1 Introduction

Agriculture in tropical and subtropical regions faces significant challenges due to the characteristics of the soils, which are often highly weathered and have low natural fertility [1]. These soils are typically acidic, with low levels of organic matter and nutrients, making them less productive and more susceptible to degradation [2]. Traditional farming practices, such as slash-and-burn agriculture and excessive use of chemical fertilizers, have further exacerbated these issues, leading to soil degradation, nutrient depletion, and environmental pollution [3].

In recent years, there has been a growing interest in sustainable agriculture practices that aim to improve soil fertility, enhance crop productivity, and minimize environmental impact. One such practice involves the use of alternative materials as sources of nutrients for plants [4]. These materials, which can include organic and mineral-based amendments, have the potential to provide a sustainable and environmentally friendly solution to the challenges facing agriculture in tropical and subtropical regions [5].

Basalt powder is one such alternative material that has shown promise as a source of nutrients for plants in these regions [6, 7]. Basalt is a common volcanic rock that is rich in essential nutrients such as calcium, magnesium, and trace elements [8]. When finely ground into powder, basalt releases these nutrients slowly over time, providing a long-lasting source of nutrition for plants [9]. Additionally, the application of basalt powder to the soil helps retain water over the years, aiding in maintaining crops during periods of drought. According to Ferreira et al. [10], plants from areas where rock powder is applied show an increase in root area, enabling greater absorption of water and nutrients from deeper soil layers.

Several studies have investigated the use of basalt powder as a nutrient source in tropical and subtropical agriculture, with promising results. For example, research conducted by Silva et al. [11] found that the application of basalt powder increased the nutrient content of Phaseolus vulgaris. Writzl et al. [12] evaluating the efficiency of basalt rock powder (BRP), used in its pure form or associated with chicken litter (CL) in the development of plants and grain yield of Zea mays in Oxisol, found similar yields to those of chemical fertilization, showing the potential of alternative fertilization in high-fertility soil. Similarly, studies by Hu et al. [13] have shown that the addition of basalt powder can improve soil microbial activity, leading to enhanced nutrient cycling and soil health.

Despite these positive findings, the use of basalt powder in agriculture is not without challenges. One of the main challenges is the low solubility of basalt powder, which can limit its immediate impact on plant nutrition. However, strategies such as the use of microbial inoculants and organic amendments have been shown to enhance the solubility of basalt powder, increasing its effectiveness as a nutrient source [14].

The dissolution of rock powder in the soil is a complex process influenced by various factors, including the composition of the soil solution, plant interactions, and environmental conditions such as climate, temperature, and pH changes in the rhizosphere [15, 16]. Organic acids play a role in chelation and redox processes [17]. Exploring the intricate mechanisms by which plants such as Urochloa spp. respond to the limited nutrients found in rock powder, and how they activate internal signals to reconfigure metabolic and genetic pathways for optimal growth, is a captivating and ongoing area of research [18].

One of the key adaptations in Urochloa spp. is its root system architecture [19], which includes spatial arrangement adjustments at different growth stages and successions [20], increased lateral root proliferation, and elongation of root hairs [21]. These adaptations collectively enhance the surface area available for nutrient uptake. The plasticity of the Urochloa spp. root system is genetically determined and is closely linked to plant hormone interactions [22]. For instance, roots can adapt to nutrient-poor soil by altering the distribution of auxin [23]. In Zea Mays, high nitrate levels inhibit root growth, which is associated with reduced auxin levels in the root [24]. Cytokinins also play a role in nutrient signaling, affecting the balance of various nutrients such as nitrogen (N), P, S, and iron (Fe). They are known to modulate the response of Arabidopsis thaliana roots to inorganic phosphate deficiency [25]. These complex interactions highlight the importance of understanding plant-soil interactions in the context of nutrient availability and plant growth. Studying these mechanisms in Urochloa spp. can provide valuable insights into sustainable agriculture practices, particularly in regions with nutrient-poor soils.

