Analysis of soil moisture conservation techniques with dry season maize crop on hill land at Rubirizi, Rwanda

Source: OAI

ABSTRACT Rwanda is an agriculture based country where crop production is carried out under rain fed situation with wide range of agro climatic conditions. Field experiments were conducted with in-situ soil moisture conservation techniques in bench terraces and unterraced field by using maize crop variety Kathumani from June 2007 to October 2007 by involving three land management practices viz. ridges and furrows, compartmental bunding and control. The study explores the best technical option to resolve the constraints related to water management in rainfed farming in Rwanda. Insufficient rainfall during dry season attracts the need of water harvesting and soil moisture conservation. The study is based on weekly soil moisture analysis in 90cm soil depth. Analysis of rainfall and crop water demand indicates that it is inevitable to provide supplemental irrigation and in-situ moisture conservation for successful crop. Bench terrace increased the average soil moisture content in 90cm soil depth by more than 50 per cent than that of unterraced land. Within the bench terraced field compartmental bunding increased soil moisture by 18.2 per cent higher than plain bed (control) with a coefficient of variation of 20.6 per cent and ridges & furrows increased by 27.8 per cent with coefficient of variation of 29.3 per cent. This indicates that in-situ moisture conservation measures are effective to increase soil moisture compared to plain bed. It is also found that mean soil moisture fluctuation in the soil profile is moderately more at 60cm depth compared to 30 cm irrespective of type of conservation techniques. Performance of ridges & furrows, compartmental bunding and plain land (control) was evaluated in terms of soil moisture conservation. The study reveals that Compartmental bunding performed well in both 30cm and 60cm soil depths followed by ridges & furrows because of consistent soil moisture as evidenced by less coefficient of variation. Higher moisture content in these two techniques is due to water barrier to harvest rainwater. Average soil moisture content for compartmental bunding and ridges & furrows varied between 16 to 17 per cent at both 30cm 60 cm soil depths and 13 per cent for plain bed (control). In all the three techniques, actual soil water during the entire cropping period remains below field capacity posing soil moisture stress. The maize yield was very poor in all the techniques because the soil water depleted to 60 per cent and above from the beginning of the cropping period inferring the need for supplementary irrigation. Plain bed (control) exhibited lowest degree of fluctuation of deficit water indicating poorly influenced by rain fall as compared to ridges & furrows and compartmental bunding. In terms of efficiency of moisture conservation during the cropping period, ridges & furrows performed well with 85.8% followed by compartmental bunding with 75.9 per cent in terraced field. Unterraced field with 15 per cent slope conserved moisture very poorly with 13.9% efficiency inferring importance of bench terraces for efficient soil moisture conservation. Performance of different in-situ moisture conservation practices were analyzed in terms of available water, deficit water, crop water and its effect on maize yield was discussed in this paper. Presented at GLOBELICS 2009, 7th International Conference, 6-8 October, Dakar, Senegal. Parallel session 3: Sustainability and technology adoption in agriculture

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    Agronomy journal 01/1986; 78(6). DOI:10.2134/agronj1986.00021962007800060020x · 1.54 Impact Factor
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    ABSTRACT: Soil and Water Conservation (SWC) measures are needed to control soil erosion and sustain agricultural production on steep slopes of West Usambara mountains. However, the adoption by farmers of the recommended soil and water conservation measures is low and soil erosion continues to be a problem. It could well be that the reason for the low adoption is that the costs to invest in soil and water conservation are higher than the eventual benefits. This research assessed the costs and benefits of bench terraces, grass strips and fanya juu, which are major SWC measures. Financial Cost Benefit Analysis (FCBA) was undertaken for farmers with low, moderate and high opportunity costs of labour at different slopes and soil types. The results show that labour is the major cost item in implementing SWC measures and is higher with bench terraces than with fanya juu and grass strips. The results also show that the costs of establishing the three SWC measures exceed the returns in the initial 2 years. However, in the long term, the three SWC measures are profitable to farmers with low to medium opportunity costs of labour on gentle to moderate slopes. It was also found that SWC measures are not financially attractive to most farmers with off-farm activities and other sources of income. It is concluded that high investment costs and initial negative returns are the major hindrances to the adoption of SWC measures by smallholder farmers in West Usambara mountains. Options to overcome the initial investment costs include the gradual investment in SWC measures, introduction of high value crops and small credit facilities. The promotion of dairy cattle under zero grazing system can also increase the adoption of SWC measures because of the high benefits from grasses used to stabilise SWC measures.
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