Abstract
The influence of soil nutrients and soil condition is probably much more pronounced in seedlings than it is appreciated. In Southwestern Tanzania traditional cultivation systems especially for finger millet (Eleusine coracana L.) production focus on proper crop establishment via proper soil fertility or very good soil physical properties, with maximization of exclusion of weeds, as assurances for proper subsequent yields. Vigourous seedling growth coupled with proper seedling emergence in the field is almost enough assurance of good prospects for good yields and manpower investment. Experiments were conducted in December/January 2000/2001 and 2001/2002 in farmers’ fields to quantify sensitivity of seedlings just after emergence to various levels of soil fertility under the influence of different land preparation (cultivation) techniques. This approach originated from observations in indigenous finger millet farmer’s fields of very wide variation in seedling vigour with differences in soil fertility and soil physical characteristics resulting from different traditional cultivation systems. Treatments involved slash and burn, traditional mounds (ntumba) and ox-ploughing, with normal hand-hoe cultivation as control. Finger millet was sown in each of these treatment plots in completely randomized experimental design. Seedlings were assessed at 14 DAP for vigour using measurements of length and weight. Soil samples were also analysed to relate soil nutrients to seedling performance. Results showed growth of more vigourous seedlings in slash and burn and “cultivated fallow” (ox-ploughing and ntumba mound) systems than in no-burning or normal cultivation without fallow. The more vigourous growth (seedling size index and other attributes) in the slash and burn cultivation is attributed to increases in soil P, K+, NH4+-N and Ca2+ as a result of burning. Total % N and P were also increased in the ox-ploughed plots compared to normal cultivation plots and this is considered to be the reason for more vigourous seedlings. Improvement in soil physical conditions as a result of the “cultivated fallow” practice is also thought to have contributed to more vigourous seedling growth. This study has in addition to indicating the need for more research on field seedling vigour under various influences of soil fertility and land preparation techniques, made use of seedling size index, root penetration index, leaf and canopy characteristics of seedlings as effective techniques of assessing seedling vigour. These parameters are also used by plant breeders, agronomists and horticulturists for measuring seedling growth.
