10° 20' south latitude, and from 35° 10’ to 37° 15' west longitude of Greenwich. These surfaces formed by Tertiary Sediments are flat or slightly undulated with slopes rarely higher than 4%. It enjoys a tropical climate with a dry summer and a constant temperature throughout the year. The dominant vegetation is formed by the so-called "Atlantic Forest", presenting also minor areas of "Cerrado". Nine profiles corresponding to the soil types present in, a) the well drained surfaces of the tablelands - which classify as Oxisols, Ultisols and Oxisol-Ultisol intergrades -, and b) in poorly drained depressions - classified as Spodo-sols -, were selected for this work. The influence of the morphogenesis of the landscape and the topographical location on soil development is evident from the soils studied. The properties of the soils are strongly related to geomorphic processes. The soils were characterized in terms of their morphological, physico-chamical, mineralogical and micromorphological properties. The sedimentological analysis of the sand fraction(63 - 2000ym) was also carried out. The mineralogy of the sand fraction is similar in all profiles. The light minerals are dominant ( 91-98% ) and almost entirely composed of quartz grains and no more than traces of feldspars. In the heavy fraction the opaques are dominant, ( 84-92% ); among the transparent minerals zircon dominates, followed by tourmaline and rutile. The composition of the clay fraction is also very similar throughout the region, dominated by kaolinite and minoramounts of gibbsite and oxi-hydroxides of iron and aluminium. With the sole exception of profile 2, all the soils are developed from highly uniform parent materials. At the sametime the parent materials of the different soils are also mutually very similar from sedimentological point of view. " Selective erosion 11 of fine soil components as a consequence of run-off is throughout the plateaux the dominant morphogenetic process, which influences the physico-chemical properties, the classification and the distribution of the soils in the landscape. The micromorphological analysis indicates similar features among the dominant soils of the area; and that the illuviation of clay is present in all profiles, which however is not manifested as clay skins in the field as a result of poor structure development. The soils were classified according to Soil Taxonomy, FAO/UNESCO, the Brazilian System of Soil Classification and under the I.N.E.A.C. ( Zaire ) System.
Bodemkundige inventarissen : kwaliteit en evaluatie karakterizering, van hun geschiktheid voor specifiek landgebruik / Soil resource inventories : characterization, quality and evaluation of for their adequacy specific land use
(State University of Ghent, Belgium, 1987) Msanya, Balthazar M.
In many countries a lot of soil resource inventories (SRIs) particularly soil surveys have been made and are still being made. Their objectives are generally well stipulated and known, yet there are indications that these documents are not sufficiently being used both in developing and developed countries. It is against this background that the present study was started. The intention has been to look for ways of characterizing SRIs and to evaluate their adequacy for specified land uses. This way it was hoped that reasons behind the limited use of such documents could be identified and hence help to frame recommendations for future soil inventories. The data base in this study comprises (a) a total of 176 soil survey reports (including accompanying maps) from 46 countries, (b) 70 70 completed questionnaires from soil surveyors representing 40 countries and (c) 94 completed questionnaires from users of soil maps and reports representing 35 countries. Using the 176 SRIs, a general inventory of the documents was made as a first attempt to characterize them. Then indices to characterize the SRIs in terms of their cartographic attributes were developed. These indices were highly correlated with each other. Other observations on cartographic attributes indicated that (a) the concept of map linear reduction factors is not consistently used and (b) information on soil description sites is only rarely given in SRIs. In relation to the information content of map legends and soil reports it was observed that (a) most SRIs are produced by free survey method; (b) the most commonly used attributes in soil mapping are texture, drainage, landform, topography, parent material and soil depth; (c) information on density of field observations is often lacking in SRIs and is commonly vaguely presented; (d) USDA and FAO/Unesco classification systems are the most widely used internationally; (e) most SRIs contain interpretive data and (f) information on purity of mapping units is often not given in SRIs and in many cases only partly presented. Two methods are developd and described for estimating the utility of base maps. It was noted that many SRIs do not bear information about their compliance with specified base map accuracy standards. With regard to general legibility of