BIOSOLID QUALITY AND ITS EFFECT ON DEFORESTED SOIL

Objective: The objective of this research was to evaluate the effect of biosolids in an area of recent deforestation. Theoretical framework: Biosolids correspond to a type of organic waste resulting from different treatment processes. Method: The evaluation was carried out in 6 plots, in different sites in the same area and evaluated the growth of species height and laboratory analysis of microbiological, physical-chemical and heavy metal parameters for the soil; this to be compared with national and international regulations that regulate the use of biosolids. Results and conclusion: The growth of tree species, nutrient supply and toxicity of some parameters such as heavy metals and pathogens were identified according to treatment; as a result, the best growth in total height was obtained in plot P3, which had application of the biosolid with 26 tree species of the 124 species sampled. As for the soil, the biosolid increased the redox potential by 24% in the plots with substrate application and a low increase in Ni and Zn, trace elements that helped the growth in height of the plants due to the thickening of the roots. Implications of the research: the implications of this study compare national and international regulations, the biosolid is within the B classification (for forestry use).


INTRODUCTION
Biosolids are considered assimilable urban waste and, although they cannot be classified as toxic or hazardous, they do contain contaminants that require treatment (Zuluaga, 2007;Casa-Coila et al. 2023); These biosolids come from wastewater treatment plants, and as a residue from their treatment, these sludges undergo a stabilization process to reduce the content of pathogenic microorganisms and inhibit, reduce and eliminate the emission of volatile solids and consequently, their potential for odor production, which in turn, can increase and attract vectors (Fernandez, 2000).
Currently these sludges are disposed of as hazardous waste to avoid environmental damage, thus generating large costs; they have the capacity to be used as "biosolids", once they are treated and meet the physicochemical and microbiological requirements of the regulations R.M. 024-2017-VIVIENDA.
Depending on the treatment they receive afterwards, we can find fresh sludge, which has not undergone fermentation, and sludge stabilized by aerobic or anaerobic digestion, with a much lower content of pathogens than the former (Pomares & Canet, 2001). Huanqui, A. (2018), in his study "Use of Biosolids from a Wastewater Treatment Plant in a Mining Operating Unit", determined that efficiency tests were carried out as a soil supplement using a Completely Randomized Design (CRD), and with the species Zea mays L., using: biosolid, compost and topsoil in different concentrations. It was concluded that at a concentration of B3 (25% biosolid + 75% topsoil) the biosolid generated the highest root and stem growth.
From a nutritional point of view, the application of compounds rich in organic matter involves a gradual release fertilization, which allows their effects on natural or introduced forest vegetation to be more persistent over time than in the case of the application of inorganic fertilizers (Miller, 1990).
The effects of sewage sludge to soil resulted in anaerobically digested sludge and composted sewage sludge (CSS) being used as a slow release fertilizer in forestry and an alternative to fast release inorganic fertilizers. The effects of CSS with or without additional carbohydrates on inorganic nitrogen availability and soil animals were tested in two spruce plantations in Norway; where half of the seedlings were individually fertilized with CSS, and the rest were left as controls. Solid sucrose was added to half of the fertilized and untreated seedlings (Nieminen, et al., 2013).
Depending on various biotic and abiotic factors, biosolids have effects on vegetation that can be highly variable. Its forestry application acts positively on eventual water and nutritional limitations in the short term, improving the establishment and subsequent growth of introduced plants. Even so, there may be deleterious effects on introduced plants attributed to competition with natural vegetation, nutritional imbalances and phytotoxicity due to the accumulation of soluble salts in the rhizosphere. In dry and semi-arid areas, the effects of fertilization can also translate into an increase in water stress, which could be lethal (Fuentes, 2011).
