Effect of Blended Fertilizer Types and Rates on Growth, Yield and Yield Components of Bread Wheat ( Triticum aestivum L.) in Wondo District, Southern Ethiopia

– Soil fertility decline is one of the principal factors contributing to low productivity of crops and food insecurity in Ethiopia. The information available with regards to effect of blended fertilizer type and rates on growth and yield performance of bread wheat ( Triticum aestivum L.) for optimum production on loam soils of Wondo district is very limited. Therefore, a field experiment was conducted on loam soils of Wondo district Bachel Gigissa Peasant Association Farmers training center during 2018 cropping season to assess the effect of different blended fertilizer types and rates on growth, yield and yield components of bread wheat. The treatments studied consist of: control and three blended fertilizer formula NPS, NPSB, and NPSBZn each with four different rates (50, 100, 150 and 200 kg ha 1 ). Recommended rate of Urea (100 kg ha -1 ) was used equally for all treatments in spilt application and Danda’a variety was used as a test crop. The treatments were laid out in a Randomized Complete Block Design with three replications. Soil and crop data were collected and analyzed using the SAS statistical package program version 9.4 and LSD at 5% probability level was used to establish the difference among the means. The soil result revealed that the experimental soil site texture was classified as loam. The highest (30.06 kg -1 ) agronomic efficiency obtained from150 kg ha -1 NPSB. The results revealed that application of blended fertilizers (NPS, NPSB and NPSBZn) delayed days to flowering, and physiological maturity by (13, 9, 10) and (15, 14 and 11) days, respectively as compared to control plot. Leaf Area Index and Straw yield were significantly (p ≤ 0.01) affected by the application of different blended fertilizer rates and significantly (p ≤ 0.05) by the main effect of blended fertilizer types and interaction effect. Grains per spike and grain yield were significantly (p ≤ 0.01) affected due to the main effects of blended fertilizer types and rates, they were also significantly (p ≤ 0.05) affected due to the interaction effect. Above ground biomass was significantly (p ≤ 0.01) affected due to main effect of blended fertilizer rates and the interaction effect however, non-significant (p > 0.05) due to blended fertilizer types. This study also revealed that, blended fertilizer types and rates significantly (p≤0.05) affected DH, NFTm -2 , DPM, PH, SL and HI while TSW was significantly (p≤0.05) affected only by the main effect of blended fertilizer rates. Blended fertilizers had improved Agronomic nutrient use efficiency of wheat as compared to the control treatment. The highest (6.17t ha -1 ) grain yield was obtained from 200 kg ha -1 NPSB +100 kg ha -1 urea application followed by (6.11 t ha -1 ) from 150 kg ha -1 NPSB + 100 kg ha -1 urea, while minimum (1.95t ha -1 ) grain yield was attained from the control treatment. However, the application of 150 kg ha -1 NPSB + 100 kg ha -1 urea had highest marginal rate of return (MRR %) and Net benefit. Therefore, it would be advisable to use blended fertilizer 150 kg ha -1 NPSB + 100 kg ha -1 , for wheat production in Wondo area. Furthermore, based on yield, net benefit and relatively low total cost of production the farmers of Wondo area also can use 100 kg ha -1 NPSB+ 100 kg ha -1 urea. However, since the experiment was conducted only for one season and one site, repeating the trial at different site as well as in the same experimental site would be important in order to draw sound recommendation.


Description of the Study Area
The experiment was conducted under rain-fed condition during the main cropping season from August -December, 2018 at Wondo District, West Arsi Zone, Oromia Regional state. The specified study area is located at 7 o 4 '

Treatments and Experimental Design
The experimental treatments consisted of the control and three blended fertilizer types (NPS, NPSB and NPSBZn) with four levels (50, 100, 150 and 200 kg ha -1 ). The blanket recommended N (100 kg ha -1 Urea) was top dressed for all treatments. The experiment was laid out in a randomized complete block design (RCBD) with total of 13 treatments replicated three times. The plots within a block were separated by 1 m, whereas the blocks were separated by 1.5 m. The plot size was 3m x 4m (12 m 2 ) having 15 planting rows plot -1 spaced 20 cm apart.
In order to avoid boarder effects, the two outer most rows from both sides of each plots as well as 40cm at both ends of each row were left. Hence, 7.04m 2 (2.2m x 3.2m) of net plot size were used for the data collection.

