Socio-economic and agricultural characteristics
The 98 interviewees (47% women, 53% men) were on average 51 years old (24 to 75 years). On average, they had a formal education of five years, whereby the mean for women (3.5 years) and elderly people (70–80 years: 0.9 years) was considerably lower than for men (6.3 years) and young interviewees (20–30 years: 11.8 years; t-test for gender: P = 0.008; ANOVA for 10-year interval of age group: P = 0.009). Formal education was higher in Hobor (average of 6.8 years) than in Fiakornya (3.9 years) and Kweikrom (4.0 years). Average household size was 7.4 family members with no significant differences between age groups or communities (ANOVA for 10-year age interval: P = 0.27 and for communities: P = 0.76). The average interviewee farmed for 27.2 years irrespective of gender (t-test: P = 0.9) and community (ANOVA: P = 0.76). Farmers heavily depended on agriculture since 76% stated that it was their main source of income livelihood. Almost half (48%) of the respondents had and outside farm income from small-scale trading (n = 10), sale of charcoal or firewood (n = 10), work in food or agriculture related jobs (n = 7), and construction (n = 6). The obtained off-farm monthly income ranged from 7 US$ to 852 US$ per month with an average of 147 US$ (exchange rate of GHS 1 = 0.17033 US$, Oanda Currency converter, 30.06.2021).
The farmers cultivated on average one ha of land (equalling 1.8 plots with a mean plot size of 0.57 ha). Crops most cultivated were maize (n = 47), cassava (n = 29), pepper (n = 27), and groundnut (Arachis hypogaea L., n = 24), followed by pineapple, tomato, and okra. All communities included maize and cassava in their top three crops, whereas the third crop varied (Hobor: pineapple, Kweikrom: groundnut, Fiakornya: pepper). On 19% of the fields, a mixed cropping system was used, with maize-cassava as the most common crop combination. About 35% of the fields were owned by the farmers, whereas 65% belonged to family heads or traditional chiefs. Nevertheless, 53% of the rented fields were given out to the farmers for free, however, major differences were noted between Kweikrom (90%), Fiakornya (42%), and Hobor (4%). Stated reasons were that landowners gave out land to farmers to take care of it (Kweikrom) and when the land was bought by individual developers, farmers were allowed to continue working on it until construction started (all communities). The average annual rent in Hobor was 123 US$ ha-1 (21 to 253 US$ ha-1) and in Fiakornya 56 US$ ha-1 (30 to 140 US$ ha-1). Irrigation only played a minor role as 92% of the fields were rainfed. While 60% of the fields were tilled by tractors and 40% by hand, there was a significant inter-communal difference for the rate of mechanization (Hobor and Fiakornya 77% versus Kweikrom 34%; Pearson’s Chi-square test: χ2 = 23.922, P = 6.389e-06). The average price paid for land tilling was 128 US$ ha-1. On 45% of the fields, chemical fertilizer, the most common being NPK, urea, and ammonia, was applied, with no significant difference between the communities (p = 0.2). Average costs for fertilization were 133 US$ ha-1. On only 9% of the fields, organic fertilization, predominantly as cow manure, was applied and on 48% of the fields, chemical insecticides were used. For weed control, both, manual weeding and herbicides were common (herbicides only: 7%, manual weeding only: 28%, herbicides and manual weeding: 65%). Farmers spent 63 US$ ha-1 on herbicides and 290 US$ ha-1 for labour to weed and/or apply herbicides. For planting and harvesting, only 24% and 33% of the fields required hired labour, with average costs of 168 US$ ha-1 and 231 US$ ha-1, respectively. Farmers often used extended family labour, who were provided with meals or agricultural produce for planting or harvesting. On average, 3.8 family members regularly worked on the field(s) at 4.5 days per week. Agricultural products were sold to local markets (all crops) or consumed by household members (mainly maize and cassava, Table 1). About 90% of the farmers noticed yield fluctuations on their fields resulting from weather conditions and response to inputs, while 8.4% reported stable yields, and 1.4% were undecided. All farmers experienced major price fluctuations, depending on market conditions and season (Table 1).
Effects of sand mining on agricultural productivity, farmer’s livelihoods, and future perspectives
In the studied communities, sand mining had occurred year-round for several years. In Kweikrom, mining commenced in the year 2000, in Hobor in 2011, and in Fiakornya in 2013. Thereby, 63% of the interviewed farmers had experienced sand mining on their fields. In total, 121 fields (95.7 ha) were mined. Around 40% of the fields were harvested completely or remained uncultivated at the point of mining so that no yield loss occurred, while 23% experienced some yield losses and 36% a complete loss (Fig. 2). Combining the lost area per crop with the yields of the main crops (Table 1), an annual loss of 106 t pineapples (10.3 ha), 53 t maize (26 ha), 48 t cassava (11.5 ha), 12 t pepper (5.8 ha), and 10 t groundnut (6.3 ha) was calculated.
Sand mining occurred during night-time (36.7%, 34 ha), day-time (32.5%, 23 ha), and during day and night (30.8%, 38 ha). Certain fields were mined incrementally, while most of them completely disappeared within 24 h. Therefore, the farmers stated a ratio of mined size to total field size between 50 and 100%, averaging at 95%. Some sand mining sites were remined after months to years. Over 90% of the farmers were not informed beforehand about the planned mining activity, while around 5% were approached by miners and another 5% were contacted by the landowners prior to land loss. Consequently, there were no compensation payments for most of the farmers (90%) and the remaining 10% received cash compensation totalling between 7 and 51 US$ per plot. Land reclamation was hardly undertaken, only 3.5% of the fields were levelled, 4.3% were partly or sporadically reclaimed, and 92.2% remained without any reclamation once mining was finished.
