Improvement the Soil Physicochemical Properties and Fenugreek Growth Using Zeolite and Vermicompost under Water Deficit Conditions

Abstract

The low percentage of soil organic matter, especially in sandy soils in most arid and semiarid regions of the world including Iran, and the increase in the indiscriminate use of chemical fertilizers and the resulting environmental damages make it inevitable to use organic fertilizers and soil amendments for increasing the water and fertilizer efficiency in sustainable agriculture. This study aimed to investigate the physicochemical changes of soil under the organic and mineral treatments of nitrogen and zeolite and alleviation of water stress in fenugreek (Trigonella foenum-graecum). The experimental treatments included five irrigation regimes (without stress, mild water deficit stress, and severe water deficit stress (irrigation after depletion of 20%, 40%, and 60% of available soil water (ASW), respectively), in vegetative and reproductive stages) as the main plot and the factorial combination of three fertilizer treatments (control, vermicompost, and urea) and two zeolite contents (0 and 9 t ha−1) as the subplot. Mild and severe water deficit stress caused at least 34 and 40% reduction in biological yield and 5% and 13% reduction in height in the first and second years, respectively. Applying vermicompost increased the soil organic carbon (OC), and the highest amount of soil nitrogen (N) was observed in the plots treated with zeolite and vermicompost. The available soil phosphorus (P) increased by applying zeolite. The zeolite treatment was more effective than vermicompost in increasing the soil cation exchange capacity (CEC). The treatments with zeolite or vermicompost were able to alleviate water deficit stress. Vermicompost and zeolite improved the biological yield of fenugreek by improving the physicochemical conditions of the soil, especially in the water deficit stress conditions, and reduced the usage of chemical fertilizers in line with the goals of sustainable agriculture.