Sustaining Grape Yield and Soil Health Under Saline–Sodic Irrigation Through Amendments and Canal Water Application

Abstract

The present study was undertaken for six years to appraise the responses of four-year-old established grapevines (Vitis vinifera L., cv. Perlette) to saline–sodic groundwater irrigation in relation to different amendments in a field experiment on non-saline, non-sodic calcareous sandy loam soil under a semi-arid climate at the research farm of Punjab Agricultural University, Regional Research Station, Bathinda, Punjab, India. Different water quality treatments, viz., canal water or good-quality water (GQW), poor-quality saline–sodic groundwater (PQW), alternate irrigation of canal water and groundwater (GQW/PQW), PQW with 50% gypsum (CaSO₄·2H₂O) requirement (PQW + GR₅₀), PQW with 100% gypsum requirement (PQW + GR₁₀₀), and PQW with sulphitation pressmud (by-product of sugar industry) @ 6.6 t ha⁻¹ on a dry weight basis (PQW + SPM), applied in furrows, were imposed in quadruplicate with a randomized block design. PQW with an electrical conductivity (EC) of 2.2–2.4 dS m⁻¹, residual sodium carbonate (RSC) content of 6.21–6.44 mmolc L⁻¹, and a sodium adsorption ratio (SAR) from 23.1 to 24.8 (mmolc L⁻¹)^0.5 was used during the course of experimentation. The pooled mean 6-year data showcased that the treatments GQW/PQW, PQW + GR₅₀, PQW + GR₁₀₀, and PQW + SPM improved the berry yield by 28.3%, 11.3%, 21.2%, and 31.0%, respectively, when compared with PQW. Use of amendments, i.e., gypsum, sulphitation pressmud, and practice of GQW/PQW for irrigation in a cyclic mode, helped in reducing the pH, SAR, and bulk density (BD) of surface soil (0–15 cm) and enhancing the final infiltration rate (FIR) of soil and berry yield. A maximum water use efficiency (WUE) of 3.99 q ha⁻¹-cm was recorded in the GQW treatment, followed by 3.93, 3.72, and 3.68 q ha⁻¹-cm in the PQW + SPM, GQW/PQW, and PQW + GR₁₀₀ treatments, respectively. Application of amendments alongside PQW evidenced a significant enhancement in total soluble solids (TSSs) and a decrease in the acidity of berries as compared to PQW. These results suggest that table grape yield (cv. Perlette) on calcareous sandy loam soil under saline–sodic groundwater irrigation can be sustained with the application of PQW + GR₁₀₀, sulphitation pressmud, and GQW/PQW in already-established grapevines with minimal detrimental effects on soil health.

1. Introduction

Dwindling irrigation water supplies significantly threaten farming in arid and semi-arid parts of the world. In India, good-quality water is not available in adequate quantities for crop irrigation. In the northwestern states of India, about 41–84 percent of the groundwater is brackish [1]. In Indian Punjab, 41 percent of water is of poor quality, of which sodic water comprises 54%, saline water comprises nearly 22%, and saline–sodic water accounts for 24 percent [1,2]. The major constraint in crop production in the southwestern region of Indian Punjab is an acute shortage of canal water and good-quality underground water for surface irrigation. Sub-surface water in this zone of Punjab contains modest levels of sodium and chloride and higher levels of bicarbonate salts. Bicarbonate levels are determined by the amount of available sodium in the water and its impending effect on sodium levels in the soil. Unreliable and inadequate canal water supplies are being supplemented using brackish groundwater, a common practice amongst farmers. Long-term, sustained poor-quality water irrigation harms soil physicochemical characteristics, reducing crop productivity. It also poses severe risks to soil quality and affects natural resources and the surroundings [1]. However, brackish groundwater can be used appropriately by following suitable management practices [3] and adopting different strategies, viz., growing salt-tolerant plants, using chemical and organic amendments, and/or alternating with good-quality waters. Alternate usage of canal water with poor-quality irrigation water is a feasible and concrete preference for mitigating the detrimental properties of saline/sodic irrigation water for sustaining crop productivity and soil health. ‘Sustaining’ refers to the capacity to preserve ecological balance and resource availability over time, whereas ‘soil health’ includes the biological, physical, and chemical characteristics of soil that contribute to its vitality and productivity [4,5]. The cyclic use of good- (canal water) and poor-quality irrigation waters [6,7,8] prevents the soil from becoming saline/sodic and allows for the substitution of salty water for 50% of the irrigation requirement. Moreover, the use of amendments like gypsum, sulfuric acid, hydrochloric acid, and other acid formers may also improve the quality of brackish water [7,9,10]. The salts’ concentration in the soil’s surface root zone is below the permissible limits and must be maintained to ensure viable crop production. Therefore, specific and efficient management systems need to be followed to arrest the declining trend in productivity and provide economic returns over the years [11]. Practical options should be adopted for ameliorating brackish waters to attain higher yields, accompanied by improved physical and chemical properties of soils, attaining saline or sodic or saline–sodic waters, and monitoring salinity/sodicity build-up in the soil [12,13].

