Growth, Yield Components, and Yield Parameters of Maize ( Zea mays L) as Influenced by Unified Use of NPSZnB Blended Fertilizer and Farmyard Manure

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Introduction
Several developing countries depend heavily on agriculture to promote economic development including Ethiopia. Ethiopia's economy is based mostly on agriculture, which contributes to around 41.4 percent of the gross domestic product, 83.9 percent of all exports, and 80% t of total employment [1]. So, it is not unexpected that a major focus of Ethiopian policy is on enhancing the dynamism of the agricultural area.
Ethiopia, with a fertility rate of 4.2 children born per woman, is the continent's second most populous nation after Nigeria an existing population of 102.4 million [2]. Ethiopia is expected to be among the top eight in the world in terms of population growth between 2017 and 2050, with a total estimated population of 190.9 million [3]. Te country must increase food grain production by increasing production per unit area in addition to nutritional value to feed and satisfy the needs of such a big population.
Te main source of food in Sub-Saharan Africa is maize (Zea mays L.), and its area coverage increased by nearly 60% between 2007 and 2017 [4]. Nowadays, Ethiopia has the ffthlargest area dedicated to maize cultivation, but it has the secondhighest yields (after South Africa) and the third-largest production areas (behind South Africa and Nigeria) [5]. Not only is it abundantly produced, but it is also the highest-yielding cereal in Ethiopia, ranking frst in productivity per hectare (4.2 tonnes, accounting for 30.88 percent of cereal production) and second in production area (2.5 ha, accounting for 19.46 percent of total cereals) [6,7]. More than 9 million small-holders growers cultivate maize on approximately 2 million hectares (14 percent of Ethiopia's total land area), with approximately 88 percent of the crop's output going toward food consumption [8]. Maize accounts for 42.79 percent of cultivated land and 64.27 percent of cereal grain production in the west Gojam highlands, with a yield of 4.573 t·ha −1 on average (9). In the 2020/21 summer planting season, 10,189,355.00 and 649,991.00 small-holder farmers, respectively, reportedly grew maize in the nation generally and in the West Gojam zone specifcally. National (Ethiopia) and regional (Amhara) yields of 4.179 and 4.272 tone ha −1 , respectively [9], are signifcantly inferior to the average for the world yield (57547 kg·ha −1 ) [10].
Tese high yield gaps are most probably caused by many abiotic factors including practical efectiveness gaps (i.e., limitations in crop management that result in production inefciencies), economic constraints (i.e., fnancial limitations to expand input utilization), and technology gaps (i.e., inability to access advanced technologies modern technologies) and biotic factors (disease and weed) [11].
Mineral nutrition by itself has made a substantial contribution to about 50% of crop yield increment during the 20th century, everywhere, and is anticipated to be the single biggest factor reducing crop production in the twenty-frst century [12]. But frequent use of chemical fertilizer can alter the soil's pH, disrupt benefcial microbial communities, aggravate pest problems, and potentially contribute to the release of greenhouse gases [13].
It is essential to establish a balanced fertilization program with macro and micronutrients in plant nutrition for plants to yield signifcant amounts of high-quality products by including microelements such as boron and zinc [14,15]. Macro-and micronutrient defciencies have been reported for diferent soils and crops [16]. Using organic fertilizer improves crop output per unit of nutrients supplied by creating a better physical, chemical, and microbiological environment [13]. Unless it is integrated with inorganic fertilizers, because of its comparatively small nutrient content, excessive application rates, and high labor needs, using organic fertilizer alone may not be sufcient to completely meet crop nutrients demand [17]. In addition to improving the chemical, biological, and physical characteristics of the soil, applying organic fertilizer (farmyard manure) in combination with chemical fertilizers ensured a steady supply of nutrients [18], and it promoted better growth and increased crop output. Relative to using only chemical fertilizers, integrated nutrient management (NPK + FYM) increases corn output [19][20][21]. Tus, exploiting the integrated practice of natural and artifcial fertilizer appears to be the paramount alternate for sustainable crop production while preserving the soil fertility condition in farming systems based on maize and other cereals [17].
In the 1960s, higher education institutions introduced commercial fertilizer in Ethiopia, primarily in the form of urea and DAP through limited laboratory and research operations [22]. Beginning in the early 1970s, this was followed by extensive on-farm demonstration experiments across the country, and a general rate of 100 kg·ha −1 urea + 100 kg·DAP·ha −1 was advised, regardless of crop or soil type [23]. As a result, the soil's nutrition levels gradually fall in nutrient levels in the soil and fail to address the nutrient requirements of specifc crops, including maize [24]. Currently, Ethiopia has begun utilizing blended or compound fertilizers, which can be used to supplement inadequate nutrients, and NPSZnB blended fertilizer is one of them. Also, due to the high fertilizer costs and the farming community's low purchasing power, in the country, including the experimental area, a low rate of inorganic fertilizer application has been practiced which necessitates an alternative option such option is the unifed use of inorganic fertilizer and farmyard manure. Not only the above reason but also due to a long-term imbalanced fertilization approach, a lack of other nutrients, particularly, potassium (K), sulfur (S), zinc (Zn), and boron (B), has begun to become clear [23,25,26].
Research fndings on soil fertility management utilizing farmyard manure and mineral fertilizer are currently inaccessible and have not been carried out in the selected district (Jabi Tehnan and Mecha District Agriculture Ofce report), and the soil in the experimental area has insufcient nutrients including zinc, boron, phosphorus, sulfur, and nitrogen, as indicated by the Ethio-SIS map https://www. researchgate.net/profle/Tadele-Amare-Kassie [27]. Hence, this experiment was conducted in the Jabi Tehnan and Mecha district, which is one of the main maize preproduction belt regions of the country, to determine the most efective combination rate of NPSZnB blended fertilizer and farmyard manure that improved growth, yield, and defne the optimal economic threshold of NPSZnB blended fertilizer and farmyard manure.