The effects of fertilization on natural vegetation or restocking (growth, survival, physiological or nutritional status) can reveal whether or not there are nutritional limitations in the soils in terms of plant requirements. Enrichment of typical forest soils in certain nutrients (Bones et al. 2022) This implies a greater proliferation of the roots of the natural vegetation, pointing to a limitation of its development, especially for phosphorus (Valdecantos, 2001).
Currently, there are 59 species restricted to the Tumbesian Region, fourteen of which are threatened and confined to less than 5% of their original habitat. Five percent of these species and 17.5% of the subspecies are restricted to the dry forest habitat of northwestern Peru (Stattersfield et al., 1998).
On the other hand, the addition of organic residues to the soil stimulates microbial activity (Banerjee et al., 1997;Pascual et al., 1998;García et al., 2000;Caravaca et al., 2002a;Ros et al, 2003) and improves soil physical properties such as infiltration, water retention capacity, or structural stability (Albaladejo & Díaz, 1990;Aggelides & Londra, 2000;Rostagno & Sosebee, 2001;Albiach et al., 2001;Caravaca et al., 2002b). The improvement of these aspects favors the reduction of runoff and erosion (Ros et al., 2001), and facilitates the storage of water in the soil, which means an increase in the availability of this resource for vegetation (Querejeta et al., 2000).
However, applications of biosolids at high doses imply a strong input of organic N into the soil, which can induce nutritional imbalances or marked deficiencies in certain nutrients (Harrison et al., 1996). This can be a direct result of either a lower amount of a certain nutrient in the applied biosolid, a dilution effect due to increased growth, or antagonism phenomena between different nutrients.

METHODOLOGY
The quality of the biosolid was evaluated in a deforested area; the processes and results obtained from the application of the biosolid in the soil and its performance were described. Regarding the research design in this study, laboratory analysis was performed for microbiological parameters, some physicochemical parameters and concentration of heavy metals requested by the Peruvian standard in the use of this (R.M. 024-2017-VIVIENDA).
At the same time, an analysis of the growth of the species was made by taking dasometric measurements of the different forest and tree species sampled in each sample plot (P) to compare the influence of the biosolid on the growth and regeneration of the plants affected by this activity.
The population is made up of forest and tree species in the sampling plots (P), which total 124 species evaluated in 6 sampling plots; the sample was composed of six (06) sampling plots (P1, P2, P3, P4, P5, P6), with areas of between 19m2 to 27 m2 depending on the terrain (see map of sampling plots) each one; which amount to a total area of 196.5 m2 (0.019 ha); three of these plots without application of the biosolid, which make up treatment T0, and the other three with application of the biosolid, which make up the second treatment T1. The sampling of species and soil quality was differentiated into two components, both within each plot: the first was the evaluation of species and their evolution over time in terms of silvicultural development; and the second component was the determination of heavy metals found in the soil according to the type of treatment and the biological, physical-chemical parameters in each plot. Biological analysis and heavy metals were also determined for the sludge and biosolids.
Zarumilla is one of the three provinces that make up the department of Tumbes, under the administration of the Regional Government of Tumbes, in northern Peru. It is bordered to the north by the Pacific Ocean, to the east and south by Ecuador, and to the west by the Province of Tumbes; the project was developed in the area called Conchal Rosillo in the hamlet of Cuchareta baja, district of Aguas Verdes.
According to the 2007 census, the population of the District of Zarumilla is 18,463 inhabitants, which represents 44.97%, while the District of Aguas Verdes has a population of 16,058, which represents 39.11% of the provincial population.
The dasometric measurements were recorded in a field format containing the Total Height (HT), with a 5 meter winch; these evaluations were carried out with a periodicity of 15 days for 4 months for each plot; the coordinates were also recorded in WGS84 datum with a GPSMAP 64S GARMIN of 3 meters of precision, to each of the species distributed in each plot for the elaboration of the maps (see annexes cartographic maps).
For the evaluation of biological, physical-chemical and heavy metal parameters, laboratory analyses were performed using different methodologies for the calculation of each one of them, and following different laboratory procedure guides and soil, sludge and biosolids sampling protocols.