Organic material incorporation is a viable alternative for mitigating the adverse effects of poor-quality water by utilizing native calcium from CaCO₃ and other calcium-bearing minerals [12,14,15]. Regular additions of organic materials are therefore important for maintaining good soil physical conditions and fertility when irrigating with brackish water [16,17,18]. Such practices help decrease soil pH and the exchangeable sodium percentage (ESP), while also improving the soil infiltration rate and crop yields [15]. Among the various organic materials, sulphitation pressmud—a by-product of the sugarcane industry—contains a high amount of organic matter [19]. Owing to its acidic nature, it positively influences the physicochemical properties of alkaline soils, in addition to serving as a potential source of nutrients [20]. Long-term use of water with a high sodium adsorption ratio (SAR) may harm soil health, an issue that can be alleviated through the application of amendments. Continuous irrigation with high-SAR water replaces calcium and magnesium in the soil with sodium from the irrigation water. This leads to the dispersion of clay particles, hindering the formation of stable soil aggregates. Consequently, soil structure deteriorates, reducing infiltration and permeability to applied water [21], ultimately affecting crop production.

Grapevines (Vitis vinifera L.) are moderately sensitive to salinity, with the threshold electrical conductivity of the soil saturation paste for yield reduction being 1.5 dS m⁻¹ [22,23]. However, grapevines’ response to soil salinity and sodicity depends on several factors, including cultivar, rootstock–scion combinations, irrigation management, irrigation water quality, plant development stage [24], and soil-climatic conditions (temperature, rainfall, humidity, evaporation, etc.), as well as sodicity and waterlogging [25]. Martínez-Moreno et al. [23] examined the medium-term effects of deficit irrigation using saline water on vineyard yield, vine water status, fruit composition, and vine nutrient content in a commercial vineyard in Spain during 2019–2020. They reported that deficit irrigation with saline water moderately reduced grape yield but did not significantly alter grape composition. Growth decline in grapevines under saline conditions is attributed to ion toxicity and/or low osmotic potential, which negatively affect physiological and biochemical processes. Understanding the complex interplay between brackish water use, soil health, and grapevine productivity is essential for developing sustainable farming practices that mitigate the adverse impacts of salinity while maintaining grape production under evolving environmental conditions. The primary goals of irrigation water management in vineyards are to enhance water and crop productivity, improve fruit quality [26], and minimize soil deterioration when using marginal waters. In the southwestern region of the Indian Punjab, grape cultivation is widely practiced. The underlying hypothesis of this study is that alternating the use of poor-quality water with good-quality water, combined with gypsum and sulphitation pressmud application, can mitigate the harmful effects of marginal waters on soil, thereby improving berry yield and water-use efficiency. The main objective of the research was to evaluate the potential of using poor-quality saline–sodic groundwater (PQW) in combination with chemical amendments and/or organic materials and supplemented with good-quality canal water (GQW) to achieve sustainable berry yield while minimizing soil health risks in an established vineyard under semi-arid conditions in non-sodic, non-saline, light-textured calcareous soils.

2. Materials and Methods

2.1. Experimental Location, Climate, and Soil

A field study was conducted from 2008 to 2013 at the experimental farm of Punjab Agricultural University, Regional Research Station (PAU–RRS), Bathinda, Punjab, India, on an already established grape vineyard that was in poor condition due to the lack of good-quality canal irrigation water. To address this, the performance of the existing vineyard was evaluated using natural PQW in combination with GQW and soil amendments. The experimental site (Figure 1), located in a semi-arid region with an average annual rainfall of 400 mm, receives 70–80% of its rainfall between July and September during the monsoon season. The soil texture generally ranges from loamy sand to sandy loam, and occasional frost events occur during the winter months (December–January). Climatic parameters—including total rainfall, total evaporation, mean annual relative humidity (RH_min and RH_max, %), and mean annual air temperature (mean T_min and mean T_max, °C)—were recorded at a climatological observatory located approximately 800 m from the experimental site during the study period (

Table 1. Mean annual temperature, mean annual relative humidity, total annual pan evaporation, total annual rainfall, and irrigation water applied during the growing season.

Year	Mean Annual Temperature (°C)		Mean Annual Humidity (%)		Total Annual Pan Evaporation (mm)	Total Annual Rainfall (mm)	Irrigation Water Applied (IWA, cm)
	Maximum (Tmax, °C)	Minimum (Tmin, °C)	Maximum (RHmax, %)	Minimum (RHmin, %)
2008	30.7	16.5	84.9	43.9	1714	433	308
2009	31.3	17.0	81.7	39.9	2121	293	336
2010	31.0	17.7	83.7	43.3	1795	465	336
2011	30.5	17.1	85.7	45.8	1614	431	308
2012	30.7	16.8	81.1	37.5	1924	263	308
2013	30.6	17.6	79.9	38.8	1692	262 *	308

Note: * During the study period up to June 2013.

).

Canal water irrigation in the region is supplied through a river-fed canal network under the Warabandi system. The term Warabandi is derived from two Urdu words: Wara (turns) and Bandi (fixed), referring to fixed weekly turns for irrigation allotted to farmer based on landholding size and canal discharge. The actual irrigation turn is calculated by dividing the total number of minutes in a week by the total irrigated area (in hectares) saved by a given outlet [27]. The year-wise irrigation amount and annual water use, including rainfall per vine, are presented in Table 1. However, canal water availability is often unpredictable and insufficient. Therefore, the efficient conjunctive use of brackish water with good-quality water is of paramount importance for sustaining land resources and maintaining crop productivity in such regions.

The experimental soil was classified as sandy loam, consisting of 80.2% sand, 12% silt, and 7.8% clay. At the beginning of the experiment, the surface layer (0–15 cm) had a pH of 8.36, an electrical conductivity (EC) of 0.281 dS m⁻¹, and an organic carbon (OC) content of 3.4 g kg⁻¹ soil. The topsoil also contained 135 kg ha⁻¹ nitrogen (N), 14.2 kg ha⁻¹ phosphorus (P), and 383 kg ha⁻¹ potassium (K). Additional information on the initial physicochemical properties of the soil profile is provided in

Table 2. Average physicochemical properties of the soil profile at the beginning of the experiment.