Site Description.
Two years of feld research (2016/17-2017/18) were conducted in two diferent locations in Amara National Regional State, Ethiopia: Jabi Tehnan district (at the Farmer's Training Centre (FTC) and Mecha district (at the substation of the Adet agricultural research centre and Farmer's Training Centre (FTC) (Figure 1). Jabi Tehnan is situated at latitude 10.6794°N and longitude 37.2598°E, at an altitude of 1,500-2,300 m.a.s.l, and encompasses an area of 116,954 hectares. Te average annual rainfall in the city is 1250 mm, with minimum and maximum daily temperatures of 14 and 32°C, respectively, and a mean annual rainfall of 1,885 mm ( Figure 2). Te soil type is classifed as 60% red soil, 25% brown, and 15% black soil [28]. Te soil fertility is classifed as 27% fertile, 71% medium, and 2% infertile. Agro-ecologically, Woyina Dega accounts for 88 percent of the district, while Kola accounts for the remaining 12% [29].
In each of the corresponding years, soil samples were taken at fve places diagonally between 0 and 20 cm of soil depth to identify the general soil characteristics of both experimental sites before planting. Te soil and farmyard manure samples were air-dried, crushed, and sieved through a 2 mm sieve before being analyzed to determine some selected chemicals for both soil and farmyard manure and physical characteristics for soil only. Tables1 and 2 present selected soil analysis parameters, methods, and results. Before the experiment start, soil analysis revealed that both study sites have clay texture and soil properties that are relatively comparable.

Experimental Design, Treatments, and Procedure.
BHQPY545, a variety of maize noted for its high protein content, was employed as the planting material in this experiment. Te treatments included fve levels of NPSZnB blended fertilizer (16.9% N-33.8% P-7.3% S-2.23% Zn-0.67% B) (100, 150, 200, 250, and 300 kg·ha −1 ) and four levels of welldecayed, from cattle source, aged three to six months of manure (0, 12, 16, and 20 t·ha −1 ) and one blanket recommended 150 kg·ha −1 urea (69 kg·N) and 200 kg·ha −1 DAP (40 kg·P and 18 kg·N). Since the N content of NPSZnB blended fertilizer is lower than N derived from the blanket recommended urea and DAP, where the N content of 100 kg NPSZnB blended fertilizer is 16.9 kg, the blended fertilizer was adjusted with N to N of the recommended urea and DAP. Tis shows that 87 kg·N·ha −1 of conventional fertilizer, excluding DAP and Urea, was administered to all treatments [11]. Tree replications of the experiment were conducted using a randomized complete block design (RCBD) with a factorial arrangement. Te size of every plot was 4 by 4 m (16 m 2 ) and contained fve rows, each with ten plants, a total of 50 plants per plot. Plots were 0.5 m apart, while blocks were separated by 1 m. Borders were described as the outermost single row from both sides of the plots and one plant at both ends of each row. As a result, the net plot used for data collection was 3.2 × 2.4 m (7.68 m 2 ), and the gross area for the experiment was 14 m × 94 m � 1316 m 2 . All recommended agronomic activities were carried out. NPSZnB blended fertilizer was applied by drilling once at sowing time and was well incorporated with the local soil. While only a 1/2 amount of urea and all of the DAP fertilizer were applied as a base application at sowing, the remainder N was top-dressed at 35 days (knee-height stage) later sowing for the nitrogen adjusted and the blanket recommended. Troughout the cropping seasons, the experimental plots were managed using all of the improved International Journal of Agronomy 3 culturally practiced methods for hybrid maize cultivation. From all collected farmyard manure, nondecomposable and unused components were isolated and removed and then dispersed on a plastic sheet in the shade to minimize its moisture, keeping the moisture content below 22%, and all diferent levels of farmyard manure were randomly applied one month before sowing and thoroughly mixed with the soil.

Data Collection and Measurement.
Data for the trial were gathered from days to 50% (tasselling, silking), leaf area index, plant height, and days to 90% physiological maturity (cm), and yield and yield components such as ear length, number of kernels per ear, 100 seed weight (g), grain yield (kg ha −1 ), above-ground biomass (kg ha −1 ), and harvest index (%) were recorded. By calculating the conversion factor for each treatment to get the adjusted yield, the grain yield for each treatment was adjusted to the recommended moisture level of 12.5% [47].    [43] where Y represents the actual moisture content and X; the target moisture content (which is 12.5% for cereals) to which the yield should be adjusted.
To experiment, plot-based data on yield and yield related to its components were collected.

Economic Analysis.
A fnancial study was conducted to determine commercially proftable treatments. Te costbeneft study was carried out at two separate sites (Jabi Tehnan and Mecha district) over the two growing years (2016/ 17 and 2017/18) by contrasting production costs and revenue derived from diferent treatment levels. Te analysis was carried out by using input-output statistics of maize by the CIMMYT (International Maize and Wheat Improvement Centre) method [48]. Other costs such as fertilizer transportation, pesticide application, and diferent agronomy activities also were under consideration. Te average yield was adjusted to 10% lower to account for the discrepancy between the experimental area and the anticipated output at farmers' felds and with farmers' behaviors under the same treatments [49]. For nondominated treatments, the marginal rate of return (MRR) was calculated, and MRRs were compared to a minimum acceptable rate of return (MARR) of 100 percent to determine the best treatments. Te product of maize yield for each treatment-year-location combination was used to calculate revenue (R). Benefts were calculated using the diference between revenues and expenditures.

