The Effect of Cutting Height of Senna singueana (Del.) Lock. In Mixed Intercropping System on Foliage Biomass Production and Maize Yield in Morogoro, Tanzania

摘要

A study was conducted during 1998-2001 at Kitete, Morogoro, Tanzania to determine the potential use of a commonly occurring shrub (Senna singueana (Del.) Lock.) in tropical Africa for soil fertility replenishment. Senna singueana (Senna), which is also locally known as Mhumba, was examined in mixed inter-cropping trial at four cutting heights (25, 50, 75 and 100 cm), measuring its foliage biomass production and maize yield. Senna was established using 3 months-old seedlings at 2.0 m inter-row and 0.9m intra-row spacings. Staha maize variety was used as the test-crop. Foliar biomass, maize yield and N-partitioning between maize parts (grain, straws and cobs) were determined. Senna had the highest growth rate during 4-10 months after establishment. Foliage dry matter yield (fertilizer source) increased with cutting stubble height to 75 cm after which it declined. Cutting Senna plants at 75 cm height maximized both its potential for foliar biomass production (2.70 t ha~(-1)), prunings N contributionto the maize crop (59.5 kg N ha~(-1)), yields of maize grain (2.701 ha~(-1)), straws (2.501 ha~(-1)) and cobs (0.55 t ha~(-1)) and N-partitioning between maize grain (40.1 kg N ha~(-1)), straws (12.8 kg N ha~(-1)) and cobs (3.7 kg N ha~(-1)). It is concluded that Senna grows rapidly and recovers fast to coppice profusely following foliage harvesting. Pruning Senna plants at 75 cm height optimizes soil N availability and plant uptake and promotes healthy plant growth, maximizes biomass production and yield of associated maize crops. It is, however, suggested that future genetic improvement research should focus on evaluating various Senna singueana provenances with a view of identifying the strains that maximize its productivity.