Forage yield and quality of marandugrass fertigated with treated sewage wastewater and mineral fertilizer/Rendimento e qualidade de forragem de capim-marandu fertirrigado com agua residuaria de esgoto tratado e adubo mineral.
Applying treated sewage effluent to crops is a common practice that dates back to before the BC period, starting from Germany and England within the sixteenth and seventeenth centuries (Veloso, Duarte, & Silva, 2004). These countries have had a primary goal of preventing pollution in waterways instead of raising agricultural yield.
Nations such as China and Mexico are pioneers in the use of wastewater in agriculture. In Brazil, wastewater usage is performed spontaneously and in an uncontrolled way, mainly due to the lack of wastewater treatment plants in most cities. However, it is expected that controlled applications will increase in the coming years because of economic development as well as environmental and public health pressures.
The major limitation of TSW usage in farming systems is trace elements, often present in irregular effluent. TSW pathogens such as streptococcus, Salmonella sp., Shigella sp., larvae, protozoa (cysts) and viruses (enteroviruses and rotaviruses) cannot withstand soil environment conditions for more than a few hours, except for helminth eggs.
Forage plants have been sorted for cultivation under TSW application because of their long growth cycle associated with high annual water consumption, nutrient absorption and the ability to prevent soil erosion (Fonseca, Herpin, Paula, Victoria, & Melfi, 2007a; Oliveira Filho et al., 2011). Moreover, grasses belonging to the Brachiaria genus meet the tolerance requirements of high soil moisture, salinity, organic matter content and possible toxic effects of TSW.
Grass growth in the tropics is often restrained by soil nitrogen deficiency (Vitor et al., 2009; Serafim & Galbiatti, 2012). Low forage yields are caused by a lack of scientific expertise as reflected in herd characteristics, animal weight fluctuations (i.e., within animal breeding, raising or finishing, low milk or meat yields), and consequently a lower market value. Furthermore, nitrogen is the most limiting factor in biomass production after water (Nogueira et al., 2013).
TSW is rich in macro and micronutrients essential for the growth of most crops, making its use convenient in farming (Bertoncini, 2008; Oliveira Filho et al., 2011; Silva, Matos, Borges, & Previero, 2012; Nogueira et al., 2013; Pinto, Cruz, Frigo, Frigo, & Hermes, 2013). Additionally, it also provides an increase in irrigated areas, even in those under jeopardized water use conditions (river basins under critical conditions).
The management of pastures with wastewater has been providing higher forage nutritional quality (Alencar et al., 2009, Teixeira et al., 2011; Serafim & Galbiatti, 2012; Matos, Silva, Lo Monaco, & Pereira, 2013; Nogueira et al., 2013). In addition to enhanced yield (Drumond, Zanin, Aguiar, Rodrigues, & Fernandes, 2006; Fonseca et al., 2007b; Silva et al., 2012), it is also good for supplying water and nutrient demands in a sustainable way and avoiding direct TSW discharge into water bodies (Bertoncini, 2008).
Leaf protein synthesis is assigned to water availability and soil fertility, mostly nitrogen, which reflects in higher digestible protein (CP) and reduces levels of less digestible fibre (NDF) for forages (Freitas et al., 2007; Geron et al., 2014), producing a forage of better quality for animal consumption.
Studying urban development, water resource management and the use of wastewater for irrigation in India, Van Rooijen, Biggs, Smout, and Drechsel (2010) concluded that wastewater use in agricultural lands is a contribution to food security and public health, in addition to improving the quality of water downstream of cities as well as reducing the demand for underground water in agriculture.
Reduced production costs associated with decreasing the use of mineral fertilizer may justify the economic feasibility of wastewater use in agriculture (Alencar et al., 2010; Nogueira et al., 2013). Additionally, fertigated areas should be connected to sewage treatment plants, thereby minimizing transportation costs.
Increased yields and forage quality are expected when using nitrogen fertigation with TSW in Brachiaria brizantha cultivation, coupled with reducing input costs and underground water use in agricultural lands. Investigations under these conditions would provide guidelines for wastewater use in Brazilian agriculture. Based on this research, we aimed to evaluate the response (forage yield and quality) of Brachiaria brizantha cv. Marandu to fertigation with various treated sewage wastewater rates and mineral fertilizer during the years of 2013 and 2014 in Jaboticabal, Sao Paulo State, Brazil.
Material and methods
The experiment was carried out in 2013 and 2014 at the College of Agricultural and Veterinarian Sciences at the Sao Paulo State University (FCAV-UNESP), in Jaboticabal, Sao Paulo State, Brazil (21[degrees]14'41,9" S and 48[degrees]16'25.2" W).
The soil is classified as Eutrophic Red Latosol--Lve (Red Oxisol), with a clayey texture (> 50%), high iron content, gentle landforms and high fertility (Table 1).
In this study, we used treated sewage wastewater from a sewage treatment plant (STP) near the experimental area. Treatments performed in this STP consist of a mixed system (aerobic and anaerobic) composed of an up-flow anaerobic digester and facultative lagoons. This plant collects sewage from Jaboticabal, with an average flow of 202 L [hab.sup.-1]. The city has approximately 71,662 inhabitants, in an area of 707 [km.sup.2] and a population density of 101.4 inhabits [km.sup.-2].
