evaluation of organic and inorganic amendments on nutrient uptake ...

suitable fertilizer application rates <strong>and</strong> soil acidity since the current research recommendations were developed
more than two decades ago (FURP,1994). The extent <strong>of</strong> nutrient depletion is unknown <strong>and</strong> phosphate fertilizer
<strong>and</strong> manure application by farmers is not commensurate with the plant requirements <strong>and</strong> / or nutrient levels in
the soil. Twenty years have elapsed since the last fertilizer use recommendation was carried out in Kisii districts.
Declining yields <strong>of</strong> maize which accounts for a significant proportion <strong>of</strong> the food diet for smallholder mixed
farms <strong>of</strong> Kisii districts has raised concerns about food security. There was therefore need to determine the
nutrient use efficiencies <strong>of</strong> phosphate fertilizers <strong>and</strong> manure <strong>and</strong> their effects in acidic soils <strong>of</strong> smallholder
mixed farms. It was necessary to develop appropriate recommendations that can be used by smallholder
resource poor farmers <strong>and</strong> extension agents. The appropriate recommendations <strong>of</strong> rates <strong>of</strong> fertilizers <strong>and</strong> manure
in different soils <strong>and</strong> climatic conditions may help check the deteriorating soil conditions <strong>and</strong> improve food
security in Bototo. Therefore the objective <strong>of</strong> this study was to determine suitable phosphorous fertilizers <strong>and</strong>
manure application rates <strong>and</strong> their effects on maize production in acidic soils in Kenya.
Materials <strong>and</strong> Methods
Field experiment was conducted in a farm site in Bototo having an altitude <strong>of</strong> 1590 masl, 34 0 44’E <strong>and</strong> 0 0 39’S
<strong>and</strong> 1200 – 2100 mm rainfall. The soils are mollic Nitisols or s<strong>and</strong>y loam Nitisols with moderately high fertility
(Jaetzold <strong>and</strong> Schmidt, 2006). Maize is planted twice annually, during the long rains (March – July) <strong>and</strong> short
rains (August – December).
The experimental design was R<strong>and</strong>omized Complete Block Design (RCBD) with selected farmers as blocks (ten
men <strong>and</strong> ten women).
The treatments were:
i). No phosphorus fertilizer used at planting -control
ii). Lime only - 250 kg ha -1 CaCO 3
iii). Diammonium Phosphate (DAP) - 60 kg ha –1 P 2 0 5
iv). Minjingu Rock Phosphate (MRP) - 60 kg ha –1 P 2 0 5
v). Triple Super Phosphate (TSP) - 60 kg ha –1 P 2 0 5
vi). Farm Yard Manure (FYM) -10 t ha –1
vii). ½ FYM + ½ DAP - 5 t ha –1 FYM + 30 kg ha –1 P 2 0 5
L<strong>and</strong> preparation was done prior to the start <strong>of</strong> the rains, ploughed <strong>and</strong> harrowed twice using oxen to obtain a
fine seedbed. There were 7 plots per block each measuring 3.75m wide x 4.8m long giving plot area <strong>of</strong> 18m 2 per
plot. Lime was applied in one <strong>of</strong> the seven plots per block at the rate <strong>of</strong> 250 kg ha -1 CaCO 3 two weeks before
sowing. Each plot consisted <strong>of</strong> 5 rows each with 8 hills. Maize hybrid H614 was the test crop in Bototo, chosen
on the basis <strong>of</strong> being a suitable variety for the study area (Jaetzold <strong>and</strong> Schmidt, 2006).
At the onset <strong>of</strong> the rains, three seeds were sown per hill. The seeds were planted at a spacing <strong>of</strong> 0.75m (inter –
row) by 0.60m (intra – row), <strong>and</strong> later thinned to two plants / hill at 21 days after crop emergence. Fertilizers
were applied at the time <strong>of</strong> planting along the furrows <strong>and</strong> mixed with soil to avoid direct contact with the seeds.
Uniform top dressing was done with calcium ammonium nitrate (CAN) at the recommended rate <strong>of</strong> 30 kg N ha –
1 (FURP,1994) so that N was not limiting.
Furadan was applied in each planting hole at the rate <strong>of</strong> 10 kg ha -1 to protect the seeds <strong>and</strong> seedlings against soil
borne pests after which the seeds were placed <strong>and</strong> covered with a small quantity <strong>of</strong> soil. The crop was protected
against stalk borer (Buseola fusca) by application <strong>of</strong> Kombat, a commercial insecticide, applied to the maize
funnels at 4 weeks after planting at the rate <strong>of</strong> 4 kg ha –1 .Weeding was done twice after crop germination.
Gladiator was applied in each trial site to prevent termite damage. The crop was harvested at physiological
maturity from a net harvest area <strong>of</strong> 18 m 2 <strong>and</strong> threshed by h<strong>and</strong>. All ears affected by pests or rotten were
excluded in yield measurements. All the consumable grains per plot were weighed <strong>and</strong> then sub – sampled. The
stover was cut at about 5 cm above the ground level, weighed <strong>and</strong> sub- sampled for dry matter determination.
Data included planting date, emergence date, st<strong>and</strong> count at 21 days after emergence (DAE), plant st<strong>and</strong> count at
harvest, scores for crop growth vigor on a scale <strong>of</strong> 1 to 7 at 21 DAE, common diseases, flowering date,
harvesting date, <strong>and</strong> yield per plot converted to t ha -1 . Data collection was done from the net harvest area <strong>of</strong>
18m 2 .
Crop harvest data included field grain, cob <strong>and</strong> stover weights recorded. Field grain moisture content was
recorded using a grain moisture tester (model DjGMTS. N. 0528.).
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