This study posits the hypothesis that the application of basalt powder can enhance soil fertility, increase nutrient accumulation in plants, and boost the productivity of U. brizantha. The primary objective of this research is to determine the effect of basalt powder on soil fertility through changes in its chemical characteristics and the response of U. brizantha to different application doses. Specifically, we aim to identify the most suitable doses for soils with varying fertility levels. By investigating these objectives, this study aims to contribute to the development of sustainable agricultural practices in tropical and subtropical regions, with the ultimate goals of improving food security and promoting environmental sustainability.

2 Material and methods

This research was conducted in two phases: I. Soil Incubation Study with Basalt Powder, and II. Evaluation of Urochloa brizantha as an indicator plant for basalt powder efficiency.

2.1 Soil incubation study with basalt powder

2.1.1 Experiment location and soil and basalt powder characterization

The soil incubation study with basalt powder was conducted through an experiment in pots arranged in a greenhouse at the Federal Institute of Paraná (IFPR), Campus União da Vitória, Paraná State, Brazil (26°13'43.2''S; 51°2'55.7''W—WGS84). Initially, soil samples from the surface layer (0–20 cm) of a Typic Quartzipsamment (TQ) [26] from União da Vitória, Paraná State, Brazil (26°9'10.39"S; 51°7'26.87"W—WGS84) and a Oxisol (OX) [26] from Antônio Olinto, Paraná State, Brazil (25°59'57.5''S; 49°58'42.7"W—WGS84) were collected. The primary objective of selecting two contrasting soil classes was to demonstrate the agronomic potential of basalt powder. It is generally effective in soils with low nutrient supply capacity, such as TQ, but less so in soils with high cation exchange capacity, like OX.

After collection, the samples were air-dried, sieved through a 0.5 cm mesh, and then placed in pots (item 2.1.2). The physical characterization of the soils was performed following the methodology of [27] (Table 1). For the chemical characterization, the samples were dried in a forced-air oven at 45 ºC until constant mass was obtained. They were then ground and passed through a 2 mm sieve for subsequent laboratory analysis. The pH was potentiometrically determined in suspensions with 0.01 mol L−1 CaCl2 solution at a 1: 2.5 ratio. Soil organic matter (SOM) determined after oxidation with K2Cr2O7 in the presence of H2SO4. Al3+, Ca2+ and Mg2+ were extracted by KCl solution (1.0 mol L−1) and quantified by Atomic Absorption Spectroscopy (AAS) following the methodology of Teixeira et al. [27]. For P and K+ (resin), the methodologies followed those proposed by Raij [28], with K+ determined by flame photometry and P by colorimetry. Soluble Si was determined by extraction with 0.01 mol L−1 CaCl2 aqueous solutions using the molybdenum blue method described by Korndörfer [29]. After determining the elements, the sum of bases (SB = Ca2+  + Mg2+  + K+) and potential cation exchange capacity (CEC = SB + H+  + Al3+) were calculated.

Table 1 Chemical and physical attributes of soil samples used in the experiment
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Basalt powder from a crushed stone mining company located in Paula Freitas—Paraná State, Brazil (26°11′4.51"S; 50°56′54.36"W—WGS84) was used in the study (Fig. 1). The chemical composition of the basalt powder was analyzed using X-ray fluorescence technique, and the results are presented in Table 2. Potentially toxic elements of the basalt dust used were at low concentrations (arsenic—As, < 1.0 mg kg−1; cadmium—Cd, < 1.0 mg kg−1; lead—Pb, 39.0 mg kg−1; mercury—Hg, < 0.1 mg kg−1), according to Brazilian legislation [30].

Fig. 1
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Location and sampling point of basalt powder in the city of Paula Freitas/Brazil

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Table 2 Chemical characterization of the major elements of the basalt powder sample
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The mineralogical analysis of basalt powder was conducted using petrographic evaluation [31], revealing a typical composition of tholeiitic basalts from the Paraná Basin (Table 3). The mineralogy comprises volcanic glass, diopside (a type of pyroxene), and labradorite (a type of plagioclase), along with opaque minerals composed of iron and titanium oxides. Grain-size analysis indicated that 100.00% (± 0.1) by mass of the sample passes through a 2.00-mm-mesh sieve, with 100.00% (± 0.1) also passing through a 0.840-mm-mesh sieve. Additionally, 52.0% (± 0.7) of the sample passes through a 0.300-mm-mesh sieve, and 22.0% (± 0.4) passes through a 0.075-mm-mesh sieve. This analysis revealed a reactivity of 87%, highlighting the potential for the basalt powder to interact effectively with soil components.