Depth (cm)	pH1:2	EC1:2 (dS m−1)	Bulk Density (Mg m−3)	OC (g kg−1)	Water Content (%)		Available Soil Water (cm)	CaCO3 (%)
					1/3 bar	15 bar
0–15	8.36	0.281	1.45	3.41	25.9	7.4	2.7	4.72
15–30	8.40	0.274	1.57	3.13	27.2	8.5	2.8	3.41
30–60	8.47	0.269	1.50	1.41	26.6	9.5	5.5	4.80
60–90	8.56	0.282	1.45	1.10	28.6	9.5	5.6	3.68
90–120	8.52	0.303	1.49	1.05	27.0	9.8	5.2	4.14
120–150	8.44	0.296	1.52	0.96	28.1	8.0	5.7	2.56
150–180	8.23	0.271	1.54	0.89	27.4	8.7	5.6	3.29

Note: The values are indicative of the average of single data from four soil profiles at the experimental site.

.

2.2. Water Quality

Two types of irrigation water were used in the experiment: fresh canal water of good quality (GQW) and natural tubewell groundwater of poor quality (PQW). The RSC and EC of GQW ranged from −0.6 to 0.5 mmol_cL⁻¹ {SAR = 0.85 to 0.93 (mmol_c L⁻¹)^0.5} and 0.30 to 0.45 dS m⁻¹, respectively. In contrast, PQW had RSC values of 6.21–6.44 mmol_cL⁻¹ {SAR = 23.1 to 24.8 (mmol_cL⁻¹)^0.5} and EC values of 2.2–2.4 dS m⁻¹ (

Table 3. Irrigation water quality parameters of PQW and GQW were collected every year in the pre- and post-monsoon seasons during the course of study.

Parameters	PQW	GQW
pH	9.12–9.32 (9.22) *	8.24–8.38 (8.31)
EC (dS m−1)	2.2–2.4 (2.3)	0.30–0.45 (0.38)
Na+ (mmolc L−1)	29.0–30.4 (29.7)	0.79–0.86 (0.83)
Ca2+ + Mg2+ (mmolc L−1)	3.0–3.4 (3.2)	1.4–1.7 (1.6)
${\mathrm{CO}}_3^{2-}$ (mmolc L−1)	3.22–3.76 (3.49)	0.14–0.2 (0.17)
${\mathrm{HCO}}_3^{-}$ (mmolc L−1)	4.91–5.68 (5.30)	0.8–1.0 (0.9)
RSC (mmolc L−1)	6.21–6.44 (6.33)	−0.6–0.5 (−0.05)
SAR (mmolc L−1)0.5	23.1–24.8 (24.0)	0.85–0.93 (0.89)

Note: * Values in parentheses indicate average.

). RSC, which is used to assess the sodicity hazard of waters rich in carbonates and bicarbonates, is expressed as follows [28]:

$$RSC=\left({CO}_3^{2-}+{HCO}_3^{1-}\right)-\left({Ca}^{2+}+{Mg}^{2+}\right)$$

(1)

The cations and anions were expressed in mmol_c L⁻¹. At Punjab Agricultural University, Ludhiana, Punjab, India, the permissible limits for non-hazardous use of irrigation water in crop production are set at EC < 2.0 dS m⁻¹ and RSC < 2.5 mmol_c L⁻¹ under Indian Punjab conditions. However, critical limits for evaluating RSC and EC in irrigation water may vary depending on soil type, rainfall distribution and frequency, cropping sequence, and other local factors.

2.3. Experimental Description and Treatment Designations

The experiment was conducted using a randomized block design with four replications, and the treatments were applied to four-year-old grapevines (cv. Perlette). The cultivar Perlette accounts for more than 95% of the total grape acreage in Punjab as well as across North West India. The study comprised six treatment combinations of irrigation water quality and amendments: (i) GQW, (ii) PQW, (iii) GQW/PQW, (iv) PQW + GR₅₀, (v) PQW + GR_100, and (vi) PQW + SPM at 6.6 t ha⁻¹ on a dry weight basis (

Table 4. Summary of experimental treatments.

Treatments	Treatment Designation
All irrigations with canal water or good-quality water	GQW
All irrigations with poor-quality saline–sodic groundwater	PQW
Alternate irrigation of the canal and saline–sodic groundwater	GQW/PQW
All irrigations with PQW + 50% gypsum requirement	PQW + GR50
All irrigations with PQW + 100% gypsum requirement	PQW + GR100
All irrigations with PQW + sulphitation pressmud @ 6.6 kg per vine on a dry weight basis	PQW + SPM

).

A total of 24 rows with seven vines per row, planted at 3 m × 3 m spacing under the bower system, were selected to randomize the six treatments in quadruplicate within a block. In the bower system, vines are spread over a pandal mounted 2-2.4 m above the ground on concrete poles. Vines are trained as a single stem up to approximately 6 feet and are trained to develop at least two primary arms, forming a uniform network of secondary and tertiary branches along the bower [29]. To avoid border effects, the outermost vines of all rows in each treatment and the entire perimeter row of the four blocks were excluded from measurements. The active growing period of grapevines in this region extends from February (spring) to June (mid-summer).

Organic amendment sulphitation pressmud—a by-product of the sugarcane industry [19,20]—and chemical amendment gypsum (CaSO₄.2H₂O; agricultural grade; 70% purity) were applied annually in a 1 m wide band beneath the vine canopy after pruning in January, before the spring season. Sulphitation pressmud serves as a good and inexpensive source of organic material and helps mitigate the harmful effects of poor-quality water on soil (

Table 5. Composition of sulphitation pressmud.