The experiment was performed over a floor area of 345.6 [m.sup.2], consisting of 24 plots (2.4 m wide and 6.0 m long) of 14.4 [m.sup.2]. Homogeneous distribution of water depth and gradual application of TSW were carried out by a triple-line sprinkling system (Lauer, 1983) at 30 m.c.a working pressure (0.042 ksi). Uniformity coefficients of Christiansen (CUC) and distribution (DU) were 88.8% and 83.5%, respectively; thus, it was possible to define six treatments with four replications by applying the following TSW water ratios: E5 = 1.0; E4 = 0.87; E3 = 0.6; E2 = 0.31; E1 = 0.11, and E0 = 0.0 and distribution model of TSW (Y = 0.0015 [X.sup.3] 0.029 [X.sup.2] + 0.057 X + 0.99; [R.sup.2] = 0.98; Figure 1).
TSW monthly samples were collected to analyse nitrogen concentration, and at the end of each season, complete analyses of nutrients were made using TSW samples.
Prior to the experiment, Brachiaria brizantha cv. Marandu seeds were sown into 0.2 m rows and at a rate of 10 kg [ha.sup.-1]. During this operation, fifty kilograms of superphosphate were applied per hectare.
Fertigation control was in accordance with plant nutritional demand, according Dantas et al. (2016), and consisted of 15 kg [ha.sup.-1] nitrogen (N), 3.5 kg [ha.sup.-1] phosphorus (P) and 18 kg [ha.sup.-1] potassium (K) per dry biomass megagram (Mg). However, water demand followed the FAO 56 method in the reference treatment (E3), which was considered the criterion of greatest value within a 28-day interval. In the E0 treatment, a mineral fertilizer (NPK) equivalent to nutrient demand in the reference treatment (E3) was applied. Higher rates in E3 in the same season were utilized to supply crop water requirements. The application of TSW in the experimental area considered the criteria established by the Technical Standard P4.230 (CETESB, 1999).
Dry biomass yield was assessed by harvesting grass. Grass was cut at 0.15 m height, except for the three first harvests when it was at 0.2 m, every 28 days (from Feb. 5, 2013 to Jan. 6, 2014). Eight summer harvests, 10 fallwinter harvests and 8 spring harvests were performed. The adopted management enabled 13 cut cycles and 2 harvests per year, which were done in a single month, one at the beginning and the other at the end.
Cuttings were aided by 0.25 [m.sup.2] templates randomly thrown three times (replications) over each plot and four times per treatment. Replications were homogenized and one sample was withdrawn for weighing. Then, the selected sample was dried in a forced circulation air oven at 65[degrees]C up to constant weight for dry biomass determination (Lacerda, Freitas, & Silva, 2009). Before being collected, plant height was measured using acetate sheets thrown randomly onto the lawn in six replications per plot.
Nitrogen yield was calculated by the ratio between dry biomass production and the amount of nitrogen applied.
A forage qualitative study analysing crude protein (CP) and neutral detergent fibre (NDF) was conducted in a quarterly basis per respective season using a methodology proposed by Silva and Queiroz (2006).
Forage yield data were analysed per season according to Johnson, Chaudhuri, and Kanemasu (1983), using the GLM procedure of SAS software, and the averages were compared by Tukey's test at 1% and 5% probability. Response functions were adjusted between dry biomass yield and qualitative characteristics according to the amount of nitrogen applied via TSW.
Results and discussion
TSW analyses confirmed high annual average concentrations of essential nutrients for Brachiaria growth, such as total nitrogen (52.9 [+ or -] 7.0 mg [L.sup.-1]). Concentrations of potassium (20.3 [+ or -] 7.2 mg [L.sup.-1]) and phosphorus (1.1 [+ or -] 0.4 mg [L.sup.-1]) were, respectively, ideal and low for forage fertigation purposes (Table 2). Although TSW salinity was low (< 0.46 dS [m.sup.-1]) by electrical conductivity evaluation, low sodium concentrations were observed (58.8 [+ or -] 8.7 mg [L.sup.-1]) but in a low adsorption ratio (SAR = 3.3 [+ or -] 0.6), which is above the critical level. In addition, there was also a high total coliform count and the presence of Escherichia coli in the effluent.
Other nutrients were applied in the following amounts in E5: P = 27, K = 314, Ca = 258, Mg = 92, Na = 894, SO = 369, Fe = 6, Mn = 1, and Zn = 11, in 2013, and P = 21, K = 463, Ca = 358, Mg = 108, Na = 1,428, SO = 421, Fe = 17, Mn = 2, and Zn = 3, in 2014, in kg [ha.sup.-1]. The remaining treatments were given quantities proportional to application ratios as defined for each treatment.
Mineral fertilizers (E0) were applied in summer, fall" winter and spring at the rates of 189, 85, and 182 kg [ha.sup.-1] N in 2013, and 200, 157, and 292 kg [ha.sup.-1] N in 2014. Superior nitrogen levels in E3 were applied in the same seasons to fulfil the crop water requirements.
Irrigation water depths for summer, fall-winter and spring were, respectively, 678, 500, and 675 mm in 2013, and 750, 661, and 842 mm in 2014. The total depth of irrigation and precipitation is shown in Table 3.
Mineral P and K fertilizers at the respective rates of 96 and 554 kg [ha.sup.-1] (2013) and 136 and 696 kg [ha.sup.-1] (2014) supplemented all treatments. Fertilizations were scheduled as needed for each cutting cycle of the crop (28 days).
Thus, an amount of 931 and 1,132 kg [ha.sup.-1] nitrogen was applied to the E5 treatment (Table 4). Moreover, a greater nitrogen increment in the second year stemmed from the higher dry biomass yield.
Rising temperatures, reduced rainfall, and consequently, greater water demand in 2014 led to higher forage yields. During 2013 and 2014, the average temperatures were 22.2, and 23.3[degrees]C, respectively, with maximum values of 34.1, and 36.5[degrees]C and minimum values reaching 8.2, and 11.9[degrees]C; however, annual average rainfall was 1,393 mm, and 721 mm with an evapotranspiration of 1,398 mm, and 1,616 mm.
