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EFFECT OF CONSERVATION AGRICULTURE ON MAIZE YIELD IN THE SEMI-ARID AREAS OF ZIMBABWE
- J. NYAMANGARA, K. NYENGERAI, E. N. MASVAYA, R. TIRIVAVI, N. MASHINGAIDZE, W. MUPANGWA, J. DIMES, L. HOVE, S. TWOMLOW
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- Journal:
- Experimental Agriculture / Volume 50 / Issue 2 / April 2014
- Published online by Cambridge University Press:
- 27 September 2013, pp. 159-177
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Globally, a range of agronomic factors have been reported to have an impact on the performance of conservation agriculture (CA) and often determine its performance in relation to conventional agriculture (CONV). To assess this performance in Zimbabwe, 48 CA experiments were conducted by the International Crops Research Institute for the Semi-Arid Tropics in the semi-arid areas of southern Zimbabwe from 2004 to 2010, to calculate the weighted mean difference (WMD) through meta-analytical methods. The two CA practices, planting basins (Basins) and ripper tillage (Ripper), were compared with CONV. It was hypothesised that CA results improved yield compared with CONV and that the effect of CA practices on yield is affected by soil type, rainfall amount and distribution and selected management practices, which included rates of inorganic fertilisers and manures and mulching. Basins were superior to CONV in 59% of the experiments and the overall effect was significant (p < 0.001). The effect of Ripper was non-significant. The hypothesis that CA practices result in improved maize grain yield over CONV was accepted for Basins. The WMD for experiments conducted on sandy soils was 0.365 t ha−1 for Basins and 0.184 t ha−1 for Ripper, and in both cases was significant (p < 0.05). For clay soils, only the WMD for Basins was significant. A higher rainfall regime (500–830 mm) resulted in a lower WMD for Basins (0.095 t ha−1) and Ripper (0.105 t ha−1) compared with 0.151 t ha−1 for Basins and 0.110 t ha−1 for Ripper under lower rainfall (320–500 mm). The overall effect of Basins under the higher rainfall regime was not significant. There was better yield performance for Basins when the rainfall was well distributed; the reverse was noted for the Ripper. The application of 10–30 kg ha−1 of N (micro-dose range) resulted in a higher WMD for Basins than zero N application. Without N application, the WMD of Basins was not significant. For zero manure application in Basins, the WMD was 0.043 t ha−1 compared with 0.159 t ha−1 when manure was applied. The application of mulch depressed the WMD in Basins by 44% and Ripper by 89%. The hypothesis that yield performance under CA is influenced by soil type, rainfall amount and distribution, inorganic fertiliser and manure application was accepted.
IMPROVING MAIZE (ZEA MAYS L.) PERFORMANCE IN SEMI-ARID ZIMBABWE THROUGH MICRO-DOSING WITH AMMONIUM NITRATE TABLETS
- N. MASHINGAIDZE, P. BELDER, S. TWOMLOW, L. Hove, M. MOYO
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- Journal:
- Experimental Agriculture / Volume 49 / Issue 2 / April 2013
- Published online by Cambridge University Press:
- 30 November 2012, pp. 179-196
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Although the application of small quantities of nitrogen (N) fertiliser has improved cereal yields on low-input farms in semi-arid Zimbabwe, the practice is reported to be laborious and time-consuming by farmers. In an effort to make micro-dosing less labour-intensive and more precise, an ammonium nitrate (AN) tablet, the equivalent of a micro-dose of prill AN (28 kg N ha−1) applied per maize plant, was developed by International Crops Research Institute for the Semi-Arid Tropics in collaboration with Agri-Seeds, Zimbabwe. This study characterized the physical stability, chemical (N% and solubility) and agronomic performance of AN tablets compared with prill AN. Only 10% of tablets broke when dropped from 2 m, showing that they are physically stable and can handle rough treatment. The N content in the tablets (33.3%) was comparable to that in prill AN (34.6%). However, the tablet formulation took twice as long to dissolve than prill AN when placed on a wet soil. Despite this difference in solubility, simple leaching column experiments suggest that less than 2% of the total AN applied was lost due to leaching. Agronomic trials were superimposed on the paired-plot demonstrations used to promote micro-dosing and the conservation agriculture tillage technique of planting basins from 2005 to 2008. Each tillage (plough and basins) plot was subdivided into three sub-plots on which no AN, prill AN and tableted AN treatments were superimposed. Maize was planted and management of plots was left to farmers. Micro-dosing with either prill or tableted AN significantly (p < 0.001) increased maize grain yield by over 40% in all seasons for planting basins. However, on the ploughed plot there was no yield benefit to using either AN formulation in the season with the lowest rainfall (2006–2007). There was no significant difference in grain yield and agronomic N use efficiency between prill and tableted AN formulations except for the 2005–2006 season in planting basins. During this season, in planting basins, tableted AN had significantly (p < 0.001) higher rainwater productivity than prill AN, which translated into greater grain yield. In addition, the maximum benefit to micro-dosing was observed to accrue when combined with water harvesting techniques such as planting basins. An observation supported by the host farmers, who in the second and third seasons chose to apply available basal soil fertility amendments to the basin plots over the flat plots. Thus, AN tablets if available at an affordable price can be used by smallholder farmers to more precisely apply N fertiliser. Future work should focus on the labour issues of micro-dosing, and making cost-effective tablets available to resource-poor farmers and also addressing other limiting soil nutrients.