SRIs, it was observed that (a) provision of instructions on how to use the SRIs is mostly neglected and (b) glossary of specialized terminology and ranges of soil properties of mapping units are commonly not provided in the documents. A method is developed and described for characterizing and systematically evaluating information given in map legends and soil reports about mapping units in function of specified land uses. Furthermore, a comprehensive method is also described for the assessment of the predictive adequacy of SRIs for three land uses in function of (a) cartographic attributes, (b) map legend and soil report attributes and (c) base map attributes. Guidelines outlining the assessment procedure are provided. This method was applied on 66 selected semi-detailed and detailed SRIs from 17 countries. Following strictly the stipulated criteria of adequacy it was found that only about 27 « of the documents are completely adequate for predicting performance of both corn and oil palm, and about 30 % can be considered adequate for predicting performance of Eucalyptus deglupta (forestry). A preliminary study on the adequacy for prediction of soil erosion hazards was done on 50 selected SRIs from 18 countries, Based on the adequacy criteria per se, it was found that most of the documents could be said to be adequate for the use in question, It was also noted that (a) although information on climate is given in all documents, winds are frequently not described; (b) information on topography is normally limited by the lack of contour lines printed with soils information or the lack of contour maps appended to the soil maps and (c) information on soil permeability is often not described. Analysis on the answers given by respondents of the questionnaire to soil surveyors shows that (a) soil surveyors to a great extent determine the nature of SRIs to be made and only occasionally do users have the opportunity to do so; (b) some terminologies and criteria used in soil survey eg. soil survey intensity, field soil mapping procedures and purity of mapping units are not conceived and used consistently; (c) most soil surveyors do not monitor utility of the SRIs they make; (d) soil maps are sometimes too complicated and (e) publicity about SRIs has not sufficiently been made. The results from the questionnaire to users of soil maps and reports indicate among other things that (a) soil surveys are still considered very important in development projects; (b) there are problems of knowing about the existence of soil maps, yet communication media such as radio, television and newspapers have not been used significantly to ameliorate the situation; (c) major problems encountered while using soil maps and reports include poor legibility, problems of location on the maps, use of vague and in some cases complicated terminology, A revised questionnaire to users of soil maps and reports has been proposed to accomodate changes that will take it more useful as a source of information. To put everything in a nutshell, it can be said that indeed, existing SRIs do present serious bottlenecks that need attention in future inventories. For this a series of recommendations has been suggested at various levels of the study.
Testing and improvement of a questionnaire to users soil maps
(Geo Abstracts Ltd, Norwich, 1987) Msanya, Balthazari, M; Langohr, R; Lopulisa, C
Ninety-four people from 35 countries responded to a questionnaire on the use of soil maps. Most respondents had used soil maps in the fields of agriculture, of forestry, soil conservation, environmental pollution and protection. 98% of the respondents had used soil maps for locating suitable areas for their professional work, 15% for teaching and research and 13% had also used soil maps to help get financial assistance. Less than half of the respondents had used interpretation maps derived from soil maps. Most maps were produced by government soil survey institutes, but 51% had also used soil maps produced by other government institutions including universities and research stations. Only 19% had used soil maps made by private soil survey organizations. Major problems encountered in using soil maps include poor legibility, problems of location on the maps, vague and complicated terminology. Most respondents felt that soil maps are essential for their projects. Only a few found soil maps completely useless. Based on the problems encountered while using soil maps, recommendations have been made to those involved in soil resource inventories. A revised questionnaire has also been proposed following comments made by the respondents of the previous one
Evaluation of Minjingu phosphate rock products as sources of phosphorus for maize and sorghum in some Morogoro and Hai soils
(Sokoine University of Agriculture, 1991) Kimbi, Gerald Gervas