Wastewater application increased the organic matter content, calcium, base saturation and cation exchange capacity (Table 5). Additionally, reductions of phosphorus, potassium and magnesium contents were observed, where plants absorbed some of the minerals and the remainder leached into the soil. Soil B concentration remained at an average content over time. During the evaluation period, the soil retained a low Al content, a medium to high content of Zn and Fe, and high amounts of Cu, Mn, and S-S[O.sub.4].
Seasonal effects marked forage production, with high values present from October to April and low ones between May and September (Tables 6). High yields were reported in summer (44.7%) and spring (35.7%) of 2013, due to climatic factors that increased plant metabolic activities and, thus, promoted forage growth. In contrast, the low yield in autumn-winter (19.6%) was due to sub-optimal conditions for crop growth.
In 2014, high values of average yields were obtained in spring (38.4%), followed by summer (35.9%) and fall-winter (25.7%) (Table 6). Cumulative results per season showed that in 2013, the highest average of forage performance occurred in summer (17.7 Mg [ha.sup.-1]), followed by spring (14.1 Mg [ha.sup.-1]) and fall-winter (7.8 Mg [ha.sup.-1]) (Table 7).
Rainfall reduction (672 mm) and an increase in temperature (1.1[degrees]C) and solar radiation (312.5 MJ [m.sup.-2] [year.sup.-1]), mainly from March to November of 2014, resulted in improved dry biomass yield, with a sharper production gradient in 2013. Furthermore, in 2014, there was an increase in biomass production from 25.7 Mg [ha.sup.-1] (E1) to 56.9 Mg [ha.sup.-1] (E5), corresponding to an increase of 121%. These results agree with Fonseca et al. (2007b) and Matos et al. (2013).
A variance analysis of summer forage yield revealed that the factors cultivation year, TSW rate and TSW x year interaction were significant (Table 8). The coefficient of variation was 9.6%, which shows high experimental accuracy.
The average comparisons showed a higher forage yield in 2014 compared to 2013. Statistical breakdown of the TSW x year interaction showed similar yield averages in the summer of 2013.
Initial fertilization standardized forage production at the beginning of the experiment. In the summer of 2014, the highest average yields were observed for E5, E4, and E0; however, E3, E2, and E1 had the lowest averages, but the E4 and E3 averages did not differ significantly.
During the fall-winter season, we observed significant results for the year and TSW rates; however, there was no interaction between them (Table 9). The coefficient of variation was 13.5%. Moreover, biomass yield in 2014 surpassed the findings for 2013.
When comparing TSW rates, we noticed higher yields for E5, E4, and E0, with no significant differences between E3 and E0. In addition, relatively low rates of nitrogen (E1) reduced biomass yield by up to 84.2% compared with the maximum rates (E5). During this season, biomass yield did not reach the minimal level for cattle grazing, which is 1,200 kg [ha.sup.-1] (Silva et al., 2012), within the 28-day intervals. This yield drop is associated with low temperatures, humidity and light, which are limiting factors for grass development, unlike what is observed in summer and spring. The growth of C4 grasses is highly demanding of temperature and luminosity (Matos et al., 2013). Maranhao et al. (2010) proved this fact in a study of nitrogen levels on Brachiaria, observing a 78.9% reduction in dry biomass from summer to winter. Similar results were obtained by Alencar et al. (2009) and Oliveira Filho et al. (2011).
As for spring data, we observed significant effects of year, TSW rates and their interaction, with a variation coefficient of 10.3% (Table 10). In 2014, biomass yield was higher than in 2013 (41%). Furthermore, in 2014, peaks of higher and lower biomass yield for E5 (24 Mg [ha.sup.-1]) and E1 (7 Mg [ha.sup.-1]) were recorded, respectively. It is worth mentioning that in warmer periods with high solar radiation, as in 2014, increased yields occurred.
The average rates of dry biomass growth in 2013 were 158, 56, and 126 kg h[a.sup.-1] da[y.sup.-1] in the summer, fall-winter and spring, respectively. The highest rates were observed in E0 (171 kg [ha.sup.-1] [day.sup.-1]) and E5 (170 kg [ha.sup.-1] [day.sup.-1]) during the summer, and the lowest rate was observed for E1 (38 kg [ha.sup.-1] [day.sup.-1]) in the winter. Similar results were obtained by Dupas et al. (2010), Matos et al. (2013) and Dantas et al. (2016).
In 2014, the lowest average rates of biomass growth occurred in treatments with lower inputs of TSW (E1 and E2), corresponding to 136, 78, and 146 kg [ha.sup.-1] [day.sup.-1] in the summer, fall-winter and spring, respectively. On the other hand, the largest rates were observed for E5 and E4 with 214 and 197 kg [ha.sup.-1] [day.sup.-1], respectively, during the spring; and the lowest rate was observed in E1 (55 kg [ha.sup.-1] [day.sup.-1]) in the winter. These results agree with those of Andrade et al. (2012).
The dry biomass yield increased according to the nitrogen applied to the soil via TSW in all assessed seasons for the years of 2013 and 2014. Despite the high levels of nitrogen applied via TSW, in 2013 (931 kg [ha.sup.-1]; Y = 0.016 [X.sup.2] + 2.53 X + 31,071; [R.sup.2] = 0.99) and 2014 (1,132 kg [ha.sup.-1]; Y = 0.014 [X.sup.2] + 12.53 + 24,628; [R.sup.2] = 0.99), forage yield peaks were not reached. Equivalent rates of organic and mineral nitrogen resulted in yields greater than or equal to E0 compared to E3. Similar results were obtained by Drumond et al. (2006), Silva et al. (2012), Nogueira et al. (2013) and Dantas et al. (2016).
