Integrated Nutrient Management in Faba Bean and Wheat on Nitisols

Full text

Integrated Nutrient Management in Faba Bean and Wheat on Nitisols of
central Ethiopian Highlands
Getachew Agegnehu and Chilot Yirga
Holetta Research Center, P. B. Box 2003, EIAR, Addis Ababa; Email: geta1565@yahoo.com
Running title: Integrated nutrient management

1
Introduction................................................................................................................................... 2
Methodology.................................................................................................................................. 4
Experimental sites.......................................................................................................................4
Experimental set-up.................................................................................................................... 4
Data collection and management................................................................................................ 5
Findings.......................................................................................................................................... 7
Yield and yield components of faba bean................................................................................... 7
Soil analytical results after harvesting...................................................................................... 10
Economic analysis .................................................................................................................... 11
Yield and yield components of wheat....................................................................................... 13
Economic analysis .................................................................................................................... 19
Conclusion ................................................................................................................................... 21
Acknowledgement....................................................................................................................... 22
References.................................................................................................................................... 23

2
Introduction
Integrated plant nutrient management is among the best widely used soil fertility management
methods in subsistence farming for improved crop and soil productivity. Soil acidity and
associated low nutrient availability is one of the major constraints to faba bean (Vicia faba L.)
and wheat (Triticum aestivum L.) production on Nitisols of Ethiopian highlands. Acid Nitisols
occur widely in Ethiopian highlands where the rainfall intensity is high and crop cultivation has
gone for many years (Desta, 1987; Taye and Höfner, 1993). According to Schlede (1989), about
40.9% of the Ethiopian total land is affected by soil acidity. About 27.7% of these soils are
dominated by moderate to weak acid soils (pH in KCl) 4.5 -5.5, and around 13.2% by strong acid
soils (pH in KCl) < 4.5).
The fertility status of these soils is very low due to removal of nutrients in the harvested products
and losses through erosion and leaching. Their pH is less than 5.5, which results in low yields. In
addition to the lack of proper cultural practices, the low wheat and faba bean yields could thus be
attributed mainly to the deficiency of nutrients and low soil pH (Getachew et al., 2005a and b).
In such soils, phosphate can readily be rendered unavailable to plant roots as it is the most
immobile of the major plant nutrients (Sanchez, 1976; Getachew and Sommer, 2000). The
quantity of phosphorus in soil solution needed for optimum growth of crops lies in the range of
0.13 to 1.31 kg P ha
-1
as growing crops absorb about 0.44 kg P ha
-1
per day (Mengel and Kirby,
1996). The labile fraction in the topsoil layer is in the range of 65 to 218 kg P ha
-1
, which could
replenish soil solution P (Mengel and Kirby, 1996).
Wheat (Triticum aestivum L.) and faba bean (Vicia faba L.) are among the most important crops
widely grown by smallholder farmers under rain-fed conditions on the acid soils of the Ethiopian
highlands. The area under wheat in the main season is about 1.1 million ha making up 15.7% of
the total cereal area (CSA, 2004). The national average yield is low with a mean of about 1.4 t
ha
-1
(CSA, 2004) due to poor soil fertility (Asnakew et al., 1991; Hailu et al., 1991). This is true
especially for N and P nutrients due to continuous cropping of cereals and low level of fertilizer
usage (Amsal et al., 2000). Faba bean is the major source of protein and beneficial break crop for
ameliorating soil fertility in a cereal-based cropping system. About 0.38 million ha is covered by
faba bean making up 34.7% of the total area allotted to pulses in Ethiopia (CSA, 2004).

3
Diagnostic studies in the highlands of Ethiopia indicated that farmers classify soils of their land
based on color, fertility status, slope, soil depth and suitability to various crops, drainage,
workability and resistance to erosion (Chilot et al., 2002). Based on the degree of soil fertility,
farmers in the area identify four soil groups, namely kosi, dila, dimile and koticha (Table 8). In
terms of area coverage, dimile is the most important soil followed by dila and koticha,
respectively. Of these soil categories, kosi, dila, and dimile are drained Nitisols while koticha is
characterized as having excess soil moisture. Kosi, mostly located around homesteads, is the
most fertile soil due to the accumulation of organic matter and nutrients as a result of continuous
applications of household waste and animal manure. Wheat and faba bean could be grown on
kosi soils without fertilizer and on dila soils with a modest rate of fertilizer i.e. 32/10 kg N/P ha
-1
for wheat, and 9/10 kg N/P ha
-1
for faba bean production (Getachew et al., 2002; Getachew et
al., 2003). However, dimile soil is characterized by low soil fertility as a result of continuous
cultivation and soil erosion.
Results of on-farm fertilizer trials on kosi and dimile soils indicated that N/P fertilizers
significantly increased wheat and faba bean yields on dimile soil, but not on kosi soil (Getachew
et al., 2002; Getachew et al., 2003). As a result 64/20 kg N/P ha
-1
was recommended for wheat
production on dimile soil (Getachew et al., 2002) and 18/20 kg N/P ha
-1
for faba bean production
on the same soil type (Getachew et al., 2003), but farmers could not take up the recommendation
primarily due to high fertilizer price. Thus it is worth considering searching for other affordable
plant nutrient sources. Farmyard manure is one of these plant nutrient sources which could
ameliorate the physical and chemical condition of the soil. In acid soil, where P fixation is a
problem, application of farmyard manure releases a range of organic acids that can form stable
complexes with Al and Fe thereby blocking the P retention sites. As a result the availability and
use efficiency of P is improved (Sharma et al., 1990; Marschner, 1995; Mengel and Kirby, 1996;
Prasad and Power, 1997). The positive effects of manure on crop yields have been explained on
the basis of cation exchange between root surfaces and soil colloids (Sharma et al., 1990; Ano
and Ubochi, 2007). The objectives of these experiments were, therefore, to find out the effects of
N/P fertilizers and farm yard manure (FYM) on yield and major yield components of wheat and
faba bean, and to determine the economic optimum doses of N/P fertilizers and FYM for the
production of both crops on Nitisols.

