Browsing by Author "Mrema, J.P."
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Item Effect of Minjingu phosphate rock (MPR) and farmyard manure (FYM) applied to an oxic haplustults on Bray-1-P and the response of maize to applied MPR and FYM(2003) Kitua, M.J.K.; Mrema, J.P.A glasshouse pot experiment was carrriedout at SUA farm, Morogoro. Tanzania to investigate the effect of Minjingu phosphate rock (MPR) and farmyard manure (FYM) applied to an Oxic Haplustults on Bray I-P and the response of maize (Zea mays (L.) variety staha) to the applied MPR and FYM in a 4 factorial experiment in a completely randomized block design. MPR was applied at the rates of 0.50. 100 and 150mg P kg-1 soil and FYM at the rates of 0.7, 5.15 and 30g kg-1 soil. The MPR and FYMwe re thoroughly mixed with 4.5 kg of 4mm sieved soil sample portions- in 5-litre capacity plastic pots and incubated at 75% field capacity moisture content for 28 days before sowing four maize seeds and thinned t0 two plants one week after germination. The whole plant portions above the soil level in the pots were harvested at the age of 6 weeks for dry matter yields and P content determinations. The highest MPR and FYM combination increased the amounts of Bray - 1-P by 268% and maize dry matter yields by 91%. compared to the control. The above increases were attributed to the dissolution of the MPR and the decomposition and mineralization of the FYM hence releasing P and reducing the P-retentibn capacity of the soil and improvement soil physical, chemical and biological soil conditions by the applied FYM.Item Potential of cowpea, pigeonpea and greengram to supply mineral N to maize in rotation on ferralsols in Muheza Tanga- Tanzania(2008-06) Marandu, A.E.T.; Mrema, J.P.; Nyaki, A. S.; Semu, E.A rotational field experiment of cowpea, pigeonpea and greengram with maize as married out for two rotational cycles to determine the potential of the legumes to supply N to the subsequent maize. The experiment was carried out on sandy clay Rhodic Ferralsol with bimodal rainfall pattern. The legumes were planted during the short rain season followed by maize during long rains. Soil was sampled from 0 - 20 em layer before maize planting from plots where the legumes were grown and from continuous maize plots. The composite soil samples were sieved through 6 mm screen while fresh. Sub samples equivalent to 250 g each were incubated in 500 ml wide mouth volumetric flasks at 60% field capacity and room temperature for 42 days. Destructive samplings were done at 14 days intervals and analysed for mineral N (NH4+ and N03-). The quantities of mineral N increased with incubation time. Most of the mineral N was mineralised between 0 and 14 days of incubation. Out of the total N mineralized during the entire incubation period, the proportions of the mineral N determined at the 14th day sampling were 64% for the cowpea, 50% for the pigeonpea, 73% for the greengram and 88% for the continuous maize plots. Such high proportions indicate that the subsequent maize would obtain maximum N during these early stages of growth. It was concluded that there is lack of synchrony between the release of mineral N and the maize crops' N demand which lead to the maize N deficiency symptoms and low yields observed in the legume - maize_cropping system.Item The status of Zn, Cu, Mn, and Fe in the soils and Tea- Leaves' of-Kibena -'Tea. Estates, Njombe, Tanzania(2006) Kitundu, K.M.B.; Mrema, J.P.A study was undertaken to assess Zn,- Cu;- Mn, and Fe status of the soils and tea plants at Kibena Teat Estates in Njombe, Tanzania. Low yields oltea in these estates pro,mpted this study to identifY some of the constraints to tea production. Twenty four composite soil samples were randomly collected to a 'depth of 0-40cm from the six divisions of the Kibena Tea Estates, namely; North, Lihogosa, Kilole/o; -Central, Matombololo, and [tambo. -The third leaf of the tea plants were harvestedJrom plants close to where the soils were sampled. The soils and leaves were analyzedfor available and contents ofZn, Cu, Mn/and Fe, respectively. DTPA extract' able Zn and Cu were consistently low"in almost all the soil samples, which ranged from 0.08 to 0.93 mg Znkg,J and 0.04 to 0.34 mg.Cukg~J soil. On the other hands, Fe and Mn were sufficientfor the tea plants and ranged from '26. 88 to 60.28 mg Fekg'J and 7.65 to 31.18 mg Mnkg'J soil. The plant leaf Mn, and Zn were above the critical levels in most of the plant samples, a reflection of their high contents in the soils and foliar application at a rate of 2 kgha,J, respectively. Although Fe was observed to be sufficient in soils, it was poorly reflected in tea leaves of which 65.22% of samples were deficient. This phenomena is explained by high levels of Zn in tea leaves which reduces the uptake of Fe from soils. The low content of Cu in leaves are consequences of low level of extractable Cu in soils .and - high levels of Fe in soils which induces Cu deficiency. The availability of Cu, Zn, Mn and Fe were largely controlled by the pH of the soils which ranged from 4.01 to 5.51. Application ofCu and Znfertilizers were recommended as soil fertility management strategies for sustainable tea production at the Kibena Tea Estates