Experimental Procedure and Management
The experimental field was prepared using oxen plow as farmer's conventional farm practices. In order to create good seed bed for proper crop growth, the experimental plots were plowed three times to a depth of 25-30 cm.
Seeds of bread wheat were sown by hand drilling on August 7, 2018 with the recommended seed rate of 125 kg ha -1 . All blended fertilizers were applied at planting time as per treatments while N in the form of Urea was applied in split doses 1/3 at planting and the remaining 2/3 top dressed 35 days after sowing and all agronomic practices were carried out according to recommendation for wheat.

Data Collection and Analysis Soil Sampling and Analysis
The soil samples of the experimental site were collected before planting from 0-20 cm plough depth. A representative soil samples were taken from an experimental field randomly and composited to one sample for soil characterization.
The collected soil samples were analyzed for the selected chemical properties cation exchangeable capacity (CEC), Electrical conductivity (EC), Organic Carbon, Total N, exchangeable K, available (P, S, B, and Zn). Soil samples were analyzed for texture with a hydrometer (Bouyoucos, 1962). The pH of the soil is determined with the potentiometer method (1:2.5 soil: water as described by Chopra and Kanwar (1976

Statistical Analysis
The mean values of the parameters recorded were subjected to Analysis of Variance (ANOVA) using statistical

Economic Analysis of Treatment Effects
Economic analysis was performed to investigate the economic feasibility of the treatments by using partial and marginal profit analyses according to CIMMYT (1988). To make a rational choice of alternative blended fertilizers based on their economic benefit the partial budget and marginal rate of return (MRR) were analyzed for wheat production (CIMMYT, 1988).
Where: NB = Net benefit, TVC = Total variable cost and MRR = marginal rate of return.

Physico-chemical Properties of Soil before Planting
The parameters tested and their corresponding values are indicated below.

Phenological Parameters
Days to 50% heading The analysis of current results revealed that highly significant (p≤0.01) differences among the blended fertilizer types and rates on days to 50% heading however, non-significant due to the interaction effect. The longest days to 50% heading (70 days) was recorded from blended fertilizer types NPS, while the shortest days (57 days) were recorded from the control ( Table 3). The variation in days to 50% heading among the blended fertilizer types could be attributed to the high level of N in the NPS fertilizers.
Regarding to rates, the longest days to 50% heading (71days) was recorded from 150 kg ha -1 blended fertilizer and the shortest days to 50% heading (63 days) was recorded from 50 kg ha -1 blended fertilizer rates (Table 3).
This result is in conformity with the findings of Mekonen (2005), who reported that, days to heading was significantly delayed when N fertilizer was, applied the highest rate for wheat and barley production compared to the lowest rate. Radhid et al., (2007) also reported that NP application significantly increased days to heading of barley. Generally, date of heading was delayed as NPS level increment in blended fertilizer rates, but was reduced with the increment of B and Zn rates in blended fertilizer.

Days to 90% of Physiological Maturity
The analysis of the current study revealed that, days to 90% of physiological maturity of wheat was significantly (p≤0.01) affected by the application of blended fertilizer types and rates. However, their interaction did not show significant effect on days to physiological maturity. The earliest days to physiological maturity (128 days) was recorded from the control and the latest maturity date (143 days) was recorded from NPS blended fertilizer types (Table 3).
Regarding to rates, the longest days to physiological maturity (146 days) was recorded from 150 kg ha -1 blended fertilizer rates which had statistically similar with 100 and 200 kg ha -1 blended fertilizer rates. However, the shortest (134 days) was recorded from 50 kg ha -1 (

Growth Parameters Leaf Area Index
The results of the current research showed that the main effect of blended fertilizer rates had highly significant (P≤0.01) and blended fertilizer types and their interaction had significant (P≤0.05) effects on LAI. The highest (6.03) mean LAI was recorded from 200 NPS kg ha -1 blended fertilizer rate followed by (6.01) from 150 NPSB kg ha -1 while the lowest (2.58) mean was obtained from the control treatment ( Figure 1). The leaf area index increment with the blended fertilizer application might be attributed due to better photo assimilate supply related to combination of macro and micro nutrients like B and N used for high vegetative growth that makes the plants to have broader leaves (Brady and Weil, 2008). This result was also in line with the findings of Salam et al. (2004) who reported that, application of B resulted in increased plant growth, LAI, and root length of crops. Vertical lines on bars represent standard error of the statistical means.

