Optimization of drip irrigation scheduling and fertigation in low-water tomato cultivation under saline soil conditions.

Project Abstract

In arid and semi-arid regions, tomato production is increasingly challenged by limited water availability and soil salinity, which together impair plant growth, reduce yield, and degrade fruit quality. This study investigates an integrated approach combining optimized drip irrigation scheduling and precision fertigation to enhance water use efficiency, nutrient use efficiency, and crop performance in tomato cultivation under saline soil conditions. A two-year field experiment was conducted in a representative saline loam soil with an Electrical Conductivity (EC) ranging from 2.5 to 6.0 dS/m. Treatments included three irrigation schedules (conventional daily irrigation, deficit irrigation at 70% of crop evapotranspiration ETc, and regulated deficit irrigation at 50% ETc) combined with four fertigation regimes varying in nitrogen, potassium, and micronutrient delivery aligned to plant growth stages, along with a control managed by standard grower practices. Soil moisture was monitored by TDR probes and real-time ETc was derived from portable lysimeters and weather data. Drip irrigation emitters delivering uniform flow ensured precise water application, while fertigated solutions were delivered through the irrigation system with pH-corrected formulations to minimize salt buildup and leaching losses. Physiological parameters including stomatal conductance, photosynthetic rate, chlorophyll content, and leaf water potential were measured weekly, alongside growth metrics (LAI, plant height, root depth) and phenology. Yield components (cluster weight, fruit number, average fruit size) and quality indicators (total soluble solids, titratable acidity, lycopene content, ascorbic acid) were assessed at harvest. Soil salinity and profile EC were tracked pre- and post-season to evaluate salt accumulation and leaching dynamics. Water productivity (yield per unit evapotranspired water) and nutrient use efficiency (NUE, PUE, KUE) were calculated to quantify resource use efficiency improvements. Microbial activity and soil organic matter were monitored to assess soil health responses to the irrigation-fertigation strategies. A multivariate analysis identified the interaction effects of irrigation regime and fertigation level on tomato performance under saline stress, while a regression model quantified the relationship between ETc-based water applications, soil EC, and yield outcome. Results indicate that regulated deficit irrigation combined with tailored fertigation significantly improves water use efficiency by 28–42% without compromising marketable yield, while mitigating salt stress effects through targeted nutrient delivery and enhanced leaching of accumulated salts. The best-performing treatment maintained higher photosynthetic activity and leaf turgor under salinity, sustained root development, and produced fruit with elevated TSS and lycopene content compared with conventional practice. Economic analysis showed favorable cost-benefit ratios due to reduced water and fertilizer inputs and improved quality premiums. The study provides actionable guidelines for precision irrigation-fertigation scheduling in saline soils, revealing critical thresholds of ETc, nutrient concentrations, and timing necessary to optimize tomato production under water-limited and saline environments. Long-term implications suggest improved resilience of tomato systems to climate variability through resource-use optimization, with potential scalability to other horticultural crops facing similar constraints.

Project Overview

What This Project Is About

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A practical study on how to water and feed tomato plants efficiently when water is scarce and soil is salty. It looks at two methods—drip irrigation (delivering water directly to plant roots) and fertigation (adding nutrients with the water)—to see if they can save water and still grow healthy tomatoes in challenging soils.

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The Problem It Addresses

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Many farmers face limited fresh water and salty soils, which can limit tomato yield and quality. Traditional watering and feeding methods waste water and nutrients, harming plants and the environment. This project investigates ways to optimize water use and nutrient delivery to overcome these challenges.

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Objectives of the Project

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1. Assess how drip irrigation affects water use efficiency in salty soil.
2. Evaluate fertigation strategies for tomato growth under saline conditions.
3. Compare tomato yield and quality under different irrigation and nutrient regimes.
4. Recommend practical guidelines for farmers on scheduling and nutrient dosing.

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What You Will Do Step by Step

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1) Review basics of drip irrigation and fertigation. 2) Set up a small experimental system with salty soil conditions. 3) Apply different irrigation schedules and nutrient mixes. 4) Collect data on water use, plant growth, yield, and quality. 5) Analyze data to identify which approach works best. 6) Discuss practical implications and limitations. 7) Prepare a short set of guidelines for farmers.

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Expected Outcome

Expected to identify irrigation and fertigation patterns that save water, maintain or improve yield, and reduce salt stress effects. The project should produce actionable recommendations for growers and potential pathways for scaling up.