Action Filename Size Access Description License
Show more files...


In this study we examined the impact on soil C, total soil N and available P of six rotations namely: long season tobacco cultivar ‘KM10’ grown continuously (ContKM10), medium season tobacco cultivar ‘RK8’ grown continuously (ContRK8), grass-grass-grass-KM10 (G-G-G-KM10), grass-grass-grass-RK8 (G-G-G-RK8), KM10-Crotalaria juncea (KM10-Cr) and RK8-Crotalaria juncea (RK8-Cr). The experiment was established in 1990 under irrigation on a sandy loam soil at Kutsaga Research Station, Zimbabwe. Soil samples were taken from 0- to 15-cm deep, after each season. After 9 years, tobacco-grass rotations showed higher soil C than monocropping, regardless of variety. The monocropping systems, ContKM10 and ContRK8, did not differ from KM10-Cr and RK8-Cr respectively showing that when crop intensity is maintained soil C will be reduced regardless of a winter C. juncea green manure in a sandy loam soil. After 9 years, soil N was greatest in the G-G-G-KM10 rotation. Available P was lower in the grass (G-G-G-KM10, G-G-G-RK8) relative to the other rotations regardless of variety. Available P accumulated in monocropping systems (ContRK8, ContKM10) and was consistently lower in the grass-tobacco rotations. This indicated an accumulation of P in the case of monocropping systems because of continuous inorganic fertiliser input. The results reaffirmed the deleterious effect of monocropping and suggested the need for diverse rotations.


Downloads Statistics

Download Full History