PhDThesis
Crop production in semi-arid areas is faced with different challenges that resulted
into low crop productivity, low household income and food insecurity. The main
production challenges in these areas are declining soil fertility and moisture stresses.
The integration of different techniques, which restore soil nutrients at low costs and
improve soil moisture can be used as a strategy to cope with these constraints and
ensuring sustainable crop production. The purpose of this work was to investigate the
effects of applying inorganic fertilizer at reduced amounts (micro-dose rates) under
different in-situ rainwater harvesting and soil moisture management technologies by
using tied ridges and infiltration pits in pearl millet and groundnut growth and grain
yields. It also, focused on assessing profitability of integration of fertilizer rates with
tied ridges and infiltration pits in smallholder farming communities. Field
experiments were conducted in a semi-arid central part of Tanzania from 2015 to
2017 covering Ilolo and Idifu villages located in Chamwino district, Dodoma region.
It was observed that, using tied ridges and infiltration pits increased pearl millet and
groundnut yield significantly compared with flat cultivation. Application of fertilizer
micro-doses from 25% to 75% of the recommended rate for pearl millet and from
50% to 75% of recommended rate for groundnut increased grain and kernel yields
significantly compared with zero application. Integration of flat cultivation and tied
ridges with micro-dose at 25% of recommended rate in pearl millet gave yield
advantage ranging from 295 to 455 kg/ha and 537 to 959 kg/ha, respectively,
compared to farmer practices. It also resulted into positive net profit. Flat cultivation
with zero fertilizer application resulted in lowest groundnut yield and had a negativeii
net profit. The integrations of tied ridges and fertilizer micro-dose at 50% of net profit. The integrations of tied ridges and fertilizer micro-dose at 50% of
recommended rate gave significantly higher kernel yield, ranging from 906 to 1,197
kg/ha and higher net profit ranging from 424 to 558 USD/ha compared to farmer
practice. Tied ridges and infiltration pits conserved soil moisture by 38% and 45%,
respectively, more than flat cultivation at 30 cm depth after ten days of rainfall.
Land use efficiency was 93% - 157% higher in intercropping system than in sole
cropping. Intercropping of pearl millet and groundnut along with tied ridges and
infiltration pits with micro-dose rates from 25% to 75% of recommended rate had
financial returns of 648- 998 USD/ha higher than sole pearl millet in flat cultivation
without fertilizer application. Therefore, the use of micro-dose at 25% of the
recommended rate (i.e 15 kgN/ha and 10 kg P 2 O 5 /ha) for pearl millet, and 50% of
recommended rate (22.5 kg P 2 O 5 /ha) for groundnuts along with tied ridges and flat
cultivation is recommended to resource poor farmers of central Tanzania. The study
also recommends intercropping of pearl millet and groundnut along with tied ridges
and infiltration pits with micro-dose rates at 25% and advanced to higher rates up to
recommended rate as their resources increases. This study is further recommending a
review of fertilizer package to include lower amount such as 5 kg, 10 kg, 15 kg or 25
kg bags. This will enable smallholder farmers to purchase small amount of fertilizer
as per their requirement. The study is further recommending the establishment of
government agricultural center in each village to serve famers on all agricultural
issues such as purchasing of improved inputs on time.