Out of the 140 known Cenchrus species, Cenchrus purpureus (Schumach) Morrone is one of the most important (Umer and Nurusheva 2020Umer, A.T. & Nurusheva, A. 2020. Demonstration of Improved Elephant/Napier grass (Pennisetum purpureum) Technologies for Animal Feed Resources in Dire Dawa and Harari Region rural areas. Global Journal of Ecology, 5(1): 014-017, ISSN: 2641-3094. https://dx.doi.org/10.17352/gje.000013.) for the production of animal feed, mainly as forage or through direct grazing. In the world, several conservation centers (universities, research centers and farms, among others) maintain and develop promising cultivars of C. purpureus to use their potential for forage production. In Cuba, there are important collections of C. purpureus germplasm, preserved mainly at the Institute of Animal Science (ICA). These collections are important sources of plant genetic resources and are available for genetic improvement and the distribution of certified seed (Fernández 2022Fernández, L. 2022. Los Recursos Fitogenéticos en Cuba: estado actual y perspectivas, En: Seminario de intercambio sobre los parientes silvestres afines a las cultivadas. INIFAT, La Habana, Cuba.).
Ex situ germplasm conservation is based on the maintenance of biological material in plant collections (in the field, nursery or botanical gardens), seed banks and in vitro culture banks. The maintenance of field germplasm banks can be costly and demanding in terms of labor and financial resources, since the stored plants require optimal agronomic management, due to their exposure to attack by pests, diseases and natural disasters, among others (Suárez 2020Suárez, P.I.E. 2020. Prehistoria e historia del Cultivo de Tejidos Vegetales. En: Suárez Padrón, I. E. (ed.), Cultivo de Tejidos Vegetales. Fondo Editorial Universidad de Córdoba, pp. 13-19, ISBN: 978-958-5104-09-9.). Therefore, the objective of this study was to economically analyze the maintenance of the Cenchrus purpureus germplasm collection at the ICA.
The study was developed in the C. purpureus germplasm bank, established at the "Miguel Sistachs Naya" Experimental Center for Pastures and Forages of the ICA, located in San José de las Lajas municipality, Mayabeque province, Cuba, in a typical red ferralitic soil (Hernández et al. 2015Hernández, J. A., Pérez, J. J. M., Bosch, I. D. & Castro, S.N. 2015. Clasificación de los suelos de Cuba. Ed. Ediciones INCA, Mayabeque, Cuba. pp. 93, ISBN 978-959-7023-77-7.). The germplasm conservation area of C. purpureus complies with the standards for germplasm banks of plant genetic resources for food and agriculture (FAO 2014FAO. 2014. Normas para bancos de germoplasma de recursos fitogenéticos para la alimentación y la agricultura. Edición revisada. Roma, Italia. pp. 162. ISBN: 978-92-5-308262-9.).
Direct costs involved in maintaining the C. purpureus accessions in the germplasm bank were considered. The technical sheet of the cultural maintenance labors of the bank (mechanical weed control, plot cleaning, fertilization, cutting and irrigation), which are carried out during one year, was also taken into consideration (table 1).
| Labors | Frequency | Time, hours | Human labor | Fuel, liters | Water, m3/h | Energy, kW/h | ||
|---|---|---|---|---|---|---|---|---|
| Dry season | Rainy season | Year | ||||||
| Mechanical weed control with tractor | Once a month | Twice a month | 18 | 3 | 1 | 10 | ||
| Mechanical weed control with manual brush cutter | Once a month | Twice a month | 18 | 8 | 1 | 2 | ||
| Plot cleaning | 48 in the year | 15 | 2 | |||||
| Cut | 2 | 3 | 5 | 10 | 4 | |||
| Fertilization | 1 | 1 | 2 | 4 | 2 | 1.54 | ||
| Irrigation | 12 times in the year | 5 | 1 | 51.48 | 30 | |||
The accumulation sheet of expenses in Cuban pesos was prepared based on the investment in salary, fuel, machinery and other inputs. Regarding other inputs in irrigation, the expenses in water (51.48 m3/h for 1.20 Cuban pesos per m3), electricity (30 kW/h for 3.10 Cuban pesos per kW) and purchase of fertilizer were used.