Experiments effectiveness were partially of to evaluatethe acidulated phosphate rock conducted (PAPR) and non acidulated Minjingu phosphate rock (PR) as sources of for phosphorus maize and sorghum. Two studies was the test crop in the initial pot study and two field experiments were conducted.Maize in the field experiments while sorghum was used in the residual pot study.Five soils, namely Kwa Sadala, Mlama, Mafiga,Magadu and University Gate,varying widely in properties were used. Results of these experiments showed that all the P carriers increased yields in Mlama, Magadu and University Gate soils, indicating that the three soils were P deficient and thus required supplemental P. The KwaSadala and Mafiga soils, with high available P and nearly, neutral pH values, did not respond to either of the P sources.The initial PAPRs and results study indicated non ac i dulated PRs had the nearing that pot of University Gate that the fertilizer values TSPin soilsthe PAPRs and PRs were generally Mlama soil. In the Magadu and inferior to TSP. Results of the residual pot study showed that the PAPRs and PRs had superior residual effectiveness compared to TSP in Magadu, indicating that overMlama and time the P dissolved in the three soils.University Gate soils, carriers substantially
Effect of method of terracing on some physical and chemical properties of soils of Mgeta, Morogoro, Tanzania
(Sokoine University of Agriculture, 1992) Kisanga, Danielson Ramoz
A field experiment was conducted on cultivated sandy clay loam Chromic Cambisols at Mgeta on the slopes of Uluguru mountains. The objectives were to study the effects of terracing methods on some soil physical and chemical properties and to relate the results to crop performance observed in the field. The main treatments consisted of bench and ladder terraces. The subtreatments were three positions on the slope, and five 10 cm interval soil depth sections. The physical properties assessed were particle size analysis, bulk and particle densities and available water capacity. The assessed chemical properties included pH, CEC, exchangeable cations, carbon, organic total nitrogen, and available phosphorus. There available were significant water capacity, increases in exchangeable clay, silt, calcium and magnesium contents and a decreasing trend in very coarse sand particles along the slope under ladder terraces. In the bench terraces, bulk density increased slightly while total porosity decreased significantly along the slope. Most of the soil physical and chemical properties from the bench terraces were significantly different along the slope, but lacked a defined trend, Exchangeable cations, total nitrogen, and organic carbon for the two main treatments showed a decreasing trend from surface to the bottom of the soil profile. Other soil physical and chemical properties lacked defined trends with depth. The causes of the observed trends in the bench and ladder terraces are respectively attributed to the mechanical movement of soil and gradual but continuous transportation of fine soil materials by water down the slope. The variations in soil physical and chemical properties within and between the two treatments were attributed to the nature of the soils and methods used in the construction of the terraces. Variations in the studied soil properties account for the observed crop performance. In order to improve crop performance and maintain a sustainable crop production at Mgeta, several soil management and conservation measures are proposed.
The role of microaggregation in physical edaphology
(Sokoine University of Agriculture, 1993) Mtakwa, Peter W
Soil type and the previous tensile strength and penetration resistance as a (PR) should allow the soil compared ranging fail to failure planes in between the microaggregates. function of easily along Five Tanzanian soil hardsetting Paleustalf from a extreme of strength behaviour, through a Paleudoll, Paleustult, both It was expected (the strength characteristics). that microaggregation types were can I characterized soil strength by measuring affect soil strength. matric potential cultivation history of one at Paleudalf and a to a strongly microaggregated Orthox expected to be at At each site soils that had a history of the weak end of the scale. 7 or more years of cultivation and cropping were compared with newly cultivated soils. The and Orthox Paleustult had the best PR characteristic for ease of root growth and the Paleustalf had the worst characteristic which suggested that it would not permit root growth at matric suctions exceeding 100 kPa. The Orthox also had much the most favourable tensile strength characteristic. At air dryness (100 MPa suction), the previously uncultivated and previously cultivated Orthox topsoils strength. compressive) Paleustalf topsoils. Paleustult) a previous had 3 and respectively, 9 times than less the tensile (and corresponding For three of the soils (Orthox, Paleudoll and history of cultivation was found to have significantly and substantially reduced the tensile strength of the topsoil at any given matric suction compared to the newly cultivated soil
Land use and land evaluation Systems Research Project
(Sokoine University of Agriculture, 1993) Kimaro, D. N.; Msanya, B. M.; Maggogo, J. P.; Msaky, J. J.; Araki, S.; Hirai, H.
