Evaluación de la Labranza Mecanizada y Enmiendas sobre la Calidad del Suelo, La Dinámica del C Orgánico y la Producción de Pasto Transvala (Digitaria Decumbens Stent.) en San Mateo de Alajuela, Costa Rica.
Fecha
2023
Tipo
tesis de maestría
Autores
Medina Flores, Randalth Cristobal
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Resumen
El pasto transvala (Digitaria decumbens Stent.), de gran importancia en los sistemas de producción ganadera de Costa Rica, es principalmente utilizado como pasto de corte para su henificación. A pesar de su relevancia en la economía del país, la ganadería se percibe como una de las principales actividades que contribuyen a la degradación de los suelos y el deterioro de sus propiedades. En este trabajo se establecieron parcelas experimentales con un diseño de bloques completos al azar, donde se evaluó el efecto de la labranza y enmiendas combinadas de cal (CaCO3) y compost (elaborado a base de gallinaza) sobre la dinámica del carbono orgánico del suelo, comparando dos tipos de análisis, carbono total (Ctotal) y carbono activo (Coxp). También fueron evaluadas las propiedades físicas, químicas y microbiológicas del suelo, además de la producción y calidad nutricional del pasto transvala (Digitaria decumbens Stent.) en un Ultisol de San Mateo de Alajuela, Costa Rica. Los tratamientos consistieron en Subsolador, Palín Mecánico, Descompactador, Subsolador+Enmienda, Palín Mecánico+Enmienda, Descompactador+Enmienda y un Control. Las variables fueron evaluadas 78, 173 días después de la aplicación de los tratamientos y se realizó una evaluación adicional a los 263 días para el caso del carbono activo y algunas variables físicas. El Coxp mostró ser una variable susceptible al manejo, el cual reflejó el efecto de los tratamientos durante los periodos de evaluación. Por el contrario, el Ctotal no fue alterado por efecto de los tratamientos, ya que no mostró diferencias durante el periodo de evaluación. Los valores más altos de Coxp se observaron en el Subsolador+Enmienda a los 78 días, el Descompactador+ Enmienda a los 173 días y el Palín Mecánico+Enmienda a los 263 días. El uso de enmiendas y labranza promovió la Tasa de respiración en los dos periodos que se evaluó, no así la Biomasa microbiana, que fue beneficiada por los tratamientos de solo labranza a los 78 días y que, además, el efecto de los tratamientos presenta una dilución aparente a los 173 días donde no se observaron diferencias. La combinación de labranza y enmiendas también mostró una corrección significativa de las propiedades acidas del suelo (acidez, pH, saturación de acidez), un incremento de bases como el calcio y el potasio y así mismo una reducción del contenido de hierro y manganeso edáfico, cuyos efectos más promisorios se presentaron en los tratamientos de Palín Mecánico+Enmienda y Descompactador+Enmienda. De igual forma las condiciones físicas se vieron afectadas positivamente por la labranza y la aplicación de enmiendas, ya sea de forma separada o conjunta. Para el caso de la densidad aparente y la porosidad, fueron favorecidas en todos los tratamientos a los 78 días comparados con el Control, resaltando como mejor tratamiento el Subsolador+Enmienda. Estos resultados no son permanentes, ya que con el paso del tiempo estos cambios desaparecen, alcanzando incluso las condiciones previas a la aplicación de los tratamientos. Los tratamientos fueron efectivos en la reducción de la resistencia a la penetración, la infiltración y la retención de humedad del suelo, cuyos resultados más prometedores se observaron en el Subsolador+Enmienda y Palín Mecánico+Enmienda para el caso de la infiltración y el
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Palín Mecánico como tratamiento en el que se observó mayor agua disponible. Los Ultisoles, al ser suelos ácidos, que presentan en ciertos casos condiciones físicas desfavorables y pobres en nutrientes, la implementación de labranza, el encalado y la fertilización orgánica, permitieron el incremento de la producción de pasto transvala, mejorando la disponibilidad de nutrientes para la nutrición del pasto. Estos resultados se reflejaron en ambos periodos de evaluación, lo que implica una residualidad de los tratamientos incluso a los 173 días. Sin embargo, no se encontraron diferencias en la calidad nutricional del pasto entre los tratamientos en las edades de rebrote en las que se analizó el pasto (78 y 95 días, 78 y 173 días después de la aplicación de los tratamientos respectivamente).