Data
Analysis. Te analysis of variance was carried out by Gomez and Gomez [50], using statistical analysis computer software SAS version 9.2 (Statistical Analysis System) [51]. Since the homogeneity test carried out using the F-test as described by [50], of the two years and locations for all parameters had shown homogenous and nonsignifcance of the two years on each location and heterogenous and signifcance of the two locations, a combined analysis was used for the two years on each location and analysis of each location; data were analyzed separately. Whenever there were important treatment results, mean separations were performed using the least signifcant diference (LSD) at the 5% level of signifcance, and to facilitate factorial analysis, the control was excluded. Using SAS, 9.2 versions, a correlation analysis was also performed to defne the association between plant growth parameters and yield and yield components as afected by rates of NPSZnB fertilizer and farmyard manure.

Correlation of Maize Growth, Yield, and Yield
Components. Correlation analysis of maize growth parameters revealed that all were highly and positively correlated with grain yield at both experimental sites (Tables 3  and 4). A comparison of the correlation coefcients at Jabi Tehnan revealed that plant height had a higher correlation coefcient (r � 0.966 * * ) than the other yield components, followed by above-ground biomass (r � 0.951 * * ), ear length (r � 0.932 * * ), thousand kernels mass (r � 0.921 * * ), and the number of green leaves per plant. Te above-ground biomass (r � 0.935 * * ) had the highest correlation coefcient at Mecha, followed by thousand kernels weight (r � 0.934 * * ), number of green leaves per plant (r � 0.922 * * ), plant height (r � 0.685 * * ), and ear length (r � 0.541 * * ) showed associations with grain yield with correlation coefcients of comparatively inferior extents as compared to the former yield components. Similarly, Selassie, [52] and Habtamu et al., [53] discovered that maize grain yields were positively and signifcantly associated with yield components.
Days till 50% tasselling generally decreased as the integrated application of farmyard manure, and NPSZnB mixed fertilizer was increased. By increasing the blended fertilizer rate from 100 to 250 kg·ha −1 NPSZnB blended fertilizer and farmyard manure rates from 0 to 20 t·ha −1 , days to 50% tasselling were shortened. At the Jabi Tehnan site, the integrated use of 250 kg·ha −1 NPSZnB and 20 t·ha −1     (Table 6). Te application of 100 kg·ha −1 NPSZnB without the application of farmyard manure prolonged days to 50% tasselling by 2.92 days in comparison to the blanket DAP and urea fertilizer recommendation/satellite control, and it was also statistically at par with 100 kg·ha −1 NPSZnB blended fertilizer and 12 t·ha −1 farmyard manure combination. Te earliest days' reaching 50% of tasseling in response to the highest amount of blended fertilizer NPSZnB (250 kg ha-1) and farmyard manure (20 tha-1) could also be attributed to their synergistic efect on promoting vegetative growth, which resulted in preserving enough food reserves to allow buds to develop into fower buds. Te prolonged vegetative phase of the plant could, on the other hand, be caused by the lack of nutrients or starving of the plant, which would result in delayed tasselling in response to the interaction efect of the minimum amount of blended fertilizer and farmyard waste. Tis could also be attributed to their synergistic efect, as the application of farmyard manure along with NP fertilizers provides balanced micro and macronutrients. Tis would have aided in enhancing the assimilation process in the seedling growth stage, which in turn would have enhanced the overall growth and extended through the vegetative growth stage, resulting in a prolonged period for tasselling [54].
Tese results are in line with Tetarwal et al., [55] who discovered that raising fertilizer rates decreased the number of days for maize to 50% tassel. Melaku et al. [56] also reported similar results where the application of blended NPS fertilizers and farmyard manure signifcantly afected days to tasselling. Tese results showed that the combined application of 150 kg·ha −1 NPS fertilizer and 12 t·ha −1 FYM resulted in the shortest duration for 50% tasselling (61 days), whereas the control treatment resulted in the longest period for 50% tasselling (80 days).
Mean comparisons for blended fertilizer treatments at Mecha revealed that the use of 300 kg·ha −1 blended fertilizer shortened days to 50% tasselling (51.14) by 1.05 days than the blanket fertilizer DAP and urea (52.2 days) whereas the longest 55.26 days to 50% of tasselling were recorded from 100 kg·ha −1 of NPSZnB blended fertilizer (Table 7.
Te earliness tasselling in response to the increasing amount of NPSZnB blended fertilizer could be attributed to the nutrients N, P, S, B, and Zn in NPSZnB blended fertilizer causes the crop to grow vigorously and more rapidly during the vegetative stage, which eventually causes the crop to tassel sooner rather than later. Te same results were also reported by Hailu et al., [57] where the use of blended NPS fertilizers signifcantly afected days to tasselling. When nutrients are applied in sufcient amounts, growth is quick and tasselling is accelerated, but when nutrients are applied insufciently or not at all, development is slow, and tasselling and silking are delayed [58]. Tese fndings are consistent with those of Makinde et al. [59,60], who found that maize silking and tasselling days were reduced by 50% when fertilizer rates were increased.

