Haru, Ruth Watiri2026-02-032026-02-031996https://www.suaire.sua.ac.tz/handle/20.500.14820/7276DissertationThe decomposition and nitrogen release of Senna siamea green manure was studied under glasshouse and field conditions. The effects of two soil types, two manure application rates and two methods of manure placement on the decomposition rate were monitored by use of three parameters, namely residual dry matter, organic carbon and total nitrogen. These parameters were measured at the 1st, 3 rd 6ch 9 th and 12th week of manure incubation in the glasshouse while in the field, measurements were made at the 3rd 6 th and 9ch week. The glasshouse study revealed that there was no significant (p=0.05) difference between the decomposition rates, at 10 cm depth, in a Rhodustult (soil 1) and Dystropept (soil 2) as indicated by the three parameters. The manure decomposed faster at a lower application rate (60 kg manure-N/ha) than at a higher rate (150 kg manure N/ha) . Under field conditions, buried manure decomposed faster in soil 2 than in soil 1 while for the surface placed manure the opposite was observed. In soil 1, where termite activity was appreciable, the surface-applied manure decomposed faster than the buried material while in soil 2 manure. the decomposition rate was faster for the buried. The trends of manure decomposition were similar under the two incubation conditions but the decomposition rate after the third week was significantly higher in the field than in the glasshouse. The results of the present study indicated that in the glasshouse, the decomposition rate of green manure was not affected by the soil types used. But the decomposition varied with soil type, manure application rate as well as the mode of placement in the field. Therefore these factors should be considered when conclusions are to be made with respect to nutrient release from this manure.enSoil typeManure application rateManure placement methodDecompositionNitrogen releaseSenna siamea green manureThesis