minimum acceptable rate of return, it could be recommended as an alternative source for both soil types. Key words: ameliorating effects, faba bean, integrated ...
AMELIORATING EFFECTS OF ORGANIC AND INORGANIC FERTILIZERS ON CROP PRODUCTIVITY AND SOIL PROPERTIES ON REDDISH-BROWN SOILS
Getachew Agegnehu Holetta Research Centre, P. B. Box 2003, EIAR, Addis Ababa
Running title: Integrated nutrient management
1
AMELIORATING EFFECTS OF ORGANIC AND INORGANIC FERTILIZERS ON CROP PRODUCTIVITY AND SOIL PROPERTIES ON REDDISH-BROWN SOILS
ABSTRACT Soil acidity and associated low nutrient availability is one of the constraints to faba bean (Vicia faba L.) and wheat (Triticum aestivum L.) production on Nitisols of Ethiopian highlands. Integrated nutrient management trials were conducted from 2001 to 2003 for faba bean and 2003 to 2004 cropping seasons for wheat in the highland Nitisol areas of Ethiopia. The objective of the study was to investigate the ameliorating effects of N/P fertilizers and farmyard manure (FYM) on the growth and yields of faba bean and wheat. For faba bean, three levels of decomposed FYM (0, 4 and 8 t ha-1) as main plots and five levels of phosphorus (0, 13, 26, 39 and 52 kg P ha-1) in the form of triple super-phosphate as subplots were laid out in a split plot design with four replications. While for wheat five combinations of N/P/FYM (9/10/0, 32/10/4000, 32/10/8000, 9/10/8000 and 64/20/0 kg ha-1, respectively) were arranged in a randomized complete block design with three replications. Results indicated that 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 faba bean seed yield by 34 and 53% respectively compared to the control. The application of P fertilizer also significantly increased seed yield with yield advantages of ranging 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. Similarly, wheat grain yield, total biomass and kernels per spike were significantly affected by 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 wheat grain yield 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 kg N/P ha-1). In terms 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. Besides, 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. Key words: ameliorating effects, faba bean, integrated nutrient management, Nitisols, wheat
2
INTRODUCTION Integrated plant nutrient management method is needed when seeking alternative plant nutrient management systems in subsistence farming for social and economic acceptability (Fageria and Baligar, 1998). 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). The fertility status of these soils is very low due to removal of nutrients in the harvested products and losses through erosion and leaching. Its 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., 2002, 2003). 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). The quantity of P 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 and faba bean are among the most important crops widely grown by smallholder farmers in Ethiopia. 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). 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 a major source of protein and a 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). Diagnostic studies with farmers indicated that farmers classify soils 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 groups of soils namely kosi, dila, dimile and koticha. 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, are the most fertile soil due to the accumulation of organic matter and nutrients as a result of continuous applications of household
3
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 (Getachew et al., 2002, 2003). However, dimile soil is characterized by low soil fertility as a result of continuous cultivation and soil erosion. Thus, integrated soil fertility is required in order to obtain optimum yield. Although N/P rates have already been determined and recommended for wheat and faba bean production farmers wish to have other options that may at least partially replace sources of inorganic N/P fertilizers (Chilot et al., 2002). Results of on-farm fertilizer trials on kosi and dimile soils indicated that N/P fertilizers have significantly increased wheat and faba bean yields on dimile soil, but not on kosi soil (Getachew et al., 2002, 2003). As a result 64/20 kg N/P ha-1 was recommended for wheat production (Getachew et al., 2002), but farmers could not take up the recommendation 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). The objectives of these experiments were, therefore, to find out the ameliorating effects of N/P fertilizers and FYM on crop productivity and soil properties, and to determine the optimum rates of N/P fertilizers and FYM for the production of both crops on Nitisols. MATERIALS AND METHODS Experimental set-up Integrated nutrient management trials were conducted from 2001-2003 in faba bean at the experimental fields of Holetta Research Centre and 2003 - 2004 cropping seasons in wheat on dila and dimile soils of farmers’ fields of Welmera Wereda in the central highland Nitisol areas of Ethiopia. Six wheat growers have participated in the study. The effects of three levels of airdried decomposed FYM (0, 4 and 8 t ha-1) and five levels of phosphorus fertilizer (0, 13, 26, 39 and
