Effects of Crotalaria Incorporation into Soil as a Green Manure on Growth of Strawberry and Inorganic Soil Nitrogen Level

Abstract

In this study, we evaluated the effects of soil incorporation of crotalaria as a green manure on the growth and yields of 'Seolhyang' strawberry and inorganic soil nitrogen levels in a greenhouse. Four different N treatments were used, as follows: zero N fertilizer (control), crotalaria, crotalaria with 50% urea, and 100% urea. The recommended N requirement (100% urea) for strawberry was 86 kg N•ha-1 and 50% of the recommended N (50% urea) was 43 kg N•ha-1. Crotalaria was sowed on June 17 th , 2011 and cultivated for 37 days. The amount of N supply from soil incorporation of crotalaria was 104 kg N•ha-1. Strawberry was planted on September 9 th , 2011 and cultivated for 255 days after planting. The concentrations of soluble solids and acidity of strawberry fruits for the crotalaria treatment were higher than for the crotalaria with 50% urea and 100% urea treatments. On the other hand, the growth and yield of strawberry was the highest for the crotalaria with 50% urea and 100% urea treatments, followed by the crotalaria treatment, and the lowest for the control. Soil inorganic N concentration for the crotalaria treatment was continuously decreased to 24 mg•kg-1 at the end of the growing season, while crotalaria with 50% urea and 100% urea treatments maintained an inorganic N concentration that ranged from 35 to 50 mg•kg-1. These results indicate that the amount of N supply from soil incorporation of crotalaria may not be enough because strawberry yield was lower than for other N treatments. Therefore, additional nitrogen, such as 50% urea after soil incorporation of crotalaria, is recommended.