Effects of Intercropping and Rotation on Forage Yield and Quality of Oat and Common Vetch in Jilin Province, China

The effects of intercropping row ratio and rotation on forage yield and quality of oat and common vetch were studied to understand the possibility intercrop advantages. Oat and common vetch were intercropped twice a year for three years in the field of Baicheng Academy of Agricultural Science in Jilin Province, China. The oat to common vetch intercropping rates expressed as the ratio of the numbers of rows were 0:1, 1:3, 1:2, 1:1, 2:1, 3:1 and 1:0. The intercropping advantage became significant over the years. In 2009 and 2010, intercrop sown at the row rate of 1:1, showed 97% and 23% of forage yield increase mono-cropped common vetch; and 42% and 54%  increase compare to mono-cropped oat, respectively. Nitrogen yield of the intercrop was 24% and 20% lower than mono-cropped common vetch in 2009 and 2010, but it was 79% and 93% higher than mono-cropped oat, respectively. Compared with mono-crop, intercropping presented positive effects on oat growth and dry matter accumulation, but negative effects on common vetch growth. Intercropping advantages exist when this positive effects surpluses the negative effects. Compared with continuous cropping, rotation has positive effects on oat. The effects of rotation on common vetch depended on soil nitrogen content. Higher soil N led to positive effects, while rotation on low soil N may inhibit common vetch growth. Intercropping oat with common vetch at row ratio of 1:1 under relatively low soil N content and rotation can produce the highest forage and N yield.