4
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. The sub-plot size was 20 m2. In the case of wheat five treatments comprising of 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) were arranged in randomized complete block design with three replications. Plot size was 5 m by 8 m. The sources of inorganic N/P fertilizers were urea and DAP for wheat and urea and TSP for faba bean. The source of the FYM was the livestock research division of the centre. It was kept under shade from 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. Wheat variety HAR-604 was sown at the rate of 175 kg ha-1 from mid to end of June. Faba bean (cv CS20DK) was sown from 21 to 23 June at the seed rate of 200 kg ha-1. The phosphorus was applied along with seeds as TSP. Twenty kg N ha-1 was applied as a starter dressing to all plots in the form of urea. Table 1. Initial soil chemical properties of the experimental field Faba bean Wheat field field
Dila
Dimile
Soil chemical property
Value
Value
Value
PH (1:1 H2O)
4.3
5.12
4.53
Organic carbon (%)
1.52
-
-
Total N (%)
0.17
0.21
0.18
NO3-N
21.69
9.68
NH4+-N
35.09
30.33
Available P (ppm)
4.95
19.12
9.73
Available Na (meq/100 g)
0.10
0.06
0.01
Available K (meq/100 g)
1.33
2.12
1.62
Available Ca (meq/100 g)
2.74
11.51
8.21
Available Mg (meq/100 g)
2.09
2.72
1.57
CEC (meq/100 g)
26.60
26.51
20.21
5
Composite soil samples were collected before planting and after harvesting from 0-20 cm soil depth and analysed for pH, P, N, organic carbon (OC), Na, K, Ca, Mg and cation exchange capacity (CEC), which are presented in Table 1. During application the FYM rates were adjusted on dry weight basis, thereby its moisture content was 24%. FYM samples were analysed and had 69.5% 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). Data collection and statistical analysis 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 and grain yields, and thousand grain weight of each crop species as appropriate. Economic data on fertilizer and crop prices were also collected. Total biomass and grain yields recorded on whole plot basis (20 m2 for faba bean and 40 m2 for wheat) were converted to kg ha-1 for statistical analysis. The SAS/STAT computer package 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 separate and pooled analysis of variance over years using the following model. T ijkl = u + Y i + R j (i ) + M k + YM (ik ) + R ( M ) jk + P l + YP(il ) + MV ( kl ) + YMP( ikl ) + eijkl … (1) Where Tijkl is total observation, µ = grand mean, Yi = effect of the ith year, Rj (i) is effect of the jth replication, Mk is effect of the kth manure level, Pl is effect of the lth phosphorus level, YM, YP, MP and YMP are the interactions, and eijkl is the variation due to random error
Τijk = Y i + R j (i ) + T k + TY ( ik ) + eijk ………………………………. ………………………… (2) Where Tijk is total observation, µ = grand mean, Yi = effect of the ith year, Rj (i) is effect of the jth replication (within the ith year), Tk is effect of the kth treatment, TY (ik) is the interaction of kth treatment with ith year and eijk is the random error. Results were presented as means and least significance difference (LSD) at 5% probability level was used to establish differences among means. Pearson correlation coefficient (r) among agronomic traits was calculated. Economic analysis was performed to investigate the economic feasibility of the treatments. Partial budget, dominance and marginal analyses were used. The average yield was adjusted downwards by 15% to reflect the difference between the experimental plot yield and the
6
yield farmers could expect from the same treatment. Three years (2001 – 2003) mean market price (Birr 1.31 kg-1) for faba bean and two years (2003 - 2004) average market price (ETB 1.42 kg-1) for wheat were used to convert the adjusted yields to gross field benefits. The market prices of ETB 2.94 kg-1 for phosphate fertilizer and ETB 2.61 kg-1 for urea were used for analysis. The N and P contents of the FYM were converted into equivalent prices of N/P fertilizers. For a treatment to be considered a worthwhile option to farmers, the minimum acceptable rate of return (MARR) need to be at least between 50 and 100% (CYMMT, 1988). However, the MARR of 100% was suggested as realistic. Hence, to make farmer recommendations from marginal analysis, the MARR by the farmers was taken to be 100%.
