Percentage Yield Difference, an Index for Evaluating Intercropping Efficiency

Aim: To evaluate intercropping efficiency using percentage yield difference (PYD) and to compare the index with other indices.

Study Design: The design was a 2 X 5 factorial in a randomized complete block design, and replicated three times.

Location: The study was carried out at the Lower Niger River Basin Development Authority, Ejiba (18°18°N, 5°39°E), Kogi State in the Southern Guinea Savannah Zone of Nigeria in 2008 and 2009 cropping seasons.

Methodology: Erect and prostrate cowpeas and maize were mixed at five population ratios. The five population ratios were: 100%C: 75%M, 100%C:50%M, 100%C:25%M, 75%C:25%M and 50%C:50%M (were C and M represented Cowpea and Maize respectively). Sole crops of each crop at full population were included as control treatments. Land Equivalent Ratio (LER), Area Time Equivalent Ratio (ATER), Monetary Equivalent Ratio (MER) and Percentage Yield Difference (PYD) were estimated and compared.

Results: Results of this study showed that LER, ATER, and PYD values were similar for the two cultivars in the two years.

LER values ranges between 1.18 and 1.27 in 2008 and 1.12 and 1.30 in 2009. MER did not follow the same trend as LER and ATER. Lower values were obtained particularly in 2009. However, the highest MER 1.35 and 1.23 in 2008 and 2009 respectively were obtained in prostrate cowpea / maize mixture at population ratio of 100:50. The PYD advantage varies between 5-33% in the two years.

Conclusion: The comparable values of PYD with other indices suggest that it can be used to evaluate/ intercropping efficiency in crop mixture.