Farmers’ indicators of soil health in the African highlands

<p>Soil health is key to building resilience into agricultural and food systems in sub-Saharan Africa (SSA), where climate change presents a major challenge and unsustainable land management practices have exacerbated land degradation. A suite of interventions labelled climate-smart agriculture (CSA) such as conservation agriculture (cover cropping, mulching, crop rotation, intercropping, minimum/zero tillage, crop residue management), soil and water conservation (contour planting, terraces and bunds, planting pits, and irrigation) and agroforestry are promoted in SSA to improve soil health but adoption among smallholder farmers remains low. A strong evidence base on the impacts of CSA interventions on soil health in different agro-ecosystems in SSA is lacking. This contributes to weak policies and institutional support as well as conflicting messages that farmers receive about CSA impacts, which limit their adoption and lead to disadoption. Farmers’ knowledge of their soils influences their land management decisions and is an important factor in the uptake of CSA interventions. Using a multi-method approach that combines conventional soil testing and farmers’ visual techniques, we examined the impacts of soil and water conservation techniques on soil health indicators in the East Usambara Mountains of Tanzania. The link between farmers’ soil knowledge and their land management decisions was also explored in a wider review of lessons from the African Highlands. Farmers’ observed changes in selected soil health indicators, which influenced their land management decisions did not always match results of conventional soil testing, highlighting the need for integrating farmers’ observational techniques and conventional soil testing for a more targeted and comprehensive assessment of soil health. A hybrid approach to soil assessment is outlined that could foster greater uptake of sustainable land management practices including CSA by farmers in SSA and should be proactively pursued by soil scientists to ensure that their efforts translate to actions by land managers.</p>

Cost-benefit analysis of sustainable land and water management practices in selected highland water catchments of Kenya

Suboptimal land management practices are degrading soils and undermining food production. Sustainable land management (SLM) practices can improve soil and enhance yields. This study identifies variations in SLM uptake, characterising farmers most likely to use SLM practices, identifying when it makes economic sense for farmers to implement particular SLM practices and how long it takes before benefits exceed costs. Using questionnaire data from farmers in western Kenya, we undertake a cost–benefit analysis and analyse determinants of SLM practice use. SLM implementation varied between counties and SLM practice(s), with household and farm characteristics, and access to assets and advice, playing a key role. SLM practices with high upfront and maintenance costs (e.g., terraces and agroforestry) offer low benefit‐to‐cost ratios for individual farmers who must also wait many years to break even on their investments. Nevertheless, over the policy‐relevant time horizon considered (to 2030), Net present value can be positive. Simple SLM practices (manuring and intercropping) have low input costs and offer high benefit to cost ratios, providing a positive net present value up to 2030. Findings suggest that simple practices should be prioritised within policy to improve soil and increase yields. These should be supported by subsidies or other economic measures, facilitating uptake of practices such as agroforestry, which can provide wider societal benefits (e.g., improved water retention and carbon sequestration). Economic mechanisms could be augmented with support for agricultural innovation systems, improved monitoring of land management and yield relationships, and investment in climate and soil information services.