RESULTS AND DISCUSSION 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). The combined analysis of variance over three years revealed that applications of FYM and phosphorus fertiliser positively influenced seed yield, total biomass, thousand seed weight, number of pods per plant and seeds per pod and plant height of faba bean. Farmyard manure and P fertilizer had a highly significant (p ≤ 0.001) effect on seed yield and total biomass of faba bean (Table 2). Thousand seed weight, number of seeds per plant and seeds per pod and plant height also significantly (p ≤ 0.05 and p ≤ 0.01) responded to FYM and P fertilizer applications. The application of FYM at the rates of 4 and 8 t ha-1 resulted in three-season mean seed yield advantages of about 34 and 53% over the control (Table 2). 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 fertiliser significantly and linearly increased seed yield with yield advantages of ranging between 16 and 32% over the control (Table 3). Similar findings also indicated that a significant linear and quadratic faba bean seed yield responses to P fertilizer applications (Amare et al., 1999; Getachew and Rezene, 2006; Getachew and Angaw, 2006)
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Table 2. Analysis of variance for yield and yield components of faba bean tested at three FYM and five P levels at Holetta, 2002-2003 Source
SY
TBY
TSW
PPP
PH
Y
**
**
***
**
*
M
***
***
*
**
**
Y×M
**
NS
*
NS
NS
P
***
***
*
**
**
Y×P
*
**
NS
NS
NS
M×P
**
**
*
NS
NS
Y×M×P
*
*
NS
NS
NS
Root-MSE
166.0
431.0
19.9
1.4
9.5
CV (%)
9.5
10.6
4.0
15.9
7.2
*, **, ***
Significant at ρ ≤ 0.05, ρ ≤ 0.01 and ρ ≤ 0.001 probability levels, respectively; NS = Not significant
Table 3. FYM and P effects on yield and major yield components of faba bean at Holetta, 2001-2003
Factor
Seed
Total
1000 seed Pods per Plant
yield
biomass
weight
plant
height
-1
FYM (t ha ) 0
1352c†
3137c
493b
7.3c
123b
4
1803b
4192b
506a
9.2b
136a
8
2068a
4846a
508a
10.7a
140a
73.8
191.7
8.9
0.64
4.2
P (kg ha-1) 0
1456c
3452c
495b
7.6c
127b
13
1685b
3875b
498ab
8.8b
132ab
26
1763b
4051b
507a
9.0b
134a
39
1878a
4440a
505a
9.3a
135a
52
1923a
4474a
507a
10.0a
137a
95.3
247.5
11.5
0.82
5.5
9.5
10.6
4.0
15.9
7.2
LSD (0.05)
LSD (0.05) CV (%)
†Means in a column followed by the same letter are not significantly different at P ≤ 0.05
The FYM by P fertilizer interaction significantly (p ≤ 0.05 and p ≤ 0.01) affected seed yield, total biomass and thousand seed weight of faba bean. Similarly, year by FYM and P
8
fertilizer effect had a significant (p ≤ 0.05) effect on seed yield and total biomass (Table 2). The mean seed yields of faba bean increased as the levels of the two interacting factors increased in which the highest mean seed yield was recorded from the interaction of 8 t FYM ha-1 and 39 kg p ha-1 (Table 3). Maximum total biomass and seed yield of faba bean were obtained from FYM and P treated soils in comparison with lower yields observed in the relatively lower pH (pH < 4.5) environments. The highest seed yield was recorded from the application of 8 t FYM ha-1 and 39 kg P ha-1 (Table 4). Table 4. Interaction effects of FYM and phosphorus on faba bean yield, 2002-2003 Phosphorus -1
(kg ha )
Farmyard Manure (t 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
Mean
Mean SE
58.68
According to the results of this study if the pH of the soil is improved through FYM supply the application of 13-26 kg P ha-1 could be adequate for faba bean production. Similarly, 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, which agrees with this finding. When pulse crops are grown on soils with pH values less than 5.6 they give low yields (Mahler et al., 1988). The analysis of soil samples collected after harvesting indicated that there was a higher pH levels and nutrient concentrations on plots treated with both FYM and P fertilizer compared to sole application of either FYM or P fertiliser. The lowest pH and nutrient content were observed in soils, which were not treated with FYM.