Farmers reported a loss of soil quality (104 field counts), increased soil compaction (94 counts), water issues, and soil erosion (each 89 counts) on the mined fields. Effects on surrounding fields were minor (water issues (5 counts), soil erosion (9), destruction of farmland by sand mining machinery and workers (8), and dust on plants (6)) as most of the neighbouring fields were equally mined (87 counts). Farmers did not expect the land to recover in the near future, as they estimated a soil regeneration time of > 20 years for 89% of the fields (0–10 years for 10% and 10–20 years for 1% of the fields). Accordingly, on 97% of the fields, the farmers had not restarted agricultural activity and for the few fields where agriculture had restarted, yields were drastically reduced. Three quarters of the mined fields were sold as building plots, 22% remained idle, and on 4%, farmers had no information.
Most farmers had no response strategy to their fields being mined and therefore had to accept reduced harvests and income (59%), while 35% relocated to another field (mostly combined with a reduction in farm size or a switch to backyard gardening) and 6% changed their occupation. One fifth of the farmers had stopped cultivation completely while four fifths of the farmers wanted to continue farming in the future as the vast majority had few (38%) or no (61%) job alternatives. Due to sand mining, most (54%) of the farmers saw no future for agriculture in their community, compared to seeing a future (35%) and being unsure (10%). In contrast to that, 44% of the farmers expected a continuation of sand mining activities, 34% did not, and 22% were unsure. Almost two thirds (64%) of the farmers argued for a complete ban of sand mining through collaborative law enforcement by government agencies, landowners and community elders while 18% preferred improved regulations and 19% were unsure about any effective solution.
Effects of sand mining on soil chemical and physical parameters
Sand mining significantly affected all measured soil chemical and physical properties except for the C/N ratio (Table 2 and Fig. 3). It significantly reduced soil contents of available K, Mg, P, N, and C as well as pH, compared with the near mined and unmined sites. Thus, average reductions between unmined and mined fields were noted to amount to 77 mg K kg-1, 88 mg Mg kg-1, 12.7 mg P kg-1, 0.6 g N kg-1, 6.3 g C kg-1, and 0.32 pH units, while Na increased by 16 mg kg-1, soil moisture by 4%, bulk density by 0.13 g cm-3, and penetration resistance by 0.11 MPa. Mining changed particle size distribution towards higher sand and lower silt and clay contents (Table 3). Soils at upper slope positions had significantly higher K (+ 12 mg kg-1), Mg (+ 15 mg kg-1), N (+ 0.1 g kg-1), C (+ 0.8 g kg-1), and pH (0.23 units) and lower soil moisture (- 1.2%), compared with those at lower slope positions. There was only little effect (mainly for penetration resistance but also soil moisture, P, N, and C) of the interaction of mining status and slope position (Table 2).
Community effects of sand mining
As a consequence of the loss of farmland, farmers recognized the loss of trees and natural vegetation as mining-induced problems with negative effects such as changes in microclimatic conditions leading to a hotter and less aerated climate, loss of firewood, reduced availability of natural medicinal herbs, destruction of wildlife habitat leading to snake encroachment into the communities, and a lack of cattle grazing areas (Fig. 4a,b). The latter also caused conflicts among herders and crop farmers as there were incidents of cattle grazing on farmland.
Furthermore, 87% of the farmers stated that sand mining had negative effects on water conditions (6% no effect, 1% positive effect, 6% no answer or unsure). The most mentioned associated problems were the creation of waterlogged areas (Fig. 4c), the disruption of river flows such as blocking of waterways by silt leading to flooding, the reduction in river water quality through pollution, and the destruction or sand coverage of communal watering holes. The only positive aspect mentioned was the provision of water for domestic use from ponds created by the miners.
Most farmers (73%) reported negative effects on their health, while 13% each perceived no effects or were unsure; none recognized positive effects. The negative effects could be further classified into dust-related health issues (such as asthma and catarrh, n = 25), increased risk of malaria due to water gullies becoming mosquito breeding spots (n = 21), lack of clean water for drinking and hygiene, as well as related infections (n = 16, with 12 counts in Kweikrom), psychological problems due to the loss of farmland or the fear of it (n = 5), nutritional effects (decreased food diversity and quantity, n = 3), and noise pollution through passing trucks, especially at night (n = 2).
Farmers also noted a negative effect of sand mining on the road infrastructure (81%; 10% no effect, 2% positive effect, 6% no answer or unsure). The main reason assigned by the farmers was the destruction of roads by the creation of potholes due to the passage of heavy trucks and mining machinery (Fig. 4d). Moreover, farmers mentioned that it had become difficult to build (finding land, e.g., for community buildings, construction on mined land) and therefore argued that their community was not developing despite the abundance of sand as everything had been sold out. It was further mentioned that infrastructure was damaged due to nearby sand mining activities (flooding of houses, erosion of building foundations).
Other negative effects were the increased prices of food items, higher transportation costs to reach the farms, the relocation of family members (either to rural areas to continue farming or to Accra to find another occupation), increased cleaning work due to dust in the houses, and increased land litigation conflicts within the community.
Those who mentioned positive effects cited the creation of untarred roads to the farming areas through the continuous passage of tipper trucks. Further positive effects were easy access to sand for construction and income for the youth working as support staff such as those who led trucks to sand mining sites. Overall, 24 farmers reported at least one positive effect of sand mining on community livelihoods, while 96 farmers mentioned one or more negative effects.
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