Parameters	Values
EC1:5 (dS m−1)	0.24–0.26
pH1:5	6.0–6.2
C (%)	38–40
N (%)	1.8–2.0
P (%)	1.2–1.3
K (%)	0.4–0.5
S (%)	0.27–0.31
C:N	20–21:1

). Gypsum was applied to reduce the sodium hazard of irrigation water in the soil.

Eleven to thirteen irrigations, each of 2.8 cm depth, were applied annually through 1 m wide furrows using a Parshall flume, following PAU recommendations for fruit crops [30]. All treatments received the same irrigation depth and regime. For the GQW/PQW treatment, irrigation alternated between groundwater (Tubewell) and canal water using separate channels. All other recommended cultural practices were followed [30]. Prescribed doses of nitrogen (N), phosphorus (P), and potassium (K) per vine were applied via urea (1.0 kg), single super phosphate (4.5 kg), and muriate of potash (0.8 kg), respectively [30]. The full P dose and half of the N and K doses were applied after pruning, with the remaining half of N and K applied in April after fruit set. Additionally, two foliar applications of urea (1%) were applied at full bloom and fruit set to enhance yield and fruit quality.

For data collection, leaving two vines on either side of each row, three vines were randomly selected from each quadruplicate treatment to record phenological characteristics, including days from pruning to panicle initiation, anthesis, fruit set, and fruit ripening as well as other growth traits and berry yield. A composite sample of ten randomly selected bunches per vine was used to determine mean bunch weight and size. From these, fifty berries were arbitrarily chosen to calculate average berry weight and size. TSSs (%) were measured using a hand refractometer (ATAGO Co., Ltd., Tokyo, Japan), and acidity (%) was determined following the Association of Official Analytical Chemists (AOAC) methods [31].

2.4. Soil Parameters and Total Water Use Efficiency

Surface (0–15 cm) and sub-surface (15–30 cm) soil samples were collected from the base of furrows at the periphery of selected vines at the conclusion of the experiment to assess the soil chemical properties. The samples were air-dried and sieved through a 2 mm mesh before chemical analyses. The soil was analyzed for organic carbon (using the oxidation method), NaHCO₃-extractable available P, NH₄OAC-extractable K, pH (1:2 soil solution ratio), and electrical conductivity (1:2) and to compute the SAR. SAR, which evaluates the suitability of water for agricultural irrigation and the sodicity hazard of soil, was calculated as follows [32]:

$$\mathrm{S}\mathrm{A}\mathrm{R}={\displaystyle \frac{{\mathrm{N}\mathrm{a}}^{+}}{\sqrt{\frac{{\mathrm{C}\mathrm{a}}^{2+}+{\mathrm{M}\mathrm{g}}^{2+}}{2}}}}$$

(2)

Cation concentrations were expressed in mmol_c L⁻¹. The in situ FIR was determined using the double-ring infiltrometer method, as described by Bouwer [33]. In this method, the outer and inner rings are filled with water, and the decline in water level in the inner ring is recorded at regular time intervals until a steady-state infiltration rate is achieved. BD of intact soil cores was measured using a cylindrical core sampler (7.5 cm height × 8.0 cm diameter) at two depths (0–15 cm and 15–30 cm). The collected soil was oven-dried at 105 °C for 48 h. BD was calculated as the ratio of the dry soil mass to the internal volume of the cylinder, expressed in Mg m⁻³ [34].

Total water use—which included cumulative irrigation water applied, soil moisture storage in the profile, and rainfall—was determined to calculate the total water use efficiency (TWUE) for different treatments [35]. Components of total water use, namely irrigation applied, soil profile water use, and rainfall, were recorded throughout the experimental years. Soil moisture storage up to 180 cm depth was measured annually during the active growth period using the gravimetric method. TWUE was calculated by dividing berry yield per hectare by the total water use and is expressed as q ha⁻¹-cm.

2.5. Statistical Analysis

The statistical analysis of the six-year pooled data was carried out using the procedures described by Freeman et al. [36], with CPCS1 software (version 1.0) developed by the Department of Statistics, PAU, Ludhiana [37]. Treatment effects were evaluated using analysis of variance (ANOVA), and mean comparisons were performed with the least significant difference (LSD) test at the 5% probability level (p < 0.05).

3. Results

3.1. Growth Attributes, Berry Yield, and Total Water Use Efficiency

The data on phenological traits (Figure 2a) indicated that, in the first year of the experiment, treatments showed no substantial differences in the number of days after pruning required for panicle initiation, anthesis, fruit set, and fruit ripening. However, over the study period, the use of PQW treatment significantly shortened the duration of these phenological stages compared with the control (GQW), as shown in Figure 2b. In contrast, the treatments GQW/PQW, PQW + GR₁₀₀, and PQW + SPM improved phenological performance, with PQW + GR₅₀ exhibiting only minor differences relative to GQW.

The data presented in

Table 6. Effect of irrigation water quality and application of amendments on the yield-attributing characteristics of grapes during years of study (2008–2013).