The challenges of soil degradation and climate change have led to the emergence of Conservation Agriculture (CA) as a sustainable alternative to tillage-based agriculture systems. Despite the recognition of positive impacts on soil health, CA adoption in Africa has remained low. Previous soil health studies have mainly focused on ‘scientific’ measurements, without consideration of local knowledge, which influences how farmers interpret CA impacts and future land management decisions. This study, based in Malawi, aims to 1) combine local knowledge and conventional soil science approaches to develop a contextualised understanding of the impact of CA on soil health; and 2) understand how an integrated approach can contribute to explaining farmer decision-making on land management. Key farmers' indicators of soil health were crop performance, soil consistence, moisture content, erosion, colour, and structure. These local indicators were consistent with conventional soil health indicators. By combining farmers' observations with soil measurements, we observed that CA improved soil structure, moisture (Mwansambo 7.54%–38.15% lower for CP; Lemu 1.57%–47.39% lower for CP) and infiltration (Lemu CAM/CAML 0.15 cms−1, CP 0.09 cms−1; Mwansambo CP/CAM 0.14 cms−1, CAML 0.18 cms−1). In the conventional practice, farmers perceived ridges to redistribute nutrients, which corresponded with recorded higher exchangeable ammonium (Lemu CP 76.0 mgkg −1, CAM 49.4 mgkg −1, CAML 51.7 mgkg −1), nitrate/nitrite values (Mwansambo CP 200.7 mgkg −1, CAM 171.9 mgkg −1, CAML 103.3 mgkg −1). This perception contributes to the popularity of ridges, despite the higher yield measurements under CA (Mwansambo CP 3225 kgha-1, CAML 5067 kgha-1, CAM 5160 kgha-1; Lemu CP 2886 kgha-1, CAM 2872 kgha-1, CAML 3454 kgha-1 ). The perceived carbon benefits of residues and ridge preference has promoted burying residues in ridges. Integrated approaches contribute to more nuanced and localized perceptions about land management. We propose that the stepwise integrated soil assessment framework developed in this study can be applied more widely in understanding the role of soil health in farmer-decision making, providing a learning process for downscaling technologies and widening the evidence base on sustainable land management practices.

This study was conducted with the objective of determining the returns to sustainable land management (SLM) at the national level in Bhutan. The study first uses satellite data on land change (Landsat) to examine land use change in 1990–2010 and its impact on sediment loading in hydroelectric power plants. The study then uses the Soil and Water Assessment Tool (SWAT) model to analyze the impact of land use change and land management on sediment loading. The results from the land use change and SWAT analyses are used to assess the economic benefits of SLM. We estimate the benefits and costs of SLM practices and compare them with the land-degrading practices that are most prevalent in Bhutan—that is, business as usual. An analysis of the drivers of adoption of SLM practices is also done to draw conclusions about strategies that Bhutan could use to enhance adoption of SLM practices. The land cover change results show that the vast majority of forested areas remained as such between 1994 and 2010. SWAT results show that with long-term SLM practices such as contouring, increased forested cover and density, terracing, and other SLM practices, soil erosion from forested area could be reduced by 50 %. Analysis of returns to SLM practices showed that citrus orchards are the most profitable enterprises in 13 of the 20 districts (dzongkhag), but they require farmers to wait for at least six years before the first harvest. Improved pasture management is the second most profitable enterprise—underscoring the potential role it can play to meet the growing demand for livestock products as household incomes increase. Returns to community forest management are low but profitable at a 10 % discount rate. Considering the drivers of SLM adoption, our research shows an inverse relationship between returns to land management and their corresponding adoption rates. The factors that increase adoption of SLM were land security, access to extension services, and roads. In summary, Bhutan’s policies and its cultural and historical background have set the country on the path to becoming a global green growth success story. Results of this study vindicate the country’s efforts to invest in sustainable land and forest management and highlight the additional policies and strategies that will enhance achievement of Bhutan’s SLM objectives.

Rethinking sustainable land management planning: Understanding the social and economic drivers of farmer decision-making in Africa

Smallholder farmers can adapt to climate variability and change through sustainable land management (SLM) practices that help to offset the negative impacts at farm level. However, use of these practices as adaptation strategy remains low in Ethiopia in general and the study sites in particular. This study aimed at examining the factors that determine farmers’ decision to use SLM measures and to quantify the impact of the practices on crop productivity at household and plot level. The study was based on household- and plot-level primary data and employed nearest-neighbor matching technique to quantify the impact of using the practices on value of production at household level and plot level. The results revealed that households that implemented SLM practices within the period (2004–2009) experienced a 24.1% higher value of production over non-users in 2016. Similarly, plots that received SLM measures within the period (2004–2009) experienced a 28.6% increase in value of production in 2016. The study also made further analysis at plot level using continuous treatment effects in order to take into account the number of years a plot has been under the practice. The result showed plots with SLM structure that are maintained for at least 6 years have a positive increase in value of production at the end of the 6th year, while those that received the practices recently or those that lacked continuous maintenance did not experience a statistically significant increase in value of production. The result also showed marginal benefit of sustaining the SLM practices increases over time at an increasing rate. The implication is that use of SLM measures and maintenance of the structures are crucial to reap significant benefits from the practices. Although value of production increases given the SLM practices, implementation is labor intensive and there is trade-off with other agricultural activities. Therefore, policy measures are required to incentivize implementation and maintenance of the SLM structures.