4
Methodology
Experimental sites
The trial sites were located at the experimental station of Holetta Research Center and Welmera
areas of west Shewa, central highlands of Ethiopia, between 09
o
03'N latitude and 38
o
30'E
longitude at an altitude of about 2400 m above sea level. The rainfall is bimodal with long-term
average annual rainfall of 1100 mm, about 85% of which is received from June to September and
the rest from January to May. The average minimum and maximum air temperatures are 6.1 and
21.9°C, respectively. The environment is seasonally humid and the major soil type of the trial
sites is Eutric Nitisol (FAO classification).
Experimental set-up
On-farm integrated nutrient management trials were conducted from 2001 - 2003 on faba bean at
the experimental fields of Holetta Research Center, and 2003 - 2004 cropping seasons on wheat
on dila and dimile soils (Nitisols) of Welmera Wereda, West Shewa, Ethiopia.. The effects of
three levels of air-dried decomposed FYM (0, 4 and 8 t ha
-1
) and five levels of phosphorus
fertilizer (0, 13, 26, 39 and 52 kg P ha
-1
) in the form of triple super-phosphate were studied on
growth, yield and yield components of faba bean (cv. CS 20DK). The experiment was conducted
in a split plot design with four replications where FYM and P fertilizer levels were assigned to
the main and sub-plots, respectively on a sub-plot size was 20 m
2
. The source of the FYM was
the livestock research division of Holetta Research Center. The FYM was kept under shade for
two to three months until its decomposition. The decomposed manure was applied 21-30 days
before sowing and mixed thoroughly in the upper 15-20 cm soil depth. Faba bean (cv. CS20DK)
was sown from 21 to 23 June at the seed rate of 200 kg ha
-1
. Phosphorus fertilizer was applied
along with seeds. Nitrogen was applied at the rate of 20 kg N ha
-1
as a starter dressing to all plots
in the form of urea for faba bean.
In the case of wheat six growers participated in the study. The treatments comprised of five
selected different combinations of inorganic N/P fertilizers and FYM (9/10/0, 32/10/4000,
32/10/8000, 9/10/8000 and 64/20/0 kg N/P/FYM ha
-1
, respectively). They were arranged in

5
randomized complete block design with three replications on a plot size of 5 m by 8 m. The
sources of inorganic N/P fertilizers were urea and di-ammonium phosphate (DAP). A bread
wheat variety, HAR-604, was sown at the rate of 175 kg ha
-1
from mid to end of June.
Composite soil samples collected from each replication at the depth of 0-20 cm surface soil
before FYM application were analyzed for pH, P, N, organic carbon (OC), Na, K, Ca, Mg and
cation exchange capacity (CEC), which are presented in Tables 1 and 9. Similarly, soil samples
were also collected from each faba bean plots after harvesting from 0-20 cm soil depth and
analyzed for the nutrient concentrations mentioned above (Table 5). Soil pH was measured in a
1:1 soil: water suspension using glass electrode. The standard Kjeldhal method was used for
nitrogen determination in soils. Available P in the soil was determined using Bray-II method.
The cation exchange capacity (CEC) of the soil was determined using Ammonium Acetate
Method. During application the FYM rates were adjusted on dry weight basis. Samples of the
FYM had a moisture content of 24%, 69.5% of organic carbon, 1.4% N, 0.48% P, 0.11% Na,
2.13% K, 2.09% Ca and 0.80% Mg. In order to determine the potential of manure for the supply
of nutrients and maintenance of soil fertility, the conversion factor of 320 kg of carbon (McCalla
et al., 1977), 8 kg of N, 4 kg of P and 16 kg of K per tone of dry matter could be used (Ange,
1994).
Since the soil fertility management trial on wheat was conducted on farmers’ fields, participating
farmers were advised to follow the recommended cultural practices for wheat production. They
were also encouraged to assess and compare treatments based on their own criteria. A field day
was organized for members of farmers’ research groups and other farmers, development workers
and researchers to evaluate the experiment during the grain filling stage.
Data collection and management
Data collected were plant height, spike length, number of spikelets per spike, seeds per spike,
number of pods per plant and seeds per pod, total biomass, grain yields and thousand grain
weights of each crop species as appropriate. Economic data on fertilizer and crop prices were
also collected. To estimate total biomass and grain yields the whole plot size (20 m
2
) was
harvested for faba bean and 40 m
2
for wheat. Total biomass and grain yields recorded on whole
plot basis were converted to kg ha
-1
for statistical analysis. The SAS/STAT computer package

6
version 8.2 (SAS Institute, 2001) was used to test for presence of outliers and normality of
residuals. The total variability for each trait was quantified using pooled analysis of variance
over years using the following models for faba bean (1) and wheat (2).
e
YMPMPYPP
MR
YM
M
RY
u
T
ijkl
iklklill
jk
ik
k
ijiijkl
+++
+
++++++=
)()()()()(
)(
……. (1)
eXYXRYT
ijk
ikkijiijk
+
+
+
+
+
=
)()(
µ
………………………………………………………… (2)
Where (1):
T
ijkl
is total observation,
µ
= grand mean,
Y
i
= effect of the
i
th
year,
R
j (i)
is effect of
the
j
th
replication, M
k
is effect of the k
th
manure levels, P
l
is effect of the
l
th
phosphorus levels,
YM,
YP, MP
and
YMP
are
the interactions, and
e
ijkl
is the variation due to random error.
Where (2):
T
ijk
is total observation,
µ
= grand mean,
Y
i
= effect of the
i
th
year,
R
j(i)
is effect of the
j
th
replication (within the
i
th
year),
X
k
is effect of the
k
th
treatment,
XY
(ik)
is the interaction of kth
treatment with ith year and
e
ijk
is the random error.
Results were presented as means and whenever treatments were found significantly different,
least significant difference (LSD) at 5% probability level was used to establish the differences
among the means. Pearson correlation coefficient (r) among agronomic traits was also
performed.
Economic analysis was performed to investigate the economic feasibility of the treatments for
both crops. The average yields of faba bean and wheat were adjusted downwards by 15% and
10%, respectively to reflect the difference between the experimental plot yield and the yield
farmers would expect from the same treatment under their own management. Five years (2002 –
2007) mean market price of Ethiopian Birr (ETB) 2.90 kg
-1
for faba bean and average market
price of ETB 2.61 kg
-1
for wheat were used to convert the adjusted yields to gross field benefits.
The market prices of ETB 4.18 kg
-1
for di-ammonium phosphate and ETB 3.78 kg
-1
for urea
were used for analysis. The nitrogen and phosphorus content of the farmyard manure (FYM) was
converted into equivalent price of N/P fertilizers. For a treatment to be considered as a
worthwhile option to farmers, the marginal rate of return (MRR) need to be at least between 50%
and 100% (CIMMYT, 1988). However, researchers in other parts of the country suggested a
MRR of 100% as realistic for risk-averse smallholder farmers (Amanuel et al., 1991). Hence, to

