2.3 Results
2.3.6 Coping strategies
The coping strategies of the farmers to deal with soil acidity were classified into two categories. The first were the strategies being promoted by the extension service which included recommendation to the farmers that they apply lime, mineral fertilizer and compost, and that they should diligently implement soil and water conservation measures. Shifting to production of tolerant crop species, landraces and forestry species; night corralling of cattle and manure application; spatial segregation of crop species and crop rotation were the farmers’ own coping strategies. However, the viability and hence the levels of implementation of these coping strategies was determined by various socio-economic and technical factors (Table 2.7).
2.3.6.1 Application of lime
Despite the high prevalence of acid soils in the study areas, acid soil reclamation by the application of lime had only started relatively recently, in 2007. Even so, lime utilization has been relatively insignificant. For instance, the quantity of lime utilized in the most acidic district of the study areas, Banja, over a period of 7 years was only
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433.5 t. This was equivalent to a mean use of only 62 t per annum for an area of over 12,000 ha that had been cultivated annually, a mere 5.2 kg ha-1 (Figure 2.4).
Figure 2.4 Lime utilization pattern for the most acidic district, Banja, in the years 2006- 2012 (Source: Awi Zone Office of Agricultural Development)
Various factors constrained lime use in the study areas. Lime recommendation were as much as 16 t.ha-1 in the study areas. Extremely low pH (KCl) of below 4.0 for all unlimed samples, coupled with high and medium CEC, reflected the strong buffering capacity of the soils. Liming of such soils needs large quantities of lime to neutralize the acidic cations (H+ and Al3+) in soil solution, as well as on exchange sites (Landon, 1991; Rao et al., 1993).
According to the farmers and key informants, the farmers had no cash for purchase of crop inputs because of the low productivity and low market value of the crops grown in the study areas. Thus there was no possibility of the farmers buying the large quantities of lime that were recommended to combat the soil acidity. The problem was further aggravated by the lack of all-weather roads, the absence of farm roads, the ruggedness of the terrain, and the fragmentation of each farmer’s lands. Risks of crop losses associated with hail, frost, flood, pests and diseases were other factors that made farmers unwilling to gamble on the use of lime, even when a combination of credit and a subsidy was available to the farmers in order to buy lime. Farmers also
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complained about a perceived health risk associated with manual application of lime, applied as a fine dust.
2.3.6.2 Mineral fertilizers
Due to their high level of acidity, outfields were always given priority for mineral fertilizer application. Mineral fertilizers were applied at recommended rates or higher levels on crops such as maize at Mecha and wheat at Banja and Gozamin. The farmers reported that all the outfields needed mineral fertilizer applications to give reasonable yields of all crops. Soaring fertilizer prices, the poor financial status of the farmers, the unavailability of crop insurance, the high risks posed by hail, frost, pests and disease damage, and prohibitive interest rates were among the factors that stopped farmers from using the local credit services available to them. Consequently, most of the resource poor farmers applied sub-optimal rates of mineral fertilizer, or resorted to other options.
Diammonium phosphate (DAP) and urea are two mineral fertilizers that have been applied exclusively on all soil types and in all agroecologies in Ethiopia. The farmers expressed their discontent with the use of these mineral fertilizers, describing them as
‘addictive’, in that the soil needs increasing quantities of these fertilizers, season after season. The farmers firmly believed that, “these mineral fertilizers have spoiled our soil”. The assimilation of these fertilizers in roots produces protons that are released to the external medium and thereby increase rhizosphere acidity. Furthermore, leaching of nitrate, converted from these N sources, along with basic cations increases root zone acidity (Marschner, 1995; Barak et al., 1997; Bolan and Hedley, 2003).
Declining responses of crops to recommended fertilizer levels as reported by the farmers would also be caused by the acidifying effect of these mineral fertilizers. Thus, these fertilizers should not be applied in areas with acid soils without concurrent applications of acid equivalent quantities of lime that can neutralize the acidity released from the fertilizer material alone (Bolan and Hedley, 2003). Utilization of non- acid forming fertilizers in areas affected by acid soils is a better option for resource poor farmers who cannot invest more on external inputs, and lime in particular (Bolan and Hedley, 2003).