Table 3 Mineralogical characterization of the basalt powder
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2.1.2 Experimental design and procedures

The experimental design followed the recommendations outlined by the Brazilian Agricultural Research Corporation (EMBRAPA), adhering to the Protocol for Evaluating the Agronomic Efficiency of Soil Remineralizers developed by the organization [32]. A completely randomized factorial design of 2 × 5 (2 soils with 5 dosages) with 4 replications was employed. The soils used were TQ and OX. The different dosages were based on the CaO content of the basalt powder to correct the Ca2+ levels in TQ. Different doses corresponding to varying Ca2+ content were utilized in the experiment, as outlined in Table 4.

Table 4 Description of treatments with their respective doses
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The experiment began on February 7, 2023, using 10 dm3 plastic pots filled with 7 kg of dry soil (OX, TQ) as the experimental units. After labeling the pots with their respective treatments, the basalt powder doses were added and thoroughly mixed with the entire volume of soil in each pot to ensure uniform distribution. The soil was then moistened to approximately 80% of the field capacity for both OX and TQ soils. During the incubation period, regular irrigation was performed to maintain the moisture level at approximately 80% of the field capacity. The surface was covered with plastic sheeting to minimize water evaporation.

After 170 days of incubation, soil samples were collected from each experimental unit, air-dried, sieved using a 2 mm mesh, and analyzed for pH (CaCl2), carbon (C), P, K+, Ca2+, Mg2+, S-SO42−, B, cupper (Cu), Fe, manganese (Mn), zinc (Zn), Si and Al3+ as described in Sect. 2.1.1.

2.2 Biomass production and nutrients accumulation in Urochloa brizantha

Following the incubation period, soil from each pot was transferred to a tray and disaggregated. Liquid forms of nitrogen (N) and potassium (K) were applied, while phosphorus (P) was administered in powdered form. Specifically, urea (45% N) was applied at a rate of 100 mg kg−1, with 20 mg kg−1 at sowing and the remainder divided equally at stages V3 and V5 of U. brizantha growth. Triple superphosphate (TSP, 41% P2O5) and potassium chloride (KCl, 58% K2O) were applied for phosphorus and potassium, respectively, both at a rate of 100 mg kg−1.

The experiment focused on U. brizantha, a member of the Poaceae family, chosen for its high demand for soil potassium content [4]. Ten U. brizantha seeds were sown per pot after fertilization, following the same treatments as outlined in item 2.1.2. Thinning was conducted when plants reached the V1 vegetative stage, resulting in only 4 plants remaining in each pot. After 40 days after sowing (DAS) (V7 stage), the aboveground shoot dry mass of the plants was harvested (SDM1), while the plants were maintained for regrowth. The plant material was then dried in a forced air circulation oven at 60 ºC until reaching a constant weight. Subsequently, the shoot dry mass of the plants was analyzed, along with the contents of N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn, following the methodology outlined by Silva [33].

For N analysis, tissue samples underwent initial digestion with sulfuric acid, followed by determination of total N through distillation in a semi-micro Kjeldahl device and titration with 0.025 mol L-1 sulfuric acid. Sulfur (S) analysis involved a nitric-perchloric digestion (4:1 HNO3 65%: HClO4 70% v/v), followed by precipitation of the extract with BaCl2 (98%) and determination using a UV–VIS spectrophotometer in transmittance form. The remaining nutrients were determined using inductively coupled plasma atomic emission spectrometry. Nutrient accumulation was calculated by multiplying the SDM by the content of each nutrient, with results expressed in mg per plant.

The second harvest of the shoot dry mass (SDM2), considered as regrowth or second cultivation, was conducted at 70 DAS (V7 stage). Similar to the previous harvest, the SDM was evaluated, along with the contents and accumulations of the same nutrients as before.

