| dc.description.abstract | Incorporating legume cover crops into the cropping systems and sub soiling/ripping has been
used as an alternative method of improving soil fertility, crop yields and minimizing soil
erosion problems. The current study explored the use of legumes and subsoiling in Kalama
division, Machakos District, Kenya. The area has an average annual rainfall of 600 mm which
has 66% reliability. In order to achieve this objective, a survey and a field experiment were
conducted to: identify the factors that influence the adoption of Conservation Agriculture
(CA) technologies in Machakos District; determine the effect of legume cover crop,
subsoiling/ripping on soil properties and maize growth. The survey was conducted in midseason
of the long rains in the area (LR, 2008). This was in order to observe the land use
trends, agronomic practices, farm resources and the soil fertility management practices
practiced in the area. The target population consisted of the farmers who were instructed on or
practiced conservation technologies introduced by the KARIlLRNP project in the district. The
field experiments were carried out in a randomized complete block design in four farms during
the 2008 long (LR) and short rain (SR) seasons. The first trial (LR, 2008) had three treatment
groups (T 1=maize +dolichos + subsoiling, T2=maize + dolichos + no subsoiling, T3=maize
alone + no subsoiling). The second trial (SR, 2008) had four treatment groups (T1= maize +
dolichos + susbsoiling; T2 = maize + dolichos + no subsoiling; T3= maize alone + no
subsoiling; T4 = maize with subsoiling).
Socio-economic factors played a greater role in adoption of CA technologies with respect to
gender, age, education and farmer's resources. Fifty seven percent of the respondents were
female and more men were educated than female (65%). It was thus recommended that
farmers be trained more on cover crops use as method of increasing soil fertility. Further there
is a need to improve level of education with special focus on women in the area to enhance
proper maximization of farms and improve food security.
Results from the field experiments showed that rainfall amount and its distribution affected the
growth of dolichos and maize. Early in the season, the dolichos had a higher ground cover
than maize with a peak at 8 weeks after planting (WAP) and thereafter tended to decrease
slowly due to moisture stress. A further increase in cover was noted at 14-16 \VAP after some
rainfall showers 12 WAP. The maize did not recover from the drought spell and was harvested
at 17 Wi\.P in SR, 2008.
In LR, 2008, there was crop failure due to lack of adequate rainfalL There were significant
differences in cover among the treatments at P :s 0.05 in all the different WAPs. In reference
to legume biomass, there were no significant differences among the treatments at P :s 0.05 but
T1 had greater biomass than T2. Different treatments showed differences in maize heights and
subsoiled plots gave a higher height of 2-10 cm more than in the non-subsoiled plots as the
VlAPs progressed. Plots with dolichos (Ti and T2) gave higher maize dry matter yield than the
maize alone plots (T3 and T4) in LR, 2008. In SR, 2008, the maize dry matter yield was
significantly different at P ~ 0.05 with higher yields in T3 and T4 than in TI and T2• This could
also be due to lack of competition of nutrients, water and light with the legume cover crop.
There was a significant increase in total soil nitrogen content in SR, 2008 compared to the
initial characterization of the soils and this could be attributed to the dolichos in the field. The
penetration resistance in all the plots ranged from 3.83- 4.18 kgcm' with T4 reporting the
highest and T ilowest penetration resistance. | en |