Economic analysis
9
Based on the results of partial budget analysis, the highest net benefit (Birr 4274.88) was obtained from the application of 8 t FYM ha-1 (Table 5). The net benefit (Birr 2442.82 ha-1) obtained from the control treatment (no application of either P fertiliser or FYM) was the lowest. The results of dominance analysis showed that treatments other than 0/0 FYM/P, 0/13 FYM/P, 4/13 FYM/P and 8/0 FYM/P are dominated. Hence, the dominated treatments were eliminated from further economic analysis (Table 5). The marginal rates of return for the non-dominated treatments were found to be 282, 134 and 2027% (Table 6). This implies that for each Birr 1.00 investment on FYM/P in faba bean production, the producer can get Birr 1.00 and additional Birr, 2.82, 1.34 and 20.27. Since the minimum acceptable rate of return assumed in this experiment was 100%, the treatments with applications of 0/13 FYM/P and 4/13 FYM/P has also given acceptable marginal rates of return so that they have met the requirement. Therefore, according to the results of economic analysis, despite the highest marginal rate of return from the application of 8 t FYM ha-1, the preference will be left to faba bean producers in acidic Nitisols of the central highlands of Ethiopia since 0/13 FYM/P and 4/13 FYM/P are economically alternative doses. Table 5. Partial budget analysis of FYM and phosphorus fertilizer experiment
0 FYM + 0 P 0 FYM +13 P
Average yield (kg ha-1) 991 1412
4 FYM + 0 P 0 FYM+ 26 P
Particulars
Adjusted yield 15% (kg ha-1)
Gross field benefits (Birr ha-1)
Costs that vary (Birr ha-1)
Cost of fertilizer
Cost of FYM 0.00 0.00 0.00 271.70
Cost of FYM appl. 0.00 0.00
Total costs that vary 0.00
Net benefit (Birr ha-1)
Do min anc e
842.35 1200.20
2442.82 3480.58
271.70
2442.82 3208.88
1395 1317
1185.75 1119.45
3438.68 3246.405
0.00 543.40
254.14 0.00
50 0.00
304.14 543.40
3134.53 2703.01
4 FYM + 13 P 8 FYM + 0 P
1701 1981
1445.85 1683.85
4192.97 4883.17
271.70 0.00
3617.12 4274.88
1467 1954
1246.95 1660.90
3616.16 4816.61
815.10 543.4
50 100 0.00
575.84 608.29
0 FYM + 39 P 4 FYM + 26 P
254.14 508.29 0.00 254.14
50
815.10 847.54
2801.06 3969.07
D D
8 FYM + 13 P 0 FYM + 52P
1942 1573
1650.70 1337.05
4787.03 3877.45
271.70 1086.80
508.29 0.00
100 0.00
879.99 1086.80
3907.04 2790.65
D D
4 FYM + 39 P 8 FYM + 26 P
1958 2019
1664.30 1716.15
4826.47 4976.84
815.10 543.40
254.14 508.29
50 100
1119.24 1151.69
3707.23 3825.15
D D
4 FYM + 52 P 8 FYM + 39 P
2007 2210
1705.95 1878.50
4947.26 5447.65
1086.80 815.10
254.14 508.29
50 100
1390.94 1423.39
3556.31 4024.26
D D
8 FYM + 52 P 2191 1862.35 5400.82 1086.80 508.29 Five years average price of Faba bean Birr 2.90/kg, and DAP Birr 4.18/kg
100
1695.09
3705.73
D
Table 6. Marginal analysis of FYM and P fertilizer effects on faba bean at Holetta, 2002-2003 Particulars
Treatments
10
D D
-1
Average yield (t ha ) Adjusted yield-15% (kg ha-1) Gross benefit (ETB ha-1) Costs of Fertilizer (ETB ha-1) Costs of FYM (ETB ha-1) Cost of FYM application (ETB ha-1) TCV (ETB ha-1) NB (ETB ha-1) MC (ETB ha-1) MB (ETB ha-1) MRR (%)
0 FYM + 0 P 991
0 FYM +13 P 1412
4 FYM + 13 P 1701
8 FYM + 0 P 1981
842.35 2442.82
1200.2 3480.58
1445.85 4192.97
1683.85 4883.17
0.00 0.00
271.70 0.00
271.70 254.14
0.00 508.29
0.00 0.00 2442.815
0.00 271.70 3208.88 271.70 766.07 281.95
50.00 575.84 3617.12 304.14 408.24 134.23
100.00 608.29 4274.88 32.44 657.76 2027.36
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. The nutrient contents of the soil types used in this study correspond with farmers’ classification (Table 1). The soil pH, available P, exchangeable cations and CEC in dimile soil were found to be below the optimum requirement for wheat. 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). Analysis of variance over two years indicated that the combined applications of inorganic and organic fertilizers had a highly significant effect (p ≤ 0.01 and p ≤ 0.001) on total biomass, grain yield, plant height and spike length. The year by treatment interaction (Y×T) effect was significant for spikelets spike-1 on both soil types, but plant height only on dimile soil; other parameters were not significantly affected by the interaction (Tables 7 and 8). Number of spikelets spike-1 significantly (P ≤ 0.05) responded to the application of inorganic N/P fertilizers and FYM on both soil types; but kernels spikelet-1 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 7).