2.3 Statistical analysis

Initially, the results were assessed for normality using the Shapiro–Wilk test and for homogeneity of variance using the Levene test. After meeting these assumptions, analysis of variance (ANOVA) was conducted. For variables showing a significant effect (p < 0.05) for the evaluated factors, polynomial regression was applied to the quantitative factor (basalt doses). The qualitative factor (soil type) was evaluated using a t-test where significant differences were detected. The analysis was performed using SISVAR Software Version 5.6 [34].

3 Results

3.1 pH, Al3+, Soil Organic Carbon and nutrients content of soil treated with basalt powder: results of 170 days of incubation

The F-test results (p < 0.05) revealed significant effects of both isolated factors and interactions between soil types and basalt powder doses on pH (CaCl2) and soil contents of P, K+, Ca2+, Mg2+, S-SO42−, B, Cu, Si, and Al3+. Regarding the soil type factor, Table 5 shows that the OX class generally exhibited higher values of SOC, P, K+, Ca2+, Mg2+, S-SO42−, B, Cu, and Si for most of the doses. Conversely, for the variables Fe, Mn, Zn, and Al, the TQ class generally presented higher values for these attributes. The pH (CaCl2) values were similar between the two soil classes evaluated.

Table 5 Chemical attributes observed in Typic Quartzipsamment (TQ) and Oxisol (OX) after 170 days of incubation with basalt powder
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For the pH (CaCl2) variable (Fig. 2a), both soils the maximum dose of basalt powder resulting in the highest values of this attribute (+ 6 and + 12% for TQ and OX, respectively). Regarding soil organic carbon (SOC) contents (Fig. 2b), an increase was observed only in OX (+ 16%) with the addition of basalt powder, with the maximum dose (96 Mg ha−1) showing the highest values.

Fig. 2
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Chemical attributes obtained in Typic Quartzipsamment (TQ ◦) and Oxisol (OX •) after 170 days of incubation with basalt powder

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Soil P contents increased with the addition of basalt powder (Fig. 2c), with the maximum dose (96 Mg ha−1) resulting in the highest values in both soils (TQ and OX). The model equation's adjustment differed, being polynomial for OX and linear for TQ. Soil K+, Ca2+, and Mg2+ contents showed an isolated effect of basalt powder application only in OX (Fig. 2d–f), with the maximum dose leading to the highest increments of these nutrients. S-SO42− contents increased in both soil classes with basalt powder application (Fig. 2g), with the maximum dose resulting in the highest increments of this nutrient (approximately 45% for both soil types).

For B contents (Fig. 2h), increments were observed with increasing dose in OX (+ 30%), while in TQ, the dose of 61 Mg ha−1 led to the highest values of this nutrient. Cu (Fig. 2i) and Si (Fig. 2m) contents were highest at the maximum basalt powder application rate in both soil classes (+ 48 and + 90% for TQ and OX, respectively). Fe contents reached their highest values at doses of 60 and 44 Mg ha−1 for TQ and OX, respectively (Fig. 2j). Mn (Fig. 2k) and Zn (Fig. 2l) contents showed an influence of basalt powder only in TQ, with a quadratic equation representing the additive behavior, and doses of 48 and 76 Mg ha−1 leading to the maximum increase in these variables.

Regarding Al3+ contents in the soil (Fig. 2n), contrasting behaviors were observed between soils. In OX, basalt powder application linearly decreased Al3+ levels. In contrast, for TQ, there was an increase in Al3+ with basalt powder addition up to the dose of 50 Mg ha−1, which resulted in the highest levels of this element.

3.2 Biomass production and nutrients accumulation by U. brizantha

The analysis of variance results (F-test, p < 0.05) highlighted significant effects of both individual factors and the interaction between soil types and basalt powder doses on SDM1, SDM2, and the accumulation of P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn. Regarding the soil type factor, Table 6 indicates that the OX soil class, with the exception of Mn accumulation, demonstrated higher values of accumulated nutrients. For the variables SDM1 and SDM2, plants grown in TQ produced greater biomass at lower doses, while at higher doses, OX soil facilitated greater biomass accumulation.