ABSTRACTThe relationship between farmers' education and the adoption of Sustainable Land Management (SLM) practices remains unclear in the literature. Additionally, research on the mechanisms underlying this relationship remains limited. This study investigates how farmers' education influences SLM adoption intensity, focusing on mediating factors of trust in extension agents' (EAs') advice, risk aversion, and positive belief in SLM practices. Data from 480 farmers in southeast Nigeria were analyzed using multivariable regression analyzes and Baron and Kenny's mediation approach. We report two key findings: (1) education significantly increases SLM adoption intensity (p < 0.05). A threshold effect is observed at the adoption of three or more practices (p < 0.1), indicating that higher education levels are associated with a greater likelihood of adopting multiple SLM practices; (2) farmers' trust in EAs' advice and positive belief in SLM practices mediate the relationship between education and SLM adoption intensity (p < 0.05), highlighting the psychological mechanisms underlying this relationship. Overall, this study provides insights to guide policies for promoting SLM practices among rural farmers.

Water cycle, land management, and environmental sustainability are intimately linked. Sustainable land and water management practices are vital for sustaining agricultural productivity and regional development. Unsustainable land and water management practices that violate the system's carrying capacity constraint over long periods can impose significant costs in terms of lost opportunities in farm production and regional development, say by causing waterlogging and salinity. On‐farm and regional salt and water balance dynamics are modeled as a sustainability or carrying capacity constraint, proxied by regional salt and water balance; on‐farm land and water management practices are then adjusted to meet the constraint, such that individual actions do not lead to a net change in the ground water and salt balance. Common actions across the farms would achieve the overall environmental sustainability. An irrigated area in southern Murray‐Darling Basin in Australia serves as a case study example. Integrated hydrologic, economic, agricultural, and environmental models called SWAGMAN series are used to evaluate the impacts of a range of on‐farm interventions on farm income and environmental sustainability. The results show that policies such as restrictions on area under certain crops, and tradable groundwater recharge/salinity credits both offer higher total gross margin and net present value than the business as usual scenario, specifically in the long run—win–win options for the farmers and the environment. The modeling results thus confirm the widely held view that unsustainable land and water management practices that violate the system's carrying capacity can impose significant costs on regional communities. In‐depth hydrological and economic analyses are needed to shape and guide society's vision for sustainable land and water management. Copyright © 2008 John Wiley & Sons, Ltd.

Synergizing global tools to monitor progress towards land degradation neutrality: Trends.Earth and the World Overview of Conservation Approaches and Technologies sustainable land management database

The increasing declination of the soil nutrient, land degradation and loss due to desertification has called for sustainable land management (SLM) practices. Smallholder farmers who are the major food producers in Nigeria faced challenges of land management due to land tenure security and fragmentation. However, this study examines SLM and its correlates among smallholder food crops farmers in Ogbomoso Agricultural zone of Oyo State. About 240 smallholder farmers were proportionately sampled from the study area. Using Focus group discussion, the needed information for this study was collected from the farmers. Both Descriptive statistics and Multivariate probit model was applied to analyse the information collected from the sampled farmers. About 40.8% of farmers practice mixed cropping, 27.5% and 15% practice minimum tillage and crop rotation respectively. Although, most (45.8%) acquire the farmland through inheritance, 18.3% rent the farmland while 14.2% purchase the farmland but the choice for the SLM depends on factors such as age, gender, household-size, education, farm-size, tenure security, extension contact, experience, number of farm plots and farm distance. In conclusion, demographic factors, farm-specific factors and tenure security are important drivers of the choice of SLM; therefore an urgent need to prioritize tenure security for increasing sustainability of agricultural land is required.