Nitrogen yield for treatments receiving TSW were 173.8, 77.9 and 102.5 kg of biomass per kg of N in the summer (Y = 0.0098 [X.sup.2] - 4.64 X + 585.5; [R.sup.2] = 0.95), fall-winter (Y = 0.0053 [X.sup.2] - 2.09 X + 231.49; [R.sup.2] = 0.93) and spring (Y = 0.0038 [X.sup.2] - 2.05 X + 312.81; [R.sup.2] = 0,95) and 117 (Y = 0.0046 [X.sup.2] - 2.46 X + 361.7; [R.sup.2] = 0.96), 79 (Y = 0.0014 [X.sup.2] - 0.87 X + 182.65; [R.sup.2] = 0.93) and 81.3 kg of biomass per kg of N (Y = 0.0027 [X.sup.2] 1.51 X + 236.7; [R.sup.2] = 0.95), in 2014, respectively. Regardless of the higher yield in 2014, the lowest nitrogen efficiency is related to the increase in TSW rates. Serafim and Galbiatti (2010) argued that lower rates had better nitrogen performance, thus confirming the results of our research. For Fonseca et al. (2007b), low water tension in soil derived from regular irrigation favours nitrogen performance and, as a consequence, enhances forage yield.
An improved leaf quality, in terms of CP (> 12%) and NDF (< 60%), was provided when forage had low yield. Therefore, in the fall-winter, low yields associated with a smaller leaf area and larger leaf-stem ratio resulted in higher CP content and lower NDF in both years (Tables 11 and 12). Furthermore, we observed a gradual increase in herbage quality in 2014, which occurred due to the increased TSW rates applied. Similar results were obtained by Dantas et al. (2016).
Foliar analysis showed that the reference treatment (E3) had an ideal CP content, albeit below average, for every season except fall-winter. This high content, shown in 2013, could be attributed to higher leaf production against stems since leaves carry the most nutrients, as shown in some previous reports. These results agree with those of Matos et al. (2013), Silva and Queiroz (2006), Castro et al. (2007), Serafim and Galbiatti (2012), Geron et al. (2014) and Dupas et al. (2010).
Forage fertigation with TSW has the potential to supply nitrogen and potassium to crops; however, this also causes phosphorus limitation and an average potential for soil salinization because of large concentrations of sodium and coliforms within this effluent. However, it has promoted high levels of good quality forage production, favourable for cattle feeding, weight gain per animal, reducing the use of underground water and mineral fertilizers, in addition to social and environmental benefits.
Using wastewater in agriculture enables irrigated areas to be extended and reduces the amount of sewage disposed of in receiving water bodies. It denotes an alternative to control pollution of water sources, lowering underground water and fertilizer demands, in addition to a sustainable agricultural management tool.
Brachiaria brizantha had positive responses to TSW application, increasing annual dry biomass production from 31.3 to 47.4 Mg [ha.sup.-1] in 2013 and from 25.7 to 56.9 Mg [ha.sup.-1] in 2014, between E1 and E5, respectively.
There was a marked seasonality in forage performance; the highest yields occurred in the summer (35.9 to 44.7%) and spring (35.7 to 38.4%), and the lowest yields (19.6 to 25.7%) with improved forage quality were observed in the fall-winter.
The constant use of TSW combined with growing levels resulted in forage production with an enhanced nutritional quality concerning crude protein and neutral detergent fibre.
This work was supported by the Foundation of the Sao Paulo State (FAPESP) [grant numbers 2012/12.923-3 e 2013/00362-0].
The authors thank the Self-governing Water and Sewage Service of the city of Jaboticabal (SAAEJ) for wastewater supplies and Prof. Gener Tadeu Pereira from Sao Paulo State University in Jaboticabal (FCAV-UNESP) for helping with statistical analysis.
Alencar, C. A. B.; Coser, A. C., Martins, C. E., Oliveira, R. A., Cunha, F. F., & Figueiredo, J. L. A. (2009). Producao de seus gramineas manejadas por corte sob efeito de diferentes laminas de irrigacao e estacoes anuais. Ciencia e Agrotecnologia, 33(5), 1307-1313.
Alencar, C. A. B.; Coser, A. C., Martins, C. E., Oliveira, R. A., Cunha, F. F., & Figueiredo, J. L. A. (2010). Altura de capins e cobertura do solo sob adubacao nitrogenada, irrigacao e pastejo nas estacoes do ano. Acta Scientiarum. Agronomy, 32(1), 21-27.
Andrade, A. S., Drumond, L. C. D., Maicon, F. A., Moreira, D. D., Araujo, F. C., & God, P. I. V. G. (2012). Crescimento e composicao bromatologica de Tifton 85 e Vaquero em pastagem fertirrigada. Global Science and Technology, 5(2), 56-68.
Ayers, R. S., & Westcot, D. W. (1976). Calidad del agua para la agricultura (Estudios FAO: Riegos y Drenajes, 29). Roma, IT: FAO.
Bertoncini, E. I. (2008). Tratamento de efluentes e reuso da agua no meio agricola. Revista Tecnologia & Inovacao Agropecuaria, 1(1), 152-169.
Brasil. Ministerio do Meio Ambiente. Conselho Nacional do Meio Ambiente. (2011, 13 de Maio). Resolucao n. 430, de 13 de maio de 2011. Diario oficial da Uniao, Brasilia, DF, Secao 1, n. 92, p. 89.
Castro, G. H. F., Graca, D. S., Goncalves, L. C., Mauricio, R. M., Rodriguez, N. M., Borges, I., & Tomich, T. R. (2007). Cinetica de degradacao e fermentacao ruminal da Brachiaria brizantha cv. Marandu colhida em diferentes idades ao corte. Arquivo Brasileiro de Medicina Veterinaria e Zootecnia, 59(6), 1538-1544.