Soils and land evaluation of part of the sokoine university of agriculture farm (Tanzania) for some crops under rainfed conditions
(The Center for African Area Studies, Kyoto University, 1994) Kaaya, Abel K; Mrema, Jerome P; Msanya, Balthazar M
A detailed soil survey of about 420 ha of the central part of the Sokoine Uni versity of Agriculture farm was carried out for soil characterization. laboratory physico chemical characterization, soil classification and land suitability evaluation of the area with respect to maize (Zea mays), sorghum (Sorghum bic%r), paddy rice (Oryza sativa) and field beans (Phaseo/us vulgaris); all under rainfed conditions. The soils were mapped at 1/10,000 scale besed on slope, soil drainage, topsoil texture and effective soil depth and five mapping units were identified. Land suitability evaluation indicated that none of the identi fied mapping units was highly suitable for the above listed crops
Pedological studies and characterization of some benchmark soils of Morogoro district, Tanzania
(Sokoine University of Agriculture, 1994) Msanya, B. M.; Kaaya, A. K.; Nyadzi, G. I.
A detailed characterization of soils earmarked as "Benchmark Soils of Morogoro District" in Tanzania was carried out to provide basic data required in planning and execution of soil fertility studies in the area. Benchmark soils are defined as those occuring in extensive areas and whose comprehensive characterization could contribute substantially to transfer of agro-technology from one area to another.
Land use and land evaluation research project
(Sokoine University of Agriculture, 1994) Msanya, B. M.; Msaky, J.J.T
Land use and land evaluation research work was initiated in the Department of Soil Science of Sokoine University of Agriculture (SUA) in collaboration with the Center for African Area Studies (CAAS) and Faculty of Agriculture of Kyoto University and the National Soil Service (NSS). This research project is funded through the Japan International Cooperation Agency (JICA). Among the objectives of this research project is the development of a computer-based land evaluation system specific to and using data from Tanzania. To achieve this goal, the approach has been to direct studies on the major agroecological zones of the country. Lots of data on soils, crops and climates have been and continue to be generated (Kimaro et al., 1993; Magoggo et al., 1993) based on the concepts elaborated in the original research write-up on land use and land evaluation systems research (Msanya et al., 1991). Recently the trend has been to store these data in such a way that they can easily be retrieved by various users. This current compilation gives preliminary results and partly processed data of some agriculturally important areas including Sukumaland; Mtwara and Sumbawanga.
Socio-economics of land development for sustainable agricultural production in some villages in Mikese division, Morogoro district, Tanzania.
(1995) Shayo-Ngowi, A. J.; Msanya, B. M.; Klmaro, D. N.
The purpose of this study was to examine the socio-economics of resource use in the traditional farming system in selected villages in Mikese Division, Morogoro Rural District. Data collection was based on surveys using a structured questionnaire. Tools of analysis employed included descriptive statistics, gross margins, mUltiple regression and correlation analysis. The results reveal that most of the farmers in the survey area have one plot around the homestead and additional plots located away from the households. Households with one plot vary from 35% in Mkambarani to 45% in Fulwe. Forty to thirty five percent in Rubungo and Maseyu respectively have one plot. In basically all villages, households with 2 to 3 plots ranges between 30 and 45 percent. About 25% of the households in the villages have 4 to 5 plots. Households with more than 5 plots range from 4% in Rubungo to 10% in Maseyu. Thirty five to forty five percent of the households in the four villages have their plots located 1.0 km away from the homesteads. A greater percentage of households from Fulwe and Maseyu however, have their plots located some 2.0 km away from the homesteads. Only 20% of Rubungo and 15% of Mkambarani have their plots located 2.0 km away from the homesteads. Plots located 3-5 km away from the homesteads vary from 10-15% in Rubungo, Fulwe and Maseyu and 10-25% in Mkambarani. The average cultivated area per family ranged from 10.5 to 23.5 hectares for all crops. The main crops grown in the four villages are maize, paddy, cotton, sesame, sunflower, cowpeas and cassava. The results indicate that maize was grown in all villages and form the biggest crop farm size. Maize yields per hectare varied from 800 kilogrammes per hectare in Rubungo to 1000 kilogrammes per hectare in Mkambarani. Paddy, which forms the second biggest crop farm size is mainly grown in Mkambarani (3.5 ha per household). The other villages grow about 1.0 ha per household. Cotton which forms the third biggest farm size in the villages studied yields 2,500 kilogrammes per hectare in Maseyu and 3,500 kilogrammes per hectare in Mkambarani. Mkambarani has also the biggest hectarage of sunflower with 3.9 ha per household, followed by Rubungo, Maseyu and Fulwe with 1.4, 1.3, and 1.2 hectares per household respectively. Mkambarani appears also to lead in cassava production, 1.8 ha per household followed by Rubungo and Maseyu with 1.2 ha per household each. Fulwe has an average of 0.8 ha per household.
