Can Plastic Mulching Enhance Soil Physical Conditions and Mitigate Water-Related Physiological Stress in Citrus Crops?

Abstract

Short dry spells during the rainy season have become increasingly common in Brazil, reinforcing the need for soil water conservation practices. Plastic mulching can enhance plant water use and mitigate abiotic stress. This study evaluates water use efficiency in terms of soil physical quality, root systems, and photosynthetic performance of citrus plants grown in different Inceptisols. The field experiment, in a randomized block design with a split-plot arrangement, was conducted in Lavras, Brazil, and involved citrus (orange) plants from 2012 to 2014. Undisturbed soil samples were collected at depths of 0.00–0.05, 0.20–0.25, and 0.90–0.95 m, two years after the installation of white plastic (WP), black plastic (BP), and no plastic (NP) mulching treatments in two Inceptisol types, totaling 54 samples. The soil water-retention curve, pore size distribution, and soil physical quality indicators were determined, and root system distribution maps were generated using B-splines. Leaf gas exchange was measured under contrasting precipitation conditions. Inceptisol I showed minimal impact from mulching, except for the bulk density and total porosity, which positively correlated with transpiration under BP. In contrast, in Inceptisol II, WP increased photosynthetic rates under low- and high-precipitation conditions but reduced water use efficiency, correlating positively with macropores and negatively with micropores. Plastic mulching reduces physiological stress in citrus and improves soil physical quality, with WP being the most effective across precipitation levels, particularly in less stable soils.

1. Introduction

The world production of citrus (oranges, lemons, limes, tangerines, mandarins, clementines, and satsumas) in 2020 was 135.41 million tons, with China being the most significant producer, with 33.66 million tons, and Brazil being the second, responsible for 19.31 million tons [1,2]. The 2023 citrus harvest for São Paulo and Minas Gerais ended with 314.21 million boxes of 40.8 kg each, with 23.22 million boxes produced solely in the Triângulo Mineiro region [3]. After the COVID-19 pandemic, the consumption of foods high in vitamin C increased worldwide [4], as these foods are associated with immune system support [4,5]. Thus, the global demand for citrus fruits will also remain high [1]. Brazil is preparing to diversify citrus orchards, expand areas with lemon and tangerine, intensify mechanized harvesting, and densify planting to achieve productivity gains [3,6,7].

The 2021/22 production was lower than 2022/23 by 19.49%, associated with the adverse weather impact [3]. One of the main factors that helps increase crop yield is efficient water use [8]; therefore, prioritizing soil and water conservation systems is paramount in agriculture [9]. This is due to the intensification of dry years, associated with the increase in occurrences of short dry spell periods (≥4 days) with heatwaves in the middle of the rainy season or in the autumn period in the southeast region of Brazil. Therefore, innovative management techniques adapted to drylands, for example, plastic mulch [10] and farming, have been advocated due to concerns about the scarcity of water resources for irrigation [6,11].

The Inceptisols occupy approximately 8% of the global ice-free land [12]. These soils are spread over about 5.3% of the Brazilian territory [13]. Their main characteristic is incipient development, characterized by little differentiation of horizons in morphological characteristics, mainly by color and structure [14,15,16,17]. However, these soils vary widely in depth, from shallow profiles (<0.50 m) to deep profiles exceeding 1.50 m, and show substantial variability in physical and morphological characteristics, including texture, structure, and degree of horizon development [14,15,16,18]. These soils are suitable for agricultural use once some restrictive factors are mitigated, such as stoniness, small depth, and excessive slope [14,15,16,18].

Plastic mulch was already responsible for approaching the water use efficiency in drylands compared to that of the irrigated areas for wheat and maize crops [19]. References have also shown that plastic films are responsible for increasing soil water content, fruit yield, and water use efficiency in apple crops [20], bell peppers [21], and others [22]. Therefore, plastic mulch has been revealed to be promising for use in many crops worldwide [23], and even its continued use has been proven to improve soil and groundwater quality [24]. It is highlighted that plastic mulching can vary in color; the black and white ones are the most often used, and this characteristic can reveal different effects on the water used by plants [25,26], especially in perennial fruit crops [23]. This condition results from the microclimate modification induced by plastic mulch, which provides physical insulation and moisture retention despite the absence of organic inputs. The cover improves soil physical properties compared with bare soil, leading to physiological benefits such as increased yield and weed suppression [27].

A practical way of evaluating the efficiency of water use by plants grown in soils is the A/E ratio, assimilation (A), and transpiration (E) [28,29], which indicates whether the soil physical-hydric condition has positively influenced the plants’ efficient water use. An infrared gas exchange analyzer (IRGA) is used to obtain the endpoint inputs for this ratio. The gas exchange endpoints (photosynthetic rate, stomatal conductance, and transpiration rate) tend to be increased with the greater volume of mesopores in soil, which is responsible for greater water availability to plants during stress intervals [30].

The efficient use of water by plants is also related to some common soil attributes, such as texture, mineralogy, organic matter, and structure, and this last item is modifiable according to the management system adopted [31,32]. Management practices with intense soil turnover can negatively change the size and continuity of the soil pore network, with substantial losses in the hydric conditions of this system [9,33,34]. However, by adopting management practices that preserve or positively change the soil structure, it is possible to increase the plant water availability [15,16].

The disadvantages of plastic mulching have already been cited in the literature [35]. Notably, the soil cannot adequately capture and use rainwater, and applying fertilizers becomes very difficult due to the installation of a plastic cover in the field [36]. The soil structure can also be damaged by plastic waste in this system, leading to the decreased connectivity of soil pores and soil porosity [37].

Although plastic mulching applied to the soil is widely reported as an effective technique for improving soil moisture conservation, crop performance, and water use efficiency, most available studies do not specifically address, and therefore poorly elucidate, the combined effects of plastic mulching on soil physical quality, root system spatial distribution, and the physiological responses of perennial fruit crops under contrasting precipitation conditions.

This limitation is justified, as most studies evaluating plastic mulching have focused on annual crops and soils with a relatively stable structure, in which greater macroporosity may enhance the positive effects of soil cover on water infiltration and storage. Consequently, significant knowledge gaps remain regarding how plastic mulching influences soil–plant interactions in tropical soils, particularly in Inceptisols, which are characterized by high spatial variability, incipient horizon development, and contrasting physical-hydric limitations along the soil profile. In addition, perennial fruit crops, such as citrus, exhibit deep and spatially heterogeneous root systems, resulting in long-term soil–plant interactions that differ substantially from those observed in annual cropping systems.