Treatment	Berry Weight (g Per Berry)							Bunch Number Per Plant
	2008	2009	2010	2011	2012	2013	Mean	2008	2009	2010	2011	2012	2013	Mean
GQW	2.25	1.85	1.82	2.10	2.15	2.01	2.03	70.0	75.0	75.0	77.0	78.0	72.48	74.58
PQW	1.92	1.79	1.75	1.98	1.95	1.95	1.89	62.25	60.0	60.0	64.0	62.0	60.51	61.46
GQW/PQW	1.79	1.84	1.80	1.82	2.0	1.85	1.85	73.0	70.0	70.0	73.0	70.1	69.48	70.93
PQW + GR50	1.93	1.75	1.70	2.00	2.05	1.91	1.89	66.5	65.0	65.0	68.5	66.0	63.98	65.83
PQW + GR100	1.89	1.78	1.73	1.90	2.0	1.80	1.85	70.5	67.5	67.5	70.0	68.5	68.02	68.67
PQW + SPM	1.74	1.84	1.80	1.78	2.10	1.96	1.87	72.25	73.5	73.5	75.0	74.0	73.11	73.56
LSD (0.05)	0.19	0.01	0.08	0.04	NS	0.01	NS	NS	1.72	2.08	1.46	1.63	1.62	2.20
Treatment	Bunch length (cm)							Bunch breadth (cm)
	2008	2009	2010	2011	2012	2013	Mean	2008	2009	2010	2011	2012	2013	Mean
GQW	20.75	20.10	19.75	20.15	20.15	20.10	20.17	11.30	10.28	11.15	11.10	11.25	10.75	10.97
PQW	19.25	18.28	18.0	18.85	19.35	18.70	18.74	10.80	8.50	9.92	10.35	10.90	9.80	10.05
GQW/PQW	20.05	20.0	19.67	20.0	20.0	20.0	19.95	9.55	9.83	10.92	10.90	10.30	10.10	10.27
PQW + GR50	19.18	18.55	18.53	19.20	19.15	18.80	18.91	10.43	9.38	10.12	10.60	10.60	10.0	10.19
PQW + GR100	19.30	19.93	19.35	19.95	19.40	19.60	19.59	10.55	9.20	9.92	10.75	10.75	10.0	10.20
PQW + SPM	21.33	20.33	20.06	20.25	21.0	20.60	20.60	10.88	9.65	10.67	10.95	11.0	10.45	10.60
LSD (0.05)	NS	0.27	0.23	0.18	0.21	0.23	0.09	NS	0.18	0.17	0.08	0.10	0.11	0.05

revealed that berry weight did not differ significantly among the different water quality treatments, although maximum berry weight was observed under GQW irrigation. The number of bunches per vine was statistically comparable between GQW and PQW + SPM treatments, both being significantly higher than the other treatments. Irrigation with GQW/PQW produced a substantially greater number of bunches per vine compared with PQW alone and the gypsum-amended treatments. Bunch length was significantly reduced under PQW irrigation compared with GQW but improved under GQW/PQW, PQW + GR₁₀₀, and PQW + SPM. Interestingly, bunch length in PQW and PQW + GR₅₀ remained comparable, as did that in GQW/PQW and PQW + SPM. Berry breadth, however, was not influenced by water quality or amendment treatments.

Year-wise grape yield data along with the six-year mean are presented in

Table 7. Effect of irrigation water quality and application of amendments on berry yield of grapes during 2008–2013.

Treatment	Berry Yield (t ha−1)
	2008	2009	2010	2011	2012	2013	Mean
GQW	21.2	28.4	29.5	31.0	27.9	28.7	27.8
PQW	16.6	20.0	21.6	22.6	20.5	21.0	20.4
GQW/PQW	19.2	26.8	27.2	28.6	25.5	26.2	25.6
PQW + GR50	18.9	22.3	23.3	27.9	22.0	21.6	22.7
PQW + GR100	19.9	24.8	24.0	28.6	26.1	24.9	24.7
PQW + SPM	21.9	27.4	27.6	29.2	26.6	27.4	26.7
LSD (0.05)	NS	1.0	1.7	0.9	1.0	1.0	1.3

. The pooled analysis demonstrated that berry yield varied significantly under different irrigation water qualities applied individually, conjunctively, or in combination with amendments. Compared with PQW alone, the treatments GQW/PQW, PQW + GR₅₀, PQW + GR₁₀₀, and PQW + SPM significantly increased berry yield by 28.3%, 11.3%, 21.2%, and 31.0%, respectively. Furthermore, berry yield under PQW + SPM, PQW + GR₁₀₀, and GQW/PQW improved by 17.7%, 8.8%, and 12.8%, respectively, relative to PQW + GR₅₀.

The components water use and TWUE, calculated as berry yield per unit centimeter water used, are presented in

Table 8. Water components and total water use efficiency of grapes (2008–2013).

Treatment	IWA (cm)	PWU (cm)	RF (cm)	TWU (cm)	TWUE (q ha−1-cm)	AWU/Vine (m3)
GQW	31.7	2.12	35.8	69.62	3.99	6.27
PQW	31.7	−0.31	35.8	67.19	3.03	6.05
GQW/PQW	31.7	1.26	35.8	68.76	3.72	6.19
PQW + GR50	31.7	−0.03	35.8	67.47	3.36	6.08
PQW + GR100	31.7	−0.41	35.8	67.09	3.68	6.04
PQW + SPM	31.7	0.39	35.8	67.89	3.93	6.12

Note: All values are means of 6 years; IWA: irrigation water applied; PWU: profile water use; RF: rainfall; TWU: total water use; TWUE: total water use efficiency; AWU: annual water use per vine.

. The highest TWUE (3.99 q ha⁻¹ cm) was recorded under GQW irrigation, while the lowest (3.03 q ha⁻¹ cm) was observed with PQW. However, PQW + SPM and GQW/PQW improved TWUE to 3.93 and 3.72 q ha⁻¹ cm, representing increases of 29.7% and 22.8%, respectively, compared with PQW. Similarly, TWUE improved by 10.9% and 21.4% under PQW + GR₅₀ and PQW + GR₁₀₀ treatments, respectively.

