11. Conservation tillage for sustainable crop production systems.
Project Res. Report, No. 4, Departm. of Agricult. Technical and Ext. Services, Zimbabwe; 1992, pp. 22
"Conservation Tillage for Sustainable Crop Production Systems" is a collaborative programme between the Department of Agricultural Technical and Extension Services (AGRITEX) of Zimbabwe and the Deutsche Gesellschaft fnr Technische Zusammenarbeit (GTZ) GmbH of Germany.
The primary objectives of this technical co-operation project are:
- to assess the soil and water conservation merits and yield potentials of several conservation tillage techniques based on animal traction and/or manual labour,
Ultimate project purpose is to make adequately tested tillage and cropping technologies available to resource-poor farmers in the Communal
Areas of Zimbabwe. This will be done on the basis of synthesized results of complementary on-station and on-farm trials.
In addition to the technical programme, the project also comprises a staff development scheme for Zimbabwean counterparts by providing funds for post-graduate studies overseas and offering on-the-job training.
A major factor causing soil erosion in Zimbabwe is clean tillage involving the mouldboard plough which is often used too late (after the onset of the rainy season) and/or done too shallow (approx. 125 mm) because of a general lack of (suitable) draught animals. In order to alleviate this problem, communal agriculture requires conservation tillage systems which reduce runoff, soil loss and draught power and are both practical and acceptable to the farmer. Although techniques are available, they are yet to be tested and validated for the different agro-ecological regions and the prevailing socio-economic conditions.
A two-pronged approach of complementary on-station and on-farm trials has been adopted by the project, because there is widespread understanding that, in order to assist in the development and adoption of sustainable farming practices, comprehensive approaches are required that interlink the aspects of sustainability (technical and agro-ecological factors) and acceptability.
During the early stages of project formulation, three main treatments were selected for investigation, namely: mouldboard ploughing, ripping into bare ground and no-till tied ridging.
The results of three seasons (1988/89 to 1990/91 of on-station trials showed that no-till tied ridging was best from a soil conservation point of view. Except on one occasion, sheet erosion rates were in the order of only 0,1 to 0,3 t/ha/yr at both research sites. Higher soil loss (2,2 t/ha/yr) from ridge tilled plots was measured in 1989/90 at Domboshawa, when approximately 800 mm of rain fell in a period of just six weeks. At the same time, 9,6 t/ha/yr were lost from the fields ploughed with the mouldboard plough.
The results also revealed that the seasonal influence on yield levels was highly significant. In addition, topsoil depth and soil profile and/or physical characteristics were highly related to maize yield. This interaction was particularly evident with no-till tied ridging.
From the first three years' results it would appear that, in the dry region, tied ridging will meet the criterion of equal or improved yield levels compared to mouldboard ploughing only if existing management practices, in particular with respect to timely planting and first weeding, are improved.
The paper provides an insight into the multiple problems associated with on-farm research, which not only demand close cooperation between the farmers and researchers involved, but also require skills in communication by the researcher and a strong interest in working closely with farmers.
1264 92 - 13/62
Erosion and desertification control
Africa, Tanzania, highlands, technical aspects, soils, crops, macrocontour lines, plant protection, animal traction, agroforestry, livestock keeping, extension, nutrition, integrated approach, GTZ
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