7
make farmer recommendations from the marginal analysis, a MARR of 100 % is taken as a
benchmark.
Findings
Yield and yield components of faba bean
The initial soil analysis results were found to be sub-optimal for the production of faba bean. As
presented in Table 1 the soil pH, available P and exchangeable cations were found to be by far
below the optimum requirement. In most cases soils with pH values less than 5.5 are deficient in
Ca and/or Mg and also P (Marschner, 1995; Getachew and Sommer, 2000). The results of this
study indicated that FYM and phosphorus fertilizer positively influenced seed yield, total
biomass, number of pods per plant and seeds per pod and plant height of faba bean.
Table 1. Initial soil chemical properties of the experimental field
Na K Ca Mg CEC Field
No.
pH
1:1(H2O)
P*
(ppm)
N
(%)
OC
(%) Meq/100g soil
Rep I 4.2 5.6 0.19 1.56 0.11 1.66 2.76 2.31 23.44
Rep II 4.3 5.0 0.16 1.48 0.14 1.25 2.73 2.36 28.98
Rep III 4.4 5.0 0.17 1.52 0.07 1.28 2.75 2.20 27.94
Rep IV 4.4 4.2 0.18 1.52 0.08 1.14 2.74 1.48 26.04
Mean 4.3 4.95 0.17 1.52 0.10 1.33 2.74 2.09 26.60
Results of the study revealed that farmyard manure and P fertilizer had a highly significant (P
≤
0.01 and P
≤
0.001) effect on plant height, number of pods per plant, total biomass and seed yield
of faba bean. A similar result was reported by Getachew et al. (2005a). Number of seeds per pod
and thousand seed weight also significantly (P
≤
0.05) responded to FYM and P fertilizer
applications (Table 2). The farmyard manure by phosphorus fertilizer interaction (FYM × P) also
significantly (P
≤
0.01) affected faba bean total biomass and seed yield (Table 2).

8
Table 2. Analysis of variance for faba bean grain yield and other agronomic traits tested at three FYM
rates and five phosphorus levels at Holetta, Ethiopia, 2002-2003
Source PH PPP SPP TBY SY TSW
Y * ** ** ** ** ***
M ** ** * *** *** *
Y×M NS NS NS NS ** *
P ** ** ** *** *** *
Y×P NS NS NS ** * NS
M×P NS NS NS ** ** *
YMP NS NS NS * * NS
Root-MSE 9.5 1.4 0.25 431.0 166.0 19.9
The application of FYM at the rates of 4 and 8 t ha
-1
resulted in three-season mean seed yield
advantages of 34 and 53%, respectively over the control (Table 3). Similar to the present finding
yield increases of faba bean from 250 to 1000 kg ha
-1
were reported due to the application of
farmyard manure (Hebbblethwaite et al., 1983). Likewise, the application of P fertilizer
significantly and linearly increased seed yield with yield advantages ranging from 16 to 32%
over the control (Table 3). Amare et al. (1999) and Getachew et al. (2005a) also reported a
significant linear and quadratic faba bean seed yield response to P fertilizer application at
Holetta.

9
Table 3. FYM and P effects on seed yield, total biomass, thousand seed weight, number of pods per plant
and seeds per plant and plant height of faba bean at Holetta, 2001-2003
Factor Seed yield
(kg ha
-1
)
Total biomass
(kg ha
-1
)
1000 seed
weight
Seeds per
pod
Pods per
plant
Plant
height
FYM (t ha
-1
)
0 1352c† 3137c 493b 2.6b 7.3c 123b
4 1803b 4192b 506a 3.0a 9.2b 136a
8 2068a 4846a 508a 3.2a 10.7a 140a
LSD (0.05) 73.8 191.7 8.9 0.12 0.64 4.2
P (kg ha
-1
)
0 1456c 3452c 495b 2.7b 7.6c 127b
13 1685b 3875b 498ab 2.8ab 8.8b 132ab
26 1763b 4051b 507a 2.9ab 9.0b 134a
39 1878a 4440a 505a 3.1a 9.3a 135a
52 1923a 4474a 507a 3.0a 10.0a 137a
LSD (0.05) 95.3 247.5 11.5 0.15 0.82 5.5
CV (%) 9.5 10.6 4.0 8.9 15.9 7.2
*, **, ***Significant at P<0.05, P<0.01 and P<0.001 probability levels, respectively; NS = Not significant
†Means in a column followed by the same letter are not significantly different at P ≤ 0.05.
Results indicated that the interaction of farmyard manure by phosphorus fertilizer increased faba
bean total biomass and seed yield (Table 4). The mean seed yields of faba bean increased as the
levels of the two interacting factors increased. The highest mean seed yield was recorded from
the application of 8 t FYM ha
-1
and 39 kg P ha
-1
(Table 4). While maximum total biomass and
seed yield of faba bean were obtained from FYM and P treated soils, lower yields were observed
in the relatively lower pH (pH < 4.5) environments.

