The experiment was conducted at the Faculty of Agriculture, University of Benin, Ugbowo Campus Benin City Nigeria. The experiment was conducted under rain fed condition during the early cropping season (March to November) of the year 2013. The experimental design was the Randomized Complete Block Design (RCBD) with yam and egusi-melon as the test crops. The trial consisted of 4 levels of NPK 20:10:10 fertilizer (0, 200, 400, 600kg/ha) with 3 cropping systems and replicated 3 times. It was observed that yam did well in sole than in intercropping. Average tuber yield of yam in fertilizer treatments was also greater than that of unfertilized plants. Also the average tuber yield and number of tubers were significant. The higher tuber yield of yam2.862t/ha and 2.991t/ha was obtained from 400kg/ha treatment in sole and in intercrop planting system. Higher number of tubers of 21.66 was obtained from 200kg/ha treatment in sole planting system. The mean value of egusi-melon seed yield in intercrop and sole melon was 0.0513t/ha and 0.0511t/ha respectively. And the mean value obtained from average pods size was 28.97cm for sole and 34.0cm for intercrop. From the experiment, plot which was measured 4×1.5m per sub-plot, the average number of egusi-melon gotten was 34.0 for intercrop and 44.0 for sole. The application of NPK 20:10:10 fertilizer at 400kg/ha had the greatest influence on the yield of egusi-melon both as a sole and as intercrop. The application of 400kg/ha at 6WAP influenced the pod number. The application of NPK 20:10:10 at 600kg/ha had the greatest influence on vine length and stem girth of egusi-melon both as sole and as intercrop. Average stem girth of 1.19cm in sole and 1.33cm in intercrop was obtained. Vine length of 154.3cm in intercrop as against 156.3cm recorded in sole planting.
The longest vine and the widest stem girth of yam were obtained at 400kg/ha of NPK 20:10:10 fertilizer. Average vine length of 236.2cm in intercrop and 225.7cm in sole at 8WAP was obtained. Average stem girth of 1.55cm in intercrop as against 1.64cm recorded in sole planting.
Intercropping is an agricultural practice in which two or more crops are grown together in the field (Onwueme, 1978). One advantage of intercropping is that it increases yield: more can be grown on a single plot with intercropping.
Intercropping suppresses weed better than sole cropping. It provides an opportunity to utilize crops themselves as tools for weed management. In intercropping more complete crop coverage and high population density cause some competition to weed and thus reduce the weed growth. Compatible crop mixture which reduces weed competition viz a viz increases total yield should be selected. Result of a large number of experiment have indicated that short duration pulse like green grain, cowpea, soya beans as intercrop effectively smothers weeds. Intercropping short season crops e.g. maize and melon with large season crops like yam and cassava prevents weed from adapting to the growth cycle of either crops. Low growing crops like melon, sweet potato with maize, cassava, yam ass intercrops suppresses weed growth in Nigeria (Akobundo, 1987).
For farmers who don’t have much land, it reduces farmers risk because if one crop fails, other crop may continue to grow. Mixed intercropping is common when cereals, grain legumes, and root crops are grown together and when little or no tillage is practiced (Akinola and Agboola et’al 2007). Farmers in southern Nigeria plant two or more crops simultaneously in association and on the same piece of land. The most dominant crop mixture is:
Yam + melon + maize + vegetable,
Cassava + melon
Maize + melon + cassava
Yam + melon intercrops.
However, intercropping root crop like yam (Dioscorea spp) with egusi-melon (Colocynthis citrillus) is a common practice by farmers, as egusi-melon serves as a weed suppressant in the first 6 weeks of yam growth (Ogungbaigbe, et’al 1996).
1.1 YAM (Dioscorea spp)
Yam is an annual or perennial climbing plant with underground tubers. Nigeria is by far the world largest producer of yams, accounting for over 70-75 % of the world production (FAO, 2004). More than 95 % of the world’s yams are currently grown in sub – Sahara Africa, with the reminder grown in the West Indies and parts of Asia and South and Central America.
Yam, a tropical crop in the genus Dioscorea has as many as 600 species out of which 6 are economically important staple species. These are: Dioscorea rotundata (white yam), Dioscorea cayensis (yellow yam), Dioscorea alata (water yam), Dioscorea bubifera (aerial yam), Dioscorea dumetorum (trifoliate yam), and Dioscorea esculanta (Chinese yam).out of these, D. rotundata, D. cayensis and D. alata are the most common species in Nigeria (Onwueme, 1978). Yam is in the class of roots and tuber, it is a staple of the Nigerian and West African diet, which provide some 200 calories of energy per capital daily. Yam have a cultural and traditional significance among many communities in Nigeria, this is exemplified by the occurrence of rituals to mark their harvest
Mono cropping is increasing in certain area of West Africa and Caribbean. However, in producing area of Nigeria, mixed cropping with yam and egusi melon with maize or yam with egusi melon is prevalent (Kurt, 1984).
1.2 EGUSI-MELON (Colocynthis citrillus)
Egusi-melon is a vegetable crop commonly cultivated in West Africa (Vander-Vossen, et’al 2004). Because of its creeping nature and ability to use its leaves to provide cover on the soil, farmers use it as weed suppressant in mixed cropping (Achigan-Dako, 2008). Production of the crop is more popular in the northern parts of Nigeria where there is abundance of cultivable land which has made the practice of sole and mixed cropping possible. This is unlike the eastern part of Nigeria, where the sandy area of where scarcity of farm land has force majority of the farmers to raise the crop in mixed crop farms. Despite the socio-ecological important of egusi-melon, production output has been on the decline (Ugwumba, 2010).
Egusi-melon is grown for its seed, which is used in preparing assorted foods, especially soup and stew. The seed is rich in oil and protein and contains good quantities of most of the essential amino acids.
In traditional system of farming, egusi-melon is usually planted as lich much and smothering crops in midst of other crops. The benefit of intercropping yam with egusi-melon could possibly be harnessed by adjusting the planting sequence of yam minisetts (Ikeorgu, 1991).
The importance of egusi-melon in conserving soil moisture and reducing optimal soil temperature early in the growing season, earlier reported by Ikeorgu (1991), suggest the crops suitability for intercropping with yam.
1.3 OBJECTIVE OF THE STUDY
The objectives were to determine:
- the effect of NPK fertilizer on the growth and yield of yam and egusi melon in sole and in intercrop
- yield advantage, if any due to intercropping 0f both crops.