Therefore, studying the effects of plastic mulching and adopting a holistic perspective are necessary. Innovatively, the study provides information on how the weather station data and water balance are assessed to understand water dynamics through soil physical quality indicators, root systems, and the photosynthetic performance of citrus plants in tropical soils. This study hypothesizes that plastic mulching can maintain or increase water use efficiency and reduce physiological stress in citrus plants. To test this, the properties of Inceptisols were evaluated through soil porosity, root system characterization, and the physiological responses of citrus plants. This study aimed to evaluate the effectiveness of black and white plastic mulches on soil physical properties and the physiological traits of citrus plants. Soil properties, including porosity and root system characteristics, were quantified in Inceptisols, and the effects on plant water use efficiency and physiological stress were assessed.

2. Materials and Methods

2.1. Field Experimental Design

The study was conducted in a citrus orchard in the Dr. Sílvio Menicucci experimental farm of the EPAMIG unit in the South of Minas Gerais (Southern Regional Unit of Minas Gerais—URESM), in Lavras, Minas Gerais, Brazil. The location’s geographic coordinates are 21°14′43′′ S and 44°59′59′′ W, at an altitude of 919 m. The climate and temperature are classified as Cwb (Figure 1) [38], indicating a humid–temperate climate with a dry winter and a moderately hot summer. The average annual temperature is 20.1 °C, and the annual rainfall is 1463 mm.

In the experimental area, two soils were identified according to the Brazilian Soil Classification System (BSCS) [17]: Cambissolo latossólico franco and Cambissolo franco argiloso. In Soil Taxonomy [39], they are clay loam Inceptisols, and in the World Reference Base [40] they are classified as Cambisols. The soils were tilled with a harrow, and the furrower was used to open furrows measuring 0.60 m × 0.60 m × 0.60 m. The soil pH was adjusted with lime, and fertilization was performed according to Ribeiro et al. [41], and soil chemical and physical attributes (

Table 1. Soil chemical and physical attributes of the entire area before the installation of the experiments.

Soil Chemical and Physical Attributes (0.00–0.20 m Depth)
pH (H2O)	5.3
P (mg dm−3)	19.4
K (mg dm−3)	87.3
Ca2+ (cmolc dm−3)	1.2
Mg2+ (cmolc dm−3)	0.9
Al3+ (cmolc dm−3)	0.4
H + Al (cmolc dm−3)	5.6
SB (cmolc dm−3)	2.32
t (cmolc dm−3)	2.72
T (cmolc dm−3)	7.92
SOM (dag kg−1)	3.2
P-rem (mg l−1)	27.2
V (%)	29.3
m (%)	14.7
Zn (mg dm−3)	1.4
Fe (mg dm−3)	28.7
Mn (mg dm−3)	11.2
Cu (mg dm−3)	3.9
B (mg dm−3)	0.2
S (mg dm−3)	35.9
Sand (g kg−1)	220
Clay (g kg−1)	360
Silt (g kg−1)	420

Soil pH was measured in water at a 1:2.5 soil-to-water ratio (10 g of air-dried soil (<2 mm) to 25 mL of distilled water). The available contents of potassium (K), phosphorus (P), zinc (Zn), iron (Fe), manganese (Mn), copper (Cu), and sodium (Na) were determined using the Mehlich-1 extraction method. Exchangeable aluminum (Al), calcium (Ca), and magnesium (Mg) were extracted with a 1 mol L⁻¹ KCl solution. Available boron (B) was determined using the hot water extraction method, and available sulfur (S) was measured using the monocalcium phosphate method diluted in acetic acid. The following chemical parameters were calculated: H⁺Al using the SMP extractor, sum of bases (SB), effective cation exchange capacity (t), potential cation exchange capacity (T), base saturation (V), and aluminum saturation (m). Soil organic matter (SOM) was determined using the Walkley–Black method, and remaining phosphorus (P-Rem) was also measured. Soil particle size distribution (clay, silt, and sand) was assessed using the pipette method. All procedures follow the methodologies described in Teixeira et al. [42].

). In the furrows, 300 g of dolomitic limestone (with 87% total neutralizing relative power, 39.7% of CaO, and 13.38% of MgO), 20 g of zinc sulfate (ZnSO₄), 20 g of boric acid (H₃BO₃), 40 g of superphosphate (16% phosphorus in the form of water-soluble P₂O₅, 16% calcium, and 10% sulfur), and 20 L of manure corral was used.

Seedlings of the ‘Navelina’ cultivar grafted onto Poncirus trifoliata rootstock were planted in September 2011 at a spacing of 6 × 4 m (Figure 1). The experiment was established in a randomized block design with a split-plot arrangement in space. The main plots consisted of three non-randomized soil sampling depths (0.00–0.05, 0.20–0.25, and 0.90–0.95 m). The split plots corresponded to three soil management treatments: white plastic (WP), black plastic (BP), and no plastic (NP), conventional management. Each treatment plot comprised one plant row with five plants. The treatments included two types of biodegradable plastic mulch installed in March 2012 along the plant row: a WP (40 μm) and a BP (18 μm), both containing an anti-UV additive.

In March 2014, 1.5 m-deep soil pits were excavated to assess soil physical conditions and morphological features using the profil cultural method, which is based on a soil profile evaluation directly in the field, as described by Boizard et al. [43] (Supplementary Data). In the experimental area, two soil types were classified. The first one is Inceptisol I (Cambissolo latossólico) because its diagnostic horizon missed the criteria of the Oxisol order due to its high silt content and less than 40% clay content [39], as well as for BSCS (Silt/Clay rate upper 0.7,

Table 2. Soil particle size distribution for soils of the experimental area.

		Sand	Silt	Clay
Depth (m)	Soil Horizons	(g kg−1)
Inceptisol I
0.00–0.05	A	217.4	399.7	382.9
0.20–0.25	B	215.5	439.8	344.7
0.90–0.95	C	179.9	346.7	473.4
Inceptisol II
0.00–0.05	A	332.6	292.2	375.2
0.20–0.25	Bw	319.6	317.0	363.4
0.90–0.95	C	297.9	380.7	321.4

Clay, silt, and sand were assessed using the pipette method, as described by Teixeira et al. [42]. A: Surface mineral horizon enriched with organic matter; B: Subsurface horizon altered by pedogenetic processes; Bw: Incipient B horizon with weak pedogenetic development; C: Slightly altered or unaltered parent material [39,40].