Table 6 Shoot dry mass of the first cut (SDM1), second cut (SDM2) and nutrients accumulation of U brizantha cultivated after 170 days of incubation in Typic Quartzipsamment (TQ) and Oxisol (OX) with basalt powder
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Sandy soil (TQ) exhibited higher SDM accumulation compared to clay soil (OX), with notably higher values and angular coefficients, especially at lower doses (0.0273 vs. −0.0039 in SDM1 and 0.0247 vs. −0.0032 in SDM2) (Fig. 3a, b). In TQ soil, the doses leading to maximum SDM1 and SDM2 values were 68 and 62 Mg ha−1, respectively, while in OX soil, the maximum dose (96 Mg ha−1) resulted in peak SDM1 and SDM2 values.

Fig. 3
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Shoot dry mass of the first cut (SDM1), second cut (SDM2) and nutrients accumulation of U brizantha cultivated after 170 days of incubation in Typic Quartzipsamment (TQ ◦) and Oxisol (OX •) with basalt powder

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Distinct quadratic patterns were observed in N and K accumulation between soil classes (Fig. 3c, e). In OX soil, the maximum accumulation occurred at the highest dose (96 Mg ha−1), whereas in TQ soil, the quadratic model indicated optimal accumulation at doses of 73 Mg ha−1 and 66 Mg ha−1 for N and K, respectively.

For P accumulation (Fig. 3d), different responses were noted. OX soil showed a linear increase, while TQ soil exhibited a quadratic response, with 54 Mg ha−1 being the most effective dose.

The highest Ca values (Fig. 3f) were observed at the maximum dose in both soil classes (an increase of 139% and 208% for TQ and OX, respectively). Mg, B, Cu, and Fe accumulation responded significantly to basalt powder application only in OX soil, with the maximum dose resulting in the highest accumulation of these nutrientes (Fig. 3g–k).

Both soil classes showed increased S accumulation (Fig. 3h) with basalt powder application, with the maximum dose yielding the highest accumulation (an increase of 19% and 55% for TQ and OX, respectively).

In TQ soil, Mn accumulation (Fig. 3l) showed a quadratic trend, with the 56 Mg ha−1 dose resulting in the lowest values. Zn accumulation (Fig. 3m) increased with basalt powder application in both soil classes, exhibiting a linear trend in OX soil and a quadratic trend in TQ soil.

4 Discussion

The diverse mineral composition of basalt powder demonstrates its theoretical potential as a multi-nutrient source (Table 3). Generally, the nutrients supplied by basalt powder are influenced by its mineralogy [35]. In this regard, o Volcanic glass found is characterized by low crystallinity and high reactivity, leading to the concentration of potassium from the rock. This glass can release bases, silicon, and micronutrients such as Cu, Zn, Fe, and Mn [36].

Diopside [Ca,Mg(Si2O6)] is highly reactive and can release calcium, magnesium, and silicon, contributing to an increase in pH through the hydrolysis of this base-rich silicate [35]. Labradorite [(Na,Ca)(Si,Al)4O8] also exhibits high reactivity, with the potential to release calcium, silicon, and contribute to pH increase through the hydrolysis of this silicate [7].

Although silicon is not considered an essential nutrient, it plays a crucial role in maintaining cell wall rigidity and enhancing resistance to pest attacks [37, 38]. Additionally, the silicate anion competes with the phosphate anion for the soil's fixed functional groups, thereby increasing phosphorus availability [39]. According to Korndörfer [40], soils with silicon (Si) concentrations below 20 mg dm−3 require fertilization with this nutrient. This recommendation is particularly relevant, as the soils evaluated in this study had silicon levels below this threshold.

Inert minerals, such as those formed by magnetite and ilmenite, exhibit high stability in the environment and low biological reactivity Al-jibury et al. [41]. These minerals do not release nutrients in an agronomic time scale.