BackgroundSustainable land management is considered as one of the useful approaches to combat the threat of various forms of land degradation in Ethiopia. Despite this, there is scant information regarding households’ decision towards the implementation of sustainable land management practices. This paper, therefore, looks into the determinants for the continued use and choice of the sustainable land management practices by smallholder farmers and its productivity effect in three randomly chosen districts in Tigrai region, Ethiopia. The study uses data from household survey and key informant interviews. The paper employs a binary logit to analyze the determinants for the decision of continued use of sustainable land management practices, and a multivariate probit to analyze the simultaneous adoption decision of sustainable land management practices using cross sectional data collected from 230 randomly selected households. The impact of sustainable land management practices was also evaluated using propensity score matching.ResultsFarming techniques, wealth status, agro-ecological variations, and plot level characteristics were found to be associated with the implementation decision of sustainable land management practices by rural households. Besides, institutional supports and access to basic infrastructures influenced the overall continued use of sustainable land management practices and the preference of households toward these practices. The study also finds that the value of crop production of sustainable land management users was on average 77–100% higher than that of non-users.ConclusionsThe results of the current study confirm that the implementation of various sustainable land management practices are influenced by farming technologies deployed by rural households, agro-ecological variations, plot characteristics, and institutional supports. The findings also affirm that most of the sustainable land management practices are complementary to one another, and implementing two or more sustainable land management practices on a given plot is highly associated with higher value of crop production. Such complementarity highlights that the productivity effect of a given sustainable land management practice is enhanced by the use of the other ones.

A matrix based on the six global challenges identified for soil security (food security, water security, energy security, climate change abatement, human health, biodiversity protection) and the dimensions of soil security (capability, condition, capital, connectivity, codification) is proposed as a tool to demonstrate the links between soil security, sustainable land management and soil and land evaluation. The matrix was tested using a number of published systems of sustainable land management (SLM) practices and soil and land evaluation systems. This approach clearly validated the value and potential of the soil security concept in developing and promoting sustainable land management practices. However, it also identified several issues that need further discussion and consideration including the following: the need for a realignment of the definitions of capability and condition in the soil security concept; the recognition that soil capability cannot be assessed separately from land and site characteristics; the need for more emphasis on land management practices especially in the interaction with capability to produce the resultant soil condition; and clearer, more specific definitions of what is included under the dimensions of connectivity and codification.

Current gaps impeding researchers from developing a soil and watershed health nexus include design of long-term field-scale experiments and statistical methodologies that link soil health indicators (SHI) with water quality indicators (WQI). Land cover is often used to predict WQI but may not reflect the effects of previous management such as legacy fertilizer applications, disturbance, and shifts in plant populations) and soil texture. Our research objectives were to use nonparametric Spearman rank-order correlations to identify SHI and WQI that were related across the Fort Cobb Reservoir experimental watershed (FCREW); use the resulting rho (r) and p values (P) to explore potential drivers of SHI-WQI relationships, specifically land use, management, and inherent properties (soil texture, aspect, elevation, slope); and interpret findings to make recommendations regarding assessment of the sustainability of land use and management. The SHI values used in the correlation matrix were weighted by soil texture and land management. The SHI that were significantly correlated with one or more WQI were available water capacity (AWC), Mehlich III soil P, and the sand to clay ratio (S:C). Mehlich III soil P was highly correlated with three WQI: total dissolved solids (TDS) (0.80; P<0.01), electrical conductivity of water (EC-H2 O) (0.79; P<0.01), and water nitrates (NO3 -H2 O) (0.76; P<0.01). The correlations verified that soil texture and management jointly influence water quality (WQ), but the size of the soils dataset prohibited determination of the specific processes. Adoption of conservation tillage and grasslands within the FCREW improved WQ such that water samples met the U.S. Environmental Protection Agency (EPA) drinking water standards. Future research should integrate current WQI sampling sites into an edge-of-field design representing all management by soil series combinations within the FCREW.

How farmers' characteristics influence spontaneous spreading of stone bunds in the Highlands of Ethiopia: a case study in the Girar Jarso woreda 37Chapter 4Adapting the current mass mobilization approach in Ethiopia to enhance its impact on sustainable land management: 57