). Also, it presents a deep oxic diagnostic horizon (>1.50 m) (or B latossólico in the BSCS), and a homogeneous and well-developed structure [17]. This soil type was also observed by [44]. The second soil type is Inceptisol II (Cambisol), characterized by a shallow (<0.50 m) cambic horizon (Bw), weak development of the B horizon, with no clear evidence of clay illuviation, oxide accumulation, cementation, or other advanced pedogenetic processes [39], with gravel within the soil mass (soil profile characteristics are provided in Supplementary Materials).

It is important to note that both Inceptisol I and Inceptisol II were chemically amended equally during soil correction, as the producer was unaware of the two classifications of soils within the same citrus cultivation area. Consequently, Table 1 presents the soil analysis provided by the producer before amendment and treatment implementation, while Table 2 details the particle size distribution after trench excavation and soil classification.

A detailed pedological description was performed after treatment installation for both Inceptisols and is provided in Supplementary Materials. This characterization highlights inherent differences in soil structure, aggregation, and root growth limitations along the soil profile, which are typical of Inceptisols. These soil baseline descriptions were used to support the interpretation of treatment effects within each studied Inceptisol. At the same time, the experimental design and blocking strategy were adopted to minimize the influence of inherent spatial variability on the evaluated responses.

2.2. Soil Physical Indicators

Undisturbed soil samples were collected in volumetric rings using the Uhland sampler in the 0.00–0.05 m, 0.20–0.25 m, and 0.90–0.95 m layers. In the laboratory, samples were saturated with distilled water until all pores were filled with water (approximately 24 h). After that, the saturated samples were equilibrated at the matric potentials of −2, −4, −6, and −10 kPa in Buchner funnels and matric potentials of −33, −100, −500, and −1500 kPa in Richards’ chambers. The soil water retention curve (WRC) was obtained after weighing the samples and determining their moisture content. The curve was fitted using the van Genuchten [45] model with the Mualem restriction (m = 1 − 1/n) [46], using the following equation:

θ = θ_r + (θ_res − θ_sat)/[1 + (αΨm) n]1 − 1/n

(1)

where Ψm is the matric potential (kPa); θ the water content (cm³ cm⁻³); θ_sat the water content at saturation (cm³ cm⁻³); and θ_res the residual water content (cm³ cm⁻³).

The matric potential at the inflection point (Ψ_i) was determined using Equation (2), using the methodology presented by [47].

$${\Psi }_i={\displaystyle \frac{1}{\alpha }}{\left({\displaystyle \frac{1}{m}}\right)}^{{\displaystyle \frac{1}{n}}}$$

(2)

The water content at Ψi $\left({\theta }_i\right)$ was determined using Equation (3), defined by the following:

$${\theta }_i=\left({\theta }_{sat}-{\theta }_{res}\right){\left[1+{\displaystyle \frac{1}{m}}\right]}^{-m}$$

(3)

The S index (S_gi) was determined using the slope formed at the inflection point of the WRC [48] using Equation (4):

$$S_{gi}=|-n\left(U_{sat}-U_{res}\right){\left[1+{\displaystyle \frac{1}{m}}\right]}^{-\left(m+1\right)}|$$

(4)

where Usat (g g⁻¹) is the gravimetric water content at the saturation; Ures (g g⁻¹) is the gravimetric water content of soil residual water, and α (hPa⁻¹) and n (dimensionless) are empirical parameters of curve fitting, with m = 1 − (1/n) [46].

The plant-available water capacity (AWC) was calculated via the difference between the estimated water content at the matric potential of −10 kPa, for the field capacity (FC), and the water content at the permanent wilting point (θ_PMP), estimated using the water content at the matric potential of −1500 kPa [49]. The readily available water (RAW) was considered based on the range of water content between matric potentials from −6 to −100 kPa [33]. The core method also calculated the bulk density (BD) [15,16]. Soil physical indicators of soil quality, air capacity (AC), and relative field capacity (RFC) were calculated as described by Reynolds et al. [50].

The pore size distribution was calculated through the mathematical expression proposed by Bouma, [51] in Equation (5):

[D = 4 σ Cos θ/Ψ_m]

(5)

where D is the pore diameter (μm); σ is the surface tension of water (73.43 kPa μm at 20 °C); θ is the angle of contact between the meniscus and the wall of the capillary tube (considered as 0); and Ψm is the matric potential (kPa).

Pore diameter was related to Ψm, according to the methodology used by Oliveira et al. [33]. The adopted porosity classification was based on that of Bullock et al. [52], in which macropores are those with a diameter > 73 μm, and micropores are those with a diameter < 0.2 μm.

The pore volume distribution function [S_v(h)] was described assuming the methodology by Reynolds et al. [50]. The S_v(h) was defined as the slope of the WRC from a graph of volumetric water content, θ (m³ m⁻³), versus ln(h). The normalized pore volume distribution function [S*(h)] was defined by dividing Sv(h) by Svi (Equation (6)), resulting in the following:

$$S*\left(h\right)={\displaystyle \frac{S_v\left(h\right)}{S_{vi}}}={\displaystyle \frac{m{\left(\alpha h\right)}^n{[1+m^{-1}]}^{m+1}}{{\left[1+{\left(\alpha h\right)}^n\right]}^{\left(m+1\right)}}};0\le S*(h)\le 1$$

(6)

where Svi is the peak of the pore volume distribution, corresponding to the slope of the inflection point of the WRC.

Equation (6) was plotted against the equivalent pore diameter [de (μm)]. The S*(h) was compared according to Reynolds et al. [50], using “localization” parameters defined by the mean, mode, and median equivalent pore diameter (D_mean, D_mode, and D_median) and “shape” parameters Skewness and Kurtosis.

2.3. Root System Development

Soil trenches measuring 0.50 m (width) × 0.45 m (length) × 0.30 m (depth) were opened for the root development study using the cultural profile method. The vertical wall of the trench was maintained at 0.10 m from the plant trunk under the coffee plant canopy projection, from which the scarification of up to 0.05 m towards the interior of the soil was conducted to expose the roots. The roots were coated with a thin layer of white paint to provide a clear contrast between the roots and the soil [6,18].

A grid with 0.05 × 0.05 m² squares was placed precisely parallel to the trench wall and in front of the roots. Then, using a 14-megapixel digital camera, 2D digital images were obtained. Considering the maximum furrow preparation depth of 0.80 m and the dimensional constraints of the trenches, a total of 54 sampling points were established. The images were processed and aligned in the free software ImageJ software (version 1.53; National Institutes of Health, Bethesda, MD, USA) and later submitted to the Safira© v. 1.1 software [53], generating variables in root number (RN), root volume (RV) (mm³), root surface area (RSA) (mm²), root length (RL) (mm), and root diameter (RD) (mm).