Regarding the soil classes evaluated in the experimental design, it was anticipated that the Typic Quartzipsamment (TQ), being a less buffered soil class, would exhibit a greater response to basalt powder application. In theory, this soil type should be more amenable to nutrient enhancement through the addition of external amendments. However, the limited effect of basalt powder application observed in TQ may be primarily attributed to soil biology. Although not the focus of this study, it is expected that the low soil organic carbon (SOC) content in TQ directly affects the development of microorganisms responsible for mineral solubilization from basalt [42, 43]. Similar studies have indicated that soils with lower SOC content are less responsive to amendments with low solubility, such as rock powders [7, 44].

Regarding pH values, the increase in this variable is likely due to the extended soil incubation period. This prolonged period allowed for a more significant release of alkaline compounds from the basalt powder, such as CaO and MgO, known to raise pH levels. The gradual pH increase over time indicates the sustained effect of basalt powder on soil pH, which is crucial for nutrient availability, confirming its potential to enhance this attribute [6, 45].

The increase in SOC content in OX soil after basalt powder application may be related to the formation of new mineral phases that provide more sorption sites for organic matter, as reported by Buss et al. [42]. The same study indicates that the supply of Ca and Mg from basalt enhanced soil microaggregation, which subsequently stabilized labile particulate organic matter (POM) as occluded organic matter within the aggregates by 46%.

Phosphorus contents in both soils showed a significant increase, likely due to the mineralogical composition of basalt. The presence of apatite and the release of phosphorus from silicon (Si) contribute to this effect [46]. The application of basalt dust releases silicate anions, which compete with phosphate anions for absorption sites, thus increasing phosphorus availability [6]. Furthermore, the increase in soil pH due to the application of basalt powder may have reduced the fixation of P to Fe and Al oxides and influenced the mineralization rate of organic matter. This is consistent with the findings of [1] in their study on the application of mining coproducts, where similar results were observed. These results suggest that using basalt dust can enhance phosphorus availability in the soil. Therefore, strategies focused on managing basalt dust application can help mitigate future phosphorus shortages.

The isolated effects of basalt powder on soil K+, Ca2+, and Mg2+ contents in OX possibly indicate that, due to its lower organic matter content in TQ (Table 2), there is limited acid solubilization of K+, Ca2+, and Mg2+ retained in basalt primary minerals [47]. In this sense, Rodrigues et al. [4] reported that soils rich in organic matter are expected to facilitate the release of K+ from rock powders due to higher concentrations of organic acids. These acids, through their H+ ions, facilitate the mobilization of K+ ions and contribute to the stabilization of mineral structures by incorporating them into the apical oxygens of the tetrahedral layer, thereby reducing the charge of this layer. Additionally, particularly for Ca and Mg, the significant levels of these elements in the composition of basalt powder (Table 2) allowed for an increase in these nutrients, especially Ca, as previously found in similar studies [48, 49].

Regarding the levels of S-SO42− and B, significant increases in these variables were not expected with the application of basalt powder, due to their low values in its composition. However, the increase in soil organic matter content with basalt powder application may have led to these values, as S-SO42− and B are directly related to soil organic matter. Furthermore, especially for S-SO42−, the increase in soil silicon (Si) and phosphorus (P) levels with basalt powder application may have favored competition processes among ions for soil sorption sites, which could have contributed to the increase in S-SO42− [50, 51]. These results indicate the importance of the interaction between nutrients and soil organic matter in response to basalt powder applications.

The positive effects of basalt powder application on copper levels may be attributed to its mineral composition. Basalt powder contains minerals such as bornite (Cu5FeS4), which can contribute to the increase in copper concentrations in both soil classes [52, 53]. In a study by Melo et al. [54], the authors also found a positive effect of basalt powder on copper levels, with a dose of 96 Mg ha−1 being the most efficient in enhancing this nutrient.

In the context of Fe, Mn, and Zn levels, the lower concentrations observed in the Oxisol (OX) soil and the lack of significant impact from basalt powder on enhancing these nutrients could be linked to soil pH dynamics. The pH elevation (as shown in Fig. 2a) creates an environment where zinc tends to be adsorbed onto the solid phase of the soil, while iron and manganese tend to precipitate as oxyhydroxides, thereby limiting their bioavailability [55]. Thus, the complex interactions between soil pH and the availability of micronutrients like Fe, Mn, and Zn, highlights the importance of pH management in optimizing nutrient uptake by plants.