In general, the treatments PQW + SPM, PQW + GR₁₀₀, and cyclic use of saline–sodic and canal water (GQW/PQW) proved superior to PQW + GR₅₀ in enhancing TWUE. The results suggest that in regions where good-quality canal water is scarce, TWUE comparable to that achieved with GQW can still be obtained by using sulphitation pressmud (PQW + SPM), 100% GR, and/or alternating PQW with GQW (GQW/PQW) in light-textured calcareous soils. Although all treatments received the same irrigation regime, the variation in TWUE was attributed to a difference in berry yield under the same amount of applied irrigation water. The reduction in berry yield under PQW irrigation resulted in the lowest TWUE.

3.2. Soil Properties

The chemical characteristics of the surface and sub-surface soil layers under different irrigation water qualities and amendments are presented in

Table 9. Effect of water quality and amendments on soil characteristics at the completion of the experiment.

Treatment	pH1:2		EC1:2 (dS m−1)		SAR (cmol kg−1)0.5		OC (g kg−1)		BD (Mg m−3)		FIR (cm h−1)
	0–15 cm	15–30 cm	0–15 cm	15–30 cm	0–15 cm	15–30 cm	0–15 cm	15–30 cm	0–15 cm	15–30 cm	0–15 cm
GQW	8.34	8.42	0.32	0.29	5.0	3.76	3.6	3.2	1.45	1.50	2.81
PQW	9.35	9.43	0.60	0.58	11.01	11.73	1.8	1.7	1.67	1.69	1.49
GQW/PQW	8.87	8.95	0.44	0.40	6.59	6.96	3.1	2.9	1.52	1.55	2.33
PQW + GR50	9.10	9.21	0.59	0.54	9.26	9.85	2.0	1.7	1.59	1.61	1.90
PQW + GR100	9.02	9.11	0.62	0.56	8.56	9.28	2.0	1.8	1.56	1.60	1.97
PQW + SPM	8.81	8.86	0.52	0.45	7.24	7.60	3.2	3.1	1.50	1.54	2.42
LSD (0.05)	0.51	0.40	0.72	0.57	1.26	0.92	0.48	0.42	0.12	0.10	0.31

. The six-year soil analysis revealed that irrigation solely with saline–sodic PQW increased the pH to 9.35, compared with a value of 8.34 under GQW in the surface layer (0–15 cm). In contrast, the soil pH in PQW + SPM and GQW/PQW treatments was lower than that observed in PQW + GR₅₀ and PQW + GR₁₀₀. A slight increase in pH values was also recorded in the sub-surface layer (15–30 cm) compared with the surface layer (0–15 cm).

The EC of the surface soil remained within the permissible limits for plant growth across all treatments, ranging from 0.32 dS m⁻¹ in GQW to 0.62 dS m⁻¹ in PQW + GR₁₀₀. Under the GQW/PQW alternate irrigation treatment, the EC value was 0.44 dS m⁻¹, attributed to the dilution effect of good-quality GQW on poor-quality PQW. In gypsum-amended treatments, EC values were 0.59 dS m⁻¹ and 0.62 dS m⁻¹ in PQW + GR₅₀ and PQW + GR₁₀₀, respectively, which were comparable to the EC observed under PQW irrigation alone (0.60 dS m⁻¹).

The application of sulphitation pressmud, gypsum, and alternating GQW/PQW substantially improved soil health by reducing soil pH and SAR (Table 9). The data revealed an increase of 120.2% to 212.0% in SAR values in surface and sub-surface layers compared with GQW when brackish water was applied either without amendments or without mixing with good-quality canal water. Higher SAR values were consistently observed in the sub-surface layer than in the surface layer. The increase in SAR under PQW + GR₅₀ and PQW + GR₁₀₀ was 85.2% and 71.2% over GQW, which was 40.5% and 29.9% higher than GQW/PQW and 27.9% and 18.2% higher than PQW + SPM, respectively. Thus, the use of organic amendment SPM (PQW + SPM), chemical amendment gypsum (PQW + GR₁₀₀), or alternating canal and brackish water (GQW/PQW) all reduced SAR compared with PQW alone, although SAR values still remained below the critical threshold. The addition of organic materials such as sulphitation pressmud improved soil conditions by reducing exchangeable sodium and pH, while the presence of Ca²⁺ in gypsum mitigated the adverse effects of excess Na on soil physical and chemical properties. In treatments where PQW was combined with GR₅₀ and GR₁₀₀, soil pH declined to 9.10 and 9.02, respectively, compared with 9.35 pH under PQW alone. Notably, PQW + SPM and the cyclic use of GQW/PQW were more effective than PQW + GR₅₀ and PQW + GR₁₀₀ treatments in lowering both pH and SAR.

Continuous application of poor-quality water significantly decreased the organic carbon (OC; 1.8 g kg⁻¹) content of the surface soil. In contrast, sulphitation pressmud (PQW + SPM) and GQW/PQW treatments improved the OC status of the surface layer, although OC content decreased with depth. The PQW treatment recorded a significantly higher BD of 1.67 Mg m⁻³ in the surface soil (0–15 cm) compared with 1.45 Mg m^–3 under GQW. Corresponding values in sub-surface soil (15–30 cm) were 1.69 and 1.50 Mg m⁻³, respectively. A significant reduction in BD was observed with the alternate use of PQW and GQW. The decline in BD was particularly evident in the irrigation sequences involving GQW/PQW and PQW + SPM. The maximum significant decrease in BD occurred under PQW + SPM, followed by GQW/PQW, PQW + GR₁₀₀, and PQW + GR₅₀. Although the reduction in BD was more pronounced in PQW + SPM than in GQW/PQW, the differences were statistically non-significant.