2.4. Weather

The Thornthwaite and Mather [54] method was used to evaluate the water availability, using soil properties AWC, PWP, Bd, rainfall, evapotranspiration, and temperature to perform the water balance calculations for the Lavras region, from the Lavras weather station (83687/−21.226111° E; −44.979722° S). The monthly and annual average climatological temperature and precipitation data were acquired from the [55] database from 2012 to 2014.

2.5. Physiological Analysis

The gas exchange characteristics were analyzed in August 2012, low precipitation, LP, (5 months after the installation of the plastic cover) and in March 2014, high precipitation, HP, (2 years after the installation of the plastic cover) for all treatments studied and, in both Inceptisol I and Inceptisol II, using an infrared gas exchange analyzer, IRGA (Li-6400, Li-Cor, Lincoln, NE, USA). The photosynthetic rate (PR), stomatal conductance (SC), and transpiration rate (TR) were measured as follows: three leaves of three plants within the same treatment, fully expanded leaves were selected between 9 and 11 h, and the flux density of photosynthetically active photons was set in the chamber apparatus at 1800 μmol m⁻² s⁻¹. From these measurements, the water use efficiency (WUE) was calculated via the CO₂ assimilation (A) and transpiration (E), with the A/E ratio according to Larcher [56].

2.6. Statistical Analysis

All statistical analyses were carried out in R software, version 4.3.0, with the assistance of the tidyverse package [57,58]. The WRC model and its confidence interval were performed for each model involving the combination of the soil depth and treatments in each soil type using the stats and nlstools packages [57,59]. Analysis of variance (ANOVA) was used to compare soil physical properties and plant physiological characteristics within each soil type, without performing cross-soil comparisons. The basic assumptions of analysis of variance (normality, homoscedasticity, additivity, and independence of residuals) were tested and met, and the F-test reached significance (p < 0.05). The data were analyzed using a split-plot design, with mulching treatments allocated to the main plots and soil depth to the subplots. When treatment × depth interactions were observed, simple effects were evaluated by comparing treatments within each soil depth and soil depths within each treatment using Tukey’s test. Differences between treatments at a given depth were assessed using the minimum significant difference for treatments (MSD-T). In contrast, differences among soil depths within the same treatment were evaluated using the minimum significant difference for depths (MSD-D), both at p ≤ 0.05; for these, the stats and agricolae packages were used [57,60]. The Pearson correlation was performed using the stats and corrplot packages to evaluate the correlation between the physiological parameters of plants and soil physical variables [57,61].

Root data processed by the Safira© v. 1.1 software were used as the maximum value for the NR, the average for the RD, and the sum for the RV, RSA, and RL to ensure greater accuracy of the root variables within each square of the sample grid [6,18]. With the results obtained in each sampling grid unit, spatial interpolation of the root system was performed in QGIS 3.16.13 (QGIS Development Team, Open-Source Geospatial Foundation) [62], using the Multilevel B-splines interpolation method [63].

3. Results

3.1. Rainfall Regime and Water Balance

The rainfall regime from 2012 to 2014 (Figure 2) was lower than the 30-year climatological standard dataset. Mainly during March 2012 (plastic mulching implementation), August 2012 (the first physiology evaluation), and March 2012 (the second physiology evaluation). Also, a direct relationship between temperature increase and this reduction can be observed.

The monthly water balance (Figure 3 and Figure 4) shows that in 2012 and 2013, January had the highest precipitation (Figure 3A and Figure 4A). However, water deficit situations can be observed for both Inceptisols (I and II) from February to October, regardless of the years evaluated (Figure 3B and Figure 4B). Also, in both soils, from February to October, irrespective of the year, water storage and replacement can be observed, except for some months in which a water surplus was confirmed (Figure 3B and Figure 4B). On the other hand, water withdrawal was noticed from February to May and September to October (Figure 3B and Figure 4B), regardless of the years evaluated.

3.2. Water Retention and Root System

According to

Table 3. Parameters of the water retention curve.

Soil	Depth (m)	Treatment	α	n	m	Ɵsat	Ɵres	Ɵi	Ψi	R2
Inceptisol I	0.05	NP	0.56	1.64	0.39	0.65	0.22	0.48	3.84	0.99
		WP	0.78	1.56	0.36	0.65	0.22	0.49	3.00	0.98
		BP	0.70	1.61	0.38	0.68	0.23	0.51	3.20	0.98
	0.25	NP	0.64	1.62	0.38	0.67	0.24	0.51	3.45	0.98
		WP	0.46	1.64	0.39	0.65	0.23	0.48	4.73	0.96
		BP	0.79	1.51	0.34	0.63	0.24	0.49	3.15	0.98
	0.95	NP	0.67	1.75	0.43	0.65	0.25	0.49	3.00	0.99
		WP	0.78	1.59	0.37	0.62	0.26	0.48	2.89	0.97
		BP	0.70	1.55	0.36	0.64	0.24	0.49	3.38	0.97
Inceptisol II	0.05	NP	1.10	1.50	0.33	0.60	0.20	0.45	2.28	0.97
		WP	1.73	1.40	0.29	0.54	0.17	0.41	1.69	0.98
		BP	1.89	1.38	0.28	0.54	0.16	0.41	1.60	0.98
	0.25	NP	1.12	1.39	0.28	0.54	0.22	0.43	2.66	0.97
		WP	1.35	1.39	0.28	0.53	0.17	0.40	2.19	0.90
		BP	1.01	1.34	0.26	0.52	0.16	0.40	3.22	0.97
	0.95	NP	1.24	1.26	0.21	0.52	0.29	0.45	3.29	0.78
		WP	3.35	1.05	0.05	0.50	0.30	0.48	5.79	0.91
		BP	0.38	1.22	0.18	0.47	0.26	0.41	12.52	0.86

α, n, and m: empiric parameters; Ɵ_sat: saturation water content; Ɵ_res: residual water content; Ɵ_i: soil moisture in water content at the inflection point of the van Genuchten model; Ψ_i: matric potential at the inflection point of the van Genuchten model; and R²: coefficient of determination. No plastic (NP), white plastic (WP), and black plastic (BP).

