31. Economic returns from yam/maize intercrops with various stake densities in a high-rainfall area.
Trop. Agric. (Trinidad), 69, 1992, pp. 171-175
The main objective of the study was to assess the effects of producing yam and maize under intercropping with a reduced stake population ha-1 without materially affecting their yields, and to determine the stake population ha-1 that gave the highest net economic return.
The profitability of producing yam (Dioscorea rotundata Poir.) with 0-5000 stakes ha-1 when intercropped with maize in a high-rainfall area in Nigeria was examined. Yam and maize populations used were 10,000 and 20,000 plants ha-1, respectively.
The high cost of producing yam in the forest zone of West Africa discourages farmers from increasing areas cropped with yam. The high production cost arises mainly from the cost of planting material (seed yam), the cost of stakes and a high labour requirement.
In this study tuber yield and weight tuber-1 decreased with lesser numbers of stakes ha-1. No changes occurred in maize grain and stover yields or in height and girth plant-1. Production cost was highest with 5000 stakes ha-1 and lowest in unstaked yams. Cost of staking decreased with fewer stakes ha-1, being 27, 17, an 13% of total production cost with 5000, 2500 and 1666 stakes ha-1, respectively. Trailing six stands stake-1, gave the best net return (48%) in sole yam but two stands stake-1 gave the best (22.4%) in intercropped yam, making the best net cash return in sole-cropped yam twice as profitable as a yam/maize mixture.
It is concluded that stake population density is an important factor affecting yield and net cash return in a yam/maize mixture, in addition to other factors.
If yam is to be cultivated with maize, as is practised by most farmers in this area, then not more than two stands should be tied to a stake.
When yam is intercropped with maize, the expected best net return will be only about 50% of that of sole yam trailed six stands stake-1, demonstrating that it is more profitable to grow yam as a sole crop in the environment than in mixture with maize.
Intercropping unstaked yam with maize did not affect the yield of yam.
The yam vines were expected to climb the maize stems and eventually tap more light to give a higher yield than sole, unstaked yam. Most yam vines in unstaked yam plots with maize did not climb the maize stalks.
This shows the need for the common practice of trailing yam vines to stakes to be adopted.
An appropriate stake population ha-1 or an intercropping system must therefore be used to produce yam tubers of desirable commercial size.
Medium-sized tubers are now generally preferred to big tubers by buyers because big tubers are often more prone to spoilage in storage from injuries sustained at harvest in this high-rainfall area and also because big tubers cost more than an average buyer can afford.
This study further demonstrates the high cost of producing yam, mainly from the high cost of planting material, stakes and labour.
Stake population ha-1 can be reduced in sole or intercropped yam without adversely affecting yield; such reduction is therefore a good area for reducing production cost and hence increasing profitability in yam cultivation.
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Latin America, Colombia, savannas, associations, legume, grazing effect,
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