Companhia de Tecnologia Ambiental do Estado de Sao Paulo [CETESB]. (1999). Norma Tecnica, P4.230. Sao Paulo, SP: Cetesb.
Dantas, G. de F., Faria, R. T., Santos, G. O., Dalri, A. B., & Palaretti, L. F. (2016) Produtividade e qualidade da Brachiaria irrigada no outono-inverno. Engenharia Agricola, 36(3), 469-481.
Drumond, L. C. D., Zanini, J. R., Aguiar, A. de P. A., Rodrigues, G. P., & Fernandes, A. L. T. (2006). Producao de materia seca em pastagem de Tifton 85 irrigada, com diferentes doses de dejeto liquido de suino. Engenharia Agricola, 26(2), 426-433.
Dupas, E., Buzetti, S., Sarto, A. L., Hernandez, F. B. T., & Bergamaschine, A. F. (2010). Dry matter yield and nutritional value of Marandu grass under fertilizantion and irrigation in cerrado in Sao Paulo. Revista Brasileira de Zootecnia, 39(12), 2598-2603.
Feigin, A., Ravina, I., & Shalhevet, J. (1991). Irrigation with treated sewage effluent: management for environmental protection. Berlin, GE: Springer-Verlag.
Fonseca, A. F., Herpin, U., Paula, A. M., Victoria, R. L., & Melfi, A. J. (2007a). Agricultural use of treated sewage effluents: agronomic and environmental implications and perspectives for Brazil. Scientia Agricola, 64(2), 194-209.
Fonseca, A. F., Melfi, A. J., Monteiro, F. A., Mones, C. R., Almeida, V. V., & Herpin, U. (2007b). Treated sewage effluent as a source of water and nitrogen for Tifton 85 bermudagrass. Agricultural Water Management, 87(1), 328-336.
Freitas, K. R., Rosa, B., Ruggiero, J. A., Nascimento, J. L. do, Heinemam, A. B., Macedo, R. F., ... Oliveira, I. P. de. (2007). Avaliacao da composicao quimicobromatologica do capim Mombaca (Panicum maximum Jacq.) submetido a diferentes doses de nitrogenio. Bioscience Journal, 23(3), 1-10.
Geron, L. J. V., Cabral, L. S., Machado, R. J. T., Zeoula, M. Z., Oliveira, E. B., Garcia, J., ... Aguiar, R. P. S. (2014). Avaliacao do teor de fibra em detergente neutro e acido por meio de diferentes procedimentos aplicados as plantas forrageiras. Semina: Ciencias Agrarias, 35(3), 1533-1542.
Johnson, D. E., Chaudhuri, U. N., & Kanemasu, E. T. (1983). Statistical analysis of line-source sprinkler experiments and other nonrandomized experiments using multivariate methods. Soil Science Society of American Journal, 47(2), 309-312.
Lacerda, M. J. R., Freitas, K. R., & Silva, J. W. (2009). Determinacao da materia seca de forrageiras pelos metodos de micro-ondas e convencional. Bioscience Journal, 25(3), 185-190.
Lauer, D. A. (1983). Line source sprinkler systems for experimentation with sprinkler applied nitrogen fertilizers. Soil Science Society of America Journal, 47(1), 124-128.
Maranhao, C. M. A., Bonomo, P., Pires, A. J. V., Costa, A. C. P. R., Martins, G. C. F., & Cardoso, E. O. (2010). Caracteristicas produtivas do capim-braquiaria submetido a intervalos de cortes e adubacao nitrogenada durante tres estacoes. Acta Scientiarum. Animal Sciences, 32(4), 375-384.
Matos, A. T., Silva, D. F., Lo Monaco, P. A. V., & Pereira, O. G. (2013). Produtividade e composicao quimica do capim-tifton 85 submetido a diferentes taxas de aplicacao do percolato de residuos solidos urbano. Engenharia Agricola, 33(1), 188-200.
Nogueira, S. F., Pereira, B. F. F., Gomes, T. M., Paula, A. M., Santos, J. A., & Montes, C. R. (2013). Treated sewage effluent: agronomical and economical aspects on bermudagrass production. Agricultural Water Management, 116, 151-159. doi: 10.1016/j.agwat. 2012.07.005.
Oliveira Filho, J. C., Oliveira, E. M., Oliveira, R. A., Cecon, P. R., Oliveira, R. M., & Coser, A. C. (2011). Irrigacao e diferentes doses de nitrogenio e potassio na producao do capim Xaraes. Revista Ambiente & Agua, 6(3), 255-262.
Pinto, M. C. K., Cruz, R. L., Frigo, E. P., Frigo, M. S., & Hermes, E. (2013). Contaminacao das aguas subterraneas por nitrogenio devido a irrigacao com efluente do tratamento de esgoto. Irriga, 18(2), 270-281.
Serafim, R. S., & Galbiatti, J. A. (2012). Efeito da aplicacao de agua residuaria de suinocultura na Brachiaria brizantha cv. Marandu. Revista Colombiana de Ciencia Animal, 4(1), 185-203.
Silva, D. J., & Queiroz, A. C. (2006). Analise de alimentos: metodos quimicos e biologicos (3a ed.). Vicosa, MG: UFV.
Silva, J. G. D., Matos, A. T., Borges, A. C., & Previero, C. A. (2012). Composicao quimico-bromatologica e produtividade do capim-mombaca cultivado em diferentes laminas de efluente do tratamento primario de esgoto sanitario. Revista Ceres, 59(5), 606-613.