10
Table 4. Interaction effects of FYM by phosphorus on faba bean seed yield, 2002-2003
Farmyard manure (t ha-1) Phosphorus
(kg ha-1) 0 4 8
0 991 1395 1981
13 1412 1701 1942
26 1317 1954 2019
39 1467 1958 2210
52 1573 2007 2191
SE 58.68
Soil analytical results after harvesting
The results of the study revealed that soil pH has been improved through FYM application; the
application of 13-26 kg P ha
-1
would be adequate for faba bean production. Similar to our
findings, Mahler et al. (1988) reported that in terms of nutrient availability pea, lentil, chickpea
and faba bean grow best in soils with pH values between 5.7 and 7.2 and require between 13 and
35 kg P ha
-1
for adequate yields. Mahler et al. (1988) further indicated pulse crops grown on
soils with a pH value of 5.6 and less give low yields.
The analysis of soil samples collected after harvesting indicated relatively higher pH levels and
nutrient concentrations for plots treated with both FYM and P fertilizer compared to either sole
application of FYM or P fertilizer (Table 5). Similarly, Ano and Ubochi (2007) reported that
application of animal manure increased soil pH. The finding of Eghball et al. (2004) also showed
that the residual effects of manure and compost applications significantly increased electrical
conductivity, pH levels and plant-available P and NO
3
-N concentrations. The lowest pH and
nutrient content were observed on plots not treated with FYM. In this regard, Sharma et al.
(1990) reported the use of manure might have made the soil more porous and pulverized, so as to
allow better root growth and development, thereby resulting in higher root cation exchange
capacity (CEC). Sanchez (1976) has also indicated that the application of manure directly
influences the availability of native or applied phosphorus.

11
Table 5. Chemical properties of soils of the trial site after harvesting, 2001-2003
FYM P applied Na K Ca Mg CEC
(t ha
-1
) (kg ha
-1
)
pH
1:1(H2O)
N
(%)
P*
(ppm)
OC
(%) Meq/100 g soil
0 0 4.5 0.09 4.2 1.28 T* 1.25 4.77 0.83 18.76
0 13 4.6 0.13 4.4 1.29 0.03 1.33 5.35 0.99 18.84
0 26 4.7 0.12 5.2 1.29 0.03 1.33 5.62 1.10 19.08
0 39 4.6 0.13 5.2 1.30 0.03 1.35 5.59 1.22 19.22
0 52 4.6 0.14 5.4 1.29 0.03 1.34 5.75 1.15 19.14
4 0 4.7 0.14 4.6 1.32 0.04 1.37 5.89 1.25 20.54
4 13 4.7 0.15 5.4 1.36 0.04 1.37 5.96 1.26 20.12
4 26 4.7 0.14 5.4 1.36 0.04 1.42 6.31 1.29 20.74
4 39 4.8 0.14 5.6 1.36 0.05 1.41 6.72 1.38 21.24
4 52 4.8 0.15 6.4 1.36 0.06 1.40 6.38 1.47 21.38
8 0 4.6 0.15 5.2 1.40 0.06 1.44 7.19 1.60 21.26
8 13 4.9 0.15 6.0 1.48 0.13 1.45 7.29 1.69 22.38
8 26 4.7 0.14 6.4 1.44 0.15 1.47 7.57 2.56 24.28
8 39 4.8 0.16 6.0 1.44 0.38 1.48 9.61 2.51 23.50
8 52 4.9 0.15 6.4 1.44 0.21 1.50 9.18 2.11 25.64
Mean 4.84 0.14 5.45 1.36 0.09 1.39 6.61 1.50 21.08
*T = Trace
Economic analysis
The result of the partial budget analysis is given in Table 6. The economic analysis revealed that
the highest net benefit of ETB 4274.80 was obtained from the application of 8 t FYM ha
-1
whereas the control treatment (no application of either P fertilizer or FYM) gave the lowest net
benefit (Birr 2443.00 ha
-1
). The economic analysis further revealed that the application of 8 t
FYM ha
-1
provided the highest marginal rate of return of 2027% (Table 7) suggesting for each
Birr invested in faba bean production, the producer would reap Birr 20.27 after recovering his
investment. Since the minimum acceptable rate of return (MARR) assumed in this study was
100%, the treatment with application of 8 t FYM ha
-1
gave an acceptable marginal rate of return.
Therefore, on economic grounds the application of 8 t FYM ha
-1
on faba bean would be
recommended on acidic Nitisols of the central highlands of Ethiopia.

12
Table 6. Partial budget analysis of FYM and phosphorus fertilizer trial on faba bean
Treatments
Average
yield
(kg ha
-1
)
Adjusted
yield-15%
(kg ha
-1
)
Gross
benefits
(ETB ha
-1
)
Cost of
fertilizer
Cost
of
FYM
FYM
applic
ation
cost
Total
costs
that
vary
Net
benefit
(ETB
ha
-1
)
Domi
nance
0 FYM + 0 P 991 842.35 2442.81 0.00 0.00 0 0.00 2442.81
0 FYM +13 P 1412 1200.20 3480.58 271.70 0.00 0 271.70 3208.88
4 FYM + 0 P 1395 1185.75 3438.67 0.00 254.14 50 304.14 3134.53 D
0 FYM+ 26 P 1317 1119.45 3246.40 543.40 0.00 0 543.40 2703.01 D
4 FYM + 13 P 1701 1445.85 4192.96 271.70 254.14 50 575.84 3617.12
8 FYM + 0 P 1981 1683.85 4883.17 0.00 508.29 100 608.29 4274.88
0 FYM + 39 P 1467 1246.95 3616.15 815.10 0.00 0 815.10 2801.05 D
4 FYM + 26 P 1954 1660.90 4816.61 543.40 254.14 50 847.54 3969.07 D
8 FYM + 13 P
1942 1650.70 4787.03 271.7 508.29 100 879.99 3907.04 D
0 FYM + 52P 1573 1337.05 3877.45 1086.80 0.00 0 1086.80 2790.65 D
4 FYM + 39 P 1958 1664.30 4826.47 815.10 254.14 50 1119.24 3707.23 D
8 FYM + 26 P
2019 1716.15 4976.84 543.40 508.29 100 1151.69 3825.15 D
4 FYM + 52 P 2007 1705.95 4947.25 1086.80 254.14 50 1390.94 3556.31 D
8 FYM + 39 P
2210 1878.50 5447.65 815.10 508.29 100 1423.39 4024.26 D
8 FYM + 52 P
2191 1862.35 5400.82 1086.80 508.29 100 1695.08 3705.73 D
Five years average price of faba bean is Birr 2.90/kg, and DAP Birr 4.18/kg; D = dominated
Table 7. Marginal analysis of FYM and P fertilizer effects on faba bean at Holetta, 2002-2003
Treatments
Particulars 0 FYM + 0 P 0 FYM +13 P 4 FYM + 13 P
8 FYM + 0 P
Average yield (t ha
-1
) 991 1412 1701 1981
Adjusted yield-15% (kg ha
-1
) 842 1200.2 1445.85 1683.85
Gross benefit (ETB ha
-1
) 2442.81 3480.58 4192.96 4883.16
Costs of Fertilizer (ETB ha
-1
) 0.00 271.70 271.70 0.00
Costs of FYM (ETB ha
-1
) 0.00 0.00 254.14 508.29
Cost of FYM application (ETB ha
-1
) 0.00 0.00 50.00 100.00
TCV (ETB ha
-1
) 0.00 271.70 575.84 608.29
NB (ETB ha
-1
) 2442.81 3208.88 3617.12 4274.88
MC (ETB ha
-1
)) 271.70 304.14 32.44
MB (ETB ha
-1
) 766.06 408.24 657.76
MRR (%) 281.95 134.23 2027.36

