Browsing by Author "Uwizeyimana,Jean de Dieu"

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Nitrogen mineralization and maize yield from a three years fallow of prosopis chilensis
(Sokoine University of Agriculture, 1997) Uwizeyimana,Jean de Dieu
The study was conducted to assess the effect of three-year old fallow of Prosopis chilensis (Molina Stuntz) on general soil properties, nitrogen mineralization and maize yield an Tanzania. experiment agroforestry on-going The design of the at experiment Gairo, was a on Morogoro, completely randomized block design with three treatments: Trees alone (T) , Maize (M) alone replicated four times. and Trees plus maize (T+M) each Soil samples were collected at the beginning and at the end of the experiment at 0-15 and 15-30 cm depth. Soil samples for N mineralization were collected at three weeks intervals from maize sowing up to tasselling stage. The results from the soil analysis at the beginning of the experiment showed that K+ differed significantly between treatments. The trees alone treatment had the highest level (1.0 cmol ( + ) kg1) than other treatments which had the lowest level (0.7 cmol (+) kg'1). Magnesium differed significantly between treatments, with the maize alone treatment having the highest level of Mg2+ (2.0 cmoles(+) kg'1) and the treatment with trees alone having the least (1.6 cmoles (+) kg'1). Total P differed significantly between (P<0.05) treatments with theiii trees-alone treatment having the highest total P (229.6 ppm) and treatment with maize alone having lowest value (159 ppm) . Total N, organic C, available P, inorganic P, organic P, Na+ and Ca2+ were not significantly affected by treatments. Total N and available P decreased significantly (P<0.05) with soil depth. In contrast, Mg2+ and Ca2+ were higher in the subsoil than in the top soil. At the end of the experiment, none of the nutrient analyzed differed significantly between treatments. Results from N mineralization under laboratory conditions in significant all sampling difference periods between did treatments. not In show any contrast, changes in mineral N under field conditions showed that the treatment with trees alone had the highest release of mineral N and was dominated by nitrate. Maize yield did not differ significantly between treatments. It is concluded that a three-year fallow of P. chilensis was not long enough for soil fertility improvement even though there was a significant difference on total P and release of mineral N.