Production of Arugula Under Doses of Bokashi Fermented Compound

Fermented composts are made from animal, plant and or/mineral materials. The fermentation process can be accomplished through the action of microorganisms collected from soils, plant litter and/or baker’s yeast. This study aimed to evaluate arugula (Eruca sativa) yields with application of different doses of bokashi-type fermented compost. The experimental design consisted of randomized blocks with five treatments (0, 100, 200, 300, 400 g m) and four replications. Fermentation of the compost occurred in ten days, and in this period the compost mass was turned up twice a day during the first three days and daily during the seven next days. The fertilizer was incorporated three days before planting into a 0-5 cm deep layer. The methods used for data analysis were ANOVA and regression analysis at 5% probability level. The variables examined were: number of leaves, plant height, dry and fresh weight of roots and shoots. The use of bokashi at the rate of 300 g m resulted in better agronomic performance, demonstrating to be a viable alternative for the production of arugula under local edaphoclimatic conditions.

The process to produce fermented composts employs the methodology for preparation of bokashi, a Japanese word for fermented fertilizer. It is a costly production process when it uses oilseed cake and meal. However, costs decrease considerably when the bokashi preparation principles are used with materials available in the producing regions (Magrini, Camatti-Sartori, Finkler, Torves, & Venturin, 2011).
The study of alternative fertilizer sources is of vital importance to reduce Brazilian dependence on foreign suppliers and provide national producers with access to low-cost production techniques, less harmful to the environment. This study aimed to assess the effect of different doses of the bokashi-type fermented compost on arugula productivity.

Location of the Experiment
The experiment was carried out at the experimental farm of the Federal University of Amazonas -UFAM, at the geographic coordinates 2°39′ S and 60°3′ W, and climate defined as Am, tropical, warm and humid, according to Köppen classification, and an altitude of 96 m at the highest parts. Average annual temperature, rainfall and humidity are 25 to 28 °C, 2,100 mm, and 84 to 90%, respectively (Ribeiro et al., 1999).

Soil Analysis
The textural composition indicated a Yellow Latosol soil (EMBRAPA, 2006). The chemical analysis of the soil was carried out with ten samples collected from the experimental area, comprising a total sample of 500 g (Veloso, Viégas, Oliveira, & Botelho 2006), which were analyzed at the soil laboratory of UFAM (EMBRAPA, 1997) (Table 1).

Preparation of Bokashi Fermented Compost
To prepare the fermented compost, 0.05 m 3 of laying-chicken manure (corresponding to two 50-kg bags), 0.1 m 3 of soil, 0.1 m 3 of chopped straw (Paspalum virgatum L), 0.05 m 3 of charcoal powder, 5 kg of wheat bran, 5 kg of dolomitic limestone, 5 kg of plant litter, 1 L of molasses, 100 g of granulated biological baker's yeast, 5 kg of rock powder, and water were used (Restrepo, 2014).
In 20 L of water, the molasses and the baker's yeast were dissolved, and the mixture was homogenized and kept in a container protected from the sun and rain. Five 10-cm layers were formed with the same composition, comprised of the following sublayers: 1 st -straw, 2 nd -soil, 3 rd -laying-chicken manure, 4 th -wheat bran, 5 th -charcoal powder, 6 th -plant litter, and 7 th -dolomitic limestone. Each lawyer was moistened with a solution of water, molasses and biological yeast.
The fermentation process was accomplished in ten days, and during this period the compost piles were turned up twice a day in the first three days, and daily in the seven subsequent days (Restrepo, 2014). When ready, 300g of the compost were collected and taken to the soil laboratory at UFAM for analysis-Kjeldahl method (Brasil, 2014) (Table 2).

Experiment Implementation
The experimental design consisted of randomized blocks with five treatments and four replications, each one comprised of the average of ten viable plants. The rates of fermented compost applied on the soil were 0, 100, 200, 300, 400 g m -2 , which corresponded to 0, 1, 2, 3, 4 t ha -1 , respectively.
The experiment was conducted in open field. Soil tillage consisted of clearing, plowing, harrowing, and building beds with 0.20 m in height. Three days before planting, the fermented fertilizer was spread manually on the soil. Direct sowing occurred on November 10, 2017, by laying five to seven seeds in 2-cm deep holes. Thinning was conducted seven days after planting and only one plant per hole was kept. The arugula species used was the broadleaf cultivar. Spacing was 0.10 m between rows and 0.20 m between plants (Andreani Junior, Rocha, & Kozusny-Andreani, 2016).
The area was kept weed-free by hand weeding, and no phytosanitary control was performed. Irrigation was made with a hose on the days with no occurrence of rain, given that the experiment was conducted in the period of November and December, which are the months with the highest precipitation indices in the region of the study.

Parameters Assessed
The plants were harvested in a single work's day, 30 days after planting (Menin, Rambo, Frasson, Pereira, & Santi, 2014 Plants' height: each plant was measured from the ground level to the furthest point of the highest leaf using a millimeter ruler and expressed in centimeters (Tosta et al., 2016;Soares et al., 2017).
Fresh weight: after harvest, the plant was washed under running water and the roots were separated. The entire plants and the roots were weighed using a digital scale. The fresh biomass weight was expressed in g.plant -1 (Tosta et al., 2016).
Dry weight: the plants were weighed in a digital scale after being dried to constant weight in a forced-air circulation oven at 65 °C. The weight was expressed in g.plant -1 (Soares et al., 2017).

Statistical Analysis
The data were subjected to analysis of variance (ANOVA) and regression analysis at 5% probability level, using the SISVAR software (Ferreira, 2014).

Results and Discussion
After an extensive literature search, it could be seen that there are few scientific studies on organic fertilization used in arugula cultivation, which justifies the importance of the present study. Additionally, organic fertilizers improve the physical, chemical and biological properties of soil, resulting in improved plant growth and development. Furthermore, fermented organic fertilizers have the advantage of eliminating possible contaminants due to the high temperatures used in the fermentation process . Therefore, the bokashi organic fertilizer is a viable agroecological alternative because it is easy to produce and apply, in addition to providing better yields (Carvalho et al., 2018).
Because arugula is a leafy vegetable, the variables relating to number of leaves, height and biomass have a role in the commercial value. The evaluation of these parameters in arugula plants with different rates of bokashi revealed that the recommended dose is 300 g m -2 , corresponding to 3 t ha -1 .
The dose of 300 g m -2 of bokashi increased the number of leaves of arugula plants, with an approximate average number of of nine leaves per plant, an increase of 14% when compared to the plants grown without fertilization (Figure 1). Contrasting results were found by Carvalho et al. (2018), who found that the use of straw and efficient microorganisms did not have an influence on the number of arugula leaves, and also in the study of Soares (2017), where the highest average number of arugula leaves obtained with fertilization was eight.  (Linhares, 2008), and 23.88 cm with a dose of 200 g m -2 of bokashi (Fonseca, 2013). We can infer that the height varied within the maximum growth potential of the species. With respect to the variables relating to aboveground fresh and dry biomass, the best results were found with the fermented compost dose of 300 g m -2 , exhibiting, on average, 23.9 and 22.1 g per plant, respectively (Figure 3). The increase provided by this kind of management was of 23.4% for fresh biomass and 52.2% for dry biomass, when compared with the treatment without fertilization. Sediyama et al. (2016) found a similar result in a research conducted with organic composts, where there was a biomass increase in lettuce, which was mainly due to the high supply of N found in diverse types of organic fertilizers, since this nutrient plays a function in the plant vegetative development.    Vol. 12,No. 10; result of dose n increase of 3 e, 7.9 g of dry n (Figure 4)