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The study aims at determining the economic impact of the rubber based cropping system introduced to rubber farmers in Nigeria by Rubber Research Institute of Nigeria under the sponsorship of the Common Fund for Commodity (CFC) project in Nigeria coded CFC-IRSG 21. Thirty three farmers were randomly selected in five states in Nigeria (Edo, Delta, Ogun, Kaduna and Akwa Ibom) using interview schedule. The profitability of rubber based cropping systems on farmers' farms in the five states was determined using gross margin analysis. The study revealed that rubber based cropping systems in the study area were profitable with positive gross margins for all the identified cropping systems in the study area. Furthermore, the study revealed that a gross margin of N178, 000/ha and return on investment of N4.79 was the highest for the two cropping system identified in Edo state. A gross margin of N331, 000/ha and return on investment of N7.76 per Naira was the highest for the three cropping system adopted in Delta state. For the four crop combination in Ogun state, a gross margin of N181,000 and return on investment of N6.32 per Naira was the highest. In Akwa Ibom state, a gross margin of N402, 100 and return on investment of N8.05 per Naira was the highest for the three crop combination. For the four crop combination in Kaduna state, gross margin of N 488,000 was the highest. The study however, concluded that cassava featured more in the intercropped combination and it gave higher gross returns in the rubber based cropping systems in Nigeria compared with other crops across the states.

A study to determine the financial benefits of intercropping immature rubber plantation with cassava in South Eastern Nigeria was carried out at the Rubber Research Institute of Nigeria, Iyanomo near Benin City. The study was set up in a randomized complete block design with each treatment replicated three times. Yield data generated were used to determine the profitability of the systems. The results showed economic yield from rubber as the rubber trees did not attain tappable girth throughout the duration of the study. a mean yield of about 25.72 tonnes of cassava tuber were generated from the sole cassava treatments for the four years period while a mean yield of about 22.92 tonnes of cassava tuber per hectare were generated from the cassava + rubber intercrop treatments in the same period. A total amount of 160,000 Naira was spent in four years as cost of intercropping. Total revenue generated from the sales of cassava in the rubber + cassava system was 900, 000.00 Naira per hectare with a Gross Margin and profit margin of 740,000 Naira and 673, 090.98 Naira respectively. A profitability index of the rubber + cassava system was 0.75, indicating that, 75% of the total amount invested in the rubber + cassava system was recovered in the first four years compared to the additional costs incurred in the sole rubber plantation treatment. This study showed that intercropping cassava with rubber during the immature phase of rubber plantation guarantee early return on investment and more profitable compared with sole rubber plantation systems.

The impact of four spacing of cooking banana (CB) within the immature rubber avenues on some soil fertility attributes, maturity rate of rubber trees and dry rubber content (DRC) during the initial six years after planting (YAP) were evaluated in a humid forest area of South Eastern Nigeria relative to sole rubber. The CB spacings within immature rubber avenues were 6.7 × 3.4 m; 4.0 × 2.0 m, 3.0 × 3.0 m and 2.0 × 2.0 m, while the sole rubber was at 6.7 × 3.4 m, all laid out in randomized complete block design with five replications. Quantities of soil organic C, extractable P, Ca, Mg and earthworm activities were significantly higher in the intercrops, with the highest value coming from the 4 × 2 m CB spaced plots. However a significantly higher value of K stock was observed in the sole rubber plot and declined as the CB spacing narrowed. While the highest proportion (>90%) of matured hevea tree at six YAP was observed in the 2 × 2 m CB spaced plots; the highest DRC of 1.7 t?ha^–1?yr^–1 was obtained from CB 4 × 2 m treatment. Consequently, with some of the observed soil fertility attributes and DRC recorded, 4 × 2 m CB spacing seems to be a more suitable CB spacings within immature rubber avenues, especially in view of the levels of K in the 2 × 2 CB plots