5. Conclusions and recommendations
The study showed that mulching fields with maize residues at
application rates of 4 t ha1 under CA in areas with high termite
infestation levels leads to increased termite numbers compared to
CMP. This confirms and provides scientific evidence to the farmers'
opinion that addition of crop residues attracts more termites.
Furthermore, the study shows no significant crop lodging differences
within CA systems irrespective of the residue rates applied,
but rather the shift from CMP to CA, results in significant increase in
crop lodging. Therefore, in fields infested by Macrotermitinae termites,
the general notion that application of residues minimises
crop lodging is disqualified as long as residues are applied at the
beginning of the season. We also conclude that the absence of soil
tillage through the minimum soil disturbance principle of CA,
Table 2
Effects of different residue amounts on mean termite numbers per m2
, maize yield and percent lodged plants by termites under CA compared to CMP.
Treatments Mean number of termites/m2 (SEM) Maize yield kg ha1 (SEM) Percent lodged plants (SEM)
2008/9 2009/10 Season effect (%)* 2008/9 2009/10 Season effect (%)* 2008/9e2009/10
CA- 0 t ha1 residue cover 300 (150)a 283 (56)a 6 2900 (572)a 2348 (165)a 19 47.1 (4.77)a
CA- 2t ha1 residue cover 2100 (500)b 263 (34)a 88 3055 (593)a 2814 (131)c 8 43.3 (3.7)a
CA -4t ha1 residue cover 3050 (600)b 1179 (150)b 61 3034 (691)a 2693 (105)bc 11 39 (4.5)ab
CA- 6t ha1 residue cover 2662 (450)b 1121 (100)b 60 3348 (623)a 2756 (156)bc 18 44.9 (1.24)a
Conventional ploughing (CMP) 25 (8)c 358 (145)a 1332 2117 (230)b 2570 (103)ab 21 34 (5.23)b
Means in the same column followed by the same letters are not significantly different at P < 0.05.
Numbers in parentheses refer to Standard Error of Means (SEM).
* Season effect (%) is the difference between the two seasons' means for each respective treatment expressed as a percentage of 2008/9 result.
E.F. Mutsamba et al. / Crop Protection 82 (2016) 60e64 63
contributes to increased termite activity in CA systems compared to
tilled soils.
Consequently, the study also showed that CA resulted in higher
crop yield compared to CMP. However, this higher maize yield
obtained from CA systems could not be attributed to addition of
residues as increasing residue application rates did not significantly
contribute to maize yield improvement. It is therefore recommended
that when implementing CA, particularly in environments
dominated by the Macrotermes termites, there is need for termite
control measures and timely crop harvesting to minimize yield
losses due to lodging caused by termite damage.
Acknowledgements
This work was conducted through the Research Platform ‘Production
and Conservation Partnership’ RP-PCP funded by the
French Agricultural Research Centre for International Development
(CIRAD). We therefore thank and acknowledge the Ministere
Français des Affaires Etrangeres for the support through the French
Embassy in Zimbabwe. We would also like to acknowledge additional
funds provided to us through the University of Zimbabwe by
the Regional Universities Forum for Capacity Building in Agriculture
(RUFORUM), supported by the Rockefeller Foundation. We
wish also to thank our colleague Mr. M. Mutema who was on a
parallel but complementary study, for his assistance during data
collection.