ABSTRACT Afforestation of sites disturbed after bauxite mining is the favorite technique to restore all ecosystem functions. The nature of the tree species used for revegetation of post-mining land can accelerate the recovery of soil organic matter and nutrient cycles. This study aimed to determine the litterfall production, decomposition rate and nutrient content from three types of forest cover ( Eucalyptus , Anadenanthera peregrina , mixed plantation of 16 native species) planted in a bauxite mining area in recovery. Litterfall production was evaluated monthly over 30 months, and the litter mass was assessed twice a year (dry and rainy periods). Total nutrient content was determined from samples grouped by period (dry and rainy). The annual average values for litterfall dry mass and litter mass were higher in Eucalyptus and mixed native. The period (dry or rainy) did not influence litterfall rates in A. peregrina , but Eucalyptus and mixed native presented higher amounts for litterfall during the rainy and dry periods, respectively. Litter accumulation in Eucalyptus was not affected by the season of the year, but mixed native and A. peregrina presented higher litter accumulation in the dry season. Apparent decomposition rates of A. peregrina and mixed native were higher in the rainy season, highlighting the A. peregrina with the highest values compared with the other forest covers. The mixed native presented the highest leaf content of P, K, Ca and Mg in both the litterfall and litter mass, while Eucalyptus had the lowest P, K, Ca, S and N content and the highest C content in the litterfall. Litterfall production is important in degraded areas to ensure the nutrient return to the soil. The data obtained suggest that the cultivation of a mixed of 16 native trees contribute for produce the higher annual litterfall yields, besides produces leaf litterfall of better nutritional quality in relation to P, K, Ca, Mg and S. Therefore, mixed of native trees can be a promising option for reactivation of nutrient cycling and organic matter formation in mined area of bauxite in the Brazilian Atlantic Forest.

ABSTRACT Mining is a significant driver of soil mobilization, which impacts its physical, chemical, and biological properties. Changes in land-use affect the distribution of organic matter fractions in stable aggregates, a process that is still poorly understood, especially in drastically altered areas. Recovering and monitoring soil quality to ensure the sustainable development of agricultural crops in these areas after mining is challenging. This study aimed to evaluate the influence of agronomic practices in soil rehabilitation in a bauxite-mined area after three years of field experiment installations through an assessment of organic properties in soil and aggregate classes; an attempt was also made at proposing and elaborating a Soil Quality Index (SQI), which encompasses the soil’s physical, chemical, and organic properties. Different combinations of fertilization treatments and ground cover plants intercropping with coffee were evaluated as rehabilitation practices. The results showed that after three years of rehabilitation, when organic (OF), chemical (CF), and OF+CF fertilizers were applied to the areas of coffee intercropped with Brachiaria (B), they provided higher C and N contents to the soil and aggregates classes, as well as the compartments of soil organic matter (SOM). The minimum set of soil quality indicators for reclaimed bauxite-mined areas was composed of organic indicators: labile organic carbon (LOC) and mineral-associated organic matter (C-MOM); chemical indicators including pH and effective cation-exchange capacity (t), and physical indicators such as the bulk density (BD) and stable aggregates index in water (SAIW). The t and pH were the variables most sensitive to the management systems implanted during the rehabilitation of the mined area, and, therefore, were considered the best indicators of soil quality. Brachiaria was the cover plant that contributed most to improving the soil quality of mined bauxite areas by increasing the SQI, especially when fertilized. In general, when applied to the Brachiaria, the OF+CF fertilization presented a SQI of 0.78, differing statistically from that of the natural vegetation (1.00). Fertilizers and cover crops in association with coffee in the bauxite-mined areas improved the physical, chemical, and organic properties of the soil, thus representing a viable option for reconditioning mineral exploration areas.

Abstract: Capability analysis seeks to estimate the probability that a process will produce compliant products. The capability indices are dimensionless parameters that measure how well the process can meet specifications. In the literature, eight capability indices are listed, among others, considering a stable process under statistical control and based on the normal probability distribution, defined by: Cp, Pp, Cpk, Ppk, Cpm, Ppm, Cpmk, and Ppmk. Basically, the index formulas differ in the calculations of the variability within and total, and of the shifts of the mean in relation to the nominal value and the nearest specification limit. The objective of this article was to compare these capacity indexes, and for that, it was chosen the most consistent estimator, that is, the one that improved the accuracy and efficiency as the number of observations increased. Thus, a simulation of 30,000 values of a normal random variable with a mean equal to zero and a standard deviation equal to one was performed. This made it possible to sample this process 1,000 times using 5, 10, 15, 20, 25, and 30 rational subgroups with individual observations or sample elements. Subsequently, 20 mean shifts were provoked, with values ranging from 0.1 to 2 and varying by 0.1 unit. According to the results, it was concluded that the indexes Cpk and Ppk were the most consistent in presenting higher accuracy and efficiency for at least 15 rational subgroups or sample elements, regardless of the magnitude of the mean displacement in relation to the nominal value.

