Profitability Analysis of Grain Maize Cultivation under Saline Water and Deficit Irrigation in a Tape Drip Irrigation System in Fars Province

Document Type : Research Paper

Authors

• Mahboobeh Lor Mohammad Hasani
• Rezvan Talebnejad
• Masoud Noshadi

Water Engineering Department, , Faculty of Agriculture, .Shiraz University. Shiraz. Iran

Abstract

Keywords

• Benefit-cost ratio
• unconventional water
• economic water productivity
• Water scarcity

Main Subjects

• ..

Introduction

The economies of many developing countries rely heavily on agriculture, which plays a crucial role in contributing to gross domestic product and ensuring food security. However, drought and salinity are among the most significant abiotic stresses affecting plant growth, crop productivity, and water-use efficiency. Providing sufficient food for a growing global population remains a major challenge, particularly in developing countries where population growth continues to increase pressure on agricultural systems. Consequently, the demand for food is rising, leading to the excessive exploitation of water and land resources.To mitigate the adverse effects of drought and salinity on plant growth and crop production, it is essential to adopt multiple management strategies. One such approach is the use of unconventional water resources for irrigation. Given the high-water consumption in the agricultural sector, improving water productivity has become increasingly important. Tape-drip irrigation is a suitable method in this regard due to its high application efficiency and minimal water losses. Furthermore, deficit irrigation is an effective management strategy for enhancing water productivity under conditions of limited water availability. In drip irrigation systems, water is applied precisely and uniformly to the root zone, minimizing fluctuations in soil matric potential. This helps compensate for the reduction in osmotic potential caused by saline irrigation water and maintains a more favorable water balance for plant growth. Therefore, modern irrigation systems such as drip irrigation are considered suitable for the use of saline water because of their frequent irrigation intervals and ability to maintain higher soil moisture levels in the root zone. Maize (Zea mays L.) is one of the most important cereal crops worldwide. It ranks third in cultivated area after wheat and rice and second in total production after sugarcane. Similar to wheat, barley, and rice, maize is a strategically important irrigated crop that plays a significant role in meeting the nutritional needs of both humans and livestock .Considering the economic importance of maize grain production and its extensive use in edible oil production, livestock and poultry feed, and various industrial applications, as well as the increasing challenges associated with water scarcity in the country and the region, this study aimed to evaluate the economic profitability of maize cultivation under deficit irrigation and different irrigation water salinity levels using tape-drip irrigation in the Bajgah region of Fars Province.

Materials and Methods

In order to investigate the economic profitability of grain maize cultivation at different levels of irrigation water salinity and deficit irrigation, an experiment was conducted at the research farm of the Water Engineering Department , Faculty of Agriculture, Shiraz University in 2019. The Faculty of Agriculture is located 16 kilometers north of Shiraz, at a longitude of 32°52′ and a latitude of 32°29′, at an altitude of 1810 meters above sea level. To conduct the research, a factorial experiment was conducted in a randomized complete block design with three replications. Four levels of irrigation water salinity were applied, including control (0.6), 2, 3.5, and 5 dS.m^-1, equivalent to EC1, EC2, EC3, and EC4. Irrigation water treatment was applied at three water levels: FI, 0.75FI, and 0.5FI, equivalent to full irrigation, 75% full irrigation, and 50% full irrigation. The field was irrigated using tape-drip irrigation with outlet spacing of 20 cm and a flow rate of 3 liters per hour per meter of tape length. In order to investigate the effect of different levels of irrigation water salinity and deficit irrigation in tape drip irrigation on leaf area index, plant height, and seed yield in maize, analysis of variance and Duncan's range comparison test were used in SAS software version 9.4. In this study, with the aim of evaluating the economic feasibility of planting grain maize, engineering economics methods, namely net present value (NPV) and benefit-cost ratio (BCR), were used.

Results and Discussion

The results showed that applying irrigation water salinity and deficit irrigation reduced the leaf area index, plant height, and seed yield in maize. The main effect of irrigation water salinity showed that increasing irrigation water salinity from 0.6 to 2, 3.5, and 5 dS.m^-1 caused a 1.4, 2.5, and 3.6 % reduction in plant height, respectively. The results showed that the highest economic water productivity of 0.064 USD.m^-3, present value of $1178.53, and benefit-cost ratio of 2.64 were achieved in full irrigation with irrigation water salinity of 0.6 dS.m^-1. In the full irrigation and 75% full irrigation treatments, the benefit-cost ratio was 2.64 and 1.85, respectively, at irrigation water salinity of 0.6 dS.m^-1, and 1.32 and 1.27, respectively, at irrigation water salinity of 2 dS.m^-1. The economic water productivity values for full irrigation and 75% full irrigation at irrigation water salinity of 0.6 dS/m were 0.064 and 0.044 USD.m^-3, respectively, and for irrigation water salinity of 2 dS.m^-1, they were 0.012 and 0.014 USD.m^-3, respectively. Given that these values were positive, these treatments are economically justified in terms of economic water productivity. Therefore, in terms of   benefit -cost ratio and economic efficiency of water, irrigation water salinity treatment of 3.5 and 5 dS.m^-1 in full irrigation, 75% full irrigation, and 50% deficit irrigation treatment are not economically justified at different levels of irrigation water salinity. According to the results of this study, under conditions of 50% full irrigation, the benefit-cost ratio is less than one at all levels of irrigation water salinity and the economic productivity of water is a negative number. Therefore, maize cultivation is not economically justified under 50% full irrigation in the region. These findings indicate the relative sensitivity of maize to water salinity and its high-water requirement. Therefore, in conditions of shortage of available freshwater and water shortage from the perspective of water resources management, 75% full irrigation treatment with a salinity of 2 dS.m^-1 is economically recommended for grain maize cultivation in the study area.

Funding

The study was funded by Shiraz University, Iran national Science foundation (INSF), and Grant No. 2GCU1M222614.

Authorship contribution

All authors contributed equally to the conceptualization of the article and writing of the original and subsequent drafts.

Declaration of Generative AI and AI-assisted technologies in the writing process

During the preparation of this work no AI-assisted technology was used.

Data availability statement

Data will be made available on request.

Acknowledgements

The authors gratefully acknowledge Shiraz University Research Council, the Drought Research Center, and the Iran National Science Foundation (NSF) for funding.

Ethical considerations

The authors avoided data fabrication, falsification, plagiarism, and misconduct.

Conflict of interest

The author declares no conflict of interest.