Pedological investigations of sites for slash and burn experiment in Lupilo village and soil erosion studies in Tukuzi village, Mbinga District, Tanzania
(Sokoine University of Agriculture and ARI Mlingano, 1995) Kimaro, D.N; Msanya, B.M; Maggogo, J.P
The study area (Mbinga district) is under the Miombo Woodland zone of Tanzania which are areas that are or at one time were under Miombo Woodlands. Two villages namely Lupilo and Tukuzi were covered in the study at the request of other scientists interested to carry out experiments respectively on "slash and burn" type of agriculture and on soil erosion. Detailed characterization of two sites representative of the two villages was done including general ecological conditions, pedological measurements and soil clay mineralogy.
Pedological investigations and land resources characterization in Lupilo village, Mbinga district, Tanzania
(Sokoine University of Agriculture and ARI Mlingano, 1995) Msanya, B. M.; Maggogo, P. J.; Kimaro, D. N.
This report describes the natural resources study of Lupilo village as part of the continuing project on the assessment of the natural resources of Mbinga district. The study involved measurements of terrain characteristics, quantitative investigations of soil properties, inventory of land use systems and an assessment of the ecological potential and constraints as determined from a balance sheet analysis of resources and land use requirements.
Investigation of the environmental attributes for agricultural development in kitanda village, Mbinga district, Tanzania
(Sokoine University of Agriculture, 1996) Msanya, B.M; Wickama, J.M; Kimaro, D.N; Maggogo, J.P; Meliyo, J.L
This report describes the study of environmental attributes of Kitanda village as part of the continuing project on the assessment of the natural resources of Mbinga district. The study involved measurements of terrain elements, quantitative investigations of soil properties, inventory of land use systems and an assessment of the ecological potential and constraints as determined from a balance sheet analysis of resources and land use requirements.
The effect of soil erosion on soil productivity under different management practices
(Sokoine University of Agriculture, 1996) Gebremedhin, Yemane Hallu
A study was conducted at Sokoine University of Agriculture, Morogoro, Tanzania, to evaluate the effect of erosion soil on soil productivity different under management practices using 10mx5m runoff plots with a 4 percent slope. (BF) ,permanent cropping(RO ,coarse mesh The treatments consisted of bare grass fine (GP) , flat mesh (FM) ,cropping medium fallow(CP) ,mesh ridge(MM) , and (CM). The CP and RC were planted with maize with a population density of 41 600 plants/ha. The FM, MM,and CM were simulated canopy covers with net shading rates of 80, 55, and 40 percent, respectively, stretched 40 cm above the surface.Runoff generated during every rainstorm was collected for determining amount of runoff, soil and nutrient losses from each treatment. Soil samples from the runoff plots taken at the beginning (initial) study were analyzed for and end (final) changes properties. Amount of nutrient loss and eroded sediments were in soil of the chemical in the runoff water determined. Grain yield and biomass were determined for the cultivated treatments. Runoff ranged from 143.9 m3/ha in the GP to 2398 m3/ha in the BF. The runoff from the BF, significantly different from all (p<0.05) other treatments. Soil GP, CP, and CM were amongst themselves and loss was between 0.09 Mg/ha in the GP and 12.49 Mg/ha in the CP. There was no significant difference in soil loss between the BF and CP treatments but they differed significantly from all other treatments.Organic carbon showed a significant decrease in the final soil samples in the BF, GP, RC, and FM treatments, while TN decreased significantly (P<0.05)in the CP,RC,and phosphorus CM treatments.Likewise, available was significantly lower in the final soil samples in the GP, CP, and FM. Surprisingly, both Na*and CEC were significantly higher in the final soil sample in some of the treatments. The BF and CP treatments lost significantly (P<0.05) more OM, nitrogen, and Ca2+ than all other treatments. The loss in AVP, K+, and significantly different Mg2+ the from (P<0.05) BF and CP were amongst themselves and from all other treatments.There was no significant difference in maize grain yield and biomass between the CP and RC. However, grain yield and biomass were higher in the RC treatment. Based on the results of this study, it has been shown that increasing canopy cover reduces nutrient losses. In addition, the runoff, ridges soil,were able and to effectively check soil erosion.
