Effects of Incorporation of Green Manure Crops on the Growth of Watermelonand Soil Nitrate Nitrogen Concentration

BACKGROUND:In this study, we evaluated the effects of soil incorporation of hairy vetch (HV) or ryeas a green manure on the growth and yields of watermelon and soil nitrate nitrogen in a green house.. METHODS AND RESULTS: HV and rye were cultivated for 151 days after sowing on October 30th and incorporated into soil before transplanting watermelon.The amount of N added by soil incorporation of HV and rye were 79 kg/ha and 88 kg/ha, respectively.Five different N treatments for each of HV and rye were included as follows: green manure, green manure with urea at 25%, 50%or 75%, and 100% ureafor the N recommendation rate.The growth and fruit yield of watermelon were not different among the treatments of both HV and rye.Soil nitrate N content at both HV and rye treatments decreased continuously with the lapse of days after planting (DAP) and was lowest at 75 DAP: 44 mg/kg and 52 mg/kg the for the HV and rye treatment without urea, respectively. CONCLUSION:These results indicate that the N mineralized from the soil incorporated HV or rye accounts for an important portion of N available for the growth and fruit yield of watermelon.It can be suggested that the green manures, comparable to ureacould ensure the yield of watermelon, if soil nitrate N content isabove 40 mg/kg by soil incorporation of HV and rye during watermelon cultivation.However, further studies on the relationship between soil nitrate N content during cultivation periods and the fruit yield of watermelon are required.