Days till 50%
Silking. Te combined analysis of variance over years for the days to 50% silking revealed that, at both locations, there was a signifcant diference on days to 50% silking of maize due to the main efects of NPSZnB blended fertilizer and farmyard manure. However, this parameter was unafected by their interaction impact (Table 5).
Te shortest days to 50% of silking 60.52 and 60.70 were gotten from the plots that received 250 and 300 kg·ha −1 NPSZnB blended fertilizer at Jabi Tehnan and Mecha, respectively, but it was signifcantly on par with 300 kg·ha −1 at Jabi Tehnan and 250 kg·ha −1 NPSZnB at Mecha. In the meantime, the maximum days to 50% silking 63.41 and 64.32 were recorded from the minimum rate of NPSZnB blended fertilizer of 100 kg·ha −1 at Jabi Tehnan and Mecha, respectively (Table 7).
It was recognized that NPSZnB blended fertilizers with varying concentrations of N, P, S, and Zn may have accelerated plant growth and development, reducing the time until silking. Hailu et al., [57] also discovered that the use of blended fertilizers greatly impacted the days of silking. In the interim, Kinfe et al. [67] found that 50% of silking is signifcantly infuenced by the use of mixed fertilizer rates. Te outcomes are consistent with those of Makinde and Ayoola [59]; Uwah et al., [60] noticed that maize's 50% silking days were shorter when fertilizer rates were higher. In contrast to the results of this experiment, results from several studies confrmed that NPSZnB blended fertilizer with varying amounts of N, P, S, Zn, and B had no discernible impact on the silking of the maize crop [61].
Te rise in the rate of farmyard application from 0 to 20 t·ha −1 caused a reduction in days to 50% silking (60.80 and 61.17) as maximum numbers of days to 50% silking 62.71 at Jabi Tehnan and 62.90 at Mecha were obtained from no farmyard manure application which is statistically similar to the rate of 12 t·ha −1 of farmyard manure at both locations (Table 7).
Increased amounts of cattle manure make the soil nutrients balanced, create a favorable soil environment by improving soil porosity (water holding capacity), and minimize nutrient leaching. Tese favorable conditions increased nutrient availability, especially NPK. Te plant tends to grow at its maximum capability resulting in shortening the days to silking. Tese increases in days to 50% silking coincide with Gurmu and Mintesnot's fndings [62] who reported days to 50% silking were delayed by 10.67 days (12.81%) at the control treatment compared to the application of 2.3-ton ha −1 compost that takes 83.3 days to 50% silking.

Days till 90% Physiological Maturity.
Analysis of variance over years revealed that days to 90% physiological maturity of maize were signifcantly (P < 0.0001) afected by the application of NPSZnB blended fertilizer, farmyard manure, and their interactions at Jabi Tehnan, while at Mecha, the main efects of NPSZnB blended fertilizer and farmyard manure signifcantly (P < 0.05) afected days to 90% maturity. However, their interaction results were not signifcant (P > 0.05) ( Table 5). 8 International Journal of Agronomy At Jabi Tehnan, maize on the plot which received 250 kg·ha −1 NPSZnB blended fertilizer and 20 t·ha −1 farmyard manure took the maximum days to 90% physiological maturity (144.95 days). Hence, 2.95 extra days were required to reach the maturity of maize as compared to the conventional fertilizer DAP and urea application. However, it was statically comparable to the application of 300 kg·ha −1 NPSZnB blended fertilizer integrated with 20 and 16 t·ha −1 farmyard manure. Conversely, the shortest day to reach 90% physiological maturity 131.71 was documented from both the minimum rate of NPSZnB blended fertilizer (100 kg·ha −1 ) ( Table 6).
It was known that increased nutrients especially nitrogen could have shortened the days to tasselling, silking, and maturity by encouraging the early establishment, rapid growth, and development of the crop, but the current outcome was inconsistent in this respect. Tis might be because of the increased rate of nitrogen from both sources (blended inorganic fertilizer and farmyard manure) especially the gradual discharge of nutrients from farmyard manure, which delayed physiological maturity by promoting/promoting the plants' vegetative growth and development. In addition, it could be positive interaction of nutrients in both fertilizer, and additional benefts from   [62], who notes that plants receiving lesser nutrient applications grew slowly due to a lack of nutrients, while plants receiving higher nutrient applications exhibited early maturity due to strong development, early tasselling, and early silking of the crop. At Mecha, the maximum number of days to 90% physiological maturity was 141.1, at the rate of 300 kg·ha −1 NPSZnB blended fertilizer which was 0.89 days earlier than the use of DAP and urea. However, it was signifcantly on par with the plot treated with 250 kg·ha −1 NPSZnB blended fertilizer whereas the minimum days 137.3 to reach 90% physiological maturity were recorded from the lowest rate of blended fertilizer (100 kg·ha −1 ), which was signifcantly on par with the application of 150 and 200 kg·ha −1 NPSZnB.
It was known that blended fertilizers with varied amounts of N, P, S, Zn, and B would have favored early establishment, quick growth, and development of the crop, shortening the days to tasselling, silking, and maturity. Nevertheless, the current outcome was inconsistent in this regard. Such dalliance of days to 90% of maturity might be because of the increased amount of nutrients, especially nitrogen extending the growing season and delaying crop maturation by promoting vegetative growth. Also, it might be because of the positive integrity between nutrients in blended fertilizer. Because they are required for the initial development of roots and the synthesis of chlorophyll, boron, phosphorus, and sulfur all enhance the usage of nitrogen [63]. B, K, and N fertilizers work well together to increase crop yields and maturity [64].
Tis result contradicts the fnding of Hailu et al., [57] and Kinfe et al., [61] who stated that maturity is signifcantly afected by the application of NPSZnB blended fertilizer rates, and in contrast to the control, which took the longest days to reach maturity, short maturity days were observed with the administration of NPSZnB blended fertilizer.
Regarding the efects of farmyard manure, application at the level of 16 t·ha −1 resulted in the longest maximum days to reach maturity 139.74 which was delayed by 1.8 days on plots not receiving farmyard manure (137.93) ( Table 7). However, it was signifcantly at par with all rates of farmyard manure except nil application. However, no farmyard manure application caused the shortest days to reach physiological maturity.
In addition to releasing nutrients such as nitrogen and phosphorus that encouraged vegetative growth, prolonged the growing season, and consequently delayed the maturity of the maze, increasing FYM dosage may also be caused by increases in soil moisture-holding capacity and decreased nutrient leaching. Due to their usage in the production of chlorophyll and the earliest stages of root development, phosphorus, sulfur, and boron promote the intake of nitrogen [65]. Te fndings of this investigation are consistent with those of Redda and Abay [66] who found that using a larger dose of FYM (9 t·ha −1 ) recorded longer days (122, 5) to physiological maturity.