13
Yield and yield components of wheat
Soil analytical results for samples taken before FYM application were found to be sub-optimal
for wheat production, particularly for the soil type identified as dimile (Tables 8 and 9). The
nutrient contents of the soil types used in this study correspond with farmers’ classification
(Table 8). As presented in Table 9 the soil pH, available P, exchangeable cations and CEC in
dimile soil were found to be below the optimum requirement for wheat production. In most
cases, soils whose pH is less than 5.5 are deficient in Ca, Mg and P (Marschner, 1995; Mengel
and Kirby, 1996; Somani, 1996; Getachew and Sommer, 2000).
Table 8. Farmers classification of soil types based on color, slope, fertility status, depth, suitability and types of
crops grown, drainage, workability, resistance to erosion and limitations
Local soil names based on farmers’ classification
Description Kosi Dila Dimile Koticha
Color Black or brown Red Red Black
Physiography/
slope
Gentle slope Gentle slope Gentle to steep
slope
Flat bottom lands
Fertility status High (fertile and rich in
organic matter)
Medium (relatively fertile) Low (poor in
fertility)
High to medium
(inherently fertile)
Depth High Medium Low Low
Suitability to
crop growth
High Medium Low Very low
Types of crops
grown
Tef, wheat, barley, faba
bean, rapeseed, potato,
cabbage, lettuce
Tef, wheat, barley, faba
bean, field pea, rapeseed,
linseed, potato
Tef, wheat,
barley, field pea,
linseed
Tef
Drainage Moderately drained Drained Highly drained Waterlogged
Workability Very suitable Suitable Moderately
suitable
Difficult
Resistance to
erosion
Medium Low Very low High
Limitation Induces lodging on tef
and faba bean.
Liable to change to dimile
if not properly managed.
Shallow in depth
and highly
eroded soil.
Water logging due
to excessive
moisture.
Source: Chilot et al., 2002

14
Table 9. Chemical characteristic of soils of the trial sites before FYM application, 2003-2004
PH N P NH4
+
-N NO3-N Na K Ca Mg CEC
Soil type 1:1(H2O) (%) (mg kg
-1
) meq/100g soil
Dila 5.04 0.20 21.26 37.68 21.75 0.15 2.03 12.52 3.29 25.75
Dila 5.09 0.18 18.17 39.85 19.65 0.01 2.13 9.24 2.24 23.97
Dila 5.24 0.24 17.93 27.74 23.68 0.01 2.20 12.76 2.63 29.80
Mean 5.12 0.21 19.12 35.09 21.69 0.06 2.12 11.51 2.72 26.51
Soil type
Dimile 4.46 0.20 8.40 39.46 9.83 0.01 1.41 8.95 1.76 20.78
Dimile 4.62 0.16 10.80 17.26 5.63 0.01 1.82 8.82 1.58 20.35
Dimile 4.51 0.17 10.00 34.28 13.58 0.02 1.64 6.85 1.38 19.51
Mean 4.53 0.18 9.73 30.33 9.68 0.01 1.62 8.21 1.57 20.21
Cropping season had a significant effect on thousand-kernel weight (P
≤
0.01) on both soil types
and plant height (P
≤
0.05) on dila soil, but had no significant effect on other agronomic traits
reported. This is due to the fact that the cropping seasons at which the experiment was conducted
had favorable growth periods in terms of moisture status. Analysis of variance over two years
indicated that the year by treatment interaction (Y
×
T) effect was significant for spike length and
spikelets per spike on both soil types, but plant height only on dimile soil. Other agronomic traits
were not significantly affected by the interaction (Tables 10 and 11).

15
Table 10. Inorganic N/P fertilizers and FYM effects on grain yield (GY), total biomass (TBY) and
thousand-kernel weight (TKW) of wheat on dila and dimile soils (Nitisols), 2003-2004
Dila soil type Dimile soil type
Treatment (T)
GY
(t ha
-1
)
TBY
(t ha
-1
)
TKW
(g)
GY
(t ha
-1
)
TBY
(t ha
-1
)
TKW
(g)
N/P/FYM (kg ha
-1
)
9/10/0 2.63c† 7.10c 39.22 1.63c 5.06c‡ 41.00
9/10/8000 3.05b 8.56b 39.03 2.15b 6.23b 39.62
32/10/4000 3.27ab 9.18ab 39.37 2.29b 6.37b 40.55
32/10/8000 3.44a 9.77ab 38.57 2.59a 7.45a 41.03
64/20/0 3.46a 10.06a 37.27 2.78a 8.18a 39.25
F-probability
Year (Y) NS NS ** NS NS **
Treatment (T) *** ** NS *** *** NS
Y×T NS NS NS NS NS *
LSD (0.05) 0.34 1.38 NS 0.23 0.96 NS
CV (%) 8.79 12.77 5.24 8.43 11.93 3.94
†Means in a column with different letters are significantly different at P ≤ 0.05.
*, **, ***Significant at P ≤ 0.05, 0.01 and 0.001 probability level, respectively; NS = Not significant
The combined application of inorganic N/P fertilizers and FYM had a highly significant effect on
total biomass and grain yield (P
≤
0.001), plant height and spike length (P
≤
0.01) (Tables 10 and
11). A significant wheat yield advantage was also reported due to the application of FYM and
N/P fertilizers on dila and dimile soils (Getachew et al., 2005b). Number of spikelets per spike
significantly (P
≤
0.05) also responded to the application of inorganic N/P fertilizers and FYM
on both soil types; but kernels per spikelet was significantly (P
≤
0.05) affected on dila and
highly significantly (P
≤
0.01) on dimile soils. However, there were no significant differences
among treatments for thousand-kernel weight (Table 10).