Plant Height
The results of the current study showed that wheat plant height was significantly (p≤0.01) affected by the application of different blended fertilizer types and rates, while the interaction effect was non-significant. In this

Spike Length
The results of this study depicted that, spike length was significantly (p≤0.01) affected by the application of blended fertilizer types and rates, while the interaction effect was non-significant ( Table 4). The highest (9.37 cm) mean spike length was recorded from NPSB blended fertilizer types whereas the lowest (6.14 cm) was from the control ( Table 4). The spike length increment with the blended fertilizer application might be attributed due to better photo assimilate supply (Berhan, 2012). He also suggested that the higher the length of spike the higher would be grain produced spike -1 leading to higher yield.
As regards to rates, the highest (9.18cm) spike length was recorded from 200 kg ha -1 that had the same magnitude with 150 and 100 kg ha -1 blended fertilizer rates. However, the shortest (7.53cm) was recorded from 50 kg ha -1 which was the only significant from the other treatments.

Number of Fertile Tiller m -2
The result of the current study indicated that the main effects of blended fertilizer types and rates had significant (P≤0.05) and highly significant effect (P≤0.01) on number of productive tillers, respectively. Whereas, the interaction effect of blended fertilizers types and rates did not bring significant effect.
Number of productive tillers is one of the most crucial yield determining components and has directly related to the grain yield of wheat. However, among the blended fertilizer types the maximum number of productive tillers m -2 (306) was obtained from NPSB, while the minimum (179) from the control treatment (Table 5).
Similarly, among blended fertilizer rates the maximum and minimum numbers of productive spikes m -2 (318 and 219) were recorded from 200 and 50 kg ha -1 blended fertilizer rates, respectively which were with statistically significant difference (Table 5). This result was in line with the findings of Berhan, (2012) who reported that application of blended fertilizer brought significant difference in spikes number plant -1 and fertile spikes m -2 . He also reported that the number of spikes plant -1 has a vital role in controlling yield of wheat which shows the more number of spikes, the better will be the stand of the crop, which ultimately increases the yield.

Thousand Seed Weight
The results of this study showed that, application of different blended fertilizer rates had a significant (p≤0.05) effect on thousand seed weight, while the main effect of blended fertilizer types and interaction effects were nonsignificant (Table 5). Thousand seed weight is a key factor in determining yield and makes larger contributions towards grain yield of wheat. The highest (47.56 g) thousand seed weight of wheat was obtained from 200 kg ha -1 blended fertilizer + 100 kg ha -1 urea with statistically similar magnitude with that of 150 and 100 kg ha -1 , while the lowest (38.16 g) from 50 kg ha -1 blended fertilizer rate which was the only significantly different from others (Table 5).
This variation on thousand seed weight might be due to more dry matter accumulation in the seed enhanced

Harvest Index
The analysis result of the current study showed that application of blended fertilizer types and rates had a significant (p≤0.01, p≤0.05) effect on wheat harvest index, respectively however, non-significant due to interaction effect ( Table 5). The highest (37.08%) harvest index was recorded from NPSBZn followed by (36.44%) that was obtained from NPSB blended fertilizer which were statistically similar while the lowest (28.09%) was obtained from the control treated plot (Table 5). Regarding to blended fertilizer rates, the highest (36.96%) harvest index was recorded from 200 kg ha -1 blended fertilizer that had the same magnitude with 150 kg ha -1 and the minimum (31.67%) was recorded from 50 kg ha -1 blended fertilizer (Table 5) reported that harvest index was significantly affected by the interaction of blended NPS and supplemental N rates. Mengel and Kirkby (1996) also reported that harvest indices of modern wheat cultivars normally range from 35.0 to 40.0% which were almost in consistent with this study that ranges harvest index from 28.09 to 37.08% (Table   5). Comparable reports by Berhan (2012) also showed that treatments received blended fertilizers had high harvest index compared with the control treatments.

Number of Grains Spike -1
The analysis of the current result indicated that the main effects of types and rates of blended fertilizers had highly significant effect (P≤0.01) on number of grains spike -1 . Likewise, the interaction effect of types and rates of blended fertilizers also revealed significant (P<0.05) differences on the number of grains spike -1 . The maximum grains spike -1 (101) was obtained from (200 kg ha -1 NPSB +100 kg ha -1 urea) followed by 99, 95 and 91 that was

Above Ground Biomass
The analysis result of the current study indicated that the application of different blended fertilizer rates had a significant (p≤0.01) effect on the above ground biomass. Similarly the interaction effect of the two factors was significant, while the main effect of blended fertilizer types was non-significant ( Figure 3). The highest above ground biomass (16.82 t ha -1 ) was obtained from 200 NPS +100 urea kg ha -1 followed by 200 NPSB and 150 NPSB kg ha -1 , while the minimum (6.99 t ha -1 ) was recorded from the control which was with only 46 N kg ha -1 treated plot (Figure 3).

