ARET, Annual Report 2001, p. 100-5.

The evaluation of nematode tolerant grain legumes and grasses for their use in tobacco rotations

ARET, Agricultural Research and Extension Trust, Lilongwe, Malawi
The objective of this experiment was to determine the effet of nematode tolerant legumes and grasses on soil fertility, disease incidence including nematodes, yield and quality of flue-cured tobacco. In this long term experiment, six rotation treatments were imposed on heavy soils starting from 1996/97 season and on light soifs. from 1997/98 season. The treatments are as follows: 1. Continuous tobacco mono-cropped. 2. Tobacco, legume or grass alternating every year. 3. Tobacco, then two years of legume or grass then tobacco every third year. 4. Tobacco, then three years legume or grass then tobacco every fourth year. 5. Tobacco, then four years of legume or grass and tobacco every firth year. 6. Tobacco, then five years of legume or grass and tobacco every sixth year. The legume crops were groundnuts ( Archis hypogea ), soyabeans ( Glycine max , var Ocephara 4) and pigeon peas ( Cajanus cajan ): and the grass crops were Rhodes grass ( Chloris gayana ), and maize ( Zea mays ). A combination of all these factors resulted into 25 treatments and three controls. A randomised complete block design with three replications was used. The tobacco that was grown in rotation with all crops yielded higher than the mono cropped one, and the groundnut-tobacco rotation system had the highest yields. The soybean-tobacco rotation system together with groundnut-tobacco system were the most effective in reducing root-knot nematodes in the soil.