For the analysis of physical-chemical parameters, the parameters necessary to evaluate the soil-plant relationship, soil mineral composition and soil environmental factors were considered; different methodologies were developed for each parameter; as specified in the "Manual de procedimientos de los análisis de suelos y agua con fines de riego" by Eng. M.Sc. Rubén Bazán Tapia of 2017; the parameters developed were (see Table 1; 2; 3)   In order to apply the comparison of the biological parameters and heavy metals subscribed in the national and international regulations for the maximum permissible limits for use in deforested soils, the following comparative table was drawn up (see table 4; 5)  For the evaluation of the quality of the biosolids, certain specific criteria were taken to combat deforestation:

METHODS
• That the biosolid is in class B category (for forestry use).
• Increase the water retention capacity of the soil.
• Contribution of micronutrients to plants.
• To induce the greatest number of naturally regenerating individuals.
• That it contributes to the growth of greater height of the species.
In the statistical analysis, the statistical program INFOSTAT version 2018-I was used, in which the analysis of variance and the mean tests using Tukey's criterion for the 2 treatments were elaborated. This analysis was done for the total height growth variable (HT) by plots and species.
The dependent variables for growth assessment are: Plot / meters and Species / meters. For this component, the table designed for the collection of information contains the dasometric measurements of the species in 15-day intervals for 4 months, in order to evaluate the average growth per species and apply the statistical model and the average growth per species according to the type of treatment.

RESULTS AND DISCUSSION
In the evaluation of the heights of the species, there was a difference in growth between the initial and final heights, giving as a result that P6 and P3 are the species that grew more than the other plots, since they contain more specimens of the species Chloroleucon mangense "Charán" and this species develops faster than the other species (see table 6; 7).  It should be noted that not all species are repeated in the two treatments, only the species that are repeated in both treatments were considered; for the analysis of variance between the two treatments applied to the species, a statistical analysis was performed; as a result of the analysis, the variance showed that there is a significant difference in the growth of the species according to treatment, with a coefficient of variation of 28.80%.This means that the species develop better with the application of the biosolid than without the application of the biosolid for the height variable of the species evaluated, resulting in the highest mean for P3 with 26.79 meters. Table 8 shows the growth averages of the species by type of treatment, where the growth of the species is represented by plots determined by the difference between the initial height and the final height of the evaluation, which in turn gives the average growth per species according to type of treatment (see Table 9).  The p-value was greater than 0.05, which indicates that there is no significant difference between treatments given to the species, the average growth is very similar between the species that applied biosolids and those that did not have the biosolids: Test: Tukey Alpha= 0.05 DMS= 1.16752 Error: 0.6189 gl: 5 In the mean analysis, the growth averages among the evaluated species have similar means (not significant among themselves), the standard error is 0.56 and the tukey classification is the same for all species, although the species Chloroleucon mangense "Charan" is the one with the highest growth average among the evaluated species.
The results of the data obtained from the samples taken for sludge (M01) and biosolids (M02) are shown below; both samples are composed of five point samples from the stabilization pond taken at a depth of approximately 1 meter (see Table 10). In order to evaluate the soils where the study was carried out, the results of the microbiological, physical-chemical and heavy metal parameters in the sampling plots are presented, to analyze the effect of the substrate for the T1 treatment and to analyze the development without the substrate for the T0 treatment.
