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Erosion significantly decreases the depth of a soil, the nutrients available for plants, the organic matter and, consequently, the productivity of the edaphic environment. Due to the above considerations, the objective of this study was to evaluate, through various properties, the quality of two eroded soils, one eroded by water and the other by mining activity, amended with biosolids. The quality for both soils was estimated through the selection of a minimum set of data by means of principal component analysis (PCA) and the subsequent realization of correlations, multiple regressions and finally calculations of normalized values (Vn) of those properties considered as indicators of soil quality. According to the results, inorganic nitrogen (NI) and respiratory activity (RA) were the properties selected as indicators to assess quality. For soil eroded by water and by mining activity, NI presented a low and very low quality, respectively (class 4 and 5 of quality according to the calculation of Vn). The quality of RA in soil eroded by mining extraction was very high (quality class 1 according to Vn), and thus it can be considered an ideal indicator for the evaluation of soil quality due to its sensitivity to anthropogenic changes (mining) in soil.

La aplicación de agroquímicos en la floricultura, disminuye gradualmente la fertilidad y poblaciones de microorganismos benéficos del suelo, siendo los actinomicetos indicadores biológicos de la calidad edáfica. En el presente artículo se propuso como objetivo comparar los cambios en la densidad poblacional de actinomicetos en suelos florícolas de rosa, clavel y agapando, y su tratamiento con vermicomposta. Los tratamientos fueron agapando como control, suelo con plaguicida del cultivo de rosa, suelo con plaguicida del cultivo de clavel, suelo con plaguicida del cultivo de rosa adicionado con vermicomposta a 40 Mg ha-1 y suelo con plaguicida del cultivo de clavel adicionado con vermicomposta a 40 Mg ha-1. Durante 28 días, se cuantificó la densidad de población de actinomicetos totales, por el método de conteo en placa. Los suelos florícolas son de textura franco-arenosa, por su bajo contenido en materia orgánica, se adicionó vermicomposta a los tratamientos. La población de actinomicetos totales de los suelos florícolas y vermicomposta fue del orden de 1 × 105 UFC g-1 de suelo, lo que indicó un bajo contenido. Se detectaron cambios en la densidad poblacional de actinomicetos en los tratamientos de suelos florícolas de rosa y clavel con y sin vermicomposta, siendo mayor en los suelos florícolas de rosa y clavel sin la adición de vermicomposta. Los cambios en la población de actinomicetos de los suelos cultivados con rosa y clavel indican que estos microorganismos están adaptados a la aplicación de plaguicidas. La adición de vermicomposta mejoró las propiedades fisicoquímicas de los suelos florícolas en sus respectivos tratamientos.

Phosphate-solubilizing bacteria (PSB) transform precipitated inorganic phosphorus into soluble orthophosphates. This study evaluated the efficiency of tricalcium and iron phosphate solubilization in Pikovskaya medium using five bacterial strains (A1, A2, A3, A5, and A6) cultured in acidic and alkaline pH levels. The bacterial strain that proved to be more efficient for P solubilization and was tolerant to pH variations was selected for assessing bacterial growth and P solubilization with glucose and sucrose in the culture medium. The bacterial strains were identified through 16S rRNA gene sequencing as Pseudomonas libanensis A1, Pseudomonas libanensis (A2), Bacillus pumilus (A3), Pseudomonas libanensis (A5), and Bacillus siamensis (A6). These five bacterial strains grew, tolerated pH changes, and solubilized inorganic phosphorus. The bacterial strain A3 solubilized FePO4 (4 mg L−1) and Ca3(PO4)2 (50 mg L−1). P solubilization was assayed with glucose and sucrose as carbon sources for A3 (Bacillus pumilus MN100586). After four culture days, Ca3(PO4)2 was solubilized, reaching 246 mg L−1 with sucrose in culture media. Using glucose as a carbon source, FePO4 was solubilized and reached 282 mg L−1 in six culture days. Our findings were: Pseudomonas libanensis, and Bacillus siamensis, as new bacteria, can be reported as P solubilizers with tolerance to acidic or alkaline pH levels. The bacterial strain B. pumilus grew using two sources of inorganic phosphorus and carbon, and it tolerated pH changes. For that reason, it is an ideal candidate for inorganic phosphorus solubilization and future production as a biofertilizer.

Agriculture is in a constant state of change. Its new practices and technologies represent impacts that are difficult to predict. The transition from animal traction to tractors and the substitution of manure for synthetic fertilizers are changes that are taking place particularly in developed countries, yet they are increasing in developing ones. However, the effect of these changes on agriculture and soil CO2 emissions remains controversial. The objective of this study was to measure the effects of two tillage systems and fertilization on the CO2 emissions from the soil under maize cultivation. Therefore, it consisted of two tillage systems, namely tractor (T) and animal (A) traction, and four fertilization methods. The fertilization treatments tested were: (CH) application of N, P, K chemical fertilizer; (HM) application of horse manure; (CM) application of chicken manure; and (CT) unfertilized control. We found that the soil CO2 emission rates in the maize growing season was higher than those in the tillage before the harvest season. Soil respiration peaked in June after the second fertilizer application (9394.59–12,851.35 mg CO2 m−2 h−1 at tractor and 7091.89–12,655.86 mg CO2 m−2 h−1 at animal traction). The production of corn grain only presented differences between the treatments with and without application of fertilizers.