The decreasing trend in Al3+ levels with basalt powder application may be related to the increase in soil pH resulting from these materials (Fig. 2a). As soil pH rises, the predominant form of aluminum shifts from Al3+ to less water-soluble and less readily exchangeable forms. Furthermore, the reduction in Al3+ could be associated with the removal of Al from exchange sites, possibly facilitated by the release of silicate ions from the amendment. These ions may react with aluminum to form insoluble aluminosilicates, or they may contribute to the precipitation of hydroxy aluminum following the liberation of hydroxyl ions as silicate is hydrolyzed to silicic acid [56]. Aluminum toxicity affects agricultural production on a worldwide scale, particularly in tropical regions [57]. In this sense, the potential of using basalt to help correct soil pH and Al neutralization is highlighted.

Regarding Si content, an increase due to basalt powder application was expected, as the silicate present in the rock, when hydrolyzed, can release soluble silicon in the form of silicic acid, which is easily absorbed by plants [58]. Swoboda et al. [35] reported that silicate rocks and less soluble minerals like feldspars, basalts, and granites have demonstrated the capacity to release silicon, a finding consistent with most studies that have measured it.

Soil fertility analysis, based on Pauletti and Motta [59], revealed high P contents in TQ and very high levels in OX across all doses. Although there was an increase in K+ and Mg2+ contents with basalt powder application, these elements remained classified as very low in both soil classes according to soil fertility criteria [59]. Ca2+ contents varied from low to medium in OX, depending on the dose, while remaining very low in TQ at all doses. S-SO42− and Cu were consistently classified as very high in both soil types. B contents were very high in OX and ranged from high to very high in TQ. In contrast, Mn and Zn were classified as high in TQ but low in OX.

For the variables SDM1 and SDM2 (Fig. 3a, b), the highest values observed at intermediate doses in TQ and maximum doses in OX are possibly due to the buffering capacity of these soils. Therefore, in the case of the highly buffered soil (OX), positive effects were only evident at the maximum dose (96 Mg ha−1). These results are similar to those found by Luchese et al. [6], who, while evaluating the effect of basalt powder on soil chemical properties and plant growth, observed that the shoot dry matter of soybean plants grown in clayey soil was significantly higher with certain rates of basalt powder (especially the dose of 99 Mg ha−1). This suggests that, even within a short period of interaction of this material with the soil (less than 80 days), there was an improvement in the soil characteristics, resulting in greater soybean plant development.

The significant accumulation of shoot dry mass (SDM) following the application of basalt powder indicates soil improvement. The increase in pH, as shown in Fig. 2a, likely influenced these results, benefiting SDM accumulation in both soils. Additionally, the increased nutrient accumulation also contributed to these outcomes.

For P and N accumulation, the benefits of increased soil P and SOC levels with basalt powder application favored the accumulation of these nutrients in the plant. Additionally, reports of synergies in absorption between P and N may have enhanced these results [60].

Recent assessments have challenged the long-held assumption of slow weathering rates in the field, reporting dissolution rates that surpass expectations. Weathering processes can be categorized into two stages: the first stage involves the exchange of surface K+ with H3O+ from the soil solution, while the second stage is characterized by the proton-catalyzed hydrolysis of Si–O and Al-O bonds in the framework structure. Ciceri and Allanore [61] focused on the first stage of weathering, which is less understood, and found significantly higher dissolution rates for feldspars compared to the second stage. These findings align with field observations that feldspar and other minerals present in basalt grains weather much faster than theoretical rates would suggest. This accelerated weathering is likely attributed to plant and soil microbiological processes [62]. In this context, the higher accumulation of Ca, Mg, and K with the application of basalt powder may have been a benefit caused by the presence of U. brizantha, which potentiated the weathering of minerals containing these nutrients.

