ABSTRACT
The development of double cropping after rice harvesting is considered a fundamental strategy to enhance production and income for farmers while maintaining rice production sustainability in Guilan province. Despite the vital importance of this type of cultivation in paddy fields, a vast area of these lands remains uncultivated due to various agricultural, economic, and social reasons. In order to identify profitable species of forage crops (including fodder beet, triticale, and clover) and oilseed species (including canola and camelina) for double cropping after rice, and to evaluate their effects on profitability, yield, and interference with the rice cropping calendar, an experiment was conducted in a randomized complete block design with three replications at the Soil and Water Research Station of the Rice Research Institute of Iran. Based on the results of this research, the yields of canola and camelina were approximately the same. Fresh and dry clover had different yields, and the aerial organ and root yields of fodder beet also showed different values. Fresh and dry triticale also had different yields, respectively. Economic analysis showed that the cultivation of canola, camelina, and fodder beet is not economically viable, while clover cultivation is only profitable when sold fresh. Based on the results of this research, triticale, with the least interference in the rice cropping calendar, has good yield and profitability and is recommended as a suitable option for double cropping after rice in the region.

Introduction
Given the increasing population and limited land resources, enhancing productivity per unit area is an unavoidable necessity. Double cropping serves as a strategy to boost productivity, positively impacting rural household economies and enabling optimal land utilization. However, due to agronomic, economic, and social factors, a significant portion of these lands remains uncultivated after the rice harvest. Selecting the appropriate crop and using optimized cultivation techniques are crucial for the success of double cropping. Effective marketing and economic profitability are also important for expanding the cultivated area of these products. Given the diverse conditions, region-specific research is needed to optimize crop rotation strategies in rice-based systems. This study aims to identify profitable forage and oilseed crops for second cropping after rice in the paddy fields of Gilan Province, thereby promoting optimal resource utilization and enhancing the economic and environmental sustainability of these regions

Materials and methods
To investigate the effects of crop rotation canola, camelina, clover, fodder beet, and triticale on profitability, yield, and compatibility with the rice cropping calendar, an experiment was conducted in during the 2019-2020 growing season at the Soil and Water Rice Research Station in Rasht.Each experimental plot for canola, camelina, triticale, and clover was planted in 20 rows, spaced 25 cm apart and 10 meters long. Each experimental plot for forage beet was planted in ten rows, spaced 50 cm apart and 10 meters long. All seeds were manually sown on ridges created with a furrower. Canola, camelina, forage beet, and clover were planted in the second half of October, and triticale was planted in mid-November. The spacing between treatments was one meter, and between replications was two meters. After the rice harvest, in order to prepare the land for planting the desired forage and oilseed crops, tillage operations were performed in two stages, perpendicular to each other, with a rotary plow at a depth of 10-15 cm. To improve drainage, prevent seed suffocation in waterlogged conditions, and prevent stem rot, furrows and ridges were created with a furrower. Before the experiment, soil samples were taken from the field at a depth of 0-30 cm, and the physical and chemical properties of the soil were determined. The required fertilizer for each crop was applied in different stages based on the technical recommendations of the soil and water department researchers at the Rice Research Institute. Due to sufficient rainfall during the plant growth season, no irrigation was performed, and the cultivation was rainfed. Clover was harvested at the beginning of flowering, which coincided with the milk stage of grain development in triticale. To determine the fresh forage yield per unit area, the marginal rows and half a meter from the top and bottom of each plot were removed as border effects, and the plots were harvested and immediately weighed. To measure dry forage yield, one kilogram of fresh forage was randomly selected from each treatment, and the samples were dried in an oven at 75 degrees Celsius for 48 hours and weighed. Forage yield was determined based on 15% moisture content. Statistical analysis of the data was performed using Excel software with simple and combined statistical analyses. Mean comparisons were performed using the LSD test at a 5% probability level. Finally, economic evaluation, including the determination of net annual benefits and benefit-cost ratio, was carried out by considering the costs of planting, maintenance, harvesting, and silage making, in order to select the best treatments.

Results and discussion
Variance analysis showed that the type of forage crop had a highly significant effect (P < 0.01) on fresh forage yield, dry forage yield, and plant height. This indicates significant differences in these traits among the different types of forage crops studied. In other words, the selection of forage crop type significantly affects yield and plant height. However, the effect of forage crop type on the ratio of dry to fresh forage yield was not statistically significant (P > 0.05). This suggests that the different types of forage crops studied do not differ significantly in the amount of dry matter present in the fresh forage.
Mean comparisons showed that triticale, with a fresh forage yield of 3460.7 g/m² and a dry forage yield of 395.85 g/m², significantly outperformed the other crops studied. Berseem clover, with a fresh forage yield of 1491 g/m² and a dry forage yield of 185.78 g/m², ranked next, which was significantly higher than forage canola, fodder beet, and camelina. Triticale also had the tallest plant height at 115.66 cm.
Economic analysis showed that cultivating triticale, berseem clover, and fodder beet in Guilan province resulted in positive net annual benefits and a benefit-cost ratio greater than one, indicating the profitability of these crops in the region. Among the crops studied, berseem clover had the highest economic return, with a benefit-cost ratio of 4.67 and a net annual benefit of 165,034,310 Rials.
The development of forage crop cultivation, particularly legumes, plays a significant role in providing forage, reducing erosion, improving soil texture, utilizing low-yielding areas, and ultimately, promoting sustainable agriculture.
Based on the results of the economic analysis, cultivating canola and camelina is not cost-effective in the conditions of Guilan province. In contrast, clover, triticale, and fodder beet can be recommended as a second crop after rice in the paddy fields of this province due to their suitable yield and profitability.

Conclusion
Triticale and clover, due to their suitable forage yield, adaptability to regional conditions, and high potential for producing quality forage, can be considered appropriate options for second cropping in the paddy lands of Guilan Province.Nevertheless, the development of second cropping in these lands also faces challenges such as drainage issues, a lack of suitable machinery, and inadequate markets.