, the management with plastic covering interferes with the position of the inflection point (Ψ_i). For Inceptisol I, the white plastic cover (WP) contributed to a leftward shift in Ψ_i at 0.25 m (4.73), the highest value for this soil. The Inceptisol I also showed an increase in the water saturation capacity (Ɵ_sat) at 0.05 m after the use of the black plastic cover (BP) (Table 3), at low matric potentials (0–4 kPa), confirmed by the water retention curve (WRC) shown in Figure 5. At 0.25 m, regardless of soil type, a decrease in the retention capacity was observed throughout the WRC interval, especially under BP coverage (Figure 5).

The WRC of Inceptisol II is smoother than that of Inceptisol I, with a lower water content at Ɵ_sat, as confirmed by Table 3 up to 33 kPa (Figure 5), demonstrating a reduced water capacity available to plants. The changes in the physical and hydraulic attributes were more visible in Inceptisol II. At the most superficial depths (up to 0.25 m), the plastic cover reduced water retention along the entire curve, especially between the saturation point at 0.05 m and 10 kPa, and between 10 and 1500 kPa at 0.25 m (Figure 5). At 0.95 m, the BP cover reduced water retention at low matric potentials (0–4 kPa), and the WP cover, at the same matric potentials (0–4 kPa), increased the water volume until the residual moisture (1500 kPa) (Figure 5).

The number of roots (NR) showed that covering with plastic, regardless of the color (black or white), promoted better distribution of the root system along the soil profile, which was not verified for the soil without the use of plastic cover (NP), with Inceptisol II having a higher RN than Inceptisol I (Figure 6).

3.3. Soil Physical Indicators

Analyzing bulk density (BD), the most pronounced effect was an increase in porosity of Inceptisol I (Figure 5) and a reduction in BD with BP, mainly at 0.25 m (Figure 7). There was no difference in soil depth across the treatments studied. The 0.95 m depth showed an increase in density at the surface (0.05 and 0.25 m) with the WP and BP use treatments.

The S index (Figure 8) did not promote significant changes in soil quality for any soil when comparing the treatments with the control (without using the plastic cover—NP). In Inceptisol I, the S index did not differ across soil depths; in Inceptisol II, the surface layer (0.00–0.25 m) had a higher S index across all treatments.

Compared to Inceptisol I, Inceptisol II showed a greater response to the plastic cover, resulting in a noticeable shift in the standard pore distribution curve to the left at depths of 0.25 m (Figure 9).

The mode equivalent pore diameter (D_mod) was unaffected by plastic mulching in any soil type or layer. In Inceptisol II, the application of BP decreased the mean equivalent pore diameter (D_mean) more than NP or WP. Inceptisol II had a median equivalent pore diameter (D_median) of 0.25 m at the other depths with WP application (Figure 10).

The air capacity (AC) did not change in both soils after plastic mulching (Figure 11). However, in the soil profile with the WP and BP (plastic covering), the AC was smaller at 0.95 m in depth for Inceptisol I and at 0.05 m and 0.25 m in depth for Inceptisol II.

There was no difference in relative field capacity (RFC) among treatments or at different depths in Inceptisol I. Inceptisol II showed a treatment effect only at 0.25 m, where the highest RFC values were observed without covering (Figure 11).

No significant differences were observed for micropores (Micro) and macropores (Macro) in Inceptisol I. The soil’s total porosity (TP) at 0.05 and 0.95 m was the least affected by mulching, regardless of plastic color. At 0.25 m layers, the BP showed lower TP. The TP of Inceptisol II was reduced in its entirety after plastic covering, highlighting the decrease in this variable with the use of the BP, regardless of soil depth. Macro was not influenced by plastic covering but by soil depth, decreasing in the following order: 0.05 > 0.25 > 0.95 m. Micropores exhibited the opposite behavior, being greater at 0.95 m (Figure 12).

Figure 13 shows the field capacity data related to the available water capacity (AWC) and permanent wilting point (PWP). For Inceptisol I, it did not promote significant changes in the AWC and PWP between treatments within each depth. On the other hand, at a 0.95 m depth, the absence of plastic mulching in Inceptisol I resulted in a reduced AWC, and the use of plastic, regardless of color (WP and BP), increased this variable at the superficial depth (0.05–0.25 m). Inceptisol II did not show significant differences in the AWC between treatments at each depth. Controversially, the PWP was reduced in both WP and BP compared with NP within each depth. For the same soil, a depth of 0.95 m showed an increased AWC and a decreased PWP across treatments.

3.4. Physiological Parameters

In high-precipitation (HP) conditions, the physiological endpoints evaluated (photosynthetic rate (PR), transpiration rate (TR), and stomatal conductance (SC)) did not differ significantly between treatments for Inceptisol I (Figure 14), as well as the efficiency of water use, which is obtained from the relationship between the variables PR and TR (A/E). However, the PR had significantly higher WP coverage under low-precipitation (LP) conditions than the NP. There were no significant differences from whether the plastic cover was used for the other physiological endpoints analyzed during the LP, SC, and TR periods, or in the efficiency of water use (Figure 14).

In LP and HP conditions, the photosynthetic rate was higher in the WP treatment in Inceptisol II (Figure 14). Stomatal conductance in the LP condition was higher in the WP treatment. In the HP condition, the BP treatment was higher than the NP treatment. However, it does not differ from the WP treatment (Figure 14). The transpiration rate in LP and HP was higher in WP compared with NP, but did not differ from BP.

The water use efficiency did not differ significantly between treatments in Inceptisol II. However, the WP was the treatment that showed greater improvements in the endpoints evaluated in Inceptisol II, as observed in the photosynthetic rate in Inceptisol I, regardless of rainfall. Physiological variables were generally higher under HP conditions across the soils and treatments tested (Figure 14).

3.5. Correlation Insights

The significant correlations (Figure 15) regarding Inceptisol I show that the soil bulk density (BD) has a positive relationship with SC and TR for the low rainfall season at 0.95 m, that is, higher BD (within the observed values: 1 to 1.3 g cm⁻³) results in higher SC and TR values. Higher AC values in the surface layer significantly reduced SC and TR during dry periods, but not the PR. Regarding the surface, this results in a decrease in the total porosity (TP). The correlations were significant only for the wet season in Inceptisol II. There was an increase in the TR, with a greater proportion of macroporosity at the expense of microporosity (under the established experimental conditions), and a considerable rise in WUE across the entire profile.