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Table 7. Inorganic N/P fertilizers and FYM effects on grain yield (GY), biomass yield (TBY) and thousand-kernel weight (TKW) of wheat on dila and dimile soils (Nitisols) of Welmera area, 2003-2004 Dila soil type
Dimile soil type
GY
TBY
TKW
GY
TBY
TKW
(t ha-1)
(t ha-1)
(g)
(t ha-1)
(t ha-1)
(g)
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
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
Treatment (T) N/P/FYM (kg ha-1)
F-probability
†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 and biomass yields 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 biomass yields (Table 8). 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).
12
Table 8. Inorganic N/P fertilizers and FYM effects on wheat plant height (PH), kernel/spikelet (KPS) and spikelet/spike (SPS) on dila and dimile soils of Welmera area, 2003-2004 Dila soil type
Dimile soil type
PH
KPS
SPS
PH
KPS
SPS
Treatments (T)
(cm)
(no.)
(no.)
(cm)
(no.)
(no.)
N/P/FYM (kg ha-1) 9/10/0
93.7c†
1.6c
16.1c
84.8b
1.5b
14.7b
9/10/8000
97.4bc
2.0bc
16.1bc
90.7b
1.7b
15.5ab
32/10/4000
101ab
2.1ab
16.7abc
90.9b
2.1a
15.6a
32/10/8000
97.8bc
2.4a
16.9ab
91.3b
2.2a
15.8a
64/20/0
102a
2.1ab
17.3a
97.1a
2.3a
16.2a
F-probability Year (Y)
*
NS
NS
NS
NS
NS
Treatment (T)
**
*
*
***
***
*
Y×T
NS
NS
**
*
NS
*
LSD (0.05)
4.5
0.4
0.80
4.2
0.28
0.85
CV (%)
3.8
10.4
3.8
3.8
7.6
4.5
†Means in a column with different letters are significantly different at P ≤ 0.05. *, **, ***
Significant at ρ ≤ 0.05, 0.01 and 0.001 probability level, respectively; NS = Not significant.
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 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; 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). According to Sharma et al. (1990), the use of manure could make the soil more porous and pulverised, thus allowing better root growth and development, thereby resulting in higher root CEC. Correlation statistics among some major traits showed that grain yield was significantly and positively correlated with total biomass, plant height, spike length, kernels spikelet-1 and spikelets spike-1. Grain yield was strongly correlated with total biomass yield (r = 0.89***), followed by plant height (r = 0.67***) and kernels spikelet-1 (r = 0.55**) on dila and r = 0.90***, 0.65** and 0.54**, respectively on dimile soils. In both cases, grain yield was more closely correlated with
13
biomass yield. From this result, it could be understood that high biomass yield, taller plant height and large number of kernels spikelet-1 are the traits associated with good performance of wheat.
