CONSERVATION AGRICULTURE AND RAINFALL VARIABILITY IN ZAMBIA:

Is CA a promising option for responding to droughts and floods?

Bridget Bwalya Umar and Progress. H.Nyanga

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Introduction

Smallholder farmers in Southern Africa confronted by risks related to climate, mostly rainfall

Dependence on rain fed agriculture related to low agricultural productivity and variability in production due to water stress during critical crop development stages.

Approaches for dealing with climatic risks include water harvesting.

Conservation Agriculture (CA) promoted partly for its water soil and water loss reduction benefits (Mazvimavi & Twomlow 2009)

In-situ water harvesting effect is the main benefit of CA basins (Enfor et al 2011).

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CA Basins

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CA Basins and Rainfall

Improved water harvesting and water use efficiency in low rainfall areas

Problems of water logging in high rainfall areas.

Basin variant of CA mostly promoted in low rainfall areas.

However, with increasing rainfall variability, probability for low rainfall areas receiving high amounts of rainfall in a given season increasing.

What happens then?

We report on this

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Our study

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Our study

Panel study from 2007 to 2010

640-440 households

interviews with farmers and key informants

Field observations

Focus group discussions, on experiences during drought and flood periods.

Yields from fields under CA and Conventional Agriculture systems compared.

Rainfall data for the study areas for the period.

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Results

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Farming Season

2006/2007 2007/2008 2008/2009

Average area under CA (ha) 0.22 0.42 0.42

% of cultivated area under CA 11.5 16.5 24.9

Average are under CV (ha) 1.69 2.12 1.27

Total cultivated area (ha) 1.91 2.54 1.69

Average maize yield (tons/ha) 3.39 0.77 1.65

Average rainfall (mm) 1046.3a 1086.8a 858.6b

CV = Conventional agriculture. This includes the use of mould board plough and traditional hand hoe for tillage. aMeans followed by the same letter in row are not statistically different at p≤ 0.05 probability level

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Results

% of cultivated area under CA increased steadily over the period.

Flooding experienced during the 2006/2007 and 2007/2008 seasons in the low rainfall study areas.

Large difference in the average maize yields between 2006/2007 and 2007/2008 seasons (importance of rainfall distribution)

Flooding during 2007/8 resulted in lower yields (p=0.0003)

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Discussion

Water logged basins were back-filled , raised to make small ridges. (soil disturbance increased)

FGD reported ability to harvest ”something” from CA fields despite the floods compared to conventionally tilled fields.

Similar sentiments expressed for drought periods.

Continued increase in area under ripping demonstrate farmers’ confidence in the tillage system under flood conditions.

Benefits of early land preparation and early planting associated with CA increases chances of survival of maize, and other crops.

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2006/2007 2007/2008 2008/20090.00

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Area under CA Tillage System

BasinsRipping

Farming season

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Conclusions

CA farmers adapting to climatic variability

Diversifying CA tillage systems to suit the climatic variability.

CA systems being perceived to be more robust in instances of extreme climatic events

Potential for higher production under CA during incidences of both droughts and floods.

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Thank You!