Teixeira, F. A., Bonono, P., Pires, A. J. V., Silva, F. F., Fries, D. D., & Hora, D. S. (2011) Producao anual e qualidade de pastagem de Brachiaria decumbes diferida e estrategias de adubacao nitrogenada. Acta Scientiarum. Animal Sciences, 33(3), 241-248.
Van Rooijen, D. J., Biggs, T. W., Smout, I., & Drechsel, P. (2010). Urban growth, wastewater production and use in irrigated agriculture: a comparative study of Accra, Addis Ababa and Hyderabad. Irrigation and Drainage Systems, 24(1-2), 53-64.
Veloso, M. E. C., Duarte, S. N., & Silva, I. J. O. (2004). Potencial de uso de aguas residuarias na agricultura como suprimento hidrico e nutricional. Engenharia Rural, 15, 79-86.
Vitor, C. M .T., Fonseca, D. M., Coser, A. C., Martins C. E., Nascimento Junior, D., & Ribeiro Junior, J. I. (2009). Producao de materia seca e valor nutritivo de pastagem de capim-elefante sob irrigacao e adubacao nitrogenada. Revista Brasileira de Zootecnia, 38(3), 435-442.
Received on July 21, 2016.
Accepted on December 2, 2016.
Gilmar Oliveira Santos (1) *, Rogerio Teixeira de Faria (2), Gilberto Aparecido Rodrigues (3), Geffson de Figueredo Dantas (2), Alexandre Barcellos Dalri (2) and Luiz Fabiano Palaretti (2)
(1) Universidade de Rio Verde, Fazenda Fontes do Saber, Cx. Postal 104, 75901-970, Rio Verde, Goias, Brazil. (2) Universidade de Sao Paulo, Jaboticabal, Sao Paulo, Brazil. (3) Taquaritinga Technology College, Taquaritinga, Sao Paulo, Brazil. * Author for correspondence. E-mail: firstname.lastname@example.org
Caption: Figure 1. Experimental diagram showing the lines of gradual distribution of TSW in water (left) and the distribution ratio of rainfall on the distance of irrigation lines (right).
Table 1. Soil chemical characteristics of samples collected from the experimental area within a depth of 0 to 1.0 m, in November of 2012, Jaboticabal, Sao Paulo State, Brazil. pH OM K Ca Mg H+Al BS CEC Al g [dm.sup.-3] mmol [dm.sup.-3] 5.5 20 4 25 12 27 40 68 0 pH P B Cu Fe Mn Zn S V mg [dm.sup.-3] % 5.5 53 0.3 3.4 12 18 2 24 57 Table 2. Chemical, physical and microbiological characteristics of treated sewage wastewater (TSW) from a sewage treatment plant (STP) in Jaboticabal, Sao Paulo State, Brazil, in the summer, fall-winter and spring seasons of 2013 and 2014. Factors Unit of measure Summer Fall-Winter Spring pH -- 6.7 7.2 7.1 EC dS [m.sup.-1] 0.44 0.49 0.42 TOC mg [L.sup.-1] 56.1 48.0 45.0 N[O.sub.3] mg [L.sup.-1] 2.1 5.8 4.5 N[O.sub.2] mg [L.sup.-1] 1.0 0.04 0.04 N[H.sub.3] mg [L.sup.-1] 31.4 35.7 31.6 Total N mg [L.sup.-1] 44.3 57.8 51.7 Total Fe mg [L.sup.-1] 0.28 0.62 0.60 K mg [L.sup.-1] 25.3 19.1 17.2 P mg [L.sup.-1] 1.3 1.0 1.0 Ca mg [L.sup.-1] 9.3 15.9 21.2 Mg mg [L.sup.-1] 7.5 4.9 7.0 Zn mg [L.sup.-1] 0.1 0.5 0.2 Na mg [L.sup.-1] 60.3 54.1 64.3 SAR -- 3.7 2.9 3.2 TCC MPN [100.sup.-1] ml 9,450 102,666 16,350 EC MPN [100.sup.-1] ml 495 6,370 11,650 Factors Average Acceptable level pH 7.0 [+ or -] 0.3 5-9 (a) EC 0.46 [+ or -] 0.01 <3 (b) TOC 49.4 [+ or -] 19.1 -- N[O.sub.3] 4.5 [+ or -] 2.4 <10 (c) N[O.sub.2] 0.25 [+ or -] 0.8 <0.02 (c) N[H.sub.3] 33.3 [+ or -] 15.8 1-40 (c) Total N 52.9 [+ or -] 7.0 -- Total Fe 0.53 [+ or -] 0.3 <5 (b) K 20.3 [+ or -] 7.2 10-40 (c) P 1.1 [+ or -] 0.4 <2 (b) Ca 15.5 [+ or -] 6.4 20-120 (c) Mg 6.2 [+ or -] 2.6 10-50 (c) Zn 0.27 [+ or -] 0.32 <5 (a) Na 58.8 [+ or -] 8.7 50-250 (c) SAR 3.3 [+ or -] 0.6 4.5-7.5 (c) TCC 51,371 [+ or -] 62,795 <10,000 (c) EC 6,200 [+ or -] 8,267 <1,000 (c) Obs.: pH: Hydrogen ionic potential; EC: Electrical conductivity; TOC: Total organic carbon; N[O.sub.3]: Nitrate; N[O.sub.2]: Nitrite; N[H.sub.3]: Ammonium; Total N: Total nitrogen; Total Fe: Total iron; K: Potassium; P: Phosphorus; Ca: Calcium; Mg: Magnesium; Mn: Manganese; Zn: Zinc; Na: Sodium; SAR: Sodium absorption rate; TCC: