S15 - Session P2 - Opportunities and limitations of garlic (Allium sativumL.) crop rotation systems related to upland crops in Gyeongsangnam-do Province in Korea Republic

Authors: Byeonggyu Min *, Gilseog Park, Mijin Lee, Jaecheol Seo, Taeja Kim, Injong Ha

In addition to red pepper and onion, garlic is one of the main condiments used in Korea and has received attention as a health functional food. Gyeongnam has the largest garlic cultivation area and yield among Korean local governments, and most garlic crops are cultivated in paddy fields using a rice-based cropping system. When garlic is grown in paddy fields, the fresh water has the effect of partially destroying soil pathogens, pests, and weed seeds during the rice growing period; moreover, the continuous and extended growth of large bulbs is made possible by high water and nutrient retention. Conversely, soil in paddy fields is easily acidified, and emissions of methane and other greenhouse gases may be increased. To address these problems, it is necessary to develop a garlic cropping system linked to field crops. The field crops used and linked with garlic cropping in the present study were soybeans (effective for soil improvement) and sweet potatoes (with high revenue per unit area). Warm-season "Daeseo" garlic was sown at three time points (October 7, 16, and 26). The potential development of a cropping system was assessed by reviewing the main cropping seasons (planting season, harvesting season, etc.), quantity, and economic feasibility (revenue) of the garlic and field crops, and the optimum time for garlic planting and limits under the cropping system were assessed. Of the three planting dates, the number of the yield and revenue per unit area (10a) were the highest for crops planted on October 7: 1,832 kg and 3,258 thousand won, respectively. Thus, this date is considered the optimal time to sow garlic. For crops planted on October 16 and 26, the yield per unit area (10a) was 1,574 and 1,059 kg, respectively, and revenues were 2,799 and 1,884 thousand won, respectively. For most soybean varieties, the best time to sow in the southern region is early-to-mid-June, and the yield can be maintained if sowing is complete by the end of June. The best time to harvest soybeans for short-term fermented soy sauce and tofu is mid-to-late September; harvesting in late September to early October is optimal for normal soy sauce and tofu soybeans (Rural Development Administration, 2018). Therefore, if garlic is sown on October 7, which gave the highest yield and revenue of the dates tested, an overlap occurs with the harvest period of soybeans for normal soy sauce and tofu, making the sowing impossible. Therefore, an appropriate alternative cropping system could include cultivation of short-term fermented soy sauce and tofu soybeans rather than normal soybeans. All three garlic harvest dates were May 26; consequently, the overlap with the soybean sowing period is unlikely. In the southern region, the optimal cutting period for sweet potatoes is early May, and the cutting limit period for harvest is early July. Additionally, the optimal number of days from cut planting until harvest is 110 days for early-ripening varieties and 120 days for late-maturing varieties (Rural Development Administration, 2018). Cut planting sweet potatoes following the garlic harvest on May 26 will lead to a harvest date after mid-October, which would overlap with the optimal garlic sowing period. Therefore, the application of a sweet potatongarlic cropping system remains as a challenge.