Nitrogen Fixation Mechanism and Production Benefit Analysis of Cassava and Stylosanthes Guianensis Intercropping System
Stylosanthes guianensis is an important intercropping plant,but the mechanism of nitrogen fixation between Stylosanthes guianensis and Cassava intercropping system is not clear.In this study,the intercropping system of Stylosanthes guianensis and Cassava was used to analyze the agronomic characters of Stylosanthes guianensis during its growth period and the dynamic change of nitrogen content in different tissues.The results showed that:the average nitrogen isotope value of Stylosanthes guianensis was 1.87%for roots,1.03%for stems,and 2.41%for leaves,respectively.The average nitrogen isotope value varied from different tissues.In the early stage,the nitrogen of Stylosanthes guianensis came from soil inorganic nitrogen;in the middle stage,both inorganic nitrogen and nitrogen fixation contributed;in the late stage,the number of nitrogen-fixing bacteria increased in the rapid growth stage of Stylosanthes guianensis,but its contribution gradually decreased;the main nitrogen source of Stylosanthes guianensis turned to soil inorganic nitrogen.In addition,Stylosanthes guianensis interplanting Cassava increased yield of fresh tubes 21.21%compared with single Cassava.Compared with monoculture Cassava and monoculture Stylosanthes guianensis,intercropping increased the income by 1361.09 yuan/mu and 1159.21 yuan/mu,respectively.To sum up,the intercropping system of Stylosanthes guianensis and Cassava can effectively provide nitrogen source utilization rate and economic benefits.
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