Grain Yield
The analysis of the current study revealed that application of different blended fertilizer types and rates had significant (p≤0.01) effect on grain yield of wheat on the other hand, significant (p≤0.05) effect was observed due to interaction effect. The highest (6.17 tha -1 ) grain yield was obtained from 200 kg ha -1 NPSB +100 kg ha -1 urea followed by (6.11, 5.85, 5.81 and 5.55 tha -1 ) that was obtained from (150 NPSB, 200 NPSBZn, 150 NPSBZn and 200 NPS kg ha -1 ) along with 100 kg ha -1 urea with statistically similar magnitude while the minimum (1.95 tha -1 ) was obtained from the control treatment ( Figure 4). In this regard, S and N show strong interactions in their nutritional effects on crop growth, yield and quality due to their mutual occurrence in amino acids and proteins Kowalenko (2004). was obtained from the application of 80 kg N ha -1 increasing by 13.1% with compared to the control whereas S fertilization increased grain yield by 3.58%. An increase in grain yield may be attributed due to proper nutrition of B, which play an important role in hormone synthesis and translocation, carbohydrate metabolism and DNA synthesis and probably contributes to additional growth and yield (Raza et al., 2014). In general balanced application of fertilizers resulted in higher yield than the application of nutrients alone.

Straw Yield
The analysis of this study revealed that application of different blended fertilizer types and rates as well as their 150 kg ha -1 NPS +100 kg ha -1 urea which yielded 10.33 t ha -1 while the lowest (4.77 t ha -1 ) straw yield was obtained from the control ( Figure 5). The application of 200 kg ha -1 NPS along with 100 kg ha -1 urea increased the relative straw yield by 54.6% as compared to the control treatment. The current results agree with Sharshar et al., (2000) who stated that optimum NP fertilizer enhanced growth, yield and nutrient uptake in wheat; Nitrogen alters plant growth more than any other mineral nutrient. Similarly this result agrees with the findings of Woubshet et al., (2017) who reported that the application of 150 kg ha -1 NPSB blended fertilizer with compost increased the straw yield by 5.9 t ha -1 .

Relationship between Agronomic Parameters
The Pearson correlation coefficient in (Table 6) revealed that grain yield had highly significant and positive correlations with above ground biomass (r = 0.88), spike length (r = 0.78), thousand kernels weight (r = 0.72), harvest index (r = 0.72) and number of grain spike -1 (r = 0.84). Straw yield had highly significant positive correlation with above ground biomass yield (r = 0.93), plant height (r = 0.77) ( Table 6). Harvest index had a negative significant correlation with straw yield (r = -0.05) ( Table 6). According to Abebe (2012) grain yield was significantly and positively correlated with plant height, straw yield, thousand seed weight and biomass of wheat.

Agronomic Nutrient use Efficiency
The results of the current study showed that, agronomic use efficiency (ANUE) increased with increasing combination of macro and micro-nutrient application ( Table 7). The highest 30.06 kg kg -1 agronomic nutrient use efficiency was found in plot treated with 150 kg ha -1 NPSB blended fertilizer followed by (29.46 and 27.16) which were obtained from 100 kg ha -1 NPSB and 150 kg ha -1 NPSBZn blended fertilizer respectively (Table 7). Whereas, the minimum value of agronomic nutrient use efficiency 11.50 kg ha -1 was obtained from the plot received 100 kg ha -1 NPS blended fertilizer (Table 7). This result is in line with the findings of Jones et al., (2011) who stated matching appropriate essential macro and micronutrients with crop nutrient uptake could optimize nutrient use efficiency and crop yield.

IV. CONCLUSIONS
Based on yield response and economic indicators, applying the treatment 150 kg ha -1 NPSB blended fertilizer along with 100 kg ha -1 urea would be advisable for wheat production at Bachel gigissa site Wondo district.
Application of blended and other fertilizer should be done based soil-test and site specific conditions since the availability of an element can vary depending on the nature of the soil.
Based on the results of the current study on various parameters including yield and yield components of wheat, economic feasibility and agronomic efficiency, the following recommendations could be forwarded:  Application of 150 kg ha -1 NPSB blended fertilizer along with 100 kg ha -1 urea should be adopted to improve most of the wheat growth, yield and yield components and the economics of fertilizer and obtain the highest net benefit and marginal rate of return a well as to improve some soil chemical properties of the experimental site.