Estudio del contenido de carbono orgánico del suelo en sistemas ganaderos con diferentes intensidades de pastoreo en campo natural

The objective of this work was to determine if there were differences in the SOC content, in sites subjected to different grazing intensities, on natural grasslands, and to determine, for the sites on which there was a structure of heterogeneous patches (high and low), if there were significant differences in the SOC stock between them. To achieve these objectives, two experiments were proposed within the work: analysis between sites (experiment 1) and analysis between patches (experiment 2). The experimental design used in both experiments was a DCA without repetitions, in four locations. For experiment 1, the treatments were proposed based on the grazing intensity, one treatment corresponding to grazing intensity “MA” (OF from 4 to 7% or a height greater than 5 cm on average; 1500 kg DM/ha) and the other to the grazing intensity “MB” (OF from 2 to 3% or a height of 4 cm on average; 1200 kg DM/ha). For experiment 2, the treatments were proposed based on the patches: high patches (15.6 cm average height) and low patches (4.3 cm average height). For both experiments, samples from 0 to 70 cm were obtained for the general characterization of each site and for the survey of C% and N%, and samples up to 30 cm deep were obtained for Dap, allowing the calculation of the C and N stock up to that depth. In a laboratory phase after the extraction of the samples, the physical fractionation of the SOM was carried out up to a depth of 30 cm and the percentage content of C and N was surveyed for all the extracted samples. The variables analysed were percentage of C and N, DAp (Mg/m3), stock of C and N (Mg) by fraction and total, and C:N ratio. The statistical package RStudio was used, using the "lmr" function within said statistical package. The general results for experiment 1 were that no significant differences were found between farms for any of the variables evaluated, but differences were found for some of these variables in depth. In experiment 2, significant differences were found between patches for the variables %C and Stock C in MOP, also finding significant differences for several of the variables studied in depth. From the work it can be concluded that the management of grazing intensity at farm scale to generate heterogeneity with high and low patches, generates significant in COS content between patches.