16
Table 11. Inorganic N and P fertilizers and FYM effects on yield components of wheat on dila and dimile soils
(Nitisols) of Welmera area, 2003-2004
Dila soil type Dimile soil type
Treatments (T)
Plant
height
(cm)
Spike
length
(cm)
Kernel
spikelet
-1
(no.)
Spikelet
spike
-1
(no.)
Plant
height
(cm)
Spike
length
(cm)
Kernel
spikelet
-1
(no.)
Spikelet
spike
-1
(no.)
N/P/FYM (kg ha
-1
)
9/10/0 93.75c† 9.14c 1.65c 16.06c 84.83b 7.97c 1.46b 14.75b
9/10/8000 97.42bc 9.10c 1.97bc 16.13bc 90.75b 8.38bc 1.73b 15.53ab
32/10/4000 101ab 9.53bc 2.07ab 16.67abc 90.92b 8.83ab 2.08a 15.62a
32/10/8000 97.75bc 9.88ab 2.38a 16.87ab 91.33b 8.74ab 2.16a 15.78a
64/20/0 102a 10.38a 2.10ab 17.27a 97.10a 9.07a 2.27a 16.17a
F-probability
Year (Y) * NS NS NS NS NS NS NS
Treatment (T) ** ** * * *** ** *** *
Y×T NS * NS ** * * NS *
LSD (0.05) 4.54 0.74 0.40 0.80 4.20 0.59 0.28 0.85
CV (%) 3.80 6.34 10.36 3.77 3.81 5.70 7.62 4.48
†Means in a column with different letters are significantly different at P ≤ 0.05.
*, **, ***Significant at P ≤ 0.05, 0.01 and 0.001 probability level, respectively; NS = Not significant.
On dila soil significantly higher grain yields and total biomass were obtained from the
application of 64/20/0, 32/10/8000 and 32/10/4000 kg N/P/FYM ha
-1
, while on dimile soil
64/20/0 and 32/10/8000 kg N/P/FYM ha
-1
gave significantly higher grain and total biomass
yields (Table 10). The application of N/P/FYM at the rates of 9/10/8000, 32/10/4000, 32/10/8000
and 64/20/0 kg N/P/FYM ha
-1
increased mean grain yields of wheat by 16, 24, 31 and 32%,
respectively on dila and 32, 41, 59 and 71%, respectively on dimile soils compared to the
farmers’ check (9/10/0 kg N/P/FYM ha
-1
). Similarly, the findings of Eghball and Power (1999)
and Matsi et al. (2003) indicated that application of manure at the rate of 40 Mg ha
-1
resulted in a
significant increase in nutrient uptake, biomass and grain yields of wheat similar to the inorganic
N and P fertilization. The amounts of soil available nitrate nitrogen and P were also significantly
increased due to the application of manure (Matsi et al., 2003). Above all, from this study it can
be clearly understood that yield and yield components of wheat significantly varied between the
two soil types. Dila soil type which is better in its fertility level gave remarkably higher yield and
economic benefit than dimile soil type.

17
The results revealed that the effects of inorganic N/P fertilizers either alone or in combination
with FYM were significant for grain yield and yield components of wheat on dila and dimile
soils. The works of different researchers also showed that the application of animal manure
resulted in a significant increase in nutrient concentration and uptake, grain and straw yields of
wheat (Sharma et al., 1990; Reddy and Sankara, 2000; Fageria and Baligar, 1998; Matsi et al.,
2003). It was also found that the application of animal manure increased the root CEC at each
stage of growth, indicating that its application improves significantly crop nutrition and yield
(Sharma et al., 1990; Getachew et al., 2005b). According to Sharma et al. (1990), the use of
manure could make the soil more porous and pulverized, thus allowing better root growth and
development, thereby resulting in higher root cation exchange capacity.
Partitioning of treatments into single degrees of freedom orthogonal contrasts showed that plant
height, number of spikelets per spike and kernels per spikelet, total biomass and grain yields of
wheat were significantly affected by the applications of inorganic N and P fertilizers and FYM
(Table 12). The first contrast (control vs. treatments 2-5) had a highly significant (P
≤
0.001) effect
on plant height, kernels per spikelet, total biomass and grain yields on dila, and including spike
length and spikelets per spike on dimile soil. Nevertheless, the contrast had no significant effect on
thousand-kernel weight on dila soil type. The results showed that there was no significant effect
between contrasts of higher rates of inorganic N and P fertilizers and FYM on grain yield and yield
attributes of wheat. Getachew and Sommer (2000) reported a similar result on shoot dry matter
yield and nutrient uptake of maize due to the application of NH
4
H
2
PO
4
as depot mixed with
neutral compost on acidic soils.

