| dc.description.abstract | On many smallholder farms in Kenya, organic materia
ls such as animal manures are commonly
used to replenish soil fertility. These soil amend
ments are however, in short supply and are unlikely
to
meet the nutrient requirements of crops over large
areas. There is need, therefore, to explore other n
on-
traditional organic inputs as sources of crop nutri
ents. One such organic resource is pyrethrum marc
(pymarc), a by-product of pyrethrum processing. The
researchers investigated the effect of rate and me
thod
of pymarc application i.e. spot-applied (SP) or bro
adcast (BR) on maize yields and conducted economic
analysis using partial budgeting to determine its p
otential for adoption for two consecutive seasons a
t three
sites in the Rift Valley Province. The treatments c
onsisted of two methods of pymarc application (SP a
nd
BR) in a factorial combination with two rates of py
marc i.e. 4 and 8 t ha
-1
laid down in a randomized
complete block design. There was no significant int
eraction between the method and rate of pymarc
application. There was also no significant effect o
f pymarc application method but maize yields increa
sed
with increasing rate of pymarc application which wa
s attributed mainly to increased soil phosphorus
availability. Net financial benefits were, however,
negative for all treatments in all seasons, theref
ore,
casting doubts on pymarc’s potential for adoption a
s a soil fertility management intervention.
Key Words: Pymarc, Methods of application, Maize yi
eld and Partial budgeting.
Introduction
Soil fertility depletion due to continuous cultivat
ion with little or no nutrient inputs is a major co
nstraint to
crop production in many parts of Kenya. Nitrogen an
d phosphorus are usually the most limiting nutrient
s
for crop production and their deficiencies often oc
cur simultaneously on many farms (Jama et al., 1997
). On
smallholder farms, organic materials are commonly u
sed as sources of nutrients. In most cases the orga
nic
materials are often treated as sources of N (Palm e
t al., 1997) with little attention given to their p
otential to
provide P to crops. Furthermore, most research on o
rganic inputs in Kenya has focused on the tradition
al
organic amendments such as animal and green manures
. It is now, however, clear that these amendments
are in short supply and are unlikely to meet the nu
trient requirements of crops over large areas. Ther
e is
need, therefore, to explore other non-traditional o
rganic inputs as sources of crop nutrients. One suc
h
organic resource is pymarc, a by-product of pyrethr
um processing. One ton of dry pyrethrum flowers yie
lds
about 970 kg of pymarc of which less than 10% is us
ed as animal feed (Muriuki et al., 2001). The surpl
us is
often left to waste.
Pymarc has average N, P, and K contents of 2.2, 0.2
8 and 3.8% respectively, and is therefore a relativ
ely
rich source of these nutrients (Muriuki et al., 200
1). However, while the nutrient concentration may b
e a
good indicator of the potential of an organic resou
rce to supply nutrients to crops, plant growth is u
sually
the best way of determining the effectiveness of an
organic material as a nutrient source. The rate an
d
method of application are important factors that de
termine the effectiveness of a nutrient source. The
two
also impact on profitability, which usually determi
nes whether or not a technology will be adopted.
The two common methods of application of nutrients
are spot placement (SP) and broadcast application
(BR). SP of pymarc may concentrate the nutrients cl
ose to the plant roots and therefore make it more
effective than BR. However, given the powdery natur
e of pymarc, SP may also reduce the surface area of
the pymarc in contact with the soil thus slowing do
wn microbial degradation and hence nutrient release
.
While BR increases contact between the pymarc and t
he soil thus increasing microbial degradation of th
e
organic material, the thin spreading may result in
a dilution effect whereby the effective amounts of
nutrients available to plants are greatly reduced.
The agronomic effectiveness of the two application
methods notwithstanding, SP is usually more labor i
ntensive than BR and the choice of the application
Volume 2: Issue1, 2009 Int.j. disaster manag.risk.
reduct.
ISSN: 1992-2744
2
method should therefore be based on economic consid
erations (Opala et al., 2007). Unfortunately,
economic analysis is rare in agronomic studies thus
limiting the farmers’ ability to make informed cho
ices.
High rates of nutrient application usually lead to
high yields. Most studies have however often used
unrealistically high organic input rates, such as 1
0 t ha
-1
, that are unlikely to be used by farmers. There is
therefore merit in testing the effectiveness of org
anic inputs at rates that are likely to be used by
farmers.
The objectives of this study were to determine the
(i) effects of rate and method of pymarc application i.e.
spot-applied or broadcast on the yield of maize (ii
) the economic returns of using pymarc on maize. | en |
