Sustainable agricultural requires management strategies that simultaneously enhance crop productivity, improve soil fertility, and reduce environmental degradation. Intercropping systems, have been recognized as an effective approach for increasing resource-use efficiency, improving nutrient cycling, and enhancing land productivity. In addition, the integration of fertilizers and bio fertilizers into intercropping systems has gained increasing attention due to their ability to improve soil physical, chemical, and biological properties while reducing dependence on synthetic fertilizers. Consequently, this study was conducted to evaluate the effects of different fertilizer sources on nutrient accumulation, crop yield, and land equivalent ratio.



Materials and Methods experiment

A two-year field experiment was carried out during the 2023 and 2024 growing seasons at the research farm located in Porkaposht village, Astaneh-ye Ashrafiyeh County, Guilan Province, Iran. The experiment was arranged as a factorial based on a randomized complete block design (RCBD) with three replications. The experimental factors included four planting patterns (sole cropping (I1), peanut:maize intercropping at ratios of 3:1 (I2), 2:2 (I3), and 1:3 (I4)) and five fertilizer treatments (control (F1), chemical NPK fertilizer (F2), vermicompost (F3), biofertilizer containing Azotobacter vinelandii, Pseudomonas putida, Pantoea agglomerans, Pseudomonas koreensis, and Pseudomonas vancouverensis (F4), and poultry manure (F5)). At crop maturity, grain yield and concentrations of macro- and micronutrients, including nitrogen, phosphorus, potassium, sulfur, iron, zinc, and manganese, were determined in both peanut and maize grains. In addition, the land equivalent ratio (LER) was calculated to assess the efficiency of intercropping relative to sole cropping. Data from both years were subjected to combined analysis of variance, and treatment means were compared using Duncan’s multiple range test at the 5% significance level.



Results and Discussion

The combined analysis revealed that cropping patterns, fertilizer treatments, and their interactions significantly affected grain nutrient concentrations, grain yield, and total LER. Intercropping systems generally outperformed sole cropping in terms of nutrient uptake and land-use efficiency, indicating positive complementary interactions between peanut and maize. Among the planting patterns, the 2:2 peanut–maize intercropping ratio (I3) produced the highest values of several nutritional traits. Furthermore, the highest total LER was obtained under the I3 planting pattern, demonstrating superior utilization of environmental resources and improved productivity per unit area compared with sole cropping. Fertilizer treatments also exerted substantial effects on crop performance and nutritional quality. Poultry manure (F5) consistently produced the highest nutrient concentrations and grain yields. Peanut grains under F5 contained the highest nitrogen, sulfur, iron, and zinc concentrations, with average values of 4.7%, 0.60%, 50.4 mg kg⁻¹, and 46.4 mg kg⁻¹, respectively. Moreover, this treatment resulted in the maximum peanut grain yield of 1502.4 kg ha⁻¹. In maize, poultry manure increased grain iron concentration to 74.6 mg kg⁻¹ and produced the highest grain yield of 11312 kg ha⁻¹. The interaction between planting pattern and fertilizer source further emphasized the synergistic effects of intercropping and organic nutrient management. The I3 × F5 treatment combination, as the superior treatment, resulted in the highest nutrient concentrations in both crops. In peanut grains, the highest potassium (0.30%) and manganese (45.5 mg kg⁻¹) contents were observed. Furthermore, in maize grains, this treatment combination led to the maximum values of nitrogen (2.26%), phosphorus (5112.6 mg kg⁻¹), zinc (54.5 mg kg⁻¹), and manganese (34.5 mg kg⁻¹). The superiority of the 2:2 intercropping system may be attributed to improved spatial complementarity and reduced interspecific competition, which enhanced resource acquisition and nutrient uptake. In addition, poultry manure likely improved soil nutrient availability, microbial activity, and root development, thereby facilitating greater nutrient absorption and biomass production. These findings highlight the important role of integrated nutrient management in maximizing the benefits of legume–cereal intercropping systems.



Conclusion

The results demonstrated that peanut–maize intercropping significantly improved nutrient accumulation, grain yield, and land-use efficiency compared with sole cropping systems. Organic fertilizer sources, particularly poultry manure, enhanced the nutritional status and productivity of both crops more effectively than the control treatment. Among all treatment combinations, the two-row peanut: two-row maize intercropping pattern combined with poultry manure application (I3 × F5) exhibited the highest nutrient-use efficiency, crop productivity, and land equivalent ratio. Therefore, this integrated management strategy may be recommended as a sustainable approach for improving crop production and potentially supporting soil fertility in peanut–maize intercropping systems.