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Cotton-Legume Intercrop
In spite of potential competition for soil moisture and light between the cotton plants
and the green gram plants, the cotton yield in the cotton-legume intercrop was similar to the cotton yield of the currently practised organic fertility practice, which
applied the same amount of FYM but had no intercropping. Hence, our results contradict the results of several other studies that report lower cotton yields in cottonlegume intercropping (e.g. Khan and Khaliq 2004; Nandini and Chellamuthu 2004;
Reddy and Shaik 2009; Hallikeri et al. 2007; Mankar and Nawlakhe 2009;
Sankaranarayanan et al. 2012; Khargkharate et al. 2014; Jayakumar and Surendran
2017; Singh et al. 2017). For instance, Jayakumar and Surendran (2017) associate the
lower cotton yields of intercrops with the early, vigorous growth of the intercrop that
result in a smothering effect on the cotton crop. Similarly, Singh et al. (2017) report
a significant reduction in seed cotton yield in cotton-mung bean and cotton-cowpea
intercrop as compared to sole cotton. The higher yield of the intercrop in our case
may be due to beneficial effects of the legume intercrop on soil fertility and nitrogen
supply (Thilakarathna et al. 2016). Given the rather high cotton yield in the intercrop
and the additional revenue from green gram production, cotton-green gram intercropping gives the highest land rent of all fertility treatments in both seasons. This
result is in line with results reported by Jayakumar and Surendran (2017) and Singh
et al. (2017) who also reported higher economic performance of cotton-legume intercrop compared to cotton without intercrop.
4.2 Yield as Compared to Potential Yield
The lower yield compared to the potential yield of the cotton variety UK MO8 in
seasons 1 and 2 in this study for all treatments and their combinations is linked to the
low rainfall in season 2 and soil fertility limitations. Low rainfall in season 2 severely
affected the yield and, hence, masked the effects of the fertility and pesticide treatments. The rainfall in season 2 (522 mm) was on the lower side of the minimum
water required for cotton growth (500 mm) (OECD 2008). With the same level of
nutrient and pest management in the two seasons, soil moisture was the major limiting factor to primary productivity and biomass production. A series of intra-season
dry spells were experienced in both seasons due to intermittent rain events (Fig. 2).
The cotton yield in season 1 was higher than the cotton yield in season 2 but still 36%
less than the potential yield of UK MO8, which is narrower than the average yield
gap of 43% for cotton in semi-arid Africa as reported by Hengsdijk and Langeveld
(2009). A similar study in India reported lower than potential yield in cotton in one
season with poor growing conditions due to low rainfall and waterlogging in the
conventional but not in the organic system (Forster et al. 2013). Hengsdijk and
Langeveld (2009) show that water is the main contributor to the yield gap of up to
30% in semi-arid Africa regions to various crops including cotton, and they reported
an average actual yield of 2.0 vs. a potential yield of 3.3 Mg ha
−1
. The soil properties
Yield and Profitability of Cotton Grown Under Smallholder Organic and Conventional…
Cotton-Legume Intercrop
In spite of potential competition for soil moisture and light between the cotton plants
and the green gram plants, the cotton yield in the cotton-legume intercrop was similar to the cotton yield of the currently practised organic fertility practice, which
applied the same amount of FYM but had no intercropping. Hence, our results contradict the results of several other studies that report lower cotton yields in cottonlegume intercropping (e.g. Khan and Khaliq 2004; Nandini and Chellamuthu 2004;
Reddy and Shaik 2009; Hallikeri et al. 2007; Mankar and Nawlakhe 2009;
Sankaranarayanan et al. 2012; Khargkharate et al. 2014; Jayakumar and Surendran
2017; Singh et al. 2017). For instance, Jayakumar and Surendran (2017) associate the
lower cotton yields of intercrops with the early, vigorous growth of the intercrop that
result in a smothering effect on the cotton crop. Similarly, Singh et al. (2017) report
a significant reduction in seed cotton yield in cotton-mung bean and cotton-cowpea
intercrop as compared to sole cotton. The higher yield of the intercrop in our case
may be due to beneficial effects of the legume intercrop on soil fertility and nitrogen
supply (Thilakarathna et al. 2016). Given the rather high cotton yield in the intercrop
and the additional revenue from green gram production, cotton-green gram intercropping gives the highest land rent of all fertility treatments in both seasons. This
result is in line with results reported by Jayakumar and Surendran (2017) and Singh
et al. (2017) who also reported higher economic performance of cotton-legume intercrop compared to cotton without intercrop.
4.2 Yield as Compared to Potential Yield
The lower yield compared to the potential yield of the cotton variety UK MO8 in
seasons 1 and 2 in this study for all treatments and their combinations is linked to the
low rainfall in season 2 and soil fertility limitations. Low rainfall in season 2 severely
affected the yield and, hence, masked the effects of the fertility and pesticide treatments. The rainfall in season 2 (522 mm) was on the lower side of the minimum
water required for cotton growth (500 mm) (OECD 2008). With the same level of
nutrient and pest management in the two seasons, soil moisture was the major limiting factor to primary productivity and biomass production. A series of intra-season
dry spells were experienced in both seasons due to intermittent rain events (Fig. 2).
The cotton yield in season 1 was higher than the cotton yield in season 2 but still 36%
less than the potential yield of UK MO8, which is narrower than the average yield
gap of 43% for cotton in semi-arid Africa as reported by Hengsdijk and Langeveld
(2009). A similar study in India reported lower than potential yield in cotton in one
season with poor growing conditions due to low rainfall and waterlogging in the
conventional but not in the organic system (Forster et al. 2013). Hengsdijk and
Langeveld (2009) show that water is the main contributor to the yield gap of up to
30% in semi-arid Africa regions to various crops including cotton, and they reported
an average actual yield of 2.0 vs. a potential yield of 3.3 Mg ha
−1
. The soil properties
Yield and Profitability of Cotton Grown Under Smallholder Organic and Conventional…