Plant Height (cm).
Te outcome of combined analysis of variance of two years of data, NPSZnB Blended fertilizer, farmyard manure as well as their interaction revealed signifcant diferences (p < 0.05), in plant height of the maize crop at both experimental locations (Table 5).
Te tallest plant height of 218.91 cm at Jabi Tehnan and 217.79 cm at Mecha was recorded from the combined application of 250 kg·ha −1 NPSZnB blended fertilizer and 20 t·ha −1 farmyard manure which showed an increment in length by 1.3 cm at Jabi Tehnan and by 1.79 cm at Mecha compared to the conventional DAP and urea fertilizers. However, at Mecha, the treatment combination level which was given the maximum plant height was signifcantly on par with 250 and 300 kg·ha −1 NPSZnB blended fertilizer integrated with 16 t·ha −1 farmyards and also 300 kg·ha −1 NPSZnB blended fertilizer integrated with 20 t·ha −1 farmyard manure application. Te shortest plant measures 169.1 cm in height at Jabi Tehnan and 168.83 cm at Mecha were obtained from the lower level of NPSZnB blended fertilizer (100 kg·ha −1 ) and nil farmyard manure application (Table 8).
Plants treated with the maximum blending of NPSZnB fertilizer and cattle manure showed that a substantial increase in plant height could be due to the role of nutrients individually and also their collaboration with nitrogen, which is one of the nutrients that contribute most to yield and, when present in sufcient amounts, encourages the creation of chlorophyll, which leads to better photosynthetic activity, stronger vegetative growth, and taller plants. Shoot and root tips, where metabolism is high and cell division is quick, require a signifcant amount of phosphorus. Te same is true with sulfur, which encourages the production of chlorophyll, increased photosynthetic activity, robust vegetative development, and taller plants. Due to boron's crucial function in cell division and nitrogen absorption from the soil, which promotes plant growth and eventually increases plant height, the addition of boron in the NPSZnB blended fertilizer also considerably boosted plant height. Zinc promotes the production of chlorophyll, photosynthesis, nitrogen uptake, and metabolism [67].

Leaf Area Index.
Te combined analysis of variance over years exhibited that the impact of NPSZnB blended fertilizer and farmyard manure on leaf area index was signifcant (P < 0.0001) ( Table 5), and their interaction results, however, were not signifcant at both locations.
Te leaf area index (LAI) is a signifcant growth indicator that assesses a plant's ability to capture solar energy for photosynthesis. It has a signifcant impact on the plant's growth and output. Application of 300 kg·ha −1 NPSZnB blended fertilizer resulted in the highest leaf area index 3.93 and 3.37 at Jabi Tehnan and Mecha, respectively (Table 9), which shows a relative reduction of leaf area index by (8.23%) at Jabi Tehnan and (17.10%) at Mecha than the conventional DAP and urea, while the lowest leaf area index (2.92) at Jabi Tehnan and (2.6314) at Mecha was recorded from the least level of blended (NPSZnB) fertilizer (100 kg·ha −1 ). However, at both locations, the NPSZnB blended fertilizer rate that resulted in the smallest leaf area index was statistically similar to the 150 and NPSZnB kg ha −1 application. Te improved leaf area index with increased NPSZnB blended fertilizer rate could be attributed to the vigorous growth and leaf enlargement in length and width in response to the signifcant role of individual nutrients and their synergy as well. Nitrogen causes the production of more above-ground biomass with enlarged leaves. In addition, phosphorus encourages the rapid development of the canopy and aids in the division of root cells. Due to their roles in the synthesis of chlorophyll, activation of enzymes, increased resilience to biotic and abiotic stressors, and defense against oxidative damage, phosphorus, boron, sulfur, and zinc boost the uptake of nitrogen [68].
Farmyard manure (20 t·ha −1 ) exhibited the greatest leaf area index (3.72) and (3.16), 16.73%, and 17.10% more compared to the blanket conventional recommended DAP and urea fertilizer at Jabi Tehnan and Mecha, respectively. However, the farmyard manure rate that resulted in the maximum leaf area index was statistically comparable to 16 t·ha −1 at both experimental location and also by 12 t·ha −1 at Jabi Tehnan while no farmyard manure application provided the lowest leaf area index (3.01) and (2.69) at Jabi Tehnan and Mecha, respectively (Table 9). However, it was statistically at par with all various rates, except  the higher rate at Jabi Tehnan and with 12 t·ha −1 farmyard manure at Mecha. In addition, it also assisted in maintaining functional leaf area throughout the growth phase in a replay to N availability, which promotes root growth and may have improved plants' ability to obtain nutrients in response to increased physical qualities of the soil [69]. Tis fnding agrees with the fndings of Sanni [70] who observed that increased leaf area in soil amended with organic fertilizer could probably be attributed to N availability which promoted leaf area during vegetative development and also helped to maintain functional leaf area during the growth period.

