SILAGE PRODUCTION, BROMATOLOGICAL COMPOSITION AND ECONOMIC VIABILITY OF INOCULATION OF VARIETAL MAIZES WITH Azospirillum brasilense

In the western region of the State of Goias family farmers that depend on the raising of livestock as one of their main sources of income are predominant. These farmers periodically grow maize for the production of silage in order to compensate their incomes. Considering the high cost of hybrid seeds and nitrogen fertilization, technologies that contribute to the reduction of silage production costs are required. In this sense, the objective of this study was to evaluate the response of maize genetic materials (Feroz Hybrid VIP3 and varieties SCS 156 and SCS 154), regarding silage production, bromatological composition and economic viability when inoculated with Azospirillum brasilense. The experiment was carried out on strips using a completely randomized design with four replications. Each cultivar responded differently to inoculation. For the Feroz hybrid and SCS 156 variety, the use of Azospirillum provided increases of 13.1% and 42.1% in green stem mass and 11.2 and 30.3% in silage nitrogen content, influencing the nutritional composition of the bulky food produced. For the SCS 154 variety, there was no response to inoculation. As for the economic viability, the use of inoculated SCS 156 variety presents a better rate of rentability, proving to be more economically attractive and viable to farmers. Keyword: family farming, silage production, inoculation, economic viability PRODUÇÃO DE SILAGEM, COMPOSIÇÃO BROMATOLÓGICA E VIABILIDADE ECONÔMICA DE MILHOS VARIEDADE INOCULADOS COM Azospirillum brasilense Resumo Na região do Oeste Goiano há um predomínio de agricultores familiares. Estes têm a pecuária como uma das principais atividades geradora de renda, cultivando periodicamente milho para produção de silagem. Considerando o elevado custo das sementes híbridas e da adubação nitrogenada, necessita-se de tecnologias que contribuam na redução dos custos de produção. Neste sentido, objetivou-se avaliar a resposta de materiais genéticos de milho (Híbrido Feroz VIP3 e variedades SCS 156 e SCS 154), quanto a produção de silagem, composição bromatológica e viabilidade econômica, quando inoculados com Azospirillum brasilense. O experimento foi implantado em faixas utilizando-se delineamento inteiramente casualizado, com quatro repetições. Os materiais genéticos responderam de forma diferenciada à inoculação. Para o híbrido Feroz VIP3 e variedade SCS 156, o uso de Azospirillum proporcionou incrementos de 13,1% e 42,1% na produção de massa fresca pela parte aérea e de 11,2 e 30,3 % no teor de nitrogênio da silagem, influenciando na composição nutricional do alimento volumoso produzido. Já para a variedade SCS 154, não houve resposta a inoculação. Quanto a viabilidade econômica, o uso da variedade SCS 156 inoculada apresentou melhor taxa de rentabilidade, demonstrando ser economicamente mais atrativa e viável para os produtores rurais. Palavras-chave: agricultura familiar, produção de silagem, inoculação, viabilidade econômica. ISSN 1980 6477 Journal homepage: www.abms.org.br/site/paginas Thays Gabriella Lima Silva(1), Romano Roberto Valicheski(1) ( ), Flávio Lopes Cláudio(1), Estênio Moreira Alves(1), Mateus de Sousa Peres(1) and Paulo Alexandre Perdomo Salviano(1) (1) Instituto Federal Goiano – Campus Iporá, E-mail: thayslima.agro@gmail.com romano.roberto@ifgoiano.edu.br flavio.claudio@ifgoiano.edu.br estenio.moreira@ifgoiano.edu.br mateusperes20@gmail.com paulo.salviano@ifgoiano.edu.br


