Abstract:
A study was conducted at Sokoine University of Agriculture (SUA), Morogoro,
Tanzania during 2007/08. The objective of the study was to evaluate extent of
mineralization of N and P from four commonly used animal manure in Tanzania
namely; poultry, pig, goat and cattle. The study involved a ten week incubation
experiment and a glass house experiment in which okra was used as a test crop .The
experimental design for the two experiments was split plot with manure types as the
main plots and application rates as sub-plots. Results of the incubation experiment
indicated that application of the four manure types significantly (p<0.01) increased N
and P levels. Generally, Poultry manure resulted in highest levels of net N and P
followed by pig, goat and cattle manure. The trend of N mineralization from the four
manure types resembled that of P mineralization. Similar trends were observed for
the attributes evaluated in the pot experiment .Okra shoot dry weight and root dry
weight were highest in poultry manure amended pots and lowest in cattle manure
amended pots. Poultry manure had the highest levels of N and P and narrowest ratios
of C/N and C/P suggesting superior mineralization of N and P. Based on the
fertilizer recommendation of N and P for maize in Southern Highlands of Tanzania
(N=80kg N/ha and 20kgP/ha) and the highest application rate of 300kgN/ha used in
this study, applications of 10.75tons/ha of poultry manure 12.84tons/ha of pig
manure 18.47tons/ha of goat manure and 21.27tons/ha of cattle manure will meet the
recommendation of 80kgN/ha. The above application rates will also provide
12.43kgP/ha, kgP/ha,11.54kgP/ha,13.76 kgP/ha and 10.97kgP/ha for poultry, pig,
goat and cattle manure respectively which will not meet P recommendation. Based
on the above the following are recommended: (1) Efforts should be directed towards
improvement of animal manure quality in order to reduce amounts required to meet
N and P recommendations. (2) Manures should be supplemented with inorganic P or
other sources such as rock phosphate. (3)Training programmes should be designed
for farmers and extension staff to sensitize them on manure use and management
practices.
