نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه زنجان، زنجان، ایران
2 گروه صنعتی پژوهشی فرهیختگان زرنام، استان البرز، شهر هشتگرد، ایران.
3 گروه علوم و مهندسی خاک، دانشکده کشاورزی، دانشگاه زنجان، زنجان، ایران.
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
A greenhouse experiment was conducted using a completely randomized factorial design with three replications to evaluate the effects of different levels of amino acid–rich soluble organic fertilizers enriched with various iron sources on maize growth and soil enzymatic activity in calcareous soils. Fertilizer type was considered as the first factor at eight levels, and fertilizer application rate as the second factor at two levels. The treatments included: control (C); 3% iron-containing ferrous sulfate solution (S); organic fertilizer without iron enrichment (O); separate application of organic fertilizer without iron and 3% ferrous sulfate (OS); organic fertilizer enriched with 3% iron from ferrous sulfate (A); organic fertilizer enriched with 1.5% iron from Fe-EDTA and 1.5% from ferrous sulfate (AE); organic fertilizer enriched with 1.5% iron from Fe-DTPA and 1.5% from ferrous sulfate (AD); and organic fertilizer enriched with 1.5% iron from Fe-EDDHA and 1.5% from ferrous sulfate (AH). These fertilizers were applied via fertigation at two levels, 50 and 100 L ha⁻¹, corresponding to 0.08 and 0.16 g per 3 kg of soil, respectively. The results showed that all fertilizer treatments increased fresh and dry weights of shoots and roots, plant height, and soil enzymatic activity compared to the control. The AH treatment at 100 L ha⁻¹ (AH100) exhibited the highest yield, increasing dry shoot and root weights and plant height by 34%, 31%, and 36.9%, respectively, compared to the control, as well as enhancing alkaline phosphatase, catalase, and urease activities by 23.2%, 22.3%, and 21.5%, respectively. Application of the organic fertilizer containing Fe-EDDHA significantly improved maize growth and physiological status, which was attributed to enhanced iron nutrition, chlorophyll content, and soil biological activity.
کلیدواژهها [English]
During the wet-milling process of maize in grain refineries, a by-product rich in organic matter, known as corn steep liquor is generated. Through enzymatic and fermentative hydrolysis, corn steep liquor can release bioactive compounds that act as signaling molecules and plant growth stimulators, making it a promising raw material for the production of soluble organic fertilizers. Moreover, considering the widespread iron (Fe) deficiency in neutral and alkaline soils, developing iron-enriched fertilizers that are both effective in correcting this deficiency and more environmentally compatible is regarded as an important strategy in iron nutrition management. Accordingly, this study was conducted with the aim of producing soluble organic fertilizers enriched with different iron chelates and evaluating their effects on maize growth and soil enzyme activity under calcareous soil conditions.
A factorial greenhouse experiment with two factors—fertilizer type and application rate—was conducted in a completely randomized design using fertigation, with three replications under controlled conditions, in the greenhouse of the Farhikhtegan Zarnam Industrial–Research Group during the winter of 2024. The experimental treatments included: control without fertilizer (C); ferrous sulfate solution containing 3% iron (S); unenriched liquid organic fertilizer (O); separate application of unenriched liquid organic fertilizer and ferrous sulfate solution containing 3% iron (OS); liquid organic fertilizer enriched with 3% iron from ferrous sulfate (A); liquid organic fertilizer enriched with 1.5% iron from Fe-EDTA chelate and 1.5% iron from ferrous sulfate (AE); liquid organic fertilizer enriched with 1.5% iron from Fe-DTPA chelate and 1.5% iron from ferrous sulfate (AD); and liquid organic fertilizer enriched with 1.5% iron from Fe-EDDHA chelate and 1.5% iron from ferrous sulfate (AH). The fertilizer treatments were applied at two levels (50 and 100 L ha⁻¹) in two separate stages during the growth period of hybrid maize 703 planted in 3-kg pots.
The results showed that the different fertilizer treatments had a significant effect on maize growth characteristics, yield, and microbial activity. The greatest plant height (119.63 cm), as well as the highest fresh and dry biomass of shoots and roots, were observed in the AH100 and AH50 treatments, respectively. Root length and leaf number increased by 32% and 20% compared with the control. Total chlorophyll increased by 28.8%, and carotenoids increased by 17.6% relative to the control. In contrast, the control treatment recorded the lowest values in all measurements. Regarding iron content, the highest Fe concentration was recorded in treatment (E) (117.37 µg g⁻¹ dry matter). In addition, urease and alkaline phosphatase activities in the soil increased by 23.2% and 21.5%, respectively, in the AH100 treatment compared with the control. The combination of liquid organic fertilizer with Fe-EDDHA chelate enhanced nutrient uptake—especially iron—due to its rich content of iron, organic nitrogen, amino acids, carbohydrates, and its microbial-stimulating properties. As a result, plant growth and yield were considerably improved.
The results of this study indicated that application of organic fertilizer containing Fe-EDDHA significantly improved the growth and physiological traits of maize. This fertilizer increased plant height, fresh and dry weights of shoots and roots, chlorophyll content, and soil enzyme activities, including urease, phosphatase, and catalase. The greatest positive effect was observed in the AH100 treatment (100 L ha⁻¹, equivalent to 0.16 g per 3 kg of soil), highlighting the effective role of chelated iron in plant nutrition, chlorophyll enhancement, and photosynthetic efficiency. In addition, due to its content of organic matter and amino acids, this fertilizer may improve the physical, chemical, and biological properties of soil, including stimulating beneficial microbial activity. These components may also enhance plant nitrogen nutrition and growth stability by supplying organic nitrogen and improving its uptake efficiency. Furthermore, under greenhouse conditions, application of 100 L ha⁻¹ (0.16 g per 3 kg of soil) of Fe-EDDHA–containing organic fertilizer improved iron nutrition in calcareous soils. However, due to the pot-based nature of the experiment, the results reflect plant responses under controlled conditions and cannot be directly extrapolated to field conditions. Therefore, definitive recommendations regarding this treatment require field experiments to evaluate the persistence and effectiveness of its effects under real production conditions.
Conceptualization, A. A. and A. G.; methodology, A. A. and A. G; software, A. A.; validation, A. A. and A. G.; formal analysis, A. A. and A. G.; investigation, A. A. and A. G.; resources, A. A. and A. G.; data curation, A. A. and A.G.; writing—original draft preparation, A. A.; writing—review and editing, A. G.; visualization, A. A.; supervision, A. G.; project administration, A. G., M. J. A. A. S.; funding acquisition, A. A., A. G., and M. J. A.
All authors have read and agreed to the published version of the manuscript.
The data supporting the findings of this study are available in the manuscript. If the study did not report
any data, you might add “Not applicable” here.
The authors would like to thank Zanjan Universities, Farhikhtegan Zarnam Research Industrial Group and Iranian Company for Maize Development for providing all the needed facilities.
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
The author declares no conflict of interest.
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