Resumo: A análise de capacidade busca estimar a probabilidade de um processo produzir produtos em conformidade. Os índices de capacidade são parâmetros adimensionais que medem o quanto o processo consegue atender às especificações. Na literatura são listados, além de outros, oito índices da capacidade, considerando um processo estável sob controle estatístico e baseado na distribuição normal de probabilidades, definidos por: Cp, Pp, Cpk, Ppk, Cpm, Ppm, Cpmk, e Ppmk. Basicamente, as fórmulas dos índices se diferenciam nos cálculos da variabilidade dentro e total, e dos deslocamentos da média em relação ao valor nominal e ao limite de especificação mais próximo. O objetivo deste artigo foi comparar estes índices de capacidade, e para isso, buscou-se escolher o estimador mais consistente, ou seja, que melhora a acurácia e a eficiência à medida que se aumenta o número de observações. Desse modo, foi realizada uma simulação de 30.000 valores de uma variável aleatória normal com média igual a zero e desvio-padrão igual a um. Isso possibilitou amostrar este processo em 1.000 vezes utilizando-se, para isso, 5, 10, 15, 20, 25 e 30 subgrupos racionais com observações individuais ou elementos amostrais. Posteriormente, foram provocados 20 deslocamentos da média, com valores de 0,1 a 2 e variando 0,1 unidade. De acordo com os resultados, concluiu-se que os índices Cpk e Ppk foram os mais consistentes, por apresentarem maiores acurácias e eficiências para pelo menos 15 subgrupos racionais ou elementos amostrais, independentemente da magnitude do deslocamento da média em relação ao valor nominal.

Abstract Sulfiting agents are added to crustaceans products to prolong their shelf life. However, depending on the concentration, these agents can be toxic to consumers due to the presence of SO2. In this context, a colorimetric indicator label based on starch and iodine was developed to detect SO2 in shrimp, showing whether the product is safe or not for consumers. The incorporation of iodine into the starch matrix resulted in labels with a smooth and homogeneous surface, and reduced water solubility from 9.26% to around 0.12%. In both in vitro and shrimp paste test, a visual detection response was observed in the label containing 0.02% of iodine when evaluated in the presence of 100 to 160 ppm of SO2, with ΔE* values greater than 5 (can be identifiable by the human eye). Therefore, the elaborated label showed potential as an economical and simple method to detect SO2 concentration in shrimp-based foods.

ABSTRACT Understanding soil organic matter (SOM) dynamics in production systems on tropical soils is necessary to guide strategies to increase SOM formation. This study aimed to evaluate soil carbon (C) dynamics by combining applications of different plant residues used on tropical soils. An incubation study was carried out with and without adding millet (Pennisetum americanum) residues combined with six crop residues (legumes and non-legumes); and one additional treatment with only millet residue. Higher C-CO2 fluxes recorded in jack bean, sunflower and velvet bean residues were correlated with high soluble compound contents (49.5, 49.6 and 32.1 %, respectively). Adding millet residues resulted in positive PE for all residue combinations. Soils without millet, except jack bean, had a negative PE. Residues application promoted four times increase in C-POM content (from 1.04 to 4.2 g kg-1 soil). The C-MAOM content had 2.4 times increase, being more expressive due to its high initial content (from 15.3 to 37.3 g kg-1 soil). The comparison between the final C contents in the SOM fractions showed a significant increase of 8.8 times for MAOM in relation to POM, demonstrating the larger dimension of this C reservoir in the soil. Both combinations of legumes + non-legumes and non-legume + non-legume contributed significantly to the conversion of C to MAOM. The results give insight into possible management strategies for significant C increments in the more stable SOM fractions, depending on the residue type (quality) and residue combination.