The results of the data obtained from a sample taken at a depth of 0-20 cm for the physicochemical parameters are shown below (see table 11). According to the type of treatment used, for the biosolid treatment, the highest pH corresponds to plot P1, considered as neutral pH, which is ideal for the growth of dry forest species that normally develop between neutral and moderately acid, with a pH above 5.5. The reason why the pH of the biosolid treatment is neutral is due to internal drainage, where the soil is not in constant contact with water, so the bases or alkalis such as calcium and magnesium do not react increasing the hydroxyl ions and therefore the pH of the edaphic medium is maintained. The pH decreases with increasing soil depth, causing low availability of essential elements in the lower horizons, which is why in eroded sites the availability of essential elements is not adequate for optimal plant growth (Vaides López, 2004); on the other hand, for the second treatment without application of the biosolid, the highest pH was recorded in plot P4 with 7.9, which had the slowest development of the species and no natural regeneration of any species occurred, because its pH is already close to alkaline, which decreases the growth of the species because it limits internal drainage.
As for the influence of the biosolid on the soil, it does not contribute significant differences in terms of the modification of the physical-chemical parameters (pH, humidity, temperature), but it does slightly elevate and stabilize the redox potential which originates the energy reactions given by the transfer of electrons. Oxygen (O), carbon (C), nitrogen (N), sulfur (S), iron (Fe) and manganese (Mn) are the elements involved in the redox capacity and largely determine the genesis of acid sulfate soils (Hinrich, 2002;Hicks et al., 2002); organic matter is also increased in the plots with the addition of biosolids, especially in plots P2 and P3.
For calcium concentration, it was determined that all plots had almost the same moisture conditions and pH, which caused calcium concentrations to be almost equal due to their mobility, with the highest concentration of calcium for plot P4, which generally soils with a higher pH contain more available calcium; as for phosphorus (P), the highest concentration was obtained in plot P3, where the best growth and regeneration was observed.
The results of the data obtained in a sample taken at a depth of 0-20 centimeters for the sanitization parameters are shown below (see Table 12). The sanitation parameters showed that plots P1 and P4 have the highest number of helminth eggs, salmonella does not exist in any of the sampled plots and the parameter of Escherichia coli, all are less than 3 NMP/g, which has a very low pathogenicity indicator with which there is no contagion to the species in the production chain of these.
The following are the results of the data obtained in a sample taken at a depth of 0-20 centimeters for the parameters Heavy Metals, it should be noted that these samples were homogenized according to the treatments since the difference between the distances between the plots and the soil conditions are similar (see Table 13). The results in Table 20 show that heavy metals are found in minimal quantities for most of the elements, with the exception of Ni and Zn, which are lower in the treatment without biosolids, and in the treatment with biosolids there is an increase of these elements, which help plant growth thanks to their participation in the chemical processes of the soil-plant relationship.
The results are consistent with those obtained by Carnus and Thomas Chery (2007), which showed that biosolids had no effect on the plots since the levels in the soil solution did not increase the concentration of most metals except Ni and Zn, which are essential trace elements that help plants grow taller (M. Barrios S. and S. Longa M).
Evaluation of the quality of biosolids for forestry use.

DISCUSSION
In this study, the biosolid stabilized with Lime was applied; an additional benefit of the use of Lime is that it causes the precipitation of heavy metals and phosphorus (Méndez et al. 2002). On the other hand, the pH of the sampled plots is in a neutral state, which influences the mobility of metals, especially zinc, since this metal activates its mobility in acid soils (Méndez et al. 2002).
One of the results of this study, is that there was an increase in the redox potential in the plots containing the biosolid; it is stated that the biosolid is a soil stabilizer due to its characteristics of pH regulation by increasing the redox potential, increases to some degree the organic matter content, evenly distributes heavy metals without an apparent absorption of these to the plants stated by Stefanakis and Tsihrintzis, 2012.
Several authors (TSUTIYA, 2000 and2001;MELFI andMONTES, 2001, MELO, 2000;TRIGUEIRO, 2002), state that, besides the potential benefits of biosolids in fertility and improvement of soil physical and biological conditions, it is important to highlight other advantages, the nutrients contained in biosolids are released and absorbed slowly; their effect is longer lasting, which is desirable for perennial crops (POGGIANI et al., 2000). The release of ammoniacal N does not increase soil acidity due to its When the biosolid is extracted. This procedure has been replaced by polymers that have a moderate effect on soil pH (GONÇALVES et al., 2000), which explains the stabilization of pH in the plots where the biosolid was applied.