4. Discussion

4.1. Rainfall Variability and Soil Water Balance

The unexpectedly high water precipitation in January 2012 and 2013 (Figure 3A and Figure 4A) contradicted the typical climatological pattern, as depicted in Figure 2. Precipitation at the beginning of these two years was about twice that of the same month in 2014 (Figure 2). During these periods, rainfall water can infiltrate deep layers of the soil profile, flowing to the water table or the drainage channel through subsurface runoff [64]. This condition explains why the water surplus is higher for January 2012 and 2013 than for 2014 (Figure 3B and Figure 4B).

4.2. Soil Water Deficit and Implications for Perennial Crop Development

The water deficit conditions observed in both Inceptisols from February to October, regardless of the years evaluated (Figure 3B and Figure 4B), are a worrisome condition for citrus development, as water availability is a prerequisite for terrestrial plant life, and water deficits frequently limit plant growth [65]. Carvalho et al. [66] studied coffee, a perennial crop like citrus. They reported that the plant’s water demand is often higher than its crop transpiration, leading to a water deficit. For this reason, as a water deficit is observed (Figure 3B and Figure 4B), water accumulated in the soil is required, demanding water replacement [67].

4.3. Available Water Capacity and Soil Physical Controls

Soil water storage is an efficient method for quantifying the plant’s available water [18,68,69]. Still, it depends on some variables, such as texture, organic matter content, and soil structure [14,15,70]. The Inceptisol I showed a higher AWC (117 mm) (Figure 3A) when compared to Inceptisol II (103 mm) (Figure 4A), which may be related to a higher concentration of silt and clay, to the detriment of sand-sized particles in the Inceptisol I composition (Table 2), in addition to its better structure in the soil profile than Inceptisol II, as confirmed by the Supplementary Data.

The water withdrawal from February to May and from September to October (Figure 3B and Figure 4B) is not expected for the region, so it is an atypical event, which was repeated from 2012 to 2014, justifying the use of agronomic techniques that offer alternatives to meet the perennial crop water demand, like soil covering as plastic mulch [23]. According to Gonçalves, [71], the underwater deficit can be said to retain water through the soil matrix force. Therefore, this water is maintained by adsorption, which is unfavorable to plant growth, mainly under Inceptisol [15]. Additionally, the increase in temperature and the decrease in precipitation (Figure 2) directly affect flowering and, therefore, the productivity of citrus crops [72]. The optimization of fruit production with the maximum use of available resources has gained force not only to increase productivity, but also for social reasons [3]. Thus, citrus producers must adopt good agricultural practices in compliance with labor and environmental legislation and sustainability standards [6,7]. In this scenario, the plastic cover is shown to be an advantageous alternative [23].

4.4. Effects of Plastic Mulching on Soil Physical and Hydric Properties

The inflection point is an alternative method for estimating the field capacity [14,15,73], indicating the optimal water content for satisfactory soil management and plant uptake [47]. The inflection point can be displaced to a point of greater stress in degraded soils due to the increase in microporosity [74]. For Inceptisol II, this situation is observed at depth (0.95 m) when the BP raises the Ψ_i to 12 kPa, which is much higher than that of the NP condition (3.29) (Table 3).

Corroborating with the data shown in Figure 5, Inceptisol I, under BP covering, was more effective in the superficial layer (0.05 m). This response is likely associated with changes in the surface soil structure and pore size distribution induced by reduced evaporation and rainfall impact, suggesting a temporary enhancement in water retention at low matric potentials (−4 kPa). At a 0.25 m depth, the reduced water retention observed in both soils, particularly under black plastic mulching, may be associated with changes in pore size distribution and enhanced drainage, likely driven by increased macropore continuity (Figure 9 and Figure 11), possibly due to the moisture redistribution under the plastic cover. Similar results were found in mulching studies [75,76,77,78,79]. Explicitly using the plastic cover promotes more significant moisture conservation on the soil surface [23,79,80,81]. In this way, protecting the surface layer helps conserve water and favors crop productivity, such as citrus [82]. According to Libardi, [83] more than 60% of the citrus root volume is found within the top 0.20 m of soil; therefore, improving water absorption efficiency by plants, especially in this soil layer, is beneficial. This condition confirmed the results of the present study because the presence of the plastic cover at 0.95 m (Figure 5) may indirectly improve soil conditions, potentially facilitating deeper root growth, as evidenced by greater root development (Figure 6).

The beneficial effect of water retention has been more pronounced in Inceptisol II (Figure 5) due to its soil intrinsic characteristics, such as the B incipient horizon. However, pedogenetic processes, such as clay translocation and mineral transformation, are still incipient and have not progressed sufficiently to form a well-developed B horizon with pronounced structural differentiation, color development, or clay accumulation [17]. It is emphasized that having greater water retention in the Inceptisol and greater efficiency in the water use by the plant are determining factors for better crop performance [15,16], especially in regions of hot and dry climates, with extended droughts [84], or with a critical dry period for the study region [55,85]. As reported by [86], irrigation is unavailable in this region, and evaporation exceeds the rainfall season during the year, which can be confirmed in Figure 3A and Figure 4A. According to INMET [55], the 2013/2014 rainy season showed irregular rainfall distribution, and a high rainfall deficit was observed in Minas Gerais. In this way, strong and prolonged dry spells were identified in January and February, and the water absorbed by the soil was lost through evaporation, leading to a water crisis mainly in the second half of 2014 (Figure 2).

Based on the analysis of the cultural profile (Supplementary Data), it is noteworthy that Inceptisol II had a clear stony structure at 0.95 m, which mainly reflects the general increase in BD in all treatments studied (Figure 7). A general decrease in soil BD after the plastic mulching application, as shown in Figure 7, has been reported by many studies due to better conditions maintained under the mulched plots that avoided soil crusting and compactness [35,87]. Van der Meulen et al. [88] classified soils as being loose, friable, and well-aerated, and also roots have easy access to adequate oxygen, promoting high microbial activity in plastic mulch systems [89].

However, a lack of effect on the soil bulk density was also reported, and a mitigating impact of plastic mulching on soil compaction, in that case, was observed based on other variables such as the soil penetration resistance, especially on surface layers [24]. On the other hand, Sintim et al. [24] found that plastic mulching had no significant effects on the BD of two types of soil with wheat and clover crops in the USA within the four years assessed (from 2015 to 2018).