INTEGRATING GENETICS AND NATURAL RESOURCE MANAGEMENT FOR TECHNOLOGY TARGETING AND GREATER IMPACT OF AGRICULTURAL RESEARCH IN THE SEMI-ARID TROPICS
- STEVE TWOMLOW, BEKELE SHIFERAW, PETER COOPER, J. D. H. KEATINGE
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- Journal:
- Experimental Agriculture / Volume 44 / Issue 2 / April 2008
- Published online by Cambridge University Press:
- 01 April 2008, pp. 235-256
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Good management of natural resources is the key to good agriculture. This is true everywhere – and particularly in the semi-arid tropics, where over-exploitation of fragile or inherently vulnerable agro-ecosystems is leading to land and soil degradation, productivity decline, and increasing hunger and poverty. Modern crop varieties offer high yields, but the larger share of this potential yield can only be realized with good crop management. The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), working over a vast and diverse mandate area, has learned one key lesson: that technologies and interventions must be matched not only to the crop or livestock enterprise and the biophysical environment, but also with the market and investment environment, including input supply systems and policy. Various Natural Resource Management (NRM) technologies have been developed over the years, but widespread adoption has been limited for various reasons: technical, socio-economic and institutional. To change this, ICRISAT hypothesizes that ‘A research approach, founded on the need to integrate a broad consideration of technical, socio-economic and institutional issues into the generation of agricultural innovations will result in a higher level of adoption and more sustainable and diverse impacts in the rainfed systems of the semi-arid tropics.’ Traditionally, crop improvement and NRM were seen as distinct but complementary disciplines. ICRISAT is deliberately blurring these boundaries to create the new paradigm of IGNRM or Integrated Genetic and Natural Resource Management. Improved varieties and improved resource management are two sides of the same coin. Most farming problems require integrated solutions, with genetic, management-related and socio-economic components. In essence, plant breeders and NRM scientists must integrate their work with that of private and public sector change agents to develop flexible cropping systems that can respond to rapid changes in market opportunities and climatic conditions. The systems approach looks at various components of the rural economy – traditional food grains, new potential cash crops, livestock and fodder production, as well as socio-economic factors such as alternative sources of employment and income. Crucially the IGNRM approach is participatory, with farmers closely involved in technology development, testing and dissemination. ICRISAT has begun to use the IGNRM approach to catalyse technology uptake and substantially improve food security and incomes in smallholder farm communities at several locations in India, Mali, Niger, Vietnam, China, Thailand and Zimbabwe.
LOW-INPUT WEED MANAGEMENT AND CONSERVATION TILLAGE IN SEMI-ARID ZIMBABWE
- RICHES, TWOMLOW, DHLIWAYO
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- Journal:
- Experimental Agriculture / Volume 33 / Issue 2 / April 1997
- Published online by Cambridge University Press:
- 01 April 1997, pp. 173-187
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Four weeding systems were evaluated for three seasons on sandy soils in a semi-arid area of Zimbabwe. Inter-row weeding with a plough with body (mouldboard breast) attached, produced a ridge and furrow landform. This confers the advantage of increased water retention associated with ridging without the additional investment in labour and equipment needed when ridges are made pre-planting with a ridging plough. Mid-season ridging by plough with body attached achieved more efficient weed control than the common farmer practices of using a cultivator or plough without the body. In terms of crop water use efficiency and grain yield, weeding with the plough and body performed at least as well as any existing farmer practices. Productivity, in terms of grain yield per hour worked, was considerably higher following weeding with the plough and body compared with alternative systems.