Abstract

ZAMBRANO-YEPES, Jennifer; HERRERA-VALENCIA, Wilmer  and  MOTTA-DELGADO, Pablo Andrés. Concentration of soil macronutrients in grazing areas of the department of Caquetá, Colombian Amazon. Cienc. Tecnol. Agropecuaria [online]. 2020, vol.21, n.3, e1673.  Epub Aug 31, 2020. ISSN 0122-8706.  https://doi.org/10.21930/rcta.vol21_num3_art:1673.

The establishment of livestock in the northwest of the Colombian Amazon affects production systems and decreases soil macronutrients. The aim of the study was to obtain diagnostic information of the macronutrients in soils of lomerío or rolling hills subject to grazing in nine (9) municipalities of the department of Caquetá. Four hundred sixty-three random soil samples were carried out to determine the concentration, in mg/kg, of nitrate (N-NO3), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S). Data analysis was carried out through analyses of variance, and the means were compared with Tukey’s Test. A concentration of N-NO3 with means of up to 90.57 mg/kg was evidenced in San José del Fragua, El Doncello, and San Vicente del Caguán showing statistical differences compared to Puerto Rico (18.83 mg/kg) and La Montañita (5.24 mg/kg). Phosphorous concentration in San Vicente del Caguán, Puerto Rico, and San José del Fragua recorded means between 1.4 mg/kg and 1.8 mg/kg with statistical differences in relation to La Montañita (3.5 mg/kg). The concentration of K, with a mean value between 46.9 mg/kg and 74.2 mg/kg, did not show significant differences between the localities. San Vicente del Caguán was the only municipality that discloses significant differences of Ca (1,000.9 mg/kg) and Mg (226 mg/kg) compared to the others. As for S, there were significant differences between Cartagena del Chairá (2.29 mg/kg) and San José del Fragua (4.29 mg/kg). In conclusion, there was a low generalized concentration of macronutrients compared to the optimal values of tropical soils.

Keywords : livestock feeding; chemical composition of the soil; pastures; extensive husbandry; nutrient availability; soil degradation.

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