The record of teaching practice is something relevant and presupposes, to a certain extent, a record that can be used. Thus, returning to it with its particularities becomes opportune, as this action often persists in identifying itself only as bureaucratic documentation lacking pedagogical meaning. In view of this, we consider it appropriate to investigate how the registration carried out by the teacher of the literacy cycle has contributed to their practice. Therefore, the study aims to understand the view of teachers on the record as an instrument of reflection on teaching practice in the literacy cycle, understand the purpose and use of the record by the teacher and verify the information contained in the record and its relationship with practice. Data collection was carried out in a municipal public school in the Greater ABC Paulista region, with (5) five teachers who teach at the same school for the literacy cycle. For this purpose, we used a qualitative approach and collaborative research, aimed at the participants' joint discussion and reflection on (7) seven established themes of objectives and theoretical foundation, in meetings called collaborative workshops. As a result of this process, we infer that the registration carried out by the teachers of the literacy cycle needs to be taken up for discussion, reflection, aiming at its qualification, even though it is an action practiced for a long time. This process was noted by the teachers as essential for the redefinition of their records and reorganization of practice, reflection, change in the way of seeing and recording the record and as a space for training.

El registro de la práctica docente es algo relevante y presupone, en cierta medida, un registro utilizable. Así, se vuelve oportuno volver a él con sus particularidades, pues esta acción a menudo persiste en identificarse solo como documentación burocrática carente de sentido pedagógico. Ante esto, consideramos oportuno investigar cómo ha contribuido a su práctica el registro realizado por el docente del ciclo de alfabetización. Por tanto, el estudio tiene como objetivo comprender la visión de los docentes sobre el registro como instrumento de reflexión sobre la práctica docente en el ciclo de alfabetización, comprender el propósito y uso del registro por parte del docente y verificar la información contenida en el registro y su relación con práctica. La recolección de datos se llevó a cabo en una escuela pública municipal de la región Gran ABC Paulista, con (5) cinco maestros que imparten clases en la misma escuela para el ciclo de alfabetización. Para ello, se utilizó un enfoque cualitativo e investigación colaborativa, orientada a la discusión y reflexión conjunta de los participantes sobre (7) siete temas establecidos de objetivos y fundamentación teórica, en encuentros denominados talleres colaborativos. Como resultado de este proceso, inferimos que el registro que realizan los docentes del ciclo de alfabetización debe ser retomado para la discusión, la reflexión, con miras a su calificación, aunque es una acción practicada desde hace mucho tiempo. Este proceso fue señalado por los docentes como fundamental para la redefinición de sus registros y reorganización de la práctica, la reflexión, el cambio en la forma de ver y hacer el registro y como espacio de formación.

O registro da prática docente é algo relevante e pressupõe em certa medida um registro que possa ser utilizado. Assim, retomá-lo com suas particularidades se torna oportuno, pois essa ação, muitas vezes, persiste em se identificar somente como uma documentação burocrática ausente de significado pedagógico. Diante disso, consideramos cabível investigar de que forma o registro realizado pelo professor do ciclo de alfabetização vem contribuindo para a sua prática. Para tanto, o estudo tem por objetivo compreender a visão dos professores sobre o registro como instrumento de reflexão da prática docente no ciclo de alfabetização, compreender a finalidade e utilização do registro pelo professor e verificar as informações contidas no registro e sua relação com a prática. A coleta de dados foi efetivada em uma escola pública municipal na região do Grande ABC Paulista, com (5) cinco professoras que lecionam na mesma escola para o ciclo de alfabetização. Para esse propósito, utilizamos a abordagem qualitativa e a pesquisa colaborativa, destinada a discussão e reflexão conjunta das participantes sobre (7) sete temas estabelecidos dos objetivos e fundamentação teórica, em encontros denominados de oficinas colaborativas. Como resultados desse processo inferimos que o registro realizado pelas professoras do ciclo de alfabetização necessita ser retomado para discussão, reflexão visando sua qualificação, mesmo sendo uma ação praticada a muito tempo. Esse processo foi notabilizado pelas professoras como indispensável para a ressignificação de seus registros e reorganização da prática, reflexão, mudança na forma ver e fazer o registro e como espaço de formação.

