1. Introduction
The potato (
Solanum tuberosum L.) is an important food security crop and a major source of household income for smallholder farmers in the eastern highlands of Ethiopia [
1,
2]. The crop contributes to the growth of the national economy and to the incomes of millions of smallholder farmers in the country [
3,
4]. It is the main source of calories and accounts for about 60% of the total vegetable crops cultivated in the eastern highlands of Ethiopia [
5]. Despite its importance for household food security and income generation in Ethiopia, the national average yield of the crop is only about 14.17 ton ha
−1 [
6], which is far less than the world’s average of 20.1 ton ha
−1 [
7]. The major causes of reduced national productivity of potato in Ethiopia are several biological and environmental stress factors, among which low soil fertility and drought are the most significant ones [
8,
9,
10].
The global average temperature has increased by 1 °C compared with the pre-industrial period and is projected to further increase by 1.5 °C between 2030 and 2050 if it continues to increase at the current rate [
11]. Climate change is presenting an additional challenge to potato production globally, and the challenge is exacerbated in tropical and subtropical regions wherein resource-poor farmers lack the necessary means to adapt to its impact [
12,
13,
14]. The impact of climate change has already manifested in the eastern highlands of Ethiopia through recurrent droughts and erratic rainfall in the region, which are expected to increase in frequency [
15]. Increases in soil temperature enhance the rates of organic matter decomposition which, in turn, reduces soil organic carbon and increases the release of carbon dioxide into the atmosphere [
16,
17]. Additionally, low soil moisture content reduces microbial activity in the soil and hence the decomposition of organic matter decreases [
18,
19]. Therefore, low soil fertility and low soil moisture are the major problems constraining potato production in the region [
8]. The potato is particularly susceptible to low soil fertility and low soil moisture due to its shallow and coarse root system, of which about 85% is concentrated in the upper 0.3 m of the soil profile, requiring proper soil and water management practices [
20,
21].
To reduce the vulnerability of the potato to low soil fertility and moisture stress, there is a need to use climate-smart approaches in managing the impact of the changing climate. Therefore, it is important to first analyze how farmers manage soil fertility and irrigation water at the local level to cope with the impacts of climate change. Previous studies revealed that farmers used various soil fertility management practices to cope with the impact of low soil fertility. For example, ref. [
22] reported that farmers used diammonium phosphate, urea, and manure to maintain soil fertility in the Haramaya and Kombolcha districts in the eastern highlands of Ethiopia. Ref. [
23] also analyzed nutrient management practices of onion in the Central Rift Valley region of Ethiopia and reported that 98% of the respondents (farmers) applied urea and diammonium phosphate (DAP) fertilizers. Similarly, ref. [
24] analyzed soil fertility and irrigation water management practices for vegetable production in Kumasi, Ghana, and reported that farmers used conservation tillage, crop rotation, bio-fertilizer, and poultry manure to cope with low soil fertility. Additionally, ref. [
25] analyzed soil fertility management among smallholder farmers in Mount Kenya, East region, and reported that farmers used farmyard manure, mineral fertilizers, and agroforestry to cope with low soil fertility.
Similarly, previous studies showed that farmers used various irrigation water management practices to cope with the impact of climate change-induced moisture stress. For example, ref. [
26] analyzed irrigation water management practices in the Gumselassa irrigation scheme, northern Ethiopia, and reported that farmers harvested drainage water and rainwater to cope with climate change-induced moisture stress in crop production. Similarly, ref. [
27] analyzed irrigation water management practices in smallholder vegetable production in the Central Rift Valley region of Ethiopia and reported that 90.9% of the respondents determined the sufficiency of irrigation water applied when the water level reached the furrow basin head. Furthermore, ref. [
28] analyzed smallholder farmers’ agricultural drought adaptation technologies in south-western, central, and mid-western regions of Uganda and reported that farmers used drip irrigation at night timing to reduce the effect of evapotranspiration and wind speed. Likewise, ref. [
29] analyzed smallholder farmers perception of climate change and adaptation strategies in South Africa’s Western Cape and reported that farmers used drought-tolerant crop varieties and drip irrigation to cope with climate change-induced low soil moisture in crop production.
Despite the considerable number of studies that have been conducted on various soil fertility and irrigation water management practices to cope with climate change-induced low soil fertility and moisture stress, a limited number of studies have been conducted so far in Ethiopia. Most of the existing studies did analyze the effect of climate change and farmers’ coping strategies. Smallholder farmers’ adaptation strategies that farmers use to cope with the impact of climate change depend on the accessibility and affordability of a particular adaptation technology. However, there is no documented research study aimed at investigating smallholder potato farmers’ soil fertility and irrigation water management practices as a strategy to cope with climate change-induced low soil fertility and low soil moisture in the eastern highlands of Ethiopia. This implies that there is a need to study smallholder potato farmers’ adaptation strategies used to cope with low soil fertility and low soil moisture at the local level, including observed weather trends, identifying factors affecting soil fertility, and irrigation water management practices. Therefore, it was hypothesized that smallholder potato farmers amended soil fertility in various ways and used various irrigation water management practices to cope with climate change-induced low soil fertility and low soil moisture and increase potato yields.
The results of the study provided baseline information for formulating appropriate adaptation strategies to climate change-induced low soil fertility and low soil moisture and policy measures in the study districts. Additionally, the results could play an important role in further research to provide better climate change coping strategies for smallholder potato farmers. The results of the study could also provide strategic directions for agriculture policymakers to support and strengthen the adaptive capacity and livelihoods of smallholder potato farmers in the face of climate change. Therefore, the objectives of this study were to: (1) analyze smallholder potato farmers’ adaptation strategies to climate change-induced low soil fertility and low soil moisture; (2) analyze rainfall and temperature trends and variability in selected potato growing districts in the eastern highlands of Ethiopia.
4. Conclusions
The results of this study revealed that, over the past 30-year period, the mean temperature increased whereas the mean annual rainfall decreased in the study area. To cope with the problem of moisture stress, farmers have been using supplemental irrigation during dry spells in the main growing season for potato production. However, the results showed that the irrigation practices used by the farmers are not water-efficient and sustainable. Similarly, to cope with the problem of soil degradation and nutrient depletion, potato-producing farmers have been using various soil fertility management practices, namely, applying mineral fertilizers, integrated use of mineral and farmyard manure fertilizers, and crop rotation. However, the farmers in the study areas applied lower rates of mineral fertilizer and farmyard manure than the blanket national recommendations rates for potato production. The overall results of the study highlighted that farmers made efforts to tackle the impact of climate change on potato production through various soil and irrigation water management practices. Agricultural policymakers should make efforts to support farmers’ efforts to cope with climate change by promoting the use of integrated and optimum fertilizer management and water harvesting technologies, and by supplying drought-tolerant potato varieties and water-efficient irrigation technologies. Future research efforts should focus on identifying and developing effective water-efficient irrigation technologies and formulating optimum rates of integrated fertilizer application and drought-tolerant and early maturing potato varieties.