The salary of a worker was obtained from Resolution No. 29-2020 (Ministry of Labor and Social Security 2020aMinisterio del Trabajo y la Seguridad Social. 2020a. Resolución No.29-2020. Establecimiento de la escala y tarifa salarial de los trabajadores. Gaceta 69.2020. GOC-2020-794- EX69. La Habana, Cuba.). The value of a liter of fuel was based on the provisions of Resolution No. 350-2020 (Ministry of Finance and Prices 2020bMinisterio de Finanzas y Precios. 2020b. Resolución No.350-2020. Establecimiento de precio de venta de los combustibles a entidades estatales. Gaceta 71.2020. GOC- 2020-849-EX71. La Habana, Cuba.). The price of nitrogen fertilizer was obtained from Resolution No. 344-2020 (Ministry of Finance and Prices 2020cMinisterio de Finanzas y Precios. 2020c. Resolución No.344-2020. Establecimiento de precios minoristas de los insumos, equipos e implementos agrícolas para las producciones agropecuarias. Gaceta 71.2020. GOC-2020-844-EX71. La Habana, Cuba.), in force in Cuba. The data was processed using the Microsoft Excel package.
In the economic analysis, the sheet of expenses accumulation for the maintenance of C. purpureus accessions in the germplasm bank was determined (table 2). A total annual expense of $45,840.66 Cuban pesos was found for all the cultural maintenance labors carried out in the area. Human labor expenses, expressed in salary, constitute one of the elements with the greatest impact on the maintenance of the C. purpureus germplasm collection at the ICA. Regarding salary, the economic analysis showed that the maintenance labors with the greatest expense are plot cleaning, followed by the mechanical weed control and cutting of C. purpureus accessions.
| Labors | Salary | Fuel | Machinery | Other inputs | Total |
|---|---|---|---|---|---|
| Total mechanical weed control | 2,743.13 | 3,045.96 | 38.21 | 0.00 | 5,827.30 |
| Mechanical weed control with tractor | 748.13 | 2,518.20 | 18.28 | 0.00 | 3,284.61 |
| Mechanical weed control with manual brush cutter | 1,995.00 | 527.76 | 19.93 | 0.00 | 2,542.69 |
| Plot cleaning | 19,950.00 | 0.00 | 0.00 | 0.00 | 19,950.00 |
| Fertilization | 221.67 | 43.09 | 6.58 | 1,064.00 | 1,335.34 |
| Cut | 2,770.83 | 0.00 | 0.00 | 0.00 | 2,770.83 |
| Irrigation | 831.25 | 0.00 | 12.08 | 9,286.56 | 10,129.89 |
| Total | 29,260.01 | 6,135.01 | 95.08 | 10,350.56 | 45,840.66 |
At the International Maize and Wheat Improvement Center (CIMMYT, initials in Spanish) in Mexico, Pardey et al. (2001)Pardey, P.G., Koo, B., Wright, B.D., van Dusen, M.E., Skovmand, B. & Taba, S. 2001. Costing the Conservation of Genetic Resources: CIMMYT's ex situ Maize and Wheat Collection. Crop Science, 41(4): 1286–1299, ISSN: 1435-0653. https://doi.org/10.2135/cropsci2001.4141286x. estimated that the annual expenditure for conserving wheat germplasm in the germplasm bank was US $270,138.00, about 64% of the annual amount included human labor. Maintenance practices are often species-specific and may vary depending on the use given to the collection: conservation, evaluation, distribution (FAO 2014FAO. 2014. Normas para bancos de germoplasma de recursos fitogenéticos para la alimentación y la agricultura. Edición revisada. Roma, Italia. pp. 162. ISBN: 978-92-5-308262-9.).
Irrigation represented a significant amount in the analysis, marked by the value of water and the expense of electricity, which is necessary for this work. In the study, it was considered that irrigation is applied according to the needs of the area in both periods of the year. Twelve annual irrigations were carried out, but it is not possible to define a specific amount per season, due to the variations in the behavior of climatic factors that can occur from one year to the other. As stated by FAO (2014)FAO. 2014. Normas para bancos de germoplasma de recursos fitogenéticos para la alimentación y la agricultura. Edición revisada. Roma, Italia. pp. 162. ISBN: 978-92-5-308262-9., the irrigation application system must be appropriate for the type of plant and the ecological conditions where the germplasm bank has been established.
In an analysis carried out by Herrera and Ramos (2015)Herrera, R.S. & Ramos, N. 2015. Factores que influyen en la producción de biomasa y la calidad. En: Herrera, R. S. (ed.), Producción de biomasa de variedades y clones de Pennisetum purpureum para la ganadería. EDICA, Mayabeque, Cuba. pp. 87-129, ISBN: 078-959-7171-67-6. to determine the response to irrigation applied in dry season in two varieties of C. purpureus, Napier and King grass, it was found that irrigation produced approximately twice the yield, compared to the absence of irrigation. This was related to the better use of available nutrients, since this species requires high amounts of water to express its productive potential. However, in most cases, irrigation is expensive due to the use of energy sources and specific equipment.
