Abstract:
This study was conducted to assess the effects of amending tropical sandy soils with
biochar derived from agro-industrial wastes on the leaching and utilization of nitrogen (N) by maize.
The experiment was conducted in pots in a greenhouse with two sandy soil types and two different
biochars. The biochars used in this experiment were preselected in a preliminary column experiment
that assessed the N retention capacities of the different biochars and those that exhibited the best
retention capacities chosen for experimentation. The biochars evaluated included saw dust, rice
husk and corncob pyrolyzed at 500 ◦C and the results from the column leaching experiment showed
that sawdust biochar had superior retention capacities for both NO3
− and NH4
+
, followed by rice
husk biochar. The pot experiment utilized sawdust and rice husk biochars applied at rates of 0,
20 and 40 t/ha to the soil treated with different N sources including cow dung and ammonium
sulfate and growing maize on the amendments for two seasons with each season lasting for five
weeks. The soils were leached on the 14th and 28th days after planting to determine the amount of
leachable N. Biochar amendments reduced the leaching of NO3
−N and NH4
+N with no significant
differences observed between biochar types, but between soil types. The abatement of leaching by
biochar amendments consequently enhanced N uptake by maize and dry matter production and
thus, agro-industrial waste biochar amendment is recommended for reducing leaching in tropical
sandy soils.