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In the municipality of Iporá, state of Goias, Brazil, as well as the surrounding areas, the predominant agricultural activity is the production of cattle for meat and milk. These activities function as the main source of income for these rural establishments (Dias et al., 2015). Along with these activities, the cultivation of cereals is of significant importance especially that of maize for silage, ears and stalks, utilized as feed for the herds, especially during the dry season.
The region is mostly comprised of small rural properties, with sizes no greater than 100 hectares whom are predominantly run as family farms (Dias et al., 2015).
Despite the use of hybrid seeds that have elevated silage yields, it has been observed with some frequency that the local growers are usually dissatisfied with the total produced biomass and the quality of the grain. This fact is due to the elevated demand of agricultural inputs required by these hybrid maizes in order to reach their full productive potential; inputs that are many times either nonexistent or supplied in inferior quantity by these rural properties.
Due to these conditions, one of the ways to diminish the costs of production and increase the economic feasibility of maize production is to utilize more cost effective cultivars that present a decreased input demand. For this, heirloom and open pollination variety seeds stand out whenever they have an adequate yield, good climate and soil adaptability, low input costs and also allow for the farmer to produce his own seeds for subsequent harvests (Cruz et al., 2011).
In the production of maize, one of the most demanded nutrients is nitrogen (N). Because of the low purchasing power of these family farms, there exists an insufficient supply of nitrogenized fertilizers. This fact, associated to an also diminished intake rate, usually no greater than 50% of the applied total (Hungria, 2011), contributes to the area´s low crop output.
Confronted by this situation, biological alternatives that assist in the supply of N to the plants must be established. For example, the use of bacterium belonging to the genus Azospirillum, which possess the capacity of enhancing biological nitrogen fixation (Dobbelaere et al., 2001) and contribute to the production of plants growth stimulating hormones, (Szilagyi-Zecchin et al., 2015), are interesting due to the possibility of their contributions to the plant development and greater crop yield.
According to Hungria et al. (2010), the harvesting of maize utilizing these bacteria, associated with the supplementation of 30 kg ha -1 of N, can produce a grain yield of 7,000 kg per hectare or more.
These bacteria can stimulate the plants growth by the combination of diverse mechanisms. Their capacity of biological fixation of nitrogen (Mumbach et al., 2017, Shaeffer et al., 2019, the solubilizing of phosphates (Rodriguez et al., 2004), and the production of phytohormones that stimulate root growth are some of these mechanisms (Szilagyi-Zecchin et al., 2015).
The stimulus in radicular development provided to plants inoculated with Azospirillum, can bring forth other beneficial effects like an increase in water and nutrient uptake, a greater tolerance to saline and hydric stresses, resulting in many cases with vigorous plant development (Skonieski et al., 2017, Morais et al., 2017, Souza, et al., 2019. Inoculation can also induce diverse physiological responses, such as an improvement of photosynthetic parameters (chlorophyll content and stomatal conductance), greater hydric potential, greater cellular wall elasticity, and an increase in biomass, plant height and productivity (Cunha et al. 2014, Skonieski et al. 2017, Szilagyi-Zecchin et al. 2017, Thomazini et al. 2019 In order to combat, weeds, primarily crabgrasses (Digitaria sp.), a mesotrione based herbicide was introduced at day 40 in dosage of 280 g. a.i. ha -1 . Also, a topdressing was applied twice, the first at day 15, with a dosage of 100 kg.ha -1 of 20-00-20 compound and then at day 25, 100 kg.ha -1 of urea.
Due to a small change in weather patterns that occurred during the first fortnight of January Willye type mill and stored in sealed plastic bags until they were analyzed.
Following the methodology described by Tedesco (1995), the sulfuric digestion of the plant tissue and the determination of the total nitrogen content were carried out by the micro Kjeldahl method. In order to obtain the gross protein value, the nitrogen content was multiplied by a factor of 6.25 (Rodrigues, 2010).
The determination of fiber in acid detergent (FAD) was performed in borosilicate glass filter crucibles with porous plate of medium to coarse porosity, 100 to 160 mm (Rodrigues, 2010). In respect to the FAD data, and following the recommendations of the author, total digestible nutrients (TDN), dry mass digestibility (DMD), digestible energy (DE), metabolic energy (ME), raw fiber (RF) and the net energy gain (NEG) were also obtained.
After tabulating the data, they were submitted to a variance analysis. When a significant effect of the inoculation was detected, the means were compared to each other using a Tukey test, considering a 5% probability of error, utilizing the SASM-Agri program (Canteri et al., 2001).
For the construction of the necessary cash flows in order to establish the experiments economic indicators, the total expenses for three consecutive years were considered. The agricultural inputs, mechanized activities and labor requirements of the first harvest were repeated for years two and three.
An exception was made, as liming was required at the beginning of the second harvest, after a soil analysis collected at depths of up to 0.2 m, presented some soil depletions right after the initial harvest. For net income, the market value of the first harvest's yield for each sample was also used for years two and three. As land costs, the average lease price for the region was utilized, considering a 4-month cultivation period for each of the three years destined exclusively of the production of silage.
To verify the economic and financial feasibility of the proposed study, the production cost vs return of investment was analyzed for each stage of the activity.
Since this is a comparative evaluation of varieties from the perspective of different answers for each period analyzed, we sought to consider the relational rate of rentability and profitability under investment as ideal in the economic-financial analysis, as it is an easy-to-use methodology measurement and understanding of the growers. In this sense, the rentability was calculated by evaluating the net profit divided by the total cost of investment and the profitability by dividing the net profitably the total revenue, which was obtained multiplying the market value of silage times the yield of each treatment.
This financial evaluation, in a way, presents itself as simplistic, but for this type of short-term conditions evaluation it is significant and meets the central question of this paper. It enables the local producers to analyze the opportunity costs of purchasing or producing their own silage, as well as allowing them to evaluate which inoculated varieties presents the greatest return rates for their investments.