Investigation of environmental factors for Land management in Litembo village, Mbinga District, Tanzania
(Sokoine University of Agriculture and ARI Mlingano, 1996) Kimaro, D.N; Meliyo, J.L; Msanya, B.M; Maggogo, J.P; Wickama, J.M
This report describes the natural resources study of Litembo village as part of the continuing project on the assessment of the natural resources of Mbinga district. The study covers measurements of terrain elements, soil physical and chemical properties, land use systems including farming and production systems and an appraisal of the ecological potential and constraints of the village natural resources.
Distribution and characterisics of calcretes and calcrete-soil profiles on the Northern lower slopes of Uluguru mountains in Morogoro, Tanzania
(Sokoine University of Agriculture, 1997) Sentozi, Eliab
This study was conducted on the area extending northwards from the footslopes of the Uluguru mountains towards the Ngerengere river. Kihonda transect was selected for detailed characterization of different calcrete forms and the associated soils and regolith so as to understand the origin of calcretes, their characteristics and their influence on soil properties. Near Ngerengere river, the calcrete layer is considerably thinner (27.5 cm) than those on the lower slope (76 cm), midslope (135 cm), crest (106 cm) and neighbouring depression (142 cm) implying the influence of Ngerengere river on calcrete formation. Less developed calcretes occur near the river while the most developed calcretes occur at or near the crest. Nodular, honeycomb and massive calcretes are the major forms of calcretes occurring on the transect. Their proportions along the transect which reflect their lateral extension follows the order: nodular (94.9%), honeycomb (87.2%) and massive (51.3%). A considerable difference in purity exists among different calcrete forms ranging from 47.6% in nodular calcrete, 75.0% in honeycomb and 97.5% in massive form. This difference in purity is explained in terms of their difference in degree of development. A sharp di (Terence in average CaCO3 content ranging from 7.7% in soil solum to 65.0% in calcrete layer exists. The latter implies a lithological discontinuity at the soil-calcrete interface. The difference is gradual from 65.0 to 37.7% at the calcrete-regolith interface. The source of the CaCO3 in the calcretes is therefore the underlying parent material. The calcretes are mainly constituted of micritic calcite. Sparite occurs on top of massive calcrete, in fissures, voids and around the relic minerals implying a multi-phase precipitation of calcite. Minor minerals are quartz, opaline silica and feldspars. The studied calcretes were formed during the last glacial period, about 41,000 or more years ago. The gravel and soil layers are considerably younger.
Response of maize to phosphate released from Minjingu phosphate rock and farm yard manure applications in an oxic haplustult
(Sokoine University of Agriculture, 1997) Kitua, M.J.Y.
A glasshouse pot experiment was carried out to investigate the (Zea maize of response mays L combinations of MPR-Farm yard manure (FYM) applied to an Oxic Haplustult. were 0, .7.5,)to various (kraal manure),The rates of FYM applied 15 and 30 g/kg and the rates of MPR were 0, 50, 100, and 150 mg P/kg soil. The MPR-manure combinations were incubated seeds.The one for month showed results before an the sowing increase maize Bray-1-in an increase in dry extractable P by 8.3 mg P/kg soil, matter yields of 27.3 g/kg soil and phosphate uptake by 0.13%. The above increases were attributed to the P released from the solubilization of MPR and decomposition and mineralization of the farm yard manure.The small increases in Bray-lextractable phosphate increased with increasing indicate time of the gradual contact between solubilization, soil-MPR and FYM decomposition and mineralization of MPR and FYM, respectively. Response by crops to phosphate released from MPR-FYM-combinat ions' would be more pronounced when applied to the soil 6 to 12 months before planting, to ensure optimal solubilization and decomposition of the MPR and FYM, respectively.

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