As proposed by Dexter [48], the S index is an indicator of soil quality and estimates the soil microstructure responsible for many essential physical properties. According to the limits set by Andrade and Stone [90], both soils have a good structural quality with S index values above 0.045 (Figure 8). However, when comparing the treatments studied with the NP, the plastic cover did not promote significant changes in soil quality for any soil, as assessed by the S index, even though it is considered a soil conditioner [91], which was not expected [75]. Vasques et al. [92] stated that the S index should not be considered alone to distinguish the effects of soil management, but together with other indicators such as soil bulk density, porosity, and visual assessment of the soil profile, as can also be inferred from the soil profile data from this present study. On the other hand, the lower values of the S index for Inceptisol II were attributed to 0.95 m (Figure 8), where the physical restriction due to stoniness conditions becomes quite evident for this same soil (Supplementary Data).

The different effects of plastic mulching across the two soils reflect the greater homogeneity of Inceptisol I (Supplementary Data) in pore size distribution throughout the profile, with its structural stability less affected by management (Figure 9). The opposite is observed for Inceptisol II, mainly at a depth of 0.25 m. This condition can also be associated with root development (>root number) in these depths for the same soil, as shown in Figure 6. It implies a decrease in the pore volume with a large diameter (>200 µm) (aeration function) for those with a smaller diameter (water retention function), with the most prominent variations observed when using the BP (Figure 9).

The remarkable effectiveness of black plastic in altering soil physical properties remains poorly studied. Still, the significant efficacy of black plastic material has already been demonstrated for yield, vegetative growth, and water use efficiency (WUE) due to its ability to alter the soil hydrothermal regime [93,94]. The pore space was reduced by 15% at 0.15 m by using transparent plastic mulch during two harvests (Vigna mungo and Arachis hypogaea) in Tamil Nadu, with a tropical climate in a red sandy loam soil [87]. The authors also reported reduced soil bulk density and increased hydraulic conductivity, and both soil properties contributed to higher yields and the highest net returns for these crops. Confirming this condition, Silva et al. [16] stated that the compaction caused by soil preparation equipment beyond the soil’s friability zone increased the soil density, which led to a decrease in the hydraulic conductivity of the Inceptisol.

The parameters proposed by Reynolds et al. [50], i.e., D_mod, D_mean, and D_median, were also extracted from the displacement of the standard pore distribution curves of both Inceptisols (Figure 10). This data corroborates Figure 9 concerning the most homogeneous Inceptisol I soil profile. Both pore size parameters are larger (>microns) in Inceptisol II, corroborating the soil profile description in the Supplementary Data, and have a higher sand content than Inceptisol I (Table 2), with a considerable and visible stone content (>0.02 m), also confirmed by the Supplementary Data. D_mod is related to the most frequent-diameter pores, complementing the information already extracted from Figure 10. The BP cover decreased D_mean, which is consistent with previously analyzed higher bulk density (Figure 7). This fact is associated with the leptokurtic kurtosis of the pore distribution, as shown in Figure 9 and Figure 10, indicating a greater probability of obtaining values closer to the median or mode than to the mean [6,50].

There is a greater AC and plant water availability pattern at surface layers (Figure 11, Figure 12 and Figure 13). The physical barrier of a plastic cover could mitigate erosion and the impact of rain droplets on the soil [10], thereby affecting the aggregate stability and air capacity, corroborating the results from Figure 11. Sintim et al. [24] observed this positive effect of plastic mulching. Still, significant differences between the two studies can be highlighted: experiment duration, since our research lasted half the time, and climate, since the latter was conducted in a humid subtropical and cool Mediterranean climate.

According to Reynolds et al. [50], the reference value for AC is >0.10 m³ m⁻³, and both Inceptisols presented within this limit with or without any plastic cover in all the surface layers (Figure 11). The AC in Inceptisol II is outside the optimum range at 0.95 m due to its inherent blocky structure. Reynolds et al. [50] also proposed an optimum range for AWC: 0.20 m³ m⁻³, and, as with AC, Inceptisol I had values above this threshold, but Inceptisol II is below it at 0.95 m (Figure 11). Again, the blocky structure of Inceptisol II can be responsible for this fact (Supplementary Data). Some authors have already described the RFC results (Figure 11) since using a plastic cover in the field can decrease rainwater capture and its use by plants [36].

Regarding the results shown in Figure 12, soil physical attributes, particularly macro- and microporosity, exhibited high sensitivity within Inceptisol II. This response may be attributed to the soil structure of Inceptisol II, which presents stony blocks in the subsurface, as previously described. These results are consistent with AC (Figure 11) and AWC (Figure 13) values being outside the optimal range, indicating that plastic mulching management was insufficient to improve the soil physical quality in Inceptisol II at deeper layers.

4.5. Soil–Plant Interactions and Physiological Responses of Citrus

The data relating to Figure 14 corroborate those of Liao et al. [95], who found an increase in the PR in growing apple trees under varied mulching conditions compared with cultivation without covering. Hou et al. [96] attributed the increase in the net photosynthetic rate in plastic-soil mulching treatment to optimizing the C/N, C/P, and N/P nutritional ratios in wheat leaves. For maize, Niu et al. [97] found an increase in the PR associated with a higher stomatal density and larger ostiole opening size. Li et al. [98] tested different mulches (no mulch, transparent film mulch, biodegradable transparent film mulch, and biodegradable black film mulch). They indicated that biodegradable black film mulching was the best treatment for increasing the photosynthetic capacity and productivity of the corn crop. Yamamoto and Miyamoto [99], when studying fruit crops (cherry and pear trees) in the integrated field and greenhouse experiments, verified an increase in the photosynthetic rate of 2.1 µmol CO₂ m⁻² s⁻¹ for cherry trees and 3.2 µmol CO₂ m⁻² s⁻¹ for pear trees in reflective sheet mulching conditions. Although the water use efficiency was not altered by the treatments tested in HP or LP, the suggestion of using WP coverage for Inceptisol I proved interesting, as agricultural productivity is directly associated with the higher photosynthetic rate achieved with this treatment (Figure 14) [100].

Concerning the data related to the photosynthetic and transpiration rates (Figure 14), Niu et al. [97] reported an increase in the PR when using plastic film mulching compared to no mulching in the booting and grain filling stages. According to the authors, this may have occurred because of the high photosynthetic capacity required during these phases, suggesting the need to increase transpiration to enhance nutrient absorption.