Economic analysis The results of the partial budget analysis showed that the highest net benefits, ETB 7331.54 ha-1 on dila and ETB 5734.22 ha-1 on dimile soils, 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 kg-1) gave the lowest net benefits of ETB 5968.87 ha-1 on dila and ETB 3619.87 ha-1 on dimile soil (Tables 9). The results of dominance analysis indicated that all the treatments with higher total cost that vary and lower net benefits were dominated and these treatments were eliminated from further economic analysis (Table 9). Table 9. Partial budget analysis for the combined effects of N/P fertilizers and FYM on wheat grain yield on dila and dimile soils, 2003 – 2004 Dila soil type
N/P/FYM (kg ha-1) 9/10/0
Average yield (t ha-1) 2.63
Adjuste d yield10% (t ha-1) 2367
Gross benefit (ETB ha-1) 6177.87
32/10/4000
3.27
2943
Costs that vary (Birr ha-1)
Cost of urea
209.00
Net benefit (ETB ha-1 5968.87
50
702.14
6979.09
Cost of FYM
0
Cost of DAP 209
0
FYM applic cost 0
7681.23
189
209
254.14
TVC
Do min ace
64/20/0
3.46
3114
8127.54
378
418
0
0
796.00
7331.54
9/10/8000
3.05
2745
7164.45
0
209
508.29
100
817.29
6347.16
D
32/10/8000
3.44
3096
8080.56
189
209
508.29
100
1006.29
7074.27
D
209
0.00
0.00
209.00
3619.87
Dimile soil type 9/10/0
1.63
1467
3828.87
0.00
32/10/4000
2.29
2061
5379.21
189
209
254.14
50
702.14
4677.07
64/20/0
2.78
2502
6530.22
378
418
0.00
0.00
796.00
5734.22
9/10/8000
2.15
1935
5050.35
0
209
508.29
100
817.29
4233.06
D
32/10/8000
2.59
2331
6083.91
189
209
508.29
100
1006.29
5077.62
D
Five years average price of wheat 2.61/kg; Urea 3.78/kg and DAP 4.18/kg
The results of the marginal analysis indicated that the marginal rate of return for the nondominated treatments was 205 and 214% for dila and 375 and 1126% for dimile soils (Table 10). This implies that for each ETB 1.00 investment on N/P/FYM in wheat production, the producer can get ETB 1.00 and additional ETB 2.05 and 2.14 on dila and ETB 3.5 and 11.26 on dimile soils. Since the minimum acceptable rate of return assumed in this experiment was 100%, the
14
treatments with application of 64/20/0 and 32/10/4000 kg N/P/FYM ha-1 have met the requirement. Therefore, according to the results of economic analysis, despite the highest marginal rate of return from the application of 64/20 kg N/P ha-1, the preference will be left to wheat producers in acidic Nitisols of the central highlands of Ethiopia since 32/10/4000 kg N/P/FYM ha-1 is economically an alternative dose. Table 10. Marginal analysis for the combined effects of inorganic N/P fertilizers and FYM on wheat grain yield on dila and dimile soils, 2003 – 2004 Soil type Treatments (N/P/FYM) N P FYM Average yield (t ha-1) Adjusted yield-10% (t ha-1) Gross benefit (ETB ha-1) Cost of fertilizer (ETB ha-1) Costs of FYM (ETB ha-1) Cost of FYM application (ETB ha-1) TVC (ETB ha-1) NB (ETB ha-1) MC (ETB ha-1) MR (ETB ha-1) MRR (%)
Dila
Dimile
9 10 0 2.63 2367 6177.87 209.00 0.00
32 10 4000 3.27 2943 7681.23 398.00 254.14
64 20 0 3.46 3114 8127.54 796.00 0.00
9 10 0 1.63 1467 3828.87 209.00 0.00
32 10 4000 2.29 2061 5379.21 398.00 254.14
64 20 0 2.78 2502 6530.22 796.00 0.00
0.00 209.00 5968.87
50.00 702.14 6979.09 493.14 1010.22 204.85
0.00 796.00 7331.54 93.86 352.45 375.53
0.00 209.00 3619.87
50.00 702.14 4677.07 493.14 1057.20 214.38
0.00 796.00 5734.22 93.86 1057.15 1126.36
CONCLUSION Applications 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, according to the economic analysis, application of 8 t FYM ha-1 was found to have the highest marginal rate of return for faba bean production. In the case of wheat, despite the substantial yield increment due to
application of FYM and N/P fertilizers the highest net benefit was obtained from 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 is above the minimum acceptable marginal rate of return, it could be recommended as an alternative source for wheat production for both soil types.
ACKNOWLEDGEMENTS
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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, EARO. The International Fund for Agricultural Development (IFAD) and the Ethiopian Agricultural Research Organization are highly acknowledged for funding this experiment throughout the entire period
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