18
Table 12. Variance ratios, probabilities of variance ratios, and residual mean squares of single degrees of freedom
orthogonal contrasts for N/P fertilizers and FYM effects on wheat, 2003-2004
Dila soil type
Contrasts PH SL SPS KPS TBY GY HI TGW
Trt1 vs. Trt2-5
Variance ratio 11.90 4.33 5.45 12.31 19.33 27.94 1.08 0.51
F-probability 0.0029 0.0519 0.0314 0.0080 0.0003 0.0001 0.3125 0.4857
Trt2 vs. Trt3-5
Variance ratio 2.83 8.30 7.35 2.43 4.28 6.60 0.06 0.44
F-probability 0.1095 0.0099 0.0143 0.1580 0.0533 0.0193 0.8105 0.5157
Trt3 vs. Trt4-5
Variance ratio 0.24 3.93 1.63 1.28 1.67 1.68 0.07 2.05
F-probability 0.6304 0.0629 0.2173 0.2915 0.2120 0.2112 0.7900 0.1695
Trt4 vs. Trt5
Variance ratio 4.66 2.09 1.23 2.71 0.20 0.00 0.41 1.24
F-probability 0.0447 0.1658 0.2828 0.1384 0.6634 0.9625 0.5312 0.2810
RMS (18df) 14.030 0.371 0.392 0.044 1.300 0.077 0.001 4.105
Contrasts Dimile soil type
Trt1 vs. Trt2-5
Variance ratio 23.65 12.20 10.35 39.12 30.38 86.85 4.98 1.50
F-probability 0.0001 0.0026 0.0048 0.0002 0.0001 0.0001 0.0386 0.2364
Trt2 vs. Trt3-5
Variance ratio 2.09 4.63 0.96 19.59 5.93 19.77 1.54 0.78
F-probability 0.1653 0.0452 0.3404 0.0022 0.0255 0.0003 0.2302 0.3886
Trt3 vs. Trt4-5
Variance ratio 3.61 0.08 1.05 1.66 15.84 16.90 1.88 0.26
F-probability 0.0735 0.7758 0.3181 0.2331 0.0009 0.0007 0.1871 0.6132
Trt4 vs. Trt5
Variance ratio 8.27 1.32 0.91 0.93 2.51 3.10 0.17 3.79
F-probability 0.0101 0.2657 0.3540 0.3626 0.1307 0.0951 0.6851 0.0674
RMS (18df) 12.00 0.240 0.487 0.022 0.632 0.037 0.001 2.519
a
PH = plant height, SL = spike length, SPS = spikelet per spike, KPS = kernels per spikelet, TBY = total biological
yield, GY = grain yield, HI = harvest index, TGW = thousand grain weight.
Pearson correlation coefficients among the traits were presented for the whole data set (Table
13). Grain yield was significantly and positively correlated with total biomass, plant height, spike
length, kernels per spikelet and spikelets per spike. Grain yield was strongly correlated with total

19
biomass yield (r = 0.89
***
), followed by plant height (r = 0.67***), kernels per spikelet (r =
0.55
**
), spike length (r = 0.45
*
) and spikelets per spike (r = 0.42
*
) on dila, and r = 0.90
***
, 0.65
**
,
0.35
*
, 0.61
**
and 0.54
**
on dimile soils. However, grain yield was correlated significantly
negatively with thousand-kernel weight on dila but not on dimile soil type. In both cases, grain
yield was more closely correlated with total biomass. Total biomass and spiklets per spike were
significantly positively correlated with plant height and spike length on both soil types. Plant
height and spike length were nearly equally correlated with grain yield (Table 13). From this
result, it could be understood that high total biomass, taller plant height, large number of kernels
per spikelet, large spike length and large number of spikelets per spike are the traits associated
with good performance of wheat.
Table 13. Correlation coefficients between agronomic traits tested at selected treatment combinations of inorganic
NP fertilizers and FYM under dila (upper half diagonal) and dimile soils (lower half diagonal), 2003-2004
PH† SL SPS KPS TBY GY TKW
PH 0.44* 0.41* 0.47* 0.76*** 0.67*** -0.23NS
SL 0.48** 0.78*** 0.40* 0.42* 0.45* -0.30NS
SPS 0.56** 0.82*** 0.39* 0.35* 0.42* -0.20NS
KPS 0.31NS 0.42* 0.35* 0.63** 0.55** -0.28NS
TBY 0.54** 0.71*** 0.63*** 0.40* 0.89*** -0.37*
GY 0.65*** 0.61*** 0.54** 0.35* 0.90*** -0.38*
HI 0.22NS -0.17NS -0.12NS 0.06NS -0.08NS 0.29NS 0.15NS
TKW -0.07NS -0.28NS -0.22NS -0.15NS -0.29NS -0.20NS
†PH = plant height, SL = spike length, SPS = spikelet spike-1, KPS = kernels spikelet-1, TBY = total biomass yield,
GY = grain yield, TKW = thousand-kernel weight.
*, **, *** Significant at P ≤ 0.05, 0.01 and 0.001 probability levels, respectively; NS = Not Significant.
Economic analysis
The results of the partial budget analysis indicated that the highest net benefits (ETB 7331.54 on
dila and 5734.22 on dimile soil types) were obtained from the application of 64/20/0 kg
N/P/FYM ha
-1
, while the farmers’ treatment (9/10/0 kg N/P/FYM ha
-1
) gave the lowest net
benefits of ETB 5969.00 ha
-1
on dila and ETB 3620.00 ha
-1
on dimile soil (Table 14).
Furthermore, the economic analysis indicates that the marginal rates of return (MRR) for the
non-dominated treatments were 205% and 376% for dila and 214% and 1126% for dimile soils