ABSTRACT: Accidents related to the rupture of iron ore tailings dams have dramatically impacted on the Brazilian natural ecosystem. So, the development of strategies to recover soil organic matter levels and build-up Technosols are required. This study aimed to evaluate the effect of N-mineral and -organic fertilization and the rhizospheric effect on soil organic matter mineralization from Technosols built under iron ore tailings. The experiment was carried out in a greenhouse; we used a factorial scheme 2 × 2 × 3: without and with the plant Crotalaria juncea ; without and with mineral fertilization; and three different organic fertilization (without organic fertilization, sewage sludge, and household waste composting), with four randomized blocks. The experimental units were PVC columns installed with a top layer of iron ore tailing from a dam, where gases were sampled to determine the CO2-C, CH4-C concentrations, and CO2-δ13C. The organic fertilization promoted a positive priming effect of 184 %. However, with mineral fertilization, no effect was observed in soil derived-CO2-C accumulated and priming effect. Similarly to non-planted soil, the planted soils with mineral and organic fertilization promoted a steady reduction in soil derived-CO2-C accumulated and rhizosphere priming effect. The soil with mineral fertilization improved in 5.52 and 0.45 g per column the shoot and root dry matter of Crotalaria when compared to the soil without mineral fertilization. In summary, the organic fertilization in Technosols built over iron ore tailings dams during revegetation was not enough to ensure the plant development and preservation of soil organic matter. However, the combination of mineral and organic fertilization promoted negative rhizosphere priming effect and a significant increase in plant biomass.

ABSTRACT: It remains unclear whether temperature and precipitation exert independent control on tropical vegetation and soil C pools. Likewise, it is unknown whether the feedbacks of tropical C pools to climate constraints vary with nutrient availability. These aspects are critical to improving our ability to predict the response of tropical C pools to climate dynamics. This review aimed to assess climate data and the spatial distribution of vegetation and soil C pools across the Brazilian territory to investigate i) whether mean annual precipitation (MAP) and temperature (MAT) exert independent effects on tropical C pools; ii) whether vegetation and soil C pools exhibit hierarchical feedbacks to climate; and iii) how these feedbacks reflect soil nutrient availability. To account for MAP and MAT effects on tropical C cycling, we calculated Ecosystem Effective Moisture (EEM), i.e., the difference between MAP and potential evapotranspiration. We gathered substantial evidence suggesting that under high MAT and MAP controlling EEM, plants exchange more C for water and resorb more nutrients (especially P), which limitations in plant litter reduce microbial-derived C inputs into soil organic matter. Frequent soil saturation under high EEM favors denitrification rates (“open” N cycle), allowing continuous mineralization of litter and shallow soil C pools to release nutrients, sustaining high plant C pools. With decreasing MAP levels, ecosystem C pools depend on MAT controlling evapotranspiration and EEM. Accordingly, decreasing MAP under high MAT reduces EEM, with vegetation and soil C pools co-limited by low net primary productivity (NPP), frequent fire and/or nutrient losses. Otherwise, decreasing MAP and coupled to cool temperatures allow EEM to remain positive, forcing plants to increase deep-rooting and/or shed their leaves, which nutrients are immobilized with microbial-derived C into mineral-organic associations, favoring high soil C pools. Combined, the evidence gathered suggests that the sensitivity of tropical ecosystems to global increases in temperature should not be overlooked, especially if coupled to reductions in precipitation. Overall, the horizontal distribution of vegetation and soil C pools is best described by EEM rather than temperature or precipitation alone, whereas the vertical partition of C in plant-soil systems reflects biotic responses to climate-nutrient constraints.

ABSTRACT This study aimed: i) to evaluate the influence of fertilization and irrigation management on eucalyptus plantations for soil carbon (C) dynamics; ii) to evaluate the impact of fertilization and irrigation management on eucalyptus plantations in the C allocation in depth compared to the Cerrado biome. This study was carried out in an eucalyptus plantation at the end of the third rotation (7 years), which received different fertilizations and irrigations, and a Cerrado area was used as reference. Soil samples were collected in trenches and the gases (CO2 and CH4) on the surface. The total organic carbon (TOC) is more influenced by the availability of water than nutrients. Soils under eucalyptus stands are more efficient at C stocks in depth than the Cerrado and act as a liquid drain of CO2 and CH4 from the atmosphere.