Ear Length (cm).
Based on data from a multiyear combined data analysis of variance, at Jabi Tehnan, ear length was signifcantly (P < 0.001) afected due to the applications of NPSZnB blended fertilizer, farmyard manure, and their interaction efect. At Mecha, the main factors NPSZnB blended fertilizer and farmyard manure application (P < 0.001) afected ear length; however, their interaction did not afect ear length (Table 10). Ear length is a very vital yield contributive parameter of maize. It considerably contributes to the grain yield of maize by manipulating each number of grains and grain size. A combined application of 250 kg·ha −1 NPSZnB blended fertilizer and 20 t·ha −1 farmyard manure resulted in the longest ear length (17.47) at Jabi Tehnan, which is exceeded by 5.64% over the conventional urea and DAP application whereas 100 kg·ha −1 with no farmyard manure application recorded the shortest ear length 9.07 cm (Table 11).
Te probable reason for the increment of ear length due to the increasing combined application of NPSZnB blended fertilizer with farmyard manure may be their integration creates the availability of both macro and micronutrients which encourage the growth and development of plant parts. Te results are also consistent with Biramo [71] who stated that the use of NPSZnB Blended fertilizer in conjunction with farmyard manure may have been the supply of adequate micro and macronutrients, which most likely aided in improving metabolic activity during the early growth period, which in turn aided overall growth, including ear length.
At Mecha, NPSZnB blended fertilizer rate at 300 kg·ha −1 gave the longest ear length (16.16 cm) compared to the conventional fertilizer DAP and urea but statistically similar to 200 and 250 kg·ha −1 NPSZnB blended fertilizer. However, with no signifcant statistical variation with 150 kg·ha −1 , the application of 100 kg·ha −1 NPSZnB blended fertilizer gave the shortest ear length (13.44 cm) ( Table 9).
Tese fndings are in line with those of Fayisa et al., [72] [72] who discovered that the application of NPSZnB blended fertilizer rates had an impact on maize ear length that was extremely signifcant (P 0.01). His fndings showed that the control had the least maize ear length (11.57 cm), while the application of 200 kg NPSZnB + 150.2 N produced the longest (16.10 cm) ear length 20 t·ha −1 . Farmyard manure application is caused by the longest ear length (15.73 cm) which is lower in length by 4.35% as compared with conventional fertilizer DAP and urea. However, there was no statistical diference with the rest rate of farmyard manure except for the plot treated with no farmyard manure which gives the shortest ear length of 13.91 cm (Table 9). Te stimulating impact of farmyard manure, which provides the plant with nutrients needed for the improved length of the ear, may be the cause of increased ear length with an increase in the application rates of the manure. Tese results are in agreement with those of Eleduma et al. [73] who found that maize plants amended with the maximum farmyard manure rate (20 t·ha −1 ) had superior cob length (17.38 cm) than the control (15.05 cm) which decreased with each decrease in the level of cattle manure applied.

Tousand Kernels Weight (g).
Combined data over years indicated that thousand kernel weights were signifcantly (P < 0.0001). At both trial sites, NPSZnB mixed fertilizer, farmyard manure application, and their interaction all had an impact (Table 10).
Te integrated application of 250 kg·ha −1 NPSZnB blended fertilizer and 20 t·ha −1 farmyard manure at Jabi Tehnan and 300 kg·ha −1 NPSZnB blended fertilizer with 20 t·ha −1 at Mecha had the higher thousand-grain weight of 292.6 and 290.8 g at Jabi Tehnan and Mecha, respectively, which were higher than the conventional fertilizers DAP and urea by 3.26% and 4.954%. Nonetheless, statistically speaking, it was statistically at par with the combined application of 300 kg·ha −1 NPSZnB blended fertilizer at Jabi Tehnan and 250 kg·ha −1 NPSZnB blended fertilizer at Mecha combined with 20 t·ha −1 farmyard manure. Lightweights of 253.814 and 252.629 g of thousand kernels were recorded from the combined application of 100 kg·ha −1 NPSZnB blended fertilizer with no farmyard manure application at Jabi Tehnan and Mecha, respectively (Table 12).
A signifcant rise in the weight of the thousands of kernels may be attributable to the synergistic efects of mixed fertilizers on maize grain flling and greater growthpromoting photosynthesis. Te results of Malakouti [74] support the outcome of this investigation that integrated nutrient management signifcantly improves thousands of weight of kernels. Te maximum (28.67 g) test weight is obtained after applying 75% RDF (75 N + 45 P 2 O 5 + 30 K 2 O kg·ha −1 ) with FYM (5 t·ha −1 ). On the other hand, the lowest (22.73 g) thousand weight of kernels were observed when just 50% RDF (50 N + 30 P 2 O 5 + 20 kg K 2 O kg·ha −1 ) was applied.
3.9. Above-Ground Biomass (kg ha −1 ). NPSZnB blended fertilizer and farmyard manure interacted and, in turn, stood alone to have a signifcant impact on above-ground dry biomass at both experimental locations, according to the result from combined data analysis of variance over years (Table 5).
In comparison to the conventional one, above-ground biomass yield compensations of 17.3% and 19.36% were found because of increasing NPSZnB blended fertilizer from 100 to 250 kg·ha −1 and farmyard manure from 0 to 20 t·ha −1 in a combined way at Jabi Tehnan and Mecha, respectively, than that of the conventional DAP and urea. Te combination of 250 kg·ha −1 NPSZnB blended fertilizer and 20 t·ha −1 farmyard manure resulted in the highest above-ground dry biomass 10895.0 kg and 10787.9 kg·ha −1 ( Table 13). However, no statistical variations were observed with the integrated application of 300 kg·ha −1 NPSZnB blended fertilizer with 20 t·ha −1 farmyard manure at Jabi Tehnan.
Whereas the lowest above-ground biomass 4609.4 kg·ha −1 and 4896.9 kg·ha −1 were recorded from the application of 100 kg·ha −1 NPSZnB blended fertilizer at Tehnan and Mecha, respectively, it was signifcantly on par with 100 kg·ha −1 NPSZnB blended fertilizer integrated with 12 t·ha −1 farmyard manure at Mecha (Table 13).
A greater leaf area index, more grains per ear, longer ears, thicker stems, taller plants, and more grain could all have contributed to an increase in above-ground biomass when NPSZnB mixed fertilizer and farmyard manure application amounts were increased. Te high biomass yield in the combined treatments may have been enhanced by photosynthetic production being promoted by an increase in the number of leaves and an increase in the leaf area index. Te present results are supported by Yigermal et al., [75], and during two consecutive years (2005 and 2006), the infuence of inorganic fertilizer and farmyard manure on above-ground biomass remained signifcant under diferent application levels and who attained the signifcant maximum biomass yield of maize 8579 and 8475 kg·ha −1 , respectively, from the combined application of NPK (60-45-30 kg·ha −1 ) with FYM (10 t·ha −1 ). −1 ). Combined analysis of variance over years indicates that NPSZnB blended fertilizer, and farmyard manure, and their interaction had a signifcant (p < .0001) efect on maize grain yields at both locations (Table 10). Means inside a column that begins with the same letter or letters do not signifcantly difer. BR: blanket recommendation (150 kg·ha −1 urea and 200 kg·ha −1 DAP); BF: NPSZnB blended fertilizer; FYM: farmyard manure; CV: coefcient of variation; LSD: least signifcant diference. International Journal of Agronomy 13