In the economic analysis, the amount of fertilization labor is the lowest among all the analyzed indicators. However, the value of other inputs is the highest and is determined by the value of nitrogen fertilizer in the national market. According to Resolution No. 344-2020 (Ministry of Finance and Prices 2020cMinisterio de Finanzas y Precios. 2020c. Resolución No.344-2020. Establecimiento de precios minoristas de los insumos, equipos e implementos agrícolas para las producciones agropecuarias. Gaceta 71.2020. GOC-2020-844-EX71. La Habana, Cuba.), fertilizers such as urea can cost up to $6,519.33 Cuban pesos per ton. The complete nationally produced formulas of NPK 9-23-16 and NPK 9-13-17 are sold at $11,200.24 and $8,602.19 Cuban pesos per ton, respectively.
Strategic fertilization with chemical fertilizer, which is applied with irrigation, is used in C. purpureus germplasm bank of the ICA. This strategy guarantees adequate regrowth and plant vigor. Alves et al. (2022)Alves, J.P., Mendes, S.S., Galeano, E.S., Orrico Junior, M.A.P., Fernandes, T., Retore, M., Orrico, A.C.A. & Lopes, L. da S. 2022. Forage Production and Quality of BRS Capiaçu as a Response of Cutting Age and Nitrogen Application. Tropical Animal Science Journal, 45(2): 179-186, ISSN: 2615-787X. https://doi.org/10.5398/tasj.2022.45.2.179. and Herrera (2022)Herrera, R.S. 2022. Strategic fertilization in Cenchrus purpureus varieties tolerant to drought in the western region of Cuba. Cuban Journal of Agricultural Science, 56(4): 1-9, ISSN: 2079-3472. pointed out a significant increase in yield components of C. purpureus accessions, with strategic application of chemical fertilizer.
When analyzing the work of mechanical control of total weeds, it was demonstrated that the expenses are higher with the use of the tractor, determined by the value of fuel and the time for its completion. Regarding fuel, there is a price difference. According to Resolution No. 350-2020 (Ministry of Finance and Prices 2020bMinisterio de Finanzas y Precios. 2020b. Resolución No.350-2020. Establecimiento de precio de venta de los combustibles a entidades estatales. Gaceta 71.2020. GOC- 2020-849-EX71. La Habana, Cuba.), the price of motor gasoline ranges from $14.66 to $17.37 Cuban pesos per liter. However, diesel has a price between $13.99 and $15.12 Cuban pesos per liter.
Greater expenses were evident in terms of salary for the use of the manual brush cutter, which is defined by the hours of labor used by the operator to complete the work. In this sense, the operator needs eight hours to complete the work compared to the three hours required by the tractor. These differences in time influence on efficiency and are translated into higher salary expenditure, as established in Resolution No. 29-2020 (Ministry of Labor and Social Security 2020aMinisterio del Trabajo y la Seguridad Social. 2020a. Resolución No.29-2020. Establecimiento de la escala y tarifa salarial de los trabajadores. Gaceta 69.2020. GOC-2020-794- EX69. La Habana, Cuba.).
In the C. purpureus germplasm collection of the ICA, two forms of mechanical weed control are used to ensure that the area is in optimal conditions. According to FAO (2014)FAO. 2014. Normas para bancos de germoplasma de recursos fitogenéticos para la alimentación y la agricultura. Edición revisada. Roma, Italia. pp. 162. ISBN: 978-92-5-308262-9., weed control is important for the rapid and vigorous growth of the plant. Weed control can be carried out by mechanical methods or by using chemical products (herbicides). However, the latter increase the maintenance costs of the C. purpureus bank of the ICA due to their value. According to Resolution No. 344-2020 (Ministry of Finance and Prices 2020cMinisterio de Finanzas y Precios. 2020c. Resolución No.344-2020. Establecimiento de precios minoristas de los insumos, equipos e implementos agrícolas para las producciones agropecuarias. Gaceta 71.2020. GOC-2020-844-EX71. La Habana, Cuba.), retail prices of herbicides in Cuba can range from $109.56 to $9,948.45 Cuban pesos, per kilogram or liter.
It is concluded that it is necessary to make changes to the schedule of annual cultural labors in the C. purpureus germplasm bank of the ICA to optimize investments and reduce expenses in salaries and other inputs. In addition, the figures provided in this study are recommended for use as supporting data for future analyses and investments in this area.