ABSTRACT Forest cover in areas degraded by mining is an alternative way of mitigating CO2 concentrations in the atmosphere by fixing C in tree biomass. This study evaluated the growth and C stocks of forest cover in an area of bauxite mining with four sources of fertilizer. Height (Ht), diameter at ground level (DGL), and diameter at breast height (DBH) were determined in Anadenanthera peregrina (Ap), clonal Eucalyptus (Euc), and a mixed plantation of 16 native forest species (Nat) at 6, 18, 36, and 56 months of age. Trunk+bark volume, biomass, and C stock were also determined for these forest covers at 56 months of age. The fertilization treatments were a standard (SF) adopted by the company, SF plus organic fertilizer (OF), chemical fertilizer (CF), and OF+CF. Euc displayed greater values of Ht, DGL, and DBH under OF+CF and OF. Fertilization did not influence the Ht and DBH of Ap, but DGL was higher under OF+CF at 36 months compared to SF. The Ht values of Nat were influenced by fertilization at 18 months, with the lowest values under SF. The fertilization influenced the DGL of Nat at 36 and 56 months, which did not occur with DBH. The pioneer species had higher Ht, DGL, and DGB compared to non-pioneer species, regardless of the type of fertilization studied. Fertilization influenced the Ht and DGL of pioneer species at 18 and 36 months of age and only the Ht of non-pioneer species. The estimates of Euc biomass (255 Mg ha-1) and C stocks (120 Mg ha-1) under OF+OC were four times greater than in Ap and Nat, which showed no difference between themselves or the types of fertilization. The growth and estimates of volume, biomass, and C stocks of the forest cover were comparable to those of unmined areas. Euc had the greatest growth, biomass, and C stocks.

ABSTRACT Harvesting and reform in eucalyptus can lead to changes in soil organic matter (SOM). The objective of this work was to evaluate the changes in total organic C (TOC) and N (NT), C and N in humic acid (HA), fulvic acid (FH), light organic matter (LOM) and microbial biomass (MB), in Ultisol of eucalypt stands over one, two and four years of renovated areas in Rio Grande do Sul state. After the first year of eucalyptus reform, there were 78% of increases in TOC (0.0-1.0-m soil layer). After two years, there was an increase in TN and an average reduction of 52% in LOM-C (0.0-0.1-m soil layer). FA-C, HA-C, and HU-C presented mean reductions of 43 Mg ha–1 (0.0-1.0-m soil layer) after four years of reform. The litter contribution of previous crop and the crop residues from the harvest resulted in increments of the SOM fractions. However, there is a negative effect in later years.

ABSTRACT: Eucalyptus forests in southern Bahia (BA) are planted in soils with a sandy surface layer and humid tropical climate, conditions that lead to soil carbon (C) decomposition. Recent studies have shown that nitrogen (N) may be important for soil C stabilization. The aim of this study was to evaluate the contribution of Eucalyptus harvest residues and nitrogen fertilization to C stabilization in Ultisols of southern BA. The experiment was conducted in Eucalyptus clonal plantations cultivated in two regions of Eunápolis, BA, Brazil, with different clay content: southern region (140 g kg-1 of clay) and western region (310 g kg-1 of clay). Five treatments were evaluated: one control (CTR), without Eucalyptus harvest residues and N fertilization, and four treatments with harvest residues combined with four rates of N fertilization: 0, 25, 50, and 100 kg ha-1. Soil samples were collected from the 0.00-0.10, 0.10-0.20, 0.20-0.40, and 0.40-0.60 m layers at the beginning and the end of the experiment (36 months). The amount of C and N and the C and N isotopic ratio (δ13C and δ15N) of particulate organic matter (POM) and mineral-associated organic matter (MAOM) were determined. In the southern region after 36 months, the C-MAOM stocks in the 0.00-0.10 m layer of the CTR decreased by 33 %. The addition of harvest residue followed by 100 kg ha-1 N increased C-POM and N-POM stocks (0.00-0.10 m) compared to the CTR, and the final N-POM stocks and residue-C recovery in the surface soil layer were positively correlated with the increase in N fertilization rates. In the western region, residue maintenance resulted in increased C-MAOM stocks (0.00-0.10 m) compared to the CTR, but an increase in N availability reduced this increment. The increase in N fertilization rates did not alter C stocks, but reduced N stocks of POM and MAOM in the upper soil layer. At the end of the experiment, N fertilizer recovery (0.00-0.60 m) was similar among the regions evaluated. In soil with lower clay content, higher N availability led to higher C and N stocks in the particulate fraction. In soils with high clay content, physical and chemical protections are more important than N fertilization for soil C stabilization, and just maintaining harvest residues may suffice to increase C and N in the more stable SOM fraction.

