Department of Soil and Geological Sciences

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Browsing Department of Soil and Geological Sciences by Author "Amur, N."

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    Fertility of soils cropped to rice (oryza sativa, L.) in Eastern Same District, Kilimanjaro Region, Tanzania.
    (UNISWA Journal of Agriculture, 2006) Amur, N.; Semu, E
    Decline in soil fertility has been found to be the main cause of low rice yields in many soils of Tanzania. The objective of this study was to evaluate the effects of N, P, K and Zn on their uptake by lowland rice (Oryza sativa, L.) grown in nutrient-deficient soils of Same district. Three bulk soil samples, which were low in some macro- and micro-nutrients, were collected from Kisiwani, Ndungu and Kihurio, and used for pot experiments. The response of rice (Oryza sativa, L., cv super SSD5) to N, P, K and Zn was assessed in a glasshouse experiment where plants were grown for 56 days. Plant samples were analysed for N, P, K, Ca, Mg, Zn and Fe after digestion with HNO 3-H20 2. The results showed that N, P and K increased uptake of each mineral nutrient by rice plants, in all the soils used. For example, N alone increased N uptake from 5.8 to 28.4, 8.3 to 37.0, and 3.6 to 14.2 mg/plant in Ndungu, Mbugani and Kimunyu soils, respectively. Zinc, in addition to N, P, and K, increased the nutrient uptake even further. The uptake of each nutrient applied was consistent with the increase in dry matter yields and nutrient concentrations in rice shoots reported earlier. It was thus confirmed that these soils were deficient in N, P and Zn. Iron was required in the Kisiwani (Mbugani) soils, which were severely deficient of this element.
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    Fertility of soils gropped to rice (oryza sativa, l.) in eastern Same District, Kilimanjaro Region, Tanzania
    (Sokoine University of Agriculture, Tanzania., 2006) Amur, N.; Semu, E.
    Decline in soil fertility has been found to be the main cause of low rice (Oryza sativa L.) yields in many soils cropped to rice in Tanzania. The objective of this study was to evaluate the effects of N, P, K and Zn on shoot dry matter (DM) yields of lowland rice plants grown in some soils of Same district. Three bulk soil samples were collected from Kisiwani (Mbugani), Ndungu and Kihurio (Kimunyu), which were found to be deficient in some macro- and micro-nutrients following laboratory soil analysis, and were used for this pot experiment. The responses of rice variety, super SSD5 to N, P and K, as well as to different levels of Zn, were assessed in a glasshouse experiment where plants were grown for 56 days. The results showed that N, P and K increased rice shoot DM yields in all the soils used, from 0.61, 0.74 and 0.47 in the controls to 3.01, 2.76, and 1.57 g/plant in the highest N:P:K treatments in Ndungu, Mbugani and Kimunyu sites, respectively. It was further revealed that Zn supplementation in addition to NPK also increased rice dry matter yields further, from 3.05, 2.73 and 1.42 in the Zn controls to 4.75, 4.44, and 2.16 g/plant in the 15 kg/ha Zn treatments in Ndungu, Mbugani and Kimunyu sites, respectively. Iron (Fe) was also found to be deficient in Mbugani soils, and Fe supplementation improved plant growth. It is concluded that deficiency of these nutrients was probably a widespread problem in these and other soils cropped to rice in the district.