Document Type : Research Paper
Salinity is one of the most prominent environmental constraints affecting agricultural productivity worldwide, particularly in arid and semi‑arid regions such as central Iran. High concentrations of soluble salts in the soil or irrigation water adversely influence plant growth by reducing osmotic potential, disturbing nutrient uptake, and impairing soil physical conditions. Among cereal crops, Triticum aestivum L. (bread wheat) is relatively sensitive to salinity stress, which often results in reduced germination rate, stunted growth, lower leaf area, and ultimately, decreased grain and straw yields. These limitations are further compounded by restricted water availability and poor soil structure that typically accompanies salinized environments. Therefore, developing sustainable soil management strategies to alleviate salinity effects and enhance water use efficiency is a major concern in modern agronomy.
Organic amendments have long been recognized as a key component of sustainable soil and water management. Their multifaceted role involves improving soil aggregation, increasing water retention, enhancing microbial activity, and providing a slow‑release source of essential plant nutrients. Organic materials such as farmyard manure and composted municipal wastes possess the potential to restore fertility and enhance soil’s buffering capacity against salt accumulation. Farmyard manure, being rich in both organic colloids and humic compounds, typically enhances infiltration and aeration, while compost contributes to the gradual improvement of nutrient cycling. Previous studies have reported that organic matter can mitigate the adverse effects of high electrical conductivity (EC) in irrigation water by promoting ion exchange, reducing sodium adsorption ratio (SAR), and increasing the effective soil porosity. Despite these well‑established benefits, quantitative evaluations of how different sources and rates of organic matter interact with salinity to influence water use efficiency (WUE) in wheat remain limited, particularly under field conditions.
This study was conducted to evaluate the effect of different types and levels of organic matter on water use efficiency in wheat cultivation under saline conditions at the Rudasht Salinity Research Station in Isfahan. The experiment was carried out using a split-plot arrangement based on a randomized complete block design with three replications. The main factor was the type of organic matter (well‑decomposed farmyard manure and municipal waste compost), and the sub‑factor was the level of organic matter (0, 10, and 20 tons per hectare). The salinity of irrigation water was maintained at 8 dS m⁻¹ throughout the experiment. Each experimental plot measured 3 × 5 m with proper drainage channels between replicates. Organic amendments were incorporated evenly into the surface soil layer (0–30 cm depth) two weeks before sowing. Fertilization program followed local recommendations with identical basal application of nitrogen, phosphorus, and potassium across all treatments to maintain consistency. Irrigation was scheduled according to crop water requirement and evapotranspiration data, using saline water with fixed EC during the entire period. Standard control of pests and weeds was implemented, ensuring equal management across plots to isolate the effect of organic matter. The need for leaching fraction (leaching requirement) was calculated and incorporated.
Soil physical properties include Bulk density, infiltration rate, and field capacity and plant wilting point were determined after harvest. Soil chemical properties such as EC, sodium adsorption ratio (SAR), and organic carbon were analyzed using conventional analytical methods. Thousand‑grain weight, grain yield, straw yield, and water use efficiency (WUE) were measured. Data were subjected to analysis of variance (ANOVA) using SAS software version 9.1.
The type of organic matter significantly affected the final infiltration rate. Plots receiving farmyard manure exhibited higher infiltration compared with compost‑amended plots. This improvement was attributed to better aggregation and soil structure due to manure’s fibrous organic content. Other soil parameters such as pH and EC did not differ significantly between sources but tended to stabilize under organic treatment compared with the control. Organic carbon content increased by 50% on average after the application of organic matter.
The levels of organic matter had a highly significant effect (P < 0.001) on all yield components. Mean grain yield rose from 4350 kg ha⁻¹ in the control to approximately 5275 kg ha⁻¹ and 5452 kg ha⁻¹ in the 10 t ha⁻¹ and 20 t ha⁻¹ treatments, respectively — representing about a 23% average increase compared with the control. Similarly, straw yield exhibited marked enhancement, with the highest value recorded at the 20 t ha⁻¹ level, showing a 30% increase over the control plot. Despite the higher absolute yields at 20 t ha⁻¹, statistical analysis indicated no significant difference between the 10 t ha⁻¹ and 20 t ha⁻¹ treatments in grain yield, implying that moderate application can attain optimal productivity under saline conditions.
A major outcome of this study was the significant enhancement in water use efficiency caused by organic matter application. Statistical analysis revealed that both levels significantly differed from the control (P < 0.001), but not from one another, indicating that WUE improvement could be achieved effectively even at the lower application rate.
Measurements of thousand‑grain weight indicated clear improvement under organic treatments. In the control, TGW averaged 36 g, while in the 10 t ha⁻¹ and 20 t ha⁻¹ treatments it reached 41 g and 42 g, respectively. This likely reflects better nutrient availability (particularly nitrogen and potassium) and less physiological stress during grain filling. The overall biomass accumulation also rose substantially, contributing to enhanced straw yield. No evidence of phytotoxicity or excessive organic decomposition was detected during the growing season.
The results of this experiment demonstrate the tangible benefits of organic matter management on water use efficiency and yield of wheat under saline irrigation conditions. Application of organic materials, whether farmyard manure or municipal compost, significantly improved soil physical properties, moderated salt effects, and enhanced plant productivity. The most notable outcomes include:
Improved soil infiltration and structure: Farmyard manure exerted superior influence, promoting more uniform water movement and reduced surface runoff under saline stress.
Increased grain and straw yield: Organic matter application (10–20 t ha⁻¹) enhanced wheat performance by 23–30% relative to control, reflecting better nutrient availability and balanced soil environment.
Enhanced water use efficiency: WUE improved significantly with organic additions, indicating higher yield per unit of applied water—an essential goal in saline, water‑limited regions.
Incorporation of organic amendments represents a cost‑effective and environmentally friendly approach to mitigating salinity effects, maintaining soil health, and improving water productivity in wheat cultivation systems. Long‑term monitoring and repeated application may further stabilize soil organic carbon and augment these positive responses.
In conclusion, organic matter management—regardless of source—provides a viable and sustainable strategy for saline agriculture. By enhancing the physical integrity and biological activity of the soil, it buffers plants against salt stress and optimizes water utilization. This approach can especially benefit arid regions like central Iran, where saline irrigation is unavoidable. Hence, integrating organic matter use into standard agronomic practices for wheat can facilitate resilient production systems in saline environments. Future research should focus on multi‑season assessments, detailed physiological mechanisms of stress tolerance, and economic evaluations of material costs and benefits to guide practical recommendations at the farm scale.
The study was funded by the Soil and Water Research Department, Isfahan Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Isfahan, Iran.
For research articles with several authors, a short paragraph specifying their individual contributions must be provided. The following statements should be used “Conceptualization, P.M.; methodology, P.M and M.D.; software, P.M.; validation, P.M., M.D.; formal analysis, P.M.; investigation, P.M and M.D.; resources, P.M.; data curation, P.M.; writing—original draft preparation, P.M.; writing—review and editing, M.D.; visualization, P.M.; supervision, P.M.; project administration, P.M. All authors have read and agreed to the published version of the manuscript.” Please turn to the CRediT taxonomy for the term explanation. Authorship must be limited to those who have contributed substantially to the work re-ported.
All authors contributed equally to the conceptualization of the article and writing of the original and subsequent drafts.
No artificial intelligence tools were used in the article writing process.
The datasets analyzed during the current study can be available from the corresponding author on reasonable request.
The authors would like to thank all participants in the present study.
The authors avoided data fabrication, falsification, and plagiarism, and any form of misconduct.
The authors declare no conflict of interest.