Although the process of stomatal conductance regulates both the entry of external carbon into the plant, which will be diffused into the interior of the plant until it is assimilated by the Calvin cycle and the amount of water vapor eliminated by the plant, which is called transpiration, it is known that in the same stomatal opening, the CO₂ input is much greater than the water vapor output. Thus, the greater CO₂ input at a given stomatal conductance may intensify photosynthesis by increasing CO₂ assimilation in the biochemical phase, thereby increasing the net photosynthetic rate, but not always promoting a proportional increase in transpiration. On the other hand, regarding water use efficiency (Figure 14), the WP was the most indicated for better performance, suggesting a possible increase in productivity.

According to Brito et al. [101] and Fernandes et al. [102], in a condition of greater water availability, when an anoxic condition is not present, plant performance tends to be high or maintained. The fact that in the WP cover, the PR was maintained both in low and high precipitation (with no significant difference for the rainfall regimes) (Figure 14) demonstrates that the plastic cover can be indicated to maintain the photosynthetic rate regardless of water availability, so that the productivity of the citrus crop is not affected in a situation of water scarcity, in the different types of soils studied here. However, the ratio of the parameters PR and TR, which allows for the inference of the water use efficiency, was higher in all treatments installed in Inceptisol I under an LP condition. This situation indicates that in a condition of lower water availability, the water use efficiency of plants is adjusted, tending to an increase, so that their water-dependent functions are maintained, even with a lower availability of water in the soil [103].

The correlations presented by BD with SC and TR for the low rainfall season at 0.95 m (positive) and AC with SC and TR at 0.05 m (negative) indicate plant mechanisms to reduce water losses under water deficit conditions [103,104], corroborating the data in Figure 14. Under more humid conditions, higher AC values at a 0.95 m depth promote increases in the PR and TR. Good physical conditions favor root system development (Figure 6) and increase photosynthesis and transpiration rates (Figure 14). Due to the precipitation deficit, a reduced surface AWC (0.05 m) tends to limit actual transpiration through stomatal regulation under water stress. During the wet season, greater water availability at depth (0.95 m) may enhance root water uptake, allowing for a higher PR when absorption roots access deeper soil moisture.

A decrease in the surface total porosity (TP) significantly reduces the PR, SC, and TR, as the plant can have difficulty absorbing water in dry soil with reduced porosity. This relationship is significant only at depth (0.95 m) for wetter conditions. These soils, with oxic horizons, have good water infiltration and percolation through the profile. When associated with good root development at depth (Figure 6 and Supplementary Data), these factors favor the use of plants’ resources to increase the PR. However, this same configuration of pores with a high TP for the oxic horizon in Inceptisol I at depth (0.95 m) can lead to a decrease in the efficient use of water (WUE) by the plant, once the water balance may favor drainage rather than absorption by the roots [105,106].

In the surface layers (0.05–0.25 m), the increase in larger-diameter pores can reduce the SC and TR (Figure 15) as a plant mechanism to alleviate the water deficit. This mechanism will also be activated if, in subsoil conditions (0.95 m), the pore diameter (D_mod, D_mean, and D_median) is increased, considering that these values are already considered macropores (>73 µm) [9,52].

With increasing microporosity, meaning pores that retain water in the soil matrix with greater tension, the SC and TR rates tend to increase significantly at 0.95 m (Figure 15). However, the excess of micropores that retain water at very high tensions (PWP), characterizing the water deficit, can significantly impair plant development [14,15] by reducing the SC and TR (Figure 15), as observed at the surface (0.05 to 0.25 m). Regarding Figure 13, the reduction in the PWP observed under both plastic mulching treatments, regardless of color, may be associated with improved soil physical conditions resulting from a more favorable pore-size distribution (Figure 9 and Figure 15), which reduces the proportion of water retained at high matric potentials (Table 3 and Figure 5). These results suggest that soil protection provided by plastic mulching minimizes water retention in small pores compared with the no-cover treatment (no plastic).

4.6. Agronomic Implications of Plastic Mulching Under Water-Limited Conditions

In general, our data show that the use of plastic cover under citrus crops for Inceptisol I (deeper) and Inceptisol II (shallow) promoted changes in the physical-hydric attributes, with a greater influence in the surface layer (0.00–0.25 m). Concerning the evaluated period (2012–2014), characterized by a water deficit driven by persistent dry spells, the management based on white plastic had the best response for the photosynthetic rate, regardless of the soil studied. The superior photosynthetic performance under white plastic mulching may be attributed to its higher reflectance, a well-established property of light-colored materials, which reduces excessive soil and canopy heating and promotes a more favorable microclimate for physiological processes by maintaining more stable soil temperature and moisture conditions. The white mulching treatment was suggested to alleviate thermal and water stress, thereby enhancing photosynthetic activity. Our results corroborate those presented in studies using soil management with plastic cover for crops such as watermelon [107], tomato [108], potato [109], sweet pepper [110], onion [111], vine [112], melon [113], conventional peanut [114], maize [81], wheat [115], and more recently also for perennial fruit crops [23], such as citrus [116].

In this way, the practice of using plastic covers proved to be beneficial, as the loss of water via evaporation is generally lower when using the cover, improving water use and its conservation in the agricultural scenario [117], reflected in better fruit plant growth [23].

5. Conclusions

The use of plastic mulching on the soil surface in regions characterized by recurrent drought and water deficits proved effective in reducing physiological stress in citrus plants and improving soil physical quality indicators. Inceptisol II showed evident changes in physical-hydric attributes, particularly in the surface layer (0.00–0.25 m), where a lower soil bulk density, improved structural quality, and reduced micropore volume were observed. White plastic mulching promoted higher photosynthetic rates under both high- and low-precipitation conditions. This same plastic cover was associated with inefficient water use and showed a positive and significant correlation with macropores and micropores at all depths evaluated in Inceptisol II. Inceptisol I, due to its greater structural stability, did not show substantial impacts related to the use of plastic mulching, except for the physical attributes of soil bulk density and total porosity. Black plastic mulching produced the best results, with reductions in soil bulk density and increases in total porosity, both of which showed positive, significant correlations with the transpiration rate. However, it should be emphasized that adopting plastic mulch requires consideration of agronomic and environmental limitations, such as reduced rainwater infiltration and difficulties with fertilizer application, which require careful management practices. In addition, the accumulation of plastic residues represents an environmental concern, highlighting the importance of appropriate disposal strategies and the use of alternative materials, such as biodegradable mulches. Overall, the results indicate strong potential for the use of plastic mulching in citrus cultivation, encouraging further research focused on the operational and environmental limitations associated with soil physical quality indices and their relationships with different physiological variables, particularly in long-term studies and in areas with frequent water scarcity or economic constraints on irrigation systems across different soil types.