Grain Yield (kg ha
Te highest grain maximum grain yield 5618.5 and 5421 kg·ha −1 were observed in the integrated application of 250 kg·ha −1 of NPSZnB blended fertilizers and 20 t·ha −1 farmyard manure at Jabi Tehnan and Mecha, respectively. Tis is signifcantly higher than the blanket DAP and urea fertilizer recommendation/satellite control by 16.554% at Jabi Tehnan and 15.982% at Mecha. But the treatment combination level which gave the maximum result was statistically at par with 250 and 300 kg·ha −1 NPSZnB blended fertilizer integrated with 16 t·ha −1 farmyard manure at both locations and also 200 and 300 kg·ha −1 NPSZnB blended fertilizer combined with 20 t·ha −1 farmyard manure at Mecha. Te lowest yield, on the other hand, was obtained at Jabi Tehnan (2218.6 kg) and Mecha (2091.29) from plots that received 100 kg·ha −1 of NPSZnB blended fertilizer but no farmyard manure application. At Mecha, however, there was no statistically signifcant diference between 100 kg·ha −1 NPSZnB blended fertilizer and 12 t·ha −1 farmyard manure combination at the treatment combination level that produced the lowest result (Table 14).
Increases in both NPSZnB blended fertilizer and farmyard manure have led to an increase in grain production, which may be ascribed to the good efects of yieldcontributing traits and the benefcial interactions between nutrients in the NPSZnB blended fertilizer and farmyard manure. Te mixture of inorganic fertilizer and organic manures may have enhanced nitrogen usage efciency and recovered more micro and macronutrients, which is the other likely explanation. However, providing NPSZnB blended fertilizer at rates more than 250 kg·ha −1 with 20 t·ha −1 farmyard manure combinations tended to result in a decline in mean grain output (Table 14).
Te decline in grain yield at the higher rate of NPSZnB blended fertilizer and farmyard manure could be caused by  more assimilated products going to the vegetative components that the grain or too much amount of nutrients especially N producing high tissue N concentration, and it can be detrimental to maze growth, causing slowed growth and a decrease in grain yield [76]. Wu et al., [77] discovered that combining organic manures with inorganic fertilizer could have improved nitrogen usage quality, micro and macronutrient recovery, Increased K supply, P Solubilization, and Plant Uptake, resulting in improved maize growth and yield. For enhancing nutrient recovery, plant growth, and fnal output, a combination of organic and inorganic fertilizers is recommended; in the absence of this, larger N and P treatment rates are anticipated to result in a higher yield in maize [78]. According to Ma et al.'s research [79], mixing organic and inorganic nutrient sources boosted the synergism and coordination between nutrient release and plant regeneration, which enhanced crop growth and production. In addition, Moe et al., [80] and Negassa et al., [81] discovered that combining organic and inorganic fertilizers efciently improves nitrogen use efciency, and integrating inorganic and organic nutrients improved maize yield by 35%.

Harvest Index (%).
Te pooled analysis of variance over years revealed that either the main efect of farmyard manure or its interaction with NPSZnB blended fertilizer did not exert a signifcant efect on the harvest index (HI) at Jabi Tehnan. However, only NPSZnB blended fertilizer caused a highly signifcant (p < 0.001) efect on this parameter (Table 10). At Mecha, both signifcant (p � 0.0108) interactions and the main efect of treatment on harvest index were observed (Table 10). At Mecha, NPSZnB blended fertilizer values of 250 kg·ha −1 with a rate of farmyard manure of 12 t·ha −1 produced a maximum harvest index of 59.2 that exceeded by 14.9 percent over the conventional fertilizers DAP and urea. However, it was statistically equivalent to the application of 300 kg·ha −1 NPSZnB blended fertilizer combined with 12 and 16 t·ha −1 farmyard manure and without farmyard manure application, 200 kg·ha −1 NPSZnB blended fertilizer combined with 12, 16, and 20 t·ha −1 farmyard manure, and 250 kg·ha −1 NPSZnB blended fertilizer combined with 16 t·ha −1 farmyard manure. Whereas crops on a plot treated with the least rate of NPSZnB blended fertilizer (100 kg·ha −1 ) along with no farmyard manure application recorded the lowest harvest index of 43.8, it was statistically on par with 100 kg·ha −1 NPSZnB blended fertilizer with 12 and 20 t·ha −1 farmyard manure application and also 150 kg·ha −1 NPSZnB blended fertilizer with 12 t·ha −1 and without farmyard manure application (Table 15).
Te higher maize harvest index with increased NPSZnB blended fertilizer and farmyard manure application might be due to higher grain yield per plant. Tis might be a result of the fertilizer's ability to efectively ingest plant nutrients in response to the harmony of macro-and micronutrients and their interactions with one another (blended and farmyard manure). Te increasing trend of harvest index with an increase of both NPSZnB blended fertilizer and farmyard manure rates up to a certain level, followed by a decrease with more increasing rates of both NPSZnB blended fertilizer and farmyard manure, is probably because of excessive application of NPSZnB blended fertilizer and farmyard manure promoted more vegetative growth than grain.
Other scholars have backed up the study's fndings, according to Amanullah et al., [82], efective uptake in response to a balanced P and Zn diet increased photo assimilation and translocation to grains, resulting in a higher harvest index. According to Kugbe et al., [83], boron increases crop yield even in P-defcient soils due to synergy in phosphorus absorption through B. Contrarily, greater nutrient availability may have retarded senescence and lengthened the life cycle of the maize plant, leading to a better economic output and harvest index, according to Dong et al., [84]. Fantaye and Hintsa [85] reported that the supreme harvest index of maize was obtained from the application of 50 to 150 kg·ha −1 NPSZnB blended fertilizer, as opposed to the conventional DAP, but further increasing the NPSZnB blended fertilizer rate above 150 kg·ha −1 became the cause for the reduction of harvest index. At Jabi Tehnan, the maximum harvest index of 53.1 was obtained from 200 kg·ha −1 of NPSZnB blended fertilizer which was higher by 14.91% than the blanket rational recommended fertilizers DAP and urea treatment application. However, it was statistically on par with 250 and 300 kg·ha −1 . Meanwhile, statistically, the minimum harvest index of 44.97 was documented from the least level of NPSZnB blended fertilizer (100 kg·ha −1 ) ( Table 9).
Increases in HI and NPSZnB blended fertilizer can be correlated with nutrient availability, particularly N, which has a favorable impact on assimilate partitioning to grain yield. However, supplying NPSZnB blended fertilizer at a rate above 200 kg·ha −1 tended to cause mean HI to decline (Table 9). While vegetative biomass output is proportionally higher than grain yield at higher blended fertilizer rates, the decrease in HI at the higher rate of NPSZnB blended fertilizer may be explained by the development of more vegetative biomass than grain yield. Tis outcome is consistent with Gurmu and Mintesnot's [62] fndings, according to which the harvest index of maize was determined to be maximum at a rate of 150 kg·ha −1 NPSZnB when compared to the control treatment. Moreover, Tekle and Wassie [86] revealed that when compared to the control, blended fertilizer treatments had the highest harvest index of Tef. In agreement with this fnding, Taddesse et al.'s [87] study found that excessive nutrient treatment decreased the amount of HI in grain crops.

