Comparison of Yield and Quality of Forage in the Intercropping of Rye (Secale cereale L.) and Vetch (Vicia villosa Roth.) under Different Tillage Systems

Introduction Conservation tillage systems are a key component of sustainable agricultural management, significantly contributing to the improvement of soil’s physical, biological, and chemical properties. One of effective factors in increasing sustainable production is the intercropping of crops and fodder. In addition to increasing the diversity of economic resources of the farm, intercropping increases the yield per unit area, biodiversity and efficient use of resources and reduces possible damage from pests and diseases. One of the common types of forage intercropping is the mixed crop of legumes and cereals. Cereals are at a high level in terms of dry matter, but they are poor in terms of protein, and on the other hand, legumes are at a high level in terms of protein. Therefore, the mixture of cereals and legumes will lead to the production of high-quality forage. Since the effects of the combined use of mixed cropping and conservation tillage on fodder production have been less evaluated, and considering the importance of vetch and rye crops in fodder production and livestock feeding, improving soil fertility and production stability in agroecosystems, it seems necessary to evaluate the effect of mixed cultivation of these plants in different tillage systems. Materials and Methods In order to investigate the effect of different tillage systems on intercropping of rye (Secale cereale L.) and vetch (Vicia villosa Roth), an experiment was carried out in the cropping year of 2018-2019 in the Gariza Agricultural Research Station of Sanandaj. The experiment was carried out as a split plot based on a randomized complete block design in three replications. Tillage methods include no tillage, reduced tillage and conventional tillage as the main factor and rye and vetch intercropping system in 5 levels including 100% vetch, 75% vetch + 25% rye, 50% vetch + 50% rye, 25% vetch + 75% rye and 100% rye were considered as secondary factor. In conventional tillage system, reversible plow and disk were used, and in reduced tillage system, goose claw was used for plowing. In all three tillage systems, sowing of two crops was done simultaneously and manually on 15th of October. The studied traits included the number of nodes in the hairy vetch root, dry forage yield of hairy vetch and rye, land equivalent ratio, neutral and acid detergent insoluble fiber, digestible dry matter, and ash percentage. SAS 9.1 software was used to analyze the data and LSD test was used to compare the average of the treatments. Graphs were also drawn using Excel. Results and Discussion The results of analysis of variance showed that dry forage yield of rye and hairy vetch was influenced by the intercropping pattern and tillage systems. Among the mixed cropping combinations, the highest dry forage yield of rye (1625 kg ha-1) was achieved in the treatment of 75% rye + 25% hairy vetch under conventional tillage, which did not show a significant difference compared to the treatment of 75% rye + 25% hairy vetch under reduced tillage. In all studied tillage systems, the 50% vetch and 50% rye intercropping pattern had a higher land equivalent ratio (LER). The lowest total LER was related to the conventional tillage system and the treatment of 75% vetch + 25% rye. Assessment of the forage quality showed that the insoluble fibers in acidic (ADF) and neutral (NDF) detergent in conventional tillage and rye monoculture were more than other treatments. The amounts of ADF and NDF were reduced in low tillage and no tillage systems. Also, by increasing the proportion of vetch in intercropping treatments, the amount of insoluble fibers in acidic (ADF) and neutral (NDF) detergents decreased. The highest digestible dry matter (DMD) was in the reduced tillage treatment. The percentage of forage ash in the mixed cropping treatment with the combination of 75% vetch and 25% rye was higher than other ratios of mixed cropping. Conclusion According to the results of the present experiment, the high value of land equivalent ratio (LER) in intercropping patterns indicates a better utilization of the unit of land area in intercropping. Overall, to maximize forage yield and enhance forage quality, the findings clearly demonstrate that intercropping outperforms monoculture for the crops studied.