Introduction: In recent years, ensuring the continuous and sustainable production of healthy food products along with environmental protection and paying attention to agricultural economic and environmental problems is very important. Potassium is one of the major nutrients that its deficiency decreased the growth and yield of rapeseed. After soybean, rapeseed is the world's second produced oilseed. soil inorganic amendments such as zeolite are good strategies to improve soil quality and increase soil potassium content. The addition of zeolite plays an important role in reducing the nutrients loss and increasing fertilizer use efficiency. Considering unique characteristics of zeolites, such as the low-cost and abundance of its mines in Iran, having a special physical and chemical structure and it plays an important role in enhancing the water and nutrients uptake by plant. This research was conducted with the aim of determining the effects of natural and enriched zeolite with potassium on rapeseed yield, component yields and concentration of potassium in soil and rapeseed in two soils with different texture (sandy loam and silty clay loam).

Materials and Methods: This experiment was conducted as a split plot in pots conditions for three replicates in the research greenhouse of Sari Agricultural Sciences and Natural Resources University. In this experiment, the main factors include two types of soil (silty clay loam and sandy loam) and the secondary factors in twelve levels include the control (without zeolite and potassium sulphate) (T0), 32 mg. kg-1 potassium sulphate fertilizer (T1), 46 mg. kg-1 potassium sulphate fertilizer (T2), 2 gr zeolite with 32 mg. kg-1 potassium sulphate(T3), 4 gr zeolite with 32 mg. kg-1 potassium sulphate(T4), 6 gr zeolite with 32 mg. kg-1 potassium sulphate (T5), 2 gr zeolite with 46 mg. kg-1 potassium sulphate (T6), 4 gr zeolite with 46 mg. kg-1 potassium sulphate (T7), 6 gr zeolite with 46 mg. kg-1 potassium sulphate (T8), 2 gr enriched zeolite (T9), 4 gr enriched zeolite (T10) and 6 gr enriched zeolite (T11) were considered. Zeolite was enriched by ion saturation method. Rapeseed cultivation was done in 2021. At the end of cultivation season, harvest was done from each plot, grain yield, some yield components (pod number, thousand grain weight, grain oil), leaf potassium and grain potassium were measured. In addition, soil samples were collected from plots after harvest, and soil potassium was measured. Data analysis was done in the Statistic software and the mean comparisons were made by using LSD test.

Results and Discussion: The results showed that the effects of the soil type treatments were significant on all studied traits except seed potassium. The effects of amendment treatment were significant on all studied and the interaction effect of soil type and amendment treatment was only significant on grain yield. The highest amount of grain yield (6.46 gr) was observed in silty clay loam soil and 4 gr zeolite with 46 mg. kg-1 potassium sulphate (T7) with increasing about 49% compared the lowest amount (4.33 gr per pod) was obtained in sandy clay loam soil and control (T0). The use of 4 gr zeolite with 46 mg. kg potassium sulphate (T7) compared with the control (T0), was increased by 22% of thousand grain weight. Also the highest amount of grain oil (36.36 %) and grain potassium (2.75 %) was obtained in the treatment of 4 gr zeolite with 46 mg. kg potassium sulphate (T7). The results also revealed that the number of pod (85.16 %), leaf potassium (2.28%) and soil potassium (155.83 mg. kg-1) with increasing about 40%, 19% and 21 % respectively, compared with the control were significantly affected by 6 gr zeolite with 46 mg. kg potassium sulphate (T8). Between the enriched zeolite with potassium treatments, 4 gr enriched zeolite (T11) had the greatest effect on the studied traits.

Conclusion: overall, it can be concluded that, all studied traits except grain potassium in soil with silty clay loam texture are more than soil with sandy loam texture. The best results were obtained in 4 gr zeolite with 46 mg. kg-1 potassium sulphate (T7). Between the enriched zeolite with potassium treatments, application of 4 gr enriched zeolite with potassium was the most effective treatment on the studied traits. It can be concluded that the combined use of zeolite and potassium sulphate can be a suitable solution for improving rapeseed yield