Economic
Analysis. An economic analysis was carried out using partial and marginal analysis to determine the economic feasibility of the various prices of NPSZnB blended fertilizer and farmyard manure used in these studies. Te marginal rate of return (MRR) was determined   by dividing the successive net beneft and total variable cost ratios' change in net proft (NB) by the change in gross variable cost (TVC) [49]. Maize variable prices, total profts, and related net returns are infuenced by various rates. Tables 16 and 17 show the marginal rate of maize returns as a function of the combination of NPSZnB blended fertilizer and farmyard manure at Jabi Tehnan and Mecha. According to a partial budget study, with a rise in input price of 10% and a decrease in output price of 10%, the application of NPSZnB blended fertilizer combined with farmyard manure showed that the treatment combination of 200 kg·ha −1 NPSZnB blended fertilizer with 20 t·ha −1 farmyard manure yielded the highest net return of EB 36221.06 and 35431.04 with marginal rate returns of 22.05 and 6.78% at Jabi Tehnan and Mecha, respectively. Tis means that for every 1.00 birr invest in a 200 kg·ha −1 NPSZnB blended fertilizer application with 20 t·ha −1 farmyard manure, producers can expect to recover 1.00 birr and obtain an additional 0.46 and 0.65 birr at Jabi Tehnan and Mecha, respectively.
Terefore, in both experimental areas, it would be advisable for small-scale farmers with low production costs, and greater benefts, in this instance, were blanket recommendations (200 kg·ha −1 DAP and 150 kg·ha −1 urea). However, for farmers with unlimited resources (investors), a combination of 200 kg·ha −1 NPSZnB blended fertilizer and 20 t·ha −1 blended fertilizer was also proftable and recommended as the second option. According to Agegnehu and Fessehaie, [49], the marginal rate of return (MRR %) should have a minimum of 50% and a maximum of 100%. According to the current study, MRR for the frst option is signifcantly higher than 100% at both locations. Overall, there is strong evidence from the cost-beneft analysis that applying NPSZnB mixed fertilizer and farmyard manure together considerably boosted maize production, leading to considerable economic benefts.

Conclusion and Recommendations
Maize is a cereal crop that Ethiopia is relying on more and more for food security, notably in west Gojam, one of the country's prospective growth regions; however, its production is facing critical problems. However, its production is facing critical problems. Critical issues with maize production have arisen in Ethiopia as a result of the steadily declining fertility of the soil, continuous cropping, use of residues and manure as fuel instead of recycling, and erosion coupled with poor intrinsic fertility and organic content of the soil.
At both locations, except for days to silking and leaf area index at both location and days to physiological maturity, ear length, at Mecha, almost all parameters were signifcantly hastened and improved/increased by the individual as well as combined application of NPSZnB blended fertilizer and farmyard manure. Exceptionally, the only main efect of NPSZnB blended fertilizer was observed on the harvest index at Jabi Tehnan. Generally, on all parameters, the maximum result obtained from the interaction efect was improved and greater than that of the blanket recommendation (DAP and urea) but less in the case of main efects.
Te plant's ability to develop and perform vegetatively was greatly aided by the accessibility of nutrients from both sources.
Te results of phenology, growth, and yield parameters showed that the fertility of the soil in the experimental area was not satisfactory, as all fertilized treatments, particularly the combined application of NPSZnB blended fertilizer and farmyard manure, produced better results than the use of either of them alone did, which produced relatively poor results. Research suggested that the optimal strategy for the crop's development and production performance is comprehensive nutrient management. Te integrated strategy also has a long-term advantage in that it enhances the soil's physicochemical characteristics for sustained crop production.
In general, this research contradicts prior fndings that using farmyard manure reduced recommended inorganic fertilizer rates by half. Instead, a high rate (250 kg·ha −1 ) combined with 20 t·ha −1 of farmyard manure is the most likely combination to achieve the best grain production and proft, and it can be a viable alternative to integrated soil fertility management.

Data Availability
Te data supporting the fndings of this study are available from the corresponding author upon reasonable request.

Conflicts of Interest
Te authors declare that they have no conficts of interest.