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Compost preparation and utilization at the household level has been strongly promoted by the extension service in order to improve soil fertility. Use of organic matter in the form of manure and compost can reduce soil acidity (Haynes and Mokolobate, 2001; Wong and Swift, 2003). However a number of factors work against this approach. These include: A shortage of labour to collect and apply the materials;
difficulties in transporting large quantities of compost to outfields in the absence of roads or tractors; competing use of animal manure for fuel; and the use of green matter for animal feed (Schlede, 1989; IFPRI, 2010). Consequently, compost preparation is limited to the rainy season when there is an adequate supply of manure, green matter and moisture. Its application was also mainly restricted to the homestead areas.
2.3.6.4 Soil and water conservation (SWC)
The farmers indicated that soil acidity was worse on sloped outfields than bottom lands, flat plateaus and homesteads. Soil erosion was an active and widespread sign of physical land degradation that has captured the attention of high level policy makers and experts. Consequently, extensive work was being done on soil and water conservation (SWC) measures in the study areas through mass mobilization of the population under the supervision of national experts. The objective of soil conservation practices was to lessen the extent of soil and water loss through runoff, and to improve crop productivity through the optimal use of mineral fertilizers and compost. Research has shown that water runoff removes basic cations, including liming materials, and that it accelerates the rate of acidity development (Ritchey et al., 2012).
2.3.6.5 Shifting to production of adapted crop species and acid-tolerant landraces
At Gashena Akayita, which was the most acidic environment, a lack of adaptable and high yielding cultivars was reported to be the most important constraint of crop production (Table 2.6). Key informants also confirmed that the performance of the
“improved” varieties of wheat, tef and other crops at Gashena Akayita and Enerata was poor. Consequently, farmers had shifted to growing brown seeded tef landraces, potato, triticale, oat, lupin, and timber crops. These crops are well adapted to acid soils. According to the farmers in Enerata and Gashena Akayita, white lupin is valued
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because it tolerates soil acidity and it improves soil fertility, helping to avoid or reduce the need to apply mineral fertilizer on subsequent crops such as wheat. However, because of land shortage and its negligible value as a food and feed crop, only farmers with large areas of farming lands could afford to include lupin in their rotation or intercropping system. The lupin cultivars were exclusively high alkaloid types and were not used for forage. Hence, the main benefit of lupin is from biological nitrogen fixation by rhizobia, as well as the minerals and organic carbon released by the decomposition of its biomass after harvest.
2.3.6.6 Spatial segregation, rotation and others
The farmers broadly categorised their crop production fields into two classes, based suitability for crop growth. The first was called ‘lem’ ‘kilze’ ‘yebadima afer’ or ‘yeguaro afer’ and represented the fertile soils that were mainly located around the homesteads and the bottom lands. The second was ‘borebor’ (Enerata) or ’Kelal’ or ‘forehe’ at (Enguti) or ‘Gibiz’ at Gashena Akayita, which represented acidic outfields. In the study areas, the various crops were spatially segregated, based on the sensitivity of each crop to soil acidity. At Gashena Akayita, which was the most acidic environment, cultivation of acid sensitive crops was restricted to the homestead areas, which had the least acidic soils. Heavy feeder crops such as wheat were grown on relatively fertile and less acidic outfields with the application of mineral fertilizers at Gashena Akayita, often following a lupin fallow in the Enerata area. Oat and triticale were produced on acidic outfields without mineral fertilization. Tef and finger millet were cropped with sub-optimal applications of mineral fertilizers on outfields.
According to the farmers, increases in level of soil acidity had minimized the role of rotation crops in their farming systems. The cultivation and productivity of legumes such as faba bean and field pea on outfields had substantially decreased with increasing level of soil acidity. The decline in production of these legumes can be associated to poor adaptability of these legumes and their strains of Rhizobium to acid soils (von Uexkull, 1986; Miyasaka et al., 2007). Nodulation by Rhizobium is also affected by Al and Mn toxicities, and deficiencies of P (Caradus, 1993). Since legumes are also sensitive to Zn deficiency, the low level of Zn (<1.0 mg kg-1) in the most acidic environments would compound the problem (Sillanpaa, 1972).