The lowest FIR (1.49 cm h⁻¹) was measured in plots irrigated with PQW, whereas the highest FIR (2.81 cm h⁻¹) was recorded under GQW irrigation. When PQW was alternated with GQW, the infiltration rate increased compared with PQW alone (Table 9). Among the amendments, PQW + SPM (2.42 cm h⁻¹) resulted in a greater improvement in FIR than PQW + GR₅₀ (1.90 cm h⁻¹) and PQW + GR₁₀₀ (1.97 cm h⁻¹). The FIR was significantly higher when the proportion of GQW increased in cyclic treatments, thereby reducing the impact of PQW. These findings suggest that the application of sulphitation pressmud (PQW +SPM) and the cyclic use of GQW/PQW were more effective in enhancing FIR compared with PQW irrigation alone.

3.3. Quality of Grapes

The effect of saline–sodic water, amendments, and irrigation strategies on the fruit quality of grape cv. Perlette is summarized in

Table 10. Effect of water quality on qualitative traits of the grape cv. Perlette was influenced by the application of amendments (pooled mean 2008–2013).

Treatment	TSSs (%)	Acidity (%)	TSSs/Acidity
GQW	18.30	0.60	30.61
PQW	17.05	0.66	25.91
GQW/PQW	17.90	0.64	28.11
PQW + GR50	17.67	0.66	26.86
PQW + GR100	17.83	0.68	26.47
PQW + SPM	17.82	0.63	28.33
LSD (0.05)	0.40	0.04	0.85

. The results revealed that the significantly highest TSSs (18.30%) were achieved under GQW irrigation, followed by the cyclic use of GQW/PQW. Acidity was the lowest under GQW, resulting in the highest TSSs/acidity ratio. The application of sulphitation pressmud with poor-quality groundwater (PQW + SPM) and the cyclic irrigation strategy (GQW/PQW) significantly improved TSSs compared with PQW irrigation alone (Table 10).

4. Discussion

The present study was undertaken to explore the potential of utilizing poor-quality saline–sodic groundwater (PQW) in combination with chemical amendments and/or organic material, as well as in conjunction with good-quality water (GQW), to achieve sustainable berry yield in an established vineyard while minimizing risks to soil health under semi-arid conditions in sandy loam soil. The use of PQW alone significantly reduced grape yield (Table 7), which may be attributed to increased osmotic pressures of the soil solution caused by excessive salt accumulation, thereby reducing the availability of water and nutrients to the vines [22].

The lowest berry yield with PQW irrigation could be attributed to the higher sodic hazard of the water, which resulted in elevated soil SAR (Table 9). Irrigation water with a high SAR typically contains a greater concentration of sodium relative to calcium and magnesium, leading to sodium enrichment on the clay particle surface and depletion of calcium and magnesium. Consequently, the reduced yield under PQW irrigation may also be linked to sodium-induced calcium deficiency in plants. Overall, berry yield exhibited a declining trend with increasing SAR values (Figure 3). The primary effect of salinity, particularly at low to moderate concentrations, is osmotic stress, which restricts water availability to plants [38,39]. Maas and Hoffman [40] similarly reported reductions in crop yield under abiotic stress conditions. Furthermore, the displacement of Ca²⁺ by Na⁺ in soils irrigated with sodic water increases soil pH and exchangeable sodium percentage (ESP), thereby decreasing water permeability and inducing nutritional imbalances in the plants. In soils irrigated with brackish water, a progressive build-up of salinity/sodicity can occur unless it is mitigated through appropriate management practices [13]. Consistently, Martínez-Moreno et al. [23] observed that saline irrigation increased soil EC by 800 μd cm⁻¹ in grapevines in Spain, particularly where irrigation water was dominated by sulfate salts.

The adverse effects of excessive sodium in the soil environment can be alleviated, and berry yield improved, through the application of calcium-based chemical amendments such as gypsum and organic amendments like sulphitation pressmud or by adopting conjunctive irrigation strategies using poor-quality saline–sodic water alternated with good-quality water (GQW/PQW). Among the treatments, PQW + SPM recorded significantly higher responses in berry yield, bunch weight, and number of bunches per plant, compared with PQW alone. The positive impact of SPM arises from the formation of organic acids during its decomposition, which exerts an acidifying effect on sodic soils. In addition, Ca+Mg present in SPM replaces the Na from the exchange complex. Moreover, the Ca and Mg present in SPM replace Na⁺ on the soil exchange complex, thereby facilitating reclamation by lowering soil pH and reducing exchangeable sodium. Consequently, the combined benefits of improved nutrition availability and ameliorated soil physical and chemical properties under salt-stress conditions contribute to higher crop yield [19,20,41]. Dotaniya et al. [20] similarly reported improvements in the physical, chemical, and biological properties of soils with pressmud application.

The build-up of SAR in soil extract is directly linked to the excessive sodium content in irrigation water. Irrigation with PQW markedly increased SAR in both surface and sub-surface soils due to its high residual sodium carbonate content. However, conjunctive irrigation with GQW/PQW significantly lowered soil SAR, largely due to the dilution effect and reduced salt loading. Likewise, the application of SPM mitigated the increase in SAR, reaching values substantially below those recorded with PQW alone. This effect can be attributed to Ca²⁺ in organic manures, which displaces exchangeable sodium from soil colloids, thereby reducing sodicity [42,43].

