196
in the study area affecting soil fertility, including high soil pH, might also have
reduced cotton yield. As indicated in Bwana (2019), the soil was classified as marginally suitable for cotton production due to soil limitations.
5 Conclusions and Recommendations
Notwithstanding the different results between the two seasons, we conclude that for
the current cotton farming practices, there is no significant difference in the seed
cotton yields between smallholder organic and conventional production practices. A
difference would only occur under good rainfall conditions if the rate of nitrogen
fertilisation is increased to 60 kg N ha
−1
or more in the conventional farming system. Application of manure in combination with a low rate of inorganic nitrogen
fertilisers had a similar effect on the yield than applying a higher rate of inorganic
fertilisers. Applying neem-leaf extract and cow urine as pesticide gives a similar
yield and land rent as applying pyrethrum (in organic farming) or as applying a high
rate of a synthetic pesticide (in conventional farming). Under conditions of limited
rainfall as in the second growing season of our experiment, moisture stress becomes
limiting, and hence, fertility and pest management practices have no significant
effects on the yield. Under the prevailing semi-arid conditions, smallholder farmers
are rational to apply only low rates of fertilisers and pesticides.
Based on our study, we conclude that smallholder farmers in our study region can
improve their economic situation by intercropping cotton with grain legumes and applying neem-leaf extract and cow urine for pest management. Within the bounds of farming
practices currently practised in the study area, our results also indicate that individual
farmers with interest in organic production methods could economically benefit by
adopting organic cotton production. Further research could investigate various agronomic, environmental and economic aspects of cotton- legume intercropping (e.g. effects
of different legume species) and of using neem- leaf extract and cow urine as biopesticide.
Acknowledgements The authors acknowledge financial support by the Ministry of Foreign Affairs
of Denmark (Grant: 14-02KU) and the Government of the United Republic of Tanzania. The authors
are grateful to BioRe Tanzania for availing the research site, to Bo Markussen for advice on the statistical analyses, and to the technical staff at Aarhus University, Denmark, and the Soil Science lab,
Sokoine University of Agriculture, Morogoro, Tanzania, for their technical assistance.
References
Anwar-ul-Haq M, Akhtar J, Saqib M, Hussain A, Hussain T (2014) Integrated use of farm manure
and mineral fertilizers to maintain soil quality for better cotton (Gossypium hirsutum L.) production. Pak J Agric Sci 51(2):413–420
Bell PF, Boquet DJ, Millhollon E, Moore S, Ebelhar W, Mitchell CC, Varco J, Funderburg ER,
Kennedy C, Breitenbeck GA, Craig C (2003) Relationships between leaf-blade nitrogen and
relative seed cotton yields. Crop Sci 43(4):1367–1374
T. N. Bwana et al.
in the study area affecting soil fertility, including high soil pH, might also have
reduced cotton yield. As indicated in Bwana (2019), the soil was classified as marginally suitable for cotton production due to soil limitations.
5 Conclusions and Recommendations
Notwithstanding the different results between the two seasons, we conclude that for
the current cotton farming practices, there is no significant difference in the seed
cotton yields between smallholder organic and conventional production practices. A
difference would only occur under good rainfall conditions if the rate of nitrogen
fertilisation is increased to 60 kg N ha
−1
or more in the conventional farming system. Application of manure in combination with a low rate of inorganic nitrogen
fertilisers had a similar effect on the yield than applying a higher rate of inorganic
fertilisers. Applying neem-leaf extract and cow urine as pesticide gives a similar
yield and land rent as applying pyrethrum (in organic farming) or as applying a high
rate of a synthetic pesticide (in conventional farming). Under conditions of limited
rainfall as in the second growing season of our experiment, moisture stress becomes
limiting, and hence, fertility and pest management practices have no significant
effects on the yield. Under the prevailing semi-arid conditions, smallholder farmers
are rational to apply only low rates of fertilisers and pesticides.
Based on our study, we conclude that smallholder farmers in our study region can
improve their economic situation by intercropping cotton with grain legumes and applying neem-leaf extract and cow urine for pest management. Within the bounds of farming
practices currently practised in the study area, our results also indicate that individual
farmers with interest in organic production methods could economically benefit by
adopting organic cotton production. Further research could investigate various agronomic, environmental and economic aspects of cotton- legume intercropping (e.g. effects
of different legume species) and of using neem- leaf extract and cow urine as biopesticide.
Acknowledgements The authors acknowledge financial support by the Ministry of Foreign Affairs
of Denmark (Grant: 14-02KU) and the Government of the United Republic of Tanzania. The authors
are grateful to BioRe Tanzania for availing the research site, to Bo Markussen for advice on the statistical analyses, and to the technical staff at Aarhus University, Denmark, and the Soil Science lab,
Sokoine University of Agriculture, Morogoro, Tanzania, for their technical assistance.
References
Anwar-ul-Haq M, Akhtar J, Saqib M, Hussain A, Hussain T (2014) Integrated use of farm manure
and mineral fertilizers to maintain soil quality for better cotton (Gossypium hirsutum L.) production. Pak J Agric Sci 51(2):413–420
Bell PF, Boquet DJ, Millhollon E, Moore S, Ebelhar W, Mitchell CC, Varco J, Funderburg ER,
Kennedy C, Breitenbeck GA, Craig C (2003) Relationships between leaf-blade nitrogen and
relative seed cotton yields. Crop Sci 43(4):1367–1374
T. N. Bwana et al.