Total coliform count; EC: Escherichia coli. MPN: Most probable number. Source: (a) Brasil (2011); (b) Ayers and Westcot (1976); (c) Feigin, Ravina, and Shalhevet (1991). Table 3. Total water depth (water and effluent) and precipitation applied in the experiment in the summer, fall-winter and spring seasons of 2013 and 2014. Year Season Precipitation Irrigation Irrigation depth (mm) 2013 Summer 748 678 1,426 Fall-winter 221 500 721 Spring 424 675 1,089 Total 1,393 1,853 3,246 2014 Summer 348 750 1,098 Fall-winter 102 661 763 Spring 271 842 1,113 Total 720 2,252 2,974 Table 4. Nitrogen fertilization through TSW (kg [ha.sup.-1]) in the summer, fall-winter and spring seasons of 2013 and 2014. Year Season E5 E4 E3 E2 E1 Summer 307 270 186 95 34 2013 Fall-winter 258 227 156 80 28 Spring 365 321 221 112 40 Total 931 817 564 287 102 Summer 346 304 210 107 38 2014 Fall-winter 366 321 222 113 40 Spring 420 369 255 130 46 Total 1,132 994 687 350 124 Table 5. Average chemical characteristics of the soil in the experimental area at 0-1.0 m depths in September of 2014, Jaboticabal, Sao Paulo State, Brazil. Treatment ph OM P resin K Ca Mg g [dm.sup.-3] mg [dm.sup.-3] E5 5.7 21.0 41.5 3.7 31.7 13.7 E4 5.7 18.5 31.5 3.2 30.0 13.7 E3 5.6 21.0 43.8 3.8 32.2 14.2 E2 5.6 18.5 29.8 3.3 26.5 12.3 E1 5.5 17.3 26.5 3.5 22.8 10.7 E0 5.5 20.7 34.2 3.4 27.7 12.3 Treatment H+Al BS CEC V mmol [dm.sup.-3] % E5 24.0 49.1 73.1 65.5 E4 22.3 46.9 69.2 65.7 E3 23.7 50.1 73.8 66.0 E2 23.5 42.1 65.6 61.5 E1 24.3 37.0 61.3 57.7 E0 26.0 43.4 69.4 60.0 Treatment B Cu Fe Mn Zn S-S[O.sub.4] Al mg [dm.sup.-3] mmol [dm.sup.-3] E5 0.3 3.7 13.2 17.7 1.7 42.0 0.0 E4 0.3 3.3 11.8 12.7 1.4 42.0 0.0 E3 0.3 3.5 14.7 9.9 1.7 39.8 0.0 E2 0.3 3.1 14.2 9.5 1.4 32.7 0.0 E1 0.2 2.8 13.2 8.5 1.0 31.5 0.0 E0 0.2 3.3 15.2 15.2 1.5 25.3 0.0 Table 6. Dry biomass yield during cutting cycles in 2013. Month Date Cycle (Ms [ha.sup.-1]) E5 E4 February 02/05/13 1st 6,826 6,224 March 03/05/13 2nd 2,774 2,998 April 04/03/13 3rd 5,131 4,166 May 05/01/13 4th 1,397 1,639 May 05/28/13 5th 2,036 1,959 June 06/25/13 6th 2,444 2,530 July 07/23/13 7th 2,211 1,899 August 08/20/13 8th 1,526 1,440 September 09/17/13 9th 1,529 1,287 October 10/15/13 10th 5,376 4,356 November 11/12/13 11th 6,358 5,665 December 12/10/13 12th 5,512 6,001 January 01/07/14 13th 4,265 5,025 Total 47,385 45,189 Month (Ms [ha.sup.-1]) E3 E2 E1 E0 February 6,543 6,272 5,996 6,028 March 2,650 2,397 2,841 3,242 April 3,783 3,485 2,700 4,874 May 1,495 1,390 1,405 1,957 May 1,376 968 880 1,657 June 1,834 1,184 1,058 1,941 July 1,688 1,430 1,104 2,071 August 1,120 896 920 1,201 September 914 716 761 1,130 October 2,823 2,080 1,936 3,167 November 3,898 3,778 3,303 5,270 December 4,470 4,939 4,032 5,417 January 4,266 4,305 4,323 4,963 Total 36,862 33,840 31,260 42,918 Table 7. Dry biomass yield per treatment over the cutting cycles in 2014. Month Date Cycle (Mg [ha.sup.-1]) E5 E4 February 02/04/14 14th 4,332 3,285 March 03/04/14 15th 5,074 4,761 April 04/01/14 16th 3,611 4,077 April 04/29/14 17th 4,985 4,541 May 05/27/14 18th 2,816 2,768 June 06/24/14 19th 1,958 1,803 July 07/22/14 20th 2,397 1,955 August 08/19/14 21st 2,278 1,512 September 09/16/14 22nd 3,183 2,806 October 10/14/14 23rd 6,834 5,687 November 11/11/14 24th 7,127 6,462 December 12/09/14 25th 6,813 7,152 January 01/06/15 26th 5,497 4,444 Total 56,907 51,253 Month (Mg [ha.sup.