Organic amendments such as SPM play a dual role in improving soil quality and mitigating the adverse impacts of poor-quality water. Upon decomposition, SPM releases CO₂ and organic acids that lower the soil pH under PQW irrigation, particularly in surface soil layers [44]. Although soil EC increased in the SPM treatment, values remained below the critical threshold. This increase may be attributed to the inherent ion content of SPM (notably Ca²⁺ and K⁺) and its ability to enhance the dissolution of Ca from native CaCO₃ through the action of organic acids released during decomposition, thereby counteracting the deleterious effects of saline water [43]. Compared with gypsum, SPM appears more effective due to its additional contribution of organic matter, which improves soil fertility and supplies supplementary nourishment for grapevines (Table 5), particularly when applied alongside the recommended chemical fertilizer dose.

The observed lower OC content and higher soil pH under various treatments were strongly associated with elevated SAR values in the surface soil (Figure 4). The relatively narrow C:N ratio of SPM (Table 5) may have accelerated nutrient release, especially nitrogen, contributing to improved grapevine growth and berry yield in comparison with other treatments. Moreover, both gypsum and pressmud improved the soil’s physical condition, promoting leaching of excess salts [15]. The dilution effect under GQW/PQW irrigation further reduced osmotic stress, leading to significantly higher bunch and berry yield compared with PQW alone. Applying GQW/PQW in a rotational mode proved more effective in maintaining a lower soil salinity level in the surface soil layer than that observed with the use of blending methods [45]. In contrast, PQW irrigation alone caused a marked decline in berry yield relative to GQW and GQW/PQW treatments (Table 7). Similarly, Martínez-Moreno et al. [46] reported that saline water irrigation adversely affected vine performance and grape composition, although the extent varied with water quality and management.

The increase in BD under PQW irrigation was primarily due to soil compaction, resulting from the dispersive action of exchangeable sodium on soil colloids and altered pore size distribution [15,47]. BD values were generally higher in the sub-soil (15–30 cm), due to frequent cultivation and the overburdening weight of the surface layer. In the GQW/PQW treatment, the proportion of PQW was reduced due to its alternate use with GQW, leading to enhanced infiltration rates compared with PQW treatment. Clay dispersion under PQW caused greater clogging of soil pores, whereas treatments involving amendments with PQW, as well as the cyclic GQW/PQW treatment, experienced less pore clogging, mitigating adverse effects on BD and FIR [21].

Consequently, soil physical properties such as permeability and aeration are negatively impacted under PQW alone, creating unfavorable conditions for root extension, water uptake, and respiration. These effects contributed to poor vine growth, reduced yields, lower grape quality, diminished biomass, and decreased carbon inputs to the soil [25,48,49]. The error bar plot of FIR and BD as a function of SAR is shown in Figure 5. The alternate use of PQW and GQW in the ratio 1:1, along with amendments, improved soil conditions, promoting healthier plant growth, higher berry yield, and improved quality. This was achieved through reductions in pH, ESP, SAR, and BD, along with enhanced permeability via better infiltration rates [11,15,50].

Bradford and Letey [6] also reported that the cyclic irrigation strategy produced a higher simulated yield than blending strategies. The use of amendments with PQW resulted in a significant increase in TSSs and a decrease in berry acidity compared with PQW. Elevated SAR values directly affected grape quality, causing higher acidity and lower TSSs (Figure 6). Prior et al. [51,52] similarly reported that berry acid concentration increased under salinity, while sugar content remained unaffected. In contrast, Martínez-Moreno et al. [23] observed no significant differences in TSSs, pH, or acidity under saline water irrigation.

Limitations of the Study and Direction for Future Work

The grape orchard under study had been established and irrigated with good-quality canal water (GOW) for four years. Subsequently, due to a shortage of GQW, the experiment was modified to include natural brackish groundwater (prevalent in the southwestern region of Punjab) in combination with GQW and organic/inorganic amendments. In the present study, the impact of a single type of PQW on grapevine yield, berry quality, and soil properties was evaluated on a relatively coarse-textured sandy loam soil. It should be noted that this study does not provide information on the effects of varying water qualities (e.g., saline, sodic/alkali) on grape production in heavy-textured soils.

Therefore, future research should focus on evaluating the effect of PQW on newly planted grapevines to mitigate abiotic stress during early growth stages. Additionally, since the current study was limited to arid and semi-arid climatic conditions, future experiments could be replicated across multiple locations, encompassing different water qualities, soil types, and climatic zones to validate and broaden the applicability of the findings.

5. Conclusions

The rising salinity of agricultural soils, especially in regions where brackish water is used for irrigation, poses a significant challenge to the sustainability of grape production and overall soil health. With climate change exacerbating water scarcity and altering precipitation patterns, the use of brackish water has become increasingly common in arid and semi-arid areas. Therefore, understanding the effects of various irrigation water qualities, in combination with good quality canal water and soil amendments, on berry yield and soil properties in table grapes (Vitis vinifera cv. Perlette) is essential for developing effective management strategies. The current study concludes that the adverse impacts of natural saline–sodic groundwater (PQW) can be mitigated through efficient irrigation practices and appropriate amendments in a sandy loam calcareous soil. Specifically, the application of sulphitation pressmud, 100% gypsum requirement, and cyclic use of PQW with good-quality canal water (GQW/PQW) in a 1:1 ratio helps in sustaining berry yield while minimizing the risk of degradation under a semi-arid climate.