ABSTRACT The amount of harvest residues retained in Eucalyptus plantations strongly influences soil organic matter (SOM), but the efficiency of conversion to SOM may vary according to the type of residue. This study evaluated the recovery of C from Eucalyptus residue components - leaves, bark, branches, roots, and a mix of all residues - in different SOM fractions with or without mineral-N supplementation (200 mg kg-1 of N). Variation in natural 13C abundance was used to trace the destination of residue-derived C in the soil. The C content of the light fraction (LF) and heavy fraction (HF) of SOM increased over a 240-days decomposition period in response to incorporation of Eucalyptus residues in the soil. Bark and leaf residues showed the best results. Bark residues increased the C content of the HF by 45 % over the initial condition. Leaf residues made the largest contribution to LF-C, increasing it by 8.6 times. Leaf residues also led to the highest N contents in the LF and HF, whereas branches, roots, and the mixture of residues caused significant net transfers of N from the HF. Mineral-N supplementation had no effect on stabilization of organic C in the HF of SOM, in which the C could be maintained for longer periods due to physical/colloidal protection against microbial decomposition. These results highlight the importance of keeping Eucalyptus harvest residues in the planted area, especially the bark, which is the most abundant harvest residue component under field conditions, for maintenance of SOM.

RESUMO O objetivo desse trabalho foi avaliar o efeito do cultivo de eucalipto no estoque total de C orgânico (COT) e N total (NT), C e N associados às frações ácido fúlvico (AF), ácido húmico (AH), humina (HU), matéria orgânica leve (MOL) e biomassa microbiana (BM), em solos de diferentes texturas, no Leste do Rio Grande do Sul. O delineamento adotado foi inteiramente casualizado em parcelas subdivididas. As amostras foram coletadas nas camadas de 0-10, 10-20, 20-40, 40-60 e 60-100 cm. Em solo franco-argiloso, a área sob povoamento de eucalipto apresentou redução nos estoques de C associado ao AH, HU e BM em relação à vegetação de referência na camada de 0-100 cm. Por outro lado, no solo arenoso houve aumento nos estoques de COT, NT, C e N associados àAH, HU, MOLe de C-BM. O aumento no estoque de COTfoi principalmente na camada de superficial (0-10 cm), aproximadamente 150 % em relação a área de vegetação nativa, provavelmente devido a grande contribuição do resíduo do eucalipto. Ao comparar as áreas com eucalipto e áreas de vegetação de referência, no solo arenoso, nota-se alterações de maior magnitude nos estoques de C e N associados às frações da MOS, o que evidência a capacidade da fração argila em proteger a matéria orgânica do solo.

ABSTRACT The aim of the present study was to evaluate the effect of eucalyptus plantations on total organic C (TOC) and total N (TN) stocks as well as the C and N in the fulvic acid (FA), humic acid (HA), humin (HU), light organic matter (LOM) and microbial biomass (MB) fractions in soils with different textures in the eastern part of the state of Rio Grande do Sul, Brazil. Soil samples were collected from the 0-10-cm, 10-20-cm, 20-40-cm, 40-60-cm and 60-100-cm soil layers in a completely randomized experimental design with subdivided plots. Under the eucalyptus plantation, clay loam soil presented lower HA, HU and MB C stocks in the 0-100-cm soil layer compared to reference vegetation, whereas sandy soil presented higher and C and N in HA and LOM as well as C in MB. The observed increase in TOC in eucalyptus plantations was more pronounced in the surface soil layer (0-10 cm), i.e., approximately 150% higher than under native vegetation, which was probably due to the high contribution of the eucalyptus litter. Differences in C and N stocks in soil organic matter (SOM) fractions between eucalyptus plantations and areas with reference vegetation were more pronounced in sandy soil, showing the capacity of the clay fraction to protect SOM.

In this paper, we report the results of studies on the solubility (water solubility trial) and the response by plants (greenhouse pot experiment using Zea mays) for four types of monoammonium phosphate fertilizers (Conventional MAP - MAP1, MAP coated with a natural organic acid - MAP2, MAP coated with a synthetic organic acid - MAP3, and MAP coated with a peat humic organic acid - MAP4) applied at five increasing doses (0, 100, 300, 600 and 1200 mg P dm-3) and pre-incubated with the soil for five lengths of time before planting (0, 15, 30 and 60 d). The coating with organic acids reduced the water solubility of the P fertilizers - MAP4 provided a more gradual release of P over time. In the soil pot experiment, it was found that MAP1 required the highest dose to reach 90% of dry matter accumulation by the maize plant, followed by the Coated-Slow-Release Fertilizers (CSRF). The agronomic efficiency (AE) of P applied as the CSRF was 3 to 13% greater than that of MAP1. In addition, MAP4 led to higher values of AE (+11%) and apparent P recovery by maize (+41%) in comparison to MAP1. The physicochemical properties imposed by the chemical composition of the organic acid coatings generated fertilizers with distinct release rates and improved agronomic efficiencies.