Transvala grass (Digitaria decumbens Stent.) is of great importance in livestock production systems in Costa Rica, where it is mainly grown as a mechanical harvest grass for haymaking. Despite its importance in the country's economy, livestock farming is perceived as one of the main activities that contribute to soil degradation and the deterioration of its properties. In this work, experimental plots were established with a randomized complete block design, where the effect of tillage and combined amendments of lime (CaCO3) and compost (made from chicken manure) on the dynamics of soil organic carbon was evaluated comparing two types of analysis, total carbon (Ctotal) and active carbon (Coxp). The soil physical, chemical and microbiological properties were also evaluated, as well as production and nutritional quality of transvala grass (Digitaria decumbens Stent.) in an Ultisol from San Mateo de Alajuela, Costa Rica. The treatments consisted of Subsoiler, Mechanical Spader plow, Decompacter, Subsoiler+Amendment, Mechanical Spader plow+Amendment, Decompactor+Amendment and a Control. The variables were evaluated 78, 173 days after the application of the treatments and an additional evaluation was carried out at 263 days for active carbon and some physical variables. The Coxp was a variable susceptible to management, which reflected the effect of treatments during evaluation periods. On the contrary, Ctotal was not altered by the applied treatments, since it did not show significant differences during the study. The highest values of Coxp were observed in the Subsoiler+Amendment at 78 days, the Decompacter+Amendment at 173 days and the Mechanical spader plow+Amendment at 263 days. The use of amendments and tillage increases the soil respiration rate during the two evaluation periods, but not the soil microbial biomass, which was benefited by the treatments of only tillage at 78 days and that, in addition, the effect of the treatments disappeared at 173 days since no differences were observed. The combination of tillage and soil amendments also showed a significant correction of soil acidity (exchangeable acidity, pH, acidity saturation), an increase in soil bases such as calcium and potassium, and a reduction in soil available iron and manganese contents, whose most promising effects were observed in the spader plow+Amendment and Decompacter+Amendment treatments. Similarly, soil physical indicators were positively affected by tillage and amendment application, either applied separately or together. In the case of bulk density and porosity, they were positively changed in all treatments at 78 days compared to the Control, with Subsoiler+Amendment showing the most promising results. Nonetheless, the treatment effects were not permanent, since with the passage of time these changes disappear, even reaching the baseline conditions prior to the treatment application. The treatments were effective in reducing soil penetration resistance , increase infiltration as well as soil moisture retention, where the most interesting results were observed in the Subsoiler+Amendment and Spader plow+Amendment in the case of infiltration and the Spader plow as the treatment with significantly more available water. Ultisolsare acid soils, which in certain cases present unfavorable physical conditions and low levels of soil nutrients, where implementation of tillage, liming and organic fertilization, allowed the increase in the production of transvala grass, and improving the availability of nutrients for pasture nutrition. These results were reflected in both evaluation periods, which showed xi some degree of treatment residuality even at 173 days after treatment application. However, no differences were found in the nutritional quality of the transvala grass between the treatments at the grass regrowth (78 and 95 days grass regrowth time, which coincides with 78 and 173 days after the application of the treatments, respectively).
Transvala grass (Digitaria decumbens Stent.) is of great importance in livestock production systems in Costa Rica, where it is mainly grown as a mechanical harvest grass for haymaking. Despite its importance in the country's economy, livestock farming is perceived as one of the main activities that contribute to soil degradation and the deterioration of its properties. In this work, experimental plots were established with a randomized complete block design, where the effect of tillage and combined amendments of lime (CaCO3) and compost (made from chicken manure) on the dynamics of soil organic carbon was evaluated comparing two types of analysis, total carbon (Ctotal) and active carbon (Coxp). The soil physical, chemical and microbiological properties were also evaluated, as well as production and nutritional quality of transvala grass (Digitaria decumbens Stent.) in an Ultisol from San Mateo de Alajuela, Costa Rica. The treatments consisted of Subsoiler, Mechanical Spader plow, Decompacter, Subsoiler+Amendment, Mechanical Spader plow+Amendment, Decompactor+Amendment and a Control. The variables were evaluated 78, 173 days after the application of the treatments and an additional evaluation was carried out at 263 days for active carbon and some physical variables. The Coxp was a variable susceptible to management, which reflected the effect of treatments during evaluation periods. On the contrary, Ctotal was not altered by the applied treatments, since it did not show significant differences during the study. The highest values of Coxp were observed in the Subsoiler+Amendment at 78 days, the Decompacter+Amendment at 173 days and the Mechanical spader plow+Amendment at 263 days. The use of amendments and tillage increases the soil respiration rate during the two evaluation periods, but not the soil microbial biomass, which was benefited by the treatments of only tillage at 78 days and that, in addition, the effect of the treatments disappeared at 173 days since no differences were observed. The combination of tillage and soil amendments also showed a significant correction of soil acidity (exchangeable acidity, pH, acidity saturation), an increase in soil bases such as calcium and potassium, and a reduction in soil available iron and manganese contents, whose most promising effects were observed in the spader plow+Amendment and Decompacter+Amendment treatments. Similarly, soil physical indicators were positively affected by tillage and amendment application, either applied separately or together. In the case of bulk density and porosity, they were positively changed in all treatments at 78 days compared to the Control, with Subsoiler+Amendment showing the most promising results. Nonetheless, the treatment effects were not permanent, since with the passage of time these changes disappear, even reaching the baseline conditions prior to the treatment application. The treatments were effective in reducing soil penetration resistance , increase infiltration as well as soil moisture retention, where the most interesting results were observed in the Subsoiler+Amendment and Spader plow+Amendment in the case of infiltration and the Spader plow as the treatment with significantly more available water. Ultisolsare acid soils, which in certain cases present unfavorable physical conditions and low levels of soil nutrients, where implementation of tillage, liming and organic fertilization, allowed the increase in the production of transvala grass, and improving the availability of nutrients for pasture nutrition. These results were reflected in both evaluation periods, which showed xi some degree of treatment residuality even at 173 days after treatment application. However, no differences were found in the nutritional quality of the transvala grass between the treatments at the grass regrowth (78 and 95 days grass regrowth time, which coincides with 78 and 173 days after the application of the treatments, respectively).
Descripción
Palabras clave
Labranza, Carbono orgánico, Enmiendas, Calidad de suelo, Producción de pasto