Effect of Intercropping on Nodulation and N₂-fixation by Groundnut

Abstract

Nodulation and N,-fixation of groundnut were investigated in sole and intercropping systems.Intercropping with pearl millet, maize, or sorghum reduced nodulation and N 2 -fixation. This effect is ascribed to the shading of groundnut by the cereal component and the consequent decrease in photosynthesis of the legume canopy.

Nodulation, Nitrogen Yield and Fixation by Bambara Groundnut (Vigna Subterranea (L.)Verdc.) Landraces Intercropped with Cowpea and Maize in Southern Guinea Savanna of Nigeria

“…Results of this study showed that N fixation in sole systems were higher than in intercropping. This is in agreement with the reports of Nambiar et al (1983), which indicated that shading by tall cereal crops can reduce both yield and N fixation of shorter stature legumes. Mean quantities of N fixed by bambara groundnuts in both intercropping systems were small (11.27-34.90 kg/ha).…”

“…The observed reduction in the number and weight of nodules of intercropped bambara groundnuts when compared to sole crop treatments might be as a result of shading from the more aggressive components of intercropping (maize and cowpea). This finding was in agreement with the results of earlier studies (Egbe & Egbo, 2011;Egbe, 2007;Nambiar et al, 1983) who observed decreased nodulation in intercropped cowpea, pigeonpea and groundnuts in their separate studies and attributed the reduction in nodulation to adverse effects of shading. The number of nodules in bambara groundnut/cowpea intercropping was significantly higher than in bambara groundnut/maize intercropping system, probably because a more conducive environment (moisture, temperature, etc.)…”

Assessment of indigenous Bradyrhizobia spp. population levels in low phosphorus soils of southern Cameroon using cowpea (Vigna unguiculata L. Walp) as trap crop

“…These results showed that the levels of Bradyrhizobia populations recorded in the two study sites were adequate to give satisfactory outputs on nodulation and nitrogen fixation without inoculation. This is in agreement with earlier findings by Nambiar et al(1983) where it was shown that most cultivated tropical soils have a rhizobial population of more than 100 rhizobia cells per gram of soil capable of nodulating the legumes grown on such soils. More so, in soils where naturalized rhizobial populations are high (>10 3 rhizobium bacteria per g soil), introduction of new strains can be difficult and often unsuccessful (Thies et al, 1991;Brockwell et al, 1995).…”

Response of cereals to nitrogen in sole cropping and intercropping with different legumes

“…Where positive effects were reported either an insufficient range of fertility situations were examined (De et al, 1978;Singh, 1981), or the legume effect was confounded with plant population because the intercrops were planted in a replacement system (Remison, 1978;Eaglesham et al, 1981). In fact, legumes intercropped with cereals showed consistently reduced nitrogen fixation indicating that they are of less benefit to the cereals (Nambiar et al, 1983;Wahua and Miller, 1978). In some multilocational studies the response of maize intercropped with soybean to nitrogen fertilization was similar to that of sole-cropped maize (Ahmed and Gunasena, 1979;Ahmed and Rao, 1982).…”