Results and discussion
Both the maize varieties and the use of Azospirillum brasilense influenced the variables evaluated (Table 1) Figure 1A). Considering that all genetic materials had germination power greater than 90% at the time of planting, the smaller grain sizes of the hybrid maize seeds when compared to the varieties, may have contributed to a better seed germination.
During the first eight days after sowing there was no precipitation, a factor which may have limited the rehydration of larger seeds thus resulting in a lower germination rate. As for the plant heights ( Figure 1B Furthermore, they contribute to greater production of straw on the ground. As for the interaction effects, there was a different response of maize materials to inoculation with Azospirillum brasilense. Ear insertion heights Regarding the total production of dry matter per hectare ( Figure 2D), when inoculated, the Feroz  When non-inoculated and compared to hybrid maize, the SCS-156 and SCS-154 varieties, despite having a lower total dry mass yield ( Figure 2D), were promising in the production of green mass for silage, not being differentiable in the parameter from the Feroz VIP3 hybrid ( Figure 2C). This data reinforces the potential use of these variety seeds, primarily by those small rural growers that are predominant in the western regions of Goias, whom, due to the low/medium level of technology adopted in their properties, require seeds with lower acquisition costs.
Regarding the nutritional and chemical composition of the analyzed silage feed (Table 2), it is observed that for the N content, total protein and total protein accumulated in dry mass aerial, both the type of maize and the inoculation with Azospirillum significantly influenced these variables. As for the fiber in acid detergent (FAD), total digestible nutrients (TDN), dry mass digestibility (DMD), digestible energy (DE), metabolizable energy (ME); raw fiber (RF) and net energy gain (NEG), there was no effect of these factors.
When comparing the genetic materials of maize that were inoculated, Feroz and SCS-156 presented an increase in the nitrogen and total protein content of the feed, as well as in the total mass of accumulated protein in the silage (kg.ha -1 ). These results showed to be statistically superior to SCS-154 (Table 2).
When not inoculated, the hybrid was superior to both varieties in terms of nitrogen content and total protein accumulated per hectare. In this condition, the better performance of the hybrid is possibly related to the genetic improvements that it underwent, seeking to maximize grain production, which consequently results in more nutritious silage feed.

Considering the effects that inoculation had
within each genetic material of maize, similarly to that observed for biometric variables ( Figure   2), the plants responded differently to inoculation. This suggests that the cultivar or genetic material used is a factor that influences the efficiency of inoculation. This might possibly be caused due to the specificities of the bacterial flora and the host plant (Hungria, 2011). According to Marini et al. (2015), the effects of nitrogen fertilization and inoculation with Azospirillum brasilense on maize nutrition and productivity are also dependent on the genetic material used, however, according to Cunha

As for the economic and financial factors
of the study, total production cost per hectare,

variations. The economic and financial factors
regarding total production costs per hectare are presented in Table 3 . When inoculated, Feroz VIP3 and SCS-156 presented better economic and financial results, which were driven by the increase in silage productivity. Inoculated SCS-156 presented, overall, better results in terms of productivity and production costs. Profitability was calculated at 37.5% in year 1 and 38.7% in year 3, which makes it, among those evaluated crops, the most attractive for rural producers in terms of return on investments.
The calculated economic equilibrium, which refers to the minimum productivity required in order to pay all production costs, considering an average market value for all three years, hybrid Feroz VIP3 required 26.0 and 25.8 t.ha -1 for inoculated and control respectively. Varieties SCS-154 and SCS-156, both required a yield of 24.6 and 24.4 t.ha -1 , also for inoculated and control respectively. When comparing these values with the feed silage yield, for Feroz VIP3 without inoculation, this is zero, which indicates that the production obtained was just enough to cover production costs, since when inoculated; there is a positive balance of 3 t.ha -1 , resulting in a better rate of return on investment.
Under these same conditions, it is calculated that SCS-156 is a much more attractive cultivar for the grower, as there is a positive balance of 7.8 t.ha -1 , and consequently, a higher rate of return, 30% above the productive equilibrium point. On the other hand, when not inoculated, the silage yield for this variety was insufficient to cover production costs. For  -Inoculated Variety SCS 156 also proved to be economically more attractive and viable for rural producers, presenting an increased profitability.