- A. Laouina (1)
- N. Machouri (1)
- D. Moore (1)
- I.W. Nyakudya (1)
- G. Schwilch (1)
- M. Sfa (1)
- L. Stroosnijder (4)
Conservation tillage of rainfed maize in semi-arid Zimbabwe: A review
Nyakudya, I.W. ; Stroosnijder, L. - \ 2015
Soil & Tillage Research 145 (2015). - ISSN 0167-1987 - p. 184 - 197.
zea-mays l. - sandy soils - sustainable agriculture - water conservation - rural livelihoods - smallholder farms - southern africa - use efficiency - rainwater use - long-term
Food security in Sub-Saharan Africa, particularly in semi-arid tropics (41% of the region; 6 months of dry season) is threatened by droughts, dry spells and infertile soils. In Zimbabwe, 74% of smallholder farming areas are located in semi-arid areas mostly in areas with soils of low fertility and water holding capacity. The dominant crop in these areas, maize (Zea mays L.), is susceptible to drought. Under smallholder farming in Zimbabwe, conventional tillage entails cutting and turning the soil with a mouldboard plough thereby burying weeds and crop residues. Seed is planted by hand into a furrow made by the plough, ensuring that crops germinate in relatively weed free seedbeds. Inter-row weed control is performed using the plough or ox-drawn cultivators and hand hoes. Conventional tillage has been criticised for failure to alleviate negative effects of long dry spells on crops and to combat soil loss caused by water erosion estimated at 50 to 80 t ha-1 yr-1. Therefore, conservation tillage has been explored for improving soil and water conservation and crop yields. Our objective was to determine the maize yield advantage of the introduced technology (conservation tillage) over conventional tillage (farmers’ practice) based on a review of experiments in semi-arid Zimbabwe. We use a broad definition of conservation tillage instead of the common definition of =30% cover after planting. Eight tillage experiments conducted between 1984 and 2008 were evaluated. Conventional tillage included ploughing using the mouldboard plough and digging using a hand hoe. Conservation tillage included tied ridging (furrow diking), mulch ripping, clean ripping and planting pits. Field-edge methods included bench terraces (fanya juus) and infiltration pits. Results showed small yield advantages of conservation tillage methods below 500 mm rainfall. For grain yields =2.5 t ha-1 and rainfall =500 mm, 1.0 m tied ridging produced 144 kg ha-1 and mulch ripping 344 kg ha-1 more than conventional tillage. Above 2.5 t ha-1 and for rainfall >500 mm, conventional tillage had =640 kg ha-1 yield advantage. Planting pits had similar performance to ripping and conventional tillage but faced digging labour constraints. Experiments and modelling are required to test conservation tillage seasonal rainfall thresholds. Constraints to adoption of conservation tillage by smallholder farmers necessitate best agronomic practices under conventional tillage while work on adoption of alternative tillage methods continues.
Challenging conservation agriculture on marginal slopes in Sehoul, Morocco
Schwilch, G. ; Laouina, A. ; Chaker, M. ; Machouri, N. ; Sfa, M. ; Stroosnijder, L. - \ 2015
Renewable Agriculture and Food Systems 30 (2015)3. - ISSN 1742-1705 - p. 233 - 251.
land degradation - rainwater use - management - soil - efficiency - adoption - africa
In Sehoul, Morocco, the use of marginal land for agriculture became a necessity for the local population due to increased poverty and the occupation of the best land by new owners. Desertification poses an additional threat to agricultural production on marginal slopes, which are often stony and degraded. In a participatory process embedded in the EU DESIRE research project, potential sustainable land management measures were selected to address land degradation and desertification. Promising experiences with no-tillage practices elsewhere in Morocco had motivated the Moroccan government to promote conservation agriculture throughout the country. This combination of crop rotation, minimal soil disturbance and soil cover maintenance, however, had not yet been tested on sloping degraded land. Field trials of grazing enclosure combined with no or minimum tillage were conducted on the plots of two farmers, and trial results were analyzed based on stakeholders’ criteria. Results suggest that increased soil cover with barley residues improved rainwater use efficiency and yields only slightly, although soil water was generally enhanced. Soil moisture measurements revealed that no-tillage was favorable mainly at soil depths of 5cm and in connection with low-rainfall events (<20mm); under these circumstances, moisture content was generally higher under no-tillage than under conventional tillage. Moreover, stakeholder discussion confirmed that farmers in Sehoul remain primarily interested in animal husbandry and are reluctant to change the current grazing system. Implementation of conservation agriculture is thus challenged both by the degraded, sloping and stony nature of the land, and by the socio-economic circumstances in Sehoul.
Improving water use efficiency in drylands
Stroosnijder, L. ; Moore, D. ; Alharbi, A. ; Argaman, E. ; Elsen, H.G.M. van den - \ 2012
Current Opinion in Environmental Sustainability 4 (2012)5. - ISSN 1877-3435 - p. 497 - 506.
nutrient management - soil properties - rainwater use - mulch - irrigation - reuse - conservation - environment - repellency - ethiopia
Drylands cover 41% of the global terrestrial area and 2 billion people use it for grazing and cropping. Food security is low owing to institutional and technical constraints. Absolute water scarcity and also the inability of crops to use available water are major technical issues. Significant progress has been made in identifying land management practices that improve water use efficiency in terms of more crop per drop. Examples are presented that improve infiltration and storage of rainwater, reduce evaporation losses, harvest and conserve water in the Mediterranean region and Africa and use treated waste water for irrigation. Drylands show a wide diversity and therefore, require appropriately adapted best mitigation practices and strategies.
Assessing drought risk and irrigation need in northern Ethiopia
Araya, A. ; Stroosnijder, L. - \ 2011
Agricultural and Forest Meteorology 151 (2011)4. - ISSN 0168-1923 - p. 425 - 436.
barley hordeum-vulgare - rainwater use - dry spells - rainfall - highlands - variability - model - index - conservation - efficiency
Long-term climate data of four stations in the northern Ethiopia were analyzed in combination with information from local farmers and documented materials. From this analysis, a suitable drought-assessing technique was developed and site-specific needs for supplementary irrigation were explored. Results showed that our technique for assessing drought and crop failure corresponded well with farmer observations. The three major causes of crop failure (dry spells, short growing period and “total lack of rain”) which were explicitly listed and ranked by the local farmers were found to match the analyzed data well. The agro-meteorological variables with the most severe consequences were “short growing period” and “total lack of rain”. To prolong the growing period, supplementary irrigation is recommended in the month of September for three of the stations (Maychew, Mekelle and Adigudom) because: (1) rain frequently stops in early September or late August and crops have no other source of water for the rest of the growing period; (2) sufficient surface runoff can be harvested in July and August to be stored in farm ponds and used in September; (3) more cultivable land can be irrigated if supplementary irrigation is scheduled only for the month of September; and (4) giving supplementary irrigation in September can cut yield reduction by over 80% and crop failure by over 50%, except at Alamata. At Alamata, supplementary irrigation must be scheduled for July. The conditions experienced during the famine years of the early 1980s were primarily caused by the continued total rain failure over multiple years. Giving supplementary irrigation in July or September would probably not have mitigated the effects of these droughts, especially at Alamata and Maychew stations