Transcript Effect of conservation tillage on soil moisture and crop yields in
Effect of conservation tillage on soil moisture and crop yields in Mwala District, Kenya
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Introduction, Problem statement & Justification
Conventional tillage (CT) – the mechanical soil manipulation; the cultivation using ploughs, harrows or mechanical implements to prepare the field for crop prodn (FAO, 2000).
Causes soil compaction, affects soil phy properties, provokes biological degradation......declined crp yields.
CT in Kenya, involves hand hoes, ox drawn mould board ploughs, tractor drawn disc ploughs and harrows tog with straw collection and burning (Gachene and Kimaru, 2003).
Conservn tillage (CA) practices e.g. tied ridging, subsoiling & ripping hv the potential of soil moisture retention & mitigation of intra seasonal dry spells that result in low prodty and crp failure ( Manyatsi
et
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al.,
2011).
In Kenya, CA practices involve use of mulch, ripping and sub-soiling without inverting soil ( Gitonga
et al.,
2008 ).
Although practiced by large-scale farmers esp in the Mt Kenya region, CA is slowly being adopted by some small-scale farmers, and evaluating its performance in these condns is presently a priority.
Although CA is highly advocated, there is strong evidence that this kind of tillage may not be good with soils prone to surface crusting and sealing, a xstic of most of the soils in semi arid areas of Kenya ( Unger
et al.,
1991, Mudjeci
et al
., 2010 ).
Therefore, the objective of this study was to assess the effect of conservation tillage on soil water conservation and yields of maize and beans relative to the conventional tillage in a semi arid region of Eastern Kenya.
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Materials and Methods
Study area: Mbiuni Location, Mwala District, Kenya The mean annual rainfall for Mwala District is 596 mm Trials established during the long rains (LR) and short rains (SR) of 2012/13.
6 tillage sys: Disc plough (MB), Disc plough and Harrowing (MBH), Ox-ploughing (OX), Hand hoe and Tied Ridges (HTR), Hand hoe only (H) and subsoiling – ripping (SR) 3 cropping sys- sole maize (M), sole bean (B) and maize-bean intercrop (M + B) Split-plot design with 4 reps.
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Data collection
Soil moisture - at depths of 0 - 20 cm and 20 - 40 cm using the gravimetric method (Okalebo
et al.,
2002).
Test crops - dryland maize variety (DH 02) and beans (rose coco GLP 2) Final crop biomass and grain yields were det from plants harvested in a 2 × 2 m at the centre of the plot.
The data was subjected to ANOVA to evaluate the trt effects 5
Locally manufactured Magoye ripper and subsoiler, which can fit onto the same frame as the plough beam
(Source: Kaumbutho and Kienzle, 2007)
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T = HTR > MBH > H > OX > MB (p = 0.019
)
C = B > M > M+B (p = 0.891
)
Time x T x C = (p = 0.005)
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T = OX > SR > MB > HTR > H > MBH (p = 0.158) C = M > B > M+B ( p = 0.684
)
Time x C = (p = 0.003)
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T = OX > SR > H > MB > MBH > HTR (p = 0.003) C = B > M+B > M (p = 0.057) Time x tillage (p < 0.001) Time x C (p = 0.044)
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3 season moisture average indicate; Tillage trend is
OX > H > MB > MBH > HTR > SR.
CT practices had the highest soil moisture content compared to the CA methods (effect of pry and sec tillage implements used, which improved porosity and WHC of the soil)
Cropping sys -
Sole bean > Sole maize > Intercrop
(surface cover - reduce evaporn, increasing infiltration, increased plant popl density …higher moisture extraction.
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16,00 14,00 12,00 10,00 8,00 6,00 4,00 2,00 0,00 Maize grain and biomass yields as affected by tillage
T, S = (p < 0.001) T = (p = 0.008) S = (p < 0.001) LR 2012 SR 2012 LR 2013 Maize grain yield (Mg/ha)
Tillage
LR 2012 SR 2012 LR 2013 Maize biomass yield (Mg/ha)
H HTR MB MBH OX SR
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Maize grain and biomass yields as affected by cropping system 14,00 12,00 10,00 8,00 6,00 4,00 2,00 0,00
C = P < 0.001
LR 2012 SR 2012 LR 2013 Maize grain yield (Mg/ha)
Maize
LR 2012 SR 2012 LR 2013 Maize biomass yield (Mg/ha)
Maize + bean
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4,00 3,50 3,00 2,50 2,00 1,50 1,00 0,50 0,00 Bean grain and biomass yields as affected by tillage
T = (p = 0.046) T = (p = 0.057) LR 2012 SR 2012 Bean grain yield (Mg/ha)
H HTR MB Tillage MBH
LR 2012 SR 2012 Bean biomass yield (Mg/ha)
OX SR
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Bean grain and biomass yield as affected by cropping system 3,50 3,00 2,50 2,00 1,50 1,00 0,50 0,00 LR 2012 SR 2012 Bean grain yield (Mg/ha) Bean LR 2012 SR 2012 Bean biomass yield (Mg/ha) Maize + bean
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CONCLUSIONS
These results suggest that tillage methods and cropping sys hv an influence on soil moisture conservn and crop yields in the semi arid areas of Kenya.
Inconsistencies in relative grain and biomass yields among tillage treatments likely ass with the presence of soil moisture at the time of tillage/planting, growing season and prevailing climatic conditions Long term tillage expts are req!!! (diff locations, under various environt’l and soil condns 16
ACKNOWLEDGEMENT
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