In the plots with biosolids the soil texture was looser because Tsutiya, 2001; states that the organic matter in biosolids favors the formation of aggregates in the soil, facilitating root penetration and microbial life; it provides nutrients for plants and soil organisms after mineralization and acts as a soil conditioner, improving its characteristics depending on the treatment process undergone; the concentration of organic matter varies from 40 to 70%.
For the height growth variable (HT) all species have a similar average growth, but more uniform in the biosolid treatment, because nutrients such as phosphorus are predominantly present in the mineral form in anaerobically digested biosolids. This is an important factor for the availability of this element for plants, which is 50% in the first year of biosolids application (ANDREOLI, 1999); it should also be noted that the phosphorus contained in biosolids is less soluble than superphosphates, but offers greater consistency in supply over time (MELO et al. al., 2001;MUNHOZ, 2001). Castellanos, 2000; mentions that P fertilization favors the growth of lateral roots, trapping more nutrients for plant development.
According to Melo et al. (2001), biosolids are poor in potassium, because this element is very soluble in water, which results in the low concentration of this in the solid phase of the treatment and, consequently, in the final composition of the biosolid. In spite of this, although the totality of this existing nutrient is considered as assimilable by plants. According to the same author, the potassium content of the biosolids is not sufficient for the needs of the plants, and in that case, special care must be taken with potassium so that the plants do not lack it and, if necessary, complete their dosage with mineral fertilizer.
Biosolids are often rich in calcium when lime is used in the sludge conditioning or stabilization stage; these nutrients are present in biosolids essentially in mineral form and, according to Andreoli et al. (1999), even in small applications can meet the sulfur and magnesium requirements of most agricultural crops.
Regarding heavy metals in soils of tropical regions, there are many doubts about the mobility of heavy metals, justified due to the lack of long-term studies, aggravated by the tendency of predominantly weathered soils, low temperature and high rainfall (OLIVEIRA et al. 2002). According to Barrios M. and Longa S. 2007; when Ni and Zn were determined in the plant, the greatest accumulation occurred in the roots; and in the treatments with Zn, no symptoms of toxicity were observed in the plant. Higher plant height values were obtained at both doses of Ni and the average root length was greater at the lower dose of Cr; this would explain the greater growth in the plots with biosolids, which have the highest concentration of these elements.

CONCLUSION
The quality of the biosolid from the Campo Amor lagoon, for use in deforested soils was classified as good, being this substrate ideal to combat a deforested area in the ecosystem studied, however, it is recommended to carry out the study in areas that present a more aggressive deforestation taking into account a more eroded or degraded soil.
This research provides fundamental data on the growth of the forest species studied when they have been affected by deforestation, using a substrate extracted from a residue from domestic water treatment in sedimentation ponds, thanks to the fact that in the analysis of heavy metals in the soil there was an increase in the micronutrients Ni and Zn, in the plots with biosolids, which help the thickening of the roots; And in the physical-chemical analysis of the soil, there was no significant improvement in the parameters according to the treatments, with the exception of the redox potential, where there was an increase and stabilization in all the plots with biosolids.
It is also important to highlight that the biosolid had a notorious effect on the species Prosopis pallida "Algarrobo" which sprouted faster and its growth was more accelerated than in the species that did not receive this substrate, and for the species Chloroleucon mangense "Charán" it has better development with the biosolid than the other species evaluated, therefore, if the aim is to recover this species, the application of the biosolid is recommended.
The limitations of the research were the analysis of the penetration of the biosolid in the soil since the evaluated terrain presented irregularities of textures and slopes, the distance between the deforested area and the lagoon was not much since the transport of this substrate was taken into account, but the transport to deforested areas, which are mostly very distant, has to be taken into account.