Strip intercropping strategy including both annual and perennial legumes for increased fertilizer N substitution and climate change mitigation

Summary

Substitution of nitrogen (N) fertilization by leguminous symbiotic N2-fixation (SNF) mitigates global CO2 emissions. However, changes to present cropping methods and systems are required to obtain such advantages (Hauggaard-Nielsen et al., 2009). Strip intercropping attempts to capture the biological efficiency of intercropping (Willey, 1979) in the context of more separated crop components and efficient mechanization (Exner et al., 1999). The aim of the study is to test the use of a 6m annual winter rye-winter vetch intercrop strip adjacent to a 6m perennial grass-clover mixture.
Materials and Methods
2y field experimentation was conducted under temperate growing conditions in Denmark (55°40’N, 12°18’E).
Results
The grass-clover was more competitive towards plant growth factors reducing rye N uptake, but increasing the percentage of total aboveground vetch N accumulation derived from SNF. Equivalent dynamics were identified in the pasture with less clover found 0-50 cm away from the annual strip due to strong soil mineral N interspecific competitive interactions between grass and rye, as compared to >150 cm away.
Conclusions
Less reliance on non-renewable resources positions legumes in an important role. The present strip intercropping strategy is able to respond to temporal and spatially variable soil mineral N resources securing an efficient uptake with simultaneous SNF whenever soil N is limited. Furthermore, the inclusion of a perennial strip increase soil carbon stocks which should be taking into evaluating overall climate change mitigation.
References
Exner DN, Davidson, DG, Ghaffarzadeh M and Cruse RM (1999). Yields and returns from strip intercropping on six Iowa farms. American Journal of Alternative Agriculture 14, 69-77
Hauggaard-Nielsen, H, Gooding, M, Ambus, P, Corre-Hellou, G, Crozat, Y, Dahlmann, C, Dibet, A, von Fragstein, P, Pristeri, A, Monti, M and Jensen, ES (2009) Pea-barley intercropping for efficient symbiotic N2-fixation, soil N acquisition and use of other nutrients in European organic cropping systems. Field Crops Research 113, 64-71
Willey RW (1979) Intercropping - Its importance and research needs. Part 1. Competition and yield advantages. Field Crops Abstracts 32, 1-10