20
(Table 15). The results of the economic analysis suggest that for each ETB invested on N/P/FYM
in wheat production the producer having recovered his investment would earn additional ETB
2.05 and 3.76 on dila, and ETB 2.14 and 11.26 on dimile soils. Since the minimum acceptable
rate of return assumed in this study was 100%, the treatments with the application of 64/20/0 and
32/10/4000 kg N/P/FYM ha
-1
are economically viable and could be recommended for use by
smallholder farmers. Given that both the application of 64/20/0 and 32/10/4000 kg N/P/FYM ha
-
1
are economically viable; the choice of which of theses doses to use should be left to wheat
producers on Nitisols of the central highlands of Ethiopia. It is worth noting that the application
of FYM not only increase crop yield through the release of nutrients but also improve the
physical, biological and chemical properties of the soil. In this study, substantial yield increment
was obtained due to application of 64/20/0 kg N/P/FYM ha
-1
. In addition, since the combined
application of 32/10/4000 kg N/P/FYM ha
-1
provided a marginal rate of return well above the
minimum acceptable rate of return, it could be recommended as an alternative source for both
soil types.
Table 14. Partial budget analysis of N/P fertilizers and FYM trial in wheat on dila and dimile soil types
Partial budget analysis for dila soil type
Treatment
(kg ha
-1
)
Average
yield
(t ha
-1
)
Adjusted
yield-10%
(t ha
-1
)
Gross
benefit
(ETB ha
-1
)
Costs of
urea
(ETB)
Costs of
DAP
(ETB)
Costs of
FYM
(ETB)
FYM
applic
ation
cost
TCV
(ETB) Net
benefit
(ETB ha
-1
)
Domin
ance
N/P/FYM
9/10/0 2.63 2367 6177.87 0.00 209.00 0.00 0 209.00 5968.87
32/10/4000 3.27 2943 7681.23 189.00 209.00 254.14 50 702.14 6979.086
64/20/0 3.46 3114 8127.54 378.00 418.00 0.00 0 796.00 7331.54
9/10/8000 3.05 2745 7164.45 0.00 209.00 508.29 100 817.29 6347.162 D
32/10/8000 3.44 3096 8080.56 189.00 209.00 508.29 100 1006.29 7074.272 D
Partial budget analysis for dimile soil type
Treatments
(kg ha
-1
)
Average
yield
(t ha
-1
)
Adjusted
yield-10%
(t ha-1)
Gross
benefit
(ETB
ha-1)
Costs of
urea
(ETB)
Costs of
DAP
(ETB)
Costs of
FYM
(ETB)
FYM
applic
ation
cost
TVC
(ETB) Net
benefit
(ETB
ha-1)
Domin
ance
N/P/FYM
9/10/0 1.63 1467 3828.87 0.00 209.00 0.00 0 209.00 3619.87
32/10/4000 2.29 2061 5379.21 189.00 209.00 254.14 50 702.14 4677.07
64/20/0 2.78 2502 6530.22 378.00 418.00 0.00 0 796.00 5734.22
9/10/8000 2.15 1935 5050.35 0.00 209.00 508.29 100 817.29 4233.06 D
32/10/8000 2.59 2331 6083.91 189.00 209.00 508.29 100 1006.29 5077.62 D
TVC = Total costs that vary; D = dominated

21
Table 15. Marginal analysis for the combined effects of inorganic N and P fertilizers and FYM on wheat grain yield
on dila and dimile soils, 2003 - 2004
Soil type Dila soil type Dimile soil type
Treatments (N/P/FYM)
N (kg ha
-1
) 9
32
64 9
32
64
P (kg ha
-1
) 10
10
20 10
10
20
FYM (kg ha
-1
) 0
4000
0 0
4000
0
Average yield (t ha
-1
) 2.63
3.27
3.46 1.63
2.29
2.78
Adjusted yield-10% (kg ha
-1
) 2367 29
43
3114 1467
2061
2502
Gross benefit (ETB ha
-1
) 6177.87
7681.23
8127.54 3828.87
5379.21
6530.22
Cost of fertilizer (ETB ha
-1
) 209.00 398
.00
796.00 209.00 398
.00
796.00
Costs of FYM (ETB ha
-1
) 0.00 254.1
4
0.00 0.00 254.1
4
0.00
Cost of FYM application (ETB ha
-1
) 0.00 50
.00
0.00 0.00 50
.00
0.00
TVC (ETB ha
-1
) 209.00 702.1
4
796.00 209.00 702.1
4
796.00
NB (ETB ha
-1
) 5968.87 6979.0
9
7331.54 3619.87 4677.0
7
5734.22
MC (ETB ha
-1
)
493.14
93.86
493.14
93.86
MR (ETB ha
-1
)
1010.22
352.45
1057.20
1057.15
MRR (%)
204.85
375.53
214.38
1126.36
Conclusion
Soil acidity and associated low nutrient availability is one of the major constraints to crop
production on Nitisols in the Ethiopian highlands. In an attempt to address the aforementioned
problem an integrated nutrient management trials were conducted on faba bean and wheat in the
central highland Nitisol areas of Ethiopia. Results indicated a positive linear response of faba
bean seed yield to FYM and P fertilizer applications. Total biomass, seed yield and number of
pods per plant were positively influenced by FYM and P applications. Phosphorus by FYM
interaction significantly affected total biomass and seed yield. The application of FYM at 4 and 8
t ha
-1
increased seed yield of faba bean by 34 and 53%, respectively compared to the control.
Likewise, the application of P fertilizer significantly and linearly increased seed yield between
16 and 32% over the control. Based on the economic analysis, application of 8 t FYM ha
-1
was
found to have the highest marginal rate of return for faba bean production.
Likewise, wheat grain yield, total biomass and number of kernels per spike significantly
positively responded to N/P/FYM applications. The application of N/P/FYM at the rates of
32/10/4000, 32/10/8000, 9/10/8000 and 64/20/0 kg ha
-1
increased mean grain yield of wheat by
16, 24, 31 and 32%, respectively on dila (medium fertility), and 32, 41, 59 and 71%, respectively
on dimile (low fertility) soils compared to the farmers’ check (9/10/0 kg N/P/FYM ha
-1
). In terms

22
of economics the highest marginal rate of return was obtained from the application of 64/20/0 kg
N/P/FYM ha
-1
for both soils. Application of 32/10/4000 kg N/P/FYM ha
-1
also provided a
marginal rate of return well above the minimum acceptable rate of return and hence could be
considered as an alternative rate in situation where the cost of inorganic fertilizer is high and
availability is limited.
Furthermore, results of soil analysis after harvesting revealed that the application of farmyard
manure improved soil pH, N and available P and exchangeable cations. It is evident that
application of manure year after year enhances build up of nutrients in the soil and after
successive years of application the amount of nutrients to be applied either as inorganic or
organic forms will gradually decrease. Residual effects of manure application on crop production
and soil properties can last for several years. Hence, the profitability of application of manure
could not be precisely estimated in the short term, rather its effect is clearly seen in the long
term. Application of manure not only increases the nutrient content of soils, but also improves
the physical and biological condition of soils. In general, the results of such studies will enable
researchers and development experts develop management strategies for the efficient use of this
biological resource in soil fertility management for sustainable crop production under
smallholder farmers’ condition.
Acknowledgement
We are very grateful to Ato Chanyalew Mandefro and Ato Beyne Ofa for their technical
assistance in the execution of the field experiment. Appreciation is also due to services of the
analytical soil laboratory of the Holetta Agricultural Research Centre, EIAR. The International
Fund for Agricultural Development (IFAD) and the Ethiopian Institute of Agricultural Research
are highly acknowledged for funding this experiment throughout the entire period

23
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