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White lupin, noug, and linseed (Linum usitatissimum L.) were the main rotation crops grown on the outfields. The common rotation crop cycle in the Enerata area was noug / linseed / oat / lupin, followed by cereals (tef / wheat / triticale). In Gashena Akayita and the neighbouring highlands, most rotations included potato and cereals, but left out lupin. In the Enguti area, noug and occasionally linseed were typically rotated with cereals. However, due to a decline in the productivity of beneficial rotation crops, and because of land shortages, the cropping of cereal after cereals was becoming a common practice.
2.3.6.7 Shifting to forestry and livestock
Eucalyptus was the dominant vegetation cover of the study areas. The increasing levels and spread of soil acidity, and the prohibitive cost of mineral fertilizers and lime were the primary factors driving the planting of eucalyptus in the study areas.
Eucalyptus is highly tolerant to Al-toxicity (Neves et al., 1982; Barros and Novais, 1996). The planting of eucalyptus plantations has a number of advantages. The timber can be sold in various forms and can generate a good income. Its primary use is for fuel and building materials. The crop is tolerant of acid soils, drought, hail, diseases and pests and does not need labour for routine management, or fertilizer applications.
Furthermore, timber crops are a recognized capital asset and can also be used as collateral to borrow money from informal sources. A further advantage is that, after the planting of eucalyptus trees, no further management is needed, allowing male members of the households to migrate to urban areas to seek informal labour in order to generate a secondary income.
In addition to eucalyptus, farmers in Banja and neighbouring areas with acid soils were switching production in their outfields to green wattle (A. decurrens) plantations. This timber crop has multiple uses, especially as a feedstock for charcoal production by the farmers. Green wattle is a nitrogen-fixing tree species (Roughley, 1986) and its ectomycorrhizal association has also been reported (Reddell and Warren, 1986).
There is little information on its tolerance to acid soils, however, its luxuriant growth in the study areas suggests that it is highly tolerant of soil acidity.
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2.3.6.8 Corralling of cattle at night on crop or grazing lands
There was a traditional practice of corralling of cattle on crop land, with the objective of replenishing soil fertility through the direct application of dung and urine. This was known as “hura” in the Banja area, and “chihit” in the Gozamin and Enguti areas. It was a longstanding traditional soil fertility management that persisted mainly in Banja and other districts of the Awi Zone in north western Ethiopia. A similar practice has been reported in several African countries, where it is also used to maintain soil fertility (Murwira et al., 1993; Harris, 2002). Compared to manure collected from pens or compost, corralling of livestock at night on crop lands does not demand labour for collection, storage, preparation, transporting and application. This is particularly important because a single farmer’s outfields are often fragmented and scattered.
‘Hura’ is practiced during the wet season when cattle provided greater volumes of dung and urine, and when there is little loss of nutrients as a result of solar radiation, heat or drying winds. One challenge is that ‘Hura’ needs the collective action of farmers in a village due to the relatively few cattle held by each household.
Table 2.7. Summary of farmers’ assessment of constraints associated with soil fertility management methods at the study areas.
Management method
Contending use Poor yield response Has no long term effect Cash shortage Difficulty to transport Difficulty to apply Labour demanding Land shortage Needs collective action Technical problems Limited crop choice
Mineral fertilizer * *
Compost * * * *
Lime * * * * *
Animal manure * * * *
Rotation * * * *
Short fallow *
Night corralling * * *
Erosion control * * *
2.3.6.9 Other coping strategies
According to farmers and key informants, conversion of most acidic crop outfields to private pastures was an increasing trend in the Banja area as a strategy to cope with soil acidity. Resource poor farmers who could not afford to purchase mineral fertilizers and lime rented out or share-cropped their outfields to better-off farmers.
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