Some studies have indicated that as soil pH increases, the availability of cationic micronutrients (Cu, Fe, Mn, and Zn) decreases [45, 51]. However, in our study, the increase in soil pH due to basalt dust application had no effect on micronutrient uptake by maize plants. Our results, similar to those of Conceição et al. [9], demonstrate that soil pH and plant micronutrient uptake can increase simultaneously, facilitating the adequate development of U. brizantha plants in both soils.

In tropical areas, where high water flow conditions can lead to an ionically imbalanced soil solution, the application of basalt powder can significantly impact weathering conditions and, in turn, affect nutrient availability for plants. Factors such as temperature, pH, moisture levels, and elemental and gas concentrations vary across these regions, impacting the rate and quasi-equilibrium of reactions between the solid mineral phase and the soil solution [44].

Basalt powder's slow and continuous solubility provides a residual effect that acts as a supplementary fertilizer, reducing the demand for mineral fertilizers over time [6]. This can be particularly advantageous in tropical countries with acidic and nutrient-deficient soils, as it can reduce the need to import soluble fertilizers and contribute to their food sovereignty [4].

Historically, mineral dissolution rates have been consistently underestimated due to the oversight of plant influence on weathering kinetics [63]. Plants play a significant role in shaping soil biological and physical conditions, especially in the rhizosphere, where conditions can differ significantly from those in the bulk soil [35]. U. brizantha roots, widely cultivated in tropical and subtropical regions, can alter environmental conditions in the rhizosphere, creating a favorable environment for nutrient release from basalt minerals [4, 20]. This, in turn, increases the availability of essential elements for plant growth, particularly in planted areas. The presence of plants can increase the release of Si, Ca, Mg, Na, and Fe from basalt, providing a conducive environment for nutrient absorption by plants [6, 7, 45, 64].

Given its low solubility and the requirement for application in tons per hectare, basalt powder is recommended for areas with nearby mining operations of this material. Currently, producers in the southern region of Brazil are paying approximately $25 per ton for this material. The transportation cost varies depending on the distance from the mining site to the application area. The application cost is similar to that of applying lime, which is a common practice in tropical and subtropical countries. The same equipment used for lime application can be utilized for basalt powder, which simplifies the process and reduces the need for additional investment in new machinery.

Another of the main advantages of basalt powder over traditional soil amendments is its multi-nutrient profile. While lime primarily provides Ca and Mg, basalt powder offers a broader range of essential nutrients, including P, K, Si, and trace elements such as Cu and B. This comprehensive nutrient supply can improve soil fertility more effectively than single-nutrient amendments. Additionally, basalt powder has the advantage of being a widely available resource in South America and Africa, regions with many developing countries that often face resource limitations for importing materials. This local availability can reduce costs and increase accessibility for farmers. Furthermore, basalt powder can help reduce soil acidity and improve soil structure, enhancing overall soil health and plant growth. Its longer-lasting effect on soil fertility makes basalt powder a cost-effective and sustainable alternative for improving soil fertility in resource-limited settings, compared to more frequently applied organic amendments.

Furthermore, it is important to note that basalt powder is often a byproduct of mining, frequently discarded without proper treatment, leading to environmental problems. Relocating basalt powder to agriculture represents a significant environmental gain. The globally generated silicate mining waste potentially suitable for agricultural recycling is considerable, even when considering worldwide rock powder applications.

5 Conclusions

The study reveals that basalt powder effectively enhances soil chemical properties and promote sustainable agricultural practices. The results demonstrate that in OX soils, the maximum dose of basalt powder (96 Mg ha−1) significantly increased SOC, P, K+, Ca2+, Mg2+, Cu, and Si contents, while also elevating soil pH and a reducing Al3+ content. These findings underscore the potential of basalt powder as an alternative to traditional fertilizers in agricultural contexts. Conversely, TQ soils, on the other hand, exhibit more limited effects, with specific increases in P, S-SO42−, and Si levels, indicating the need for site-specific considerations.

Moreover, the research highlights that varying doses of basalt powder significantly enhance shoot dry mass and nutrient accumulation in U. brizantha, potentially reducing the reliance on traditional inputs and enhancing system sustainability. However, further investigations are required to fully understand the underlying mechanisms and long-term impacts of basalt powder application on soil health and agricultural productivity.