# Water Use Efficiency and Tomato Yield Under the Influence of Irrigation Water Quality and Soil Improvers Using a Drip Irrigation System

## TL;DR

This study explores using saline water with organic amendments to improve tomato yield and water efficiency in Iraq's water-scarce regions.

## Contribution

The novel approach combines saline irrigation with organic soil amendments to sustainably boost tomato productivity in arid areas.

## Key findings

- Using saline water with organic amendments increased water use efficiency by up to 21.13 kg ha−1 mm−1.
- The highest tomato yield (4.321 kg per plant) was achieved with moderate salinity water and high organic matter.
- Fresh water use was reduced by 50% without significant yield loss when using saline water and amendments.

## Abstract

As a result of Iraq’s scarcity of fresh water, there is a need to find alternative, non-traditional irrigation methods and technologies that would increase water use efficiency and reduce the negative impact of salinity on the tomato crop. The experiment was conducted in the field over two consecutive seasons in heavy soil using a drip irrigation system. The study employed two types of irrigation water with different salinity levels (low, symbolized as q1 = 0.8 ds m−1) and high, symbolized as (q2 = 5.8 ds m−1), and added in three ways: Q1 (q1), Q2 (q1, q2), and Q3 (q2). Two levels of organic matter (F2 and F3) were also used, along with a control treatment without the addition of F1. The study aimed to evaluate the effect of alternating fresh and saline water on tomato productivity, as well as to determine the impact and effectiveness of organic fertilizer in mitigating the negative effects of saline irrigation water and improving the chemical and physical properties of the soil. Statistical analysis showed that both irrigation water quality and amendments had a significant effect on the studied properties. The study year did not affect the overall characteristics of the study, but only the water conductivity and weighted diameter. The results showed an increase in water use efficiency, with averages of 20.7 and 21.13 kg ha−1 mm−1. when using fresh water and a high level of organic matter addition, sequentially. The water quality treatment Q2, combined with soil amendment F3, achieved the highest yield compared to the fresh water treatment Q1 combined with a control treatment (F1), reaching 4.321 and 3.993 kg plant−1, respectively. This was achieved while conserving fresh water by 50% when using moderately saline drainage water with added amendments, without a significant decrease in tomato yield. Therefore, this study proposes adopting a strategy of using saline water with medium electrical conductivity as a partial alternative to low-salinity water, while incorporating organic amendments to ensure sustainable production in water-scarce regions.