178
Among agricultural practices, organic farming practices are perceived to be more
environmentally benign than conventional farming because of the avoidance of
inorganic fertilisers and synthetic pesticides and the reliance on organic nutrient
cycles (Tuomisto et al. 2012; Lorenz and Lal 2016). However, it remains unclear
how the crop yields and economic performance compare between organic and conventional systems for crops grown under smallholder production systems in subSaharan Africa (SSA). Some authors argue that organic farming systems have lower
yields than conventional farming and hence would not be able to meet the world’s
growing food demand (de Ponti et al. 2012). They also argue that organic farming is
associated with low labour productivity, high production risks and high costs due to
additional costs of certification (Borlaug 2000; Trewavas 2001; Nelson et al. 2004;
Makita 2012). Others argue that under good management, yields from organic farming can be similar to or greater than those of conventional farming (Cavigelli et al.
2009; Seufert et al. 2012).
Most studies comparing yields of organic and conventional farming practices
have been done in temperate climates (Rosenstock et al. 2013), leaving a wide data
gap for tropical and subtropical conditions. This advocates for comparisons of the
two farming systems in SSA in order to be able to give recommendations for sustainable cotton production in the region (Richards et al. 2016). As farmers often
choose the production method according to their profitability, it is important that
these comparisons extend beyond agronomic performance such as yield and also
include profitability indicators such as the land rent. This study assesses the yields
and land rents of cotton grown under low-input smallholder conventional and
organic production systems.
2 Materials and Methods
2.1 Study Site Description
The field experiment was conducted in the Meatu District, Simiyu Region in
Tanzania. The area is between latitudes 3°–4° S and longitudes 34°8′–34°49′ E at
an altitude of 1000–1500 m.a.s.l. The area is within the semi-arid zone; rainfall
ranges from 900 mm per year in the north to 400 mm in the south. The soil type at
the experimental site was described to family level by Bwana (2019) as almost flat,
moderately deep, clayey, moderately to strongly alkaline isohyperthermic, Pachic
Calciustolls as per the USDA Soil Taxonomy (Soil Survey Staff 2014) and as Sodic
Pellic Vertisols (Hypereutric, Mazic, Mesotrophic) according to the World Reference
Base for Soil Resources (WRB) (IUSS Working Group WRB 2015). Crop and livestock farming are the major economic activities (URT 2017). Cotton is the main
cash crop in the area where both conventional and organic cotton production is
practised. Green gram (Vigna radiata (L.) R. Wilczek) is widely grown in the area
and used in cotton-legume rotations and to some extent for intercropping with cotton. The study was done at BioRe Tanzania Ltd.’s demonstration farm, Mwamishali
T. N. Bwana et al.
Among agricultural practices, organic farming practices are perceived to be more
environmentally benign than conventional farming because of the avoidance of
inorganic fertilisers and synthetic pesticides and the reliance on organic nutrient
cycles (Tuomisto et al. 2012; Lorenz and Lal 2016). However, it remains unclear
how the crop yields and economic performance compare between organic and conventional systems for crops grown under smallholder production systems in subSaharan Africa (SSA). Some authors argue that organic farming systems have lower
yields than conventional farming and hence would not be able to meet the world’s
growing food demand (de Ponti et al. 2012). They also argue that organic farming is
associated with low labour productivity, high production risks and high costs due to
additional costs of certification (Borlaug 2000; Trewavas 2001; Nelson et al. 2004;
Makita 2012). Others argue that under good management, yields from organic farming can be similar to or greater than those of conventional farming (Cavigelli et al.
2009; Seufert et al. 2012).
Most studies comparing yields of organic and conventional farming practices
have been done in temperate climates (Rosenstock et al. 2013), leaving a wide data
gap for tropical and subtropical conditions. This advocates for comparisons of the
two farming systems in SSA in order to be able to give recommendations for sustainable cotton production in the region (Richards et al. 2016). As farmers often
choose the production method according to their profitability, it is important that
these comparisons extend beyond agronomic performance such as yield and also
include profitability indicators such as the land rent. This study assesses the yields
and land rents of cotton grown under low-input smallholder conventional and
organic production systems.
2 Materials and Methods
2.1 Study Site Description
The field experiment was conducted in the Meatu District, Simiyu Region in
Tanzania. The area is between latitudes 3°–4° S and longitudes 34°8′–34°49′ E at
an altitude of 1000–1500 m.a.s.l. The area is within the semi-arid zone; rainfall
ranges from 900 mm per year in the north to 400 mm in the south. The soil type at
the experimental site was described to family level by Bwana (2019) as almost flat,
moderately deep, clayey, moderately to strongly alkaline isohyperthermic, Pachic
Calciustolls as per the USDA Soil Taxonomy (Soil Survey Staff 2014) and as Sodic
Pellic Vertisols (Hypereutric, Mazic, Mesotrophic) according to the World Reference
Base for Soil Resources (WRB) (IUSS Working Group WRB 2015). Crop and livestock farming are the major economic activities (URT 2017). Cotton is the main
cash crop in the area where both conventional and organic cotton production is
practised. Green gram (Vigna radiata (L.) R. Wilczek) is widely grown in the area
and used in cotton-legume rotations and to some extent for intercropping with cotton. The study was done at BioRe Tanzania Ltd.’s demonstration farm, Mwamishali
T. N. Bwana et al.