-1]) E3 E2 E1 E0 February 3,169 3,369 3,026 4,610 March 2,973 3,707 3,125 3,837 April 3,247 2,732 2,850 4,293 April 4,232 4,054 3,842 3,908 May 2,037 1,717 1,686 2,590 June 1,649 1,241 852,0 1,896 July 1,251 797,0 626,0 1,915 August 1,287 993 682 1,536 September 1,431 1,004 717 2,203 October 3,563 2,363 1,455 3,833 November 4,789 3,055 2,106 7,030 December 5,132 3,657 2,793 6,910 January 3,902 3,503 1,974 6,237 Total 38,662 32,191 25,736 50,797 Table 8. Variance analysis summary (ANOVA) and comparison of biomass yield averages of Brachiaria brizantha fertigated with treated sewage wastewater (TSW) in the summer of 2013 and 2014. Variation source DF Mean square Pr (>F) Block (B) 3 2,132,262.5 (ns) 0.4801 Year (Y) 1 69,547,860.1 * <0.0001 Interaction BXY 3 5,984,640.0 (ns) 0.0901 TSW 5 41,835,894.5 ** <0.0001 Interaction 5 7,312,756.4 * 0.0299 TSWxY V.C. (%) 9.6 Year Average yield of dry biomass (Mg [ha.sup.-1]) 2013 17.7 a 2014 15.3 b Treatment 2013 (Mg 2014 (Mg Average [ha.sup.-1]) [ha.sup.-1]) [ha.sup.-1]) E5 19.0 a 18.5 a 18.9 E4 18.4 a 16.6 ab 17.5 E3 17.2 a 13.3 bc 15.3 E2 16.5 a 13.3 bc 14.9 E1 15.8 a 10.9 c 13.4 E0 19.1 a 19.0 a 19.0 Average 17.7 15.3 -- DF--degree of freedom; Significant at 0.05 * and at 0.01 ** of probability; (ns) nonsignificant; V.C.--variation coefficient; Averages followed by the same letter in the upper right do not differ by Tukey's test (p < 0.05). Table 9. Variance analysis summary (ANOVA) and comparison of biomass yield averages of Brachiaria brizantha fertigated with treated sewage wastewater (TSW) during the fall-winter of 2013 and 2014. Variation source DF Mean square Pr (>F) Block (B) 3 6,222,510.2ns 0.018 Year (Y) 1 122,212,110.0 ** <0.0001 Interaction B x Y 3 1,631,663.1ns 0.3949 TSW 5 36,929,215.3 ** <0.0001 Interaction TSW x Y 5 1,432,577,0ns 0.4932 V.C. (%) 13.5 Year Average yield of dry biomass (Mg [ha.sup.-1]) 2013 7.8 b 2014 11.0 a Treatment 2013 2014 Average (Mg (Mg (Mg [ha.sup.-1]) [ha.sup.-1]) [ha.sup.-1]) E5 9.6 14.5 12.0 a E4 9.5 12.6 11.0 a E3 7.5 10.5 9.0 bc E2 5.9 8.8 7.4 cd E1 5.4 7.7 6.6 d E0 8.8 11.8 10.3 ab Average 7.8 11.0 -- Table 10. Variance analysis summary (ANOVA) and comparison of biomass yield averages of Brachiaria brizantha fertigated with treated sewage wastewater (TSW) in the spring of 2013 and 2014. Variation source DF Mean square Pr (>F) Block (B) 3 11,248,379 ** 0.0091 Year (Y) 1 59,748,413 ** <0.0001 Interaction BxY 3 10,628,428 * 0.0116 TSW 5 207,980,458 ** <0.0001 Interaction TSWxY 5 25,456,396 ** <0.0001 V.C. (%) 10.3 Year Average yield of dry biomass (Mg [ha.sup.-1]) 2013 16.3 a 2014 14.1 a Treatment 2013 (Mg 2014 (Mg Average [ha.sup.-1]) [ha.sup.-1]) (Mg [ha.sup./-1]) E5 18.8 Abc 24.0 a 21.4 E4 17.3 Bc 22.1 ab 19.7 E3 12.1 De 14.9 de 13.5 E2 11.5 De 10.0 fg 10.8 E1 10.0 Ef 7.0 g 8.5 E0 15.0 Cd 20.0 bc 17.5 Average 14.1 16.3 -- DF--degree of freedom; Significant at 0.05 * and at 0.01 ** of probability; (ns) nonsignificant; V.C.--variation coefficient; Averages followed by the same letter in the upper right do not differ by Tukey's test (p < 0.05). Table 11. Crude protein (%) of dry biomass of Brachiaria brizantha due to the application rates of TSW and mineral fertilizing in 2013 and 2014. Year Season Treatments Average E5 E4 E3 E2 E1 E0 2013 Summer 10.6 11.1 10.3 10.5 10.5 11.1 10.7 Fall-winter 16.4 15.0 14.0 13.4 12.6 13.9 14.2 Spring 12.3 11.0 11.8 10.7 13.2 13.6 12.1 Average 13.1 12.4 12.0 11.5 12.1 12.9 -- 2014 Summer 15.0 14.9 13.0 10.9 12.2 12.8 13.1 Fall-winter 17.7 17.8 15.7 14.4 12.7 17.5 16.0 Spring 15.5 12.0 10.6 10.2 8.1 11.8 11.4 Average 16.1 14.9 13.1 11.8 11.0 14.0 -- Table 12. Neutral detergent fibre (%) of dry biomass of Brachiaria brizantha due to the application rates of TSW and mineral fertilizing in 2013 and 2014. Year Season Treatments Average E5 E4 E3 E2 E1 E0 2013 Summer 65.8 61.0 66.7 65.2 58.1 66.4 63.9 Fall-winter 57.1 56.8 60.4 61.5 61.2 55.5 58.8 Spring 62.6 60.5 62.9 57.8 64.9 62.4 61.9 Average 61.8 59.4 63.3 61.5 61.4 61.4 -- 2014 Summer 55.1 55.8 57.0 60.6 61.1 55.1 57.5 Fall-winter 52.8 52.7 56.0 57.6 59.5 56.4 55.8 Spring 58.4 62.0 62.4 67.3 61.4 63.5 62.5 Average 55.4 56.8 58.4 61.8 60.7 58.3 --