Farmers' knowledge of soil quality indicators along a land degradation gradient in Rwanda

Abstract

The growing need to intensify smallholder farming systems to enhance food security for a rapidly growing population in sub-Saharan Africa constitutes a major sustainability challenge. Intensification of agriculture has often resulted in degraded, highly vulnerable, exhausted and unproductive soils. Even though smallholder farming systems are heterogeneous and dynamic, conventional approaches to improving soil management have focused on promoting one or two technologies, informed by coarse-resolution assessments, rather than tailoring technologies to context. This has resulted in technologies that have been promoted not being locally adapted. The research reported here explores the extent to which farmers' indicators of soil quality vary with land degradation status and gender and can be used in selecting locally appropriate land restoration practices. Knowledge was elicited from 150 smallholder farmers across a land degradation gradient in Rwanda through combined use of a systematic knowledge-based systems approach (AKT5), and a participatory knowledge sharing method for indicators of soil quality (InPaC-S). Data were analysed using R software through frequency statistics, 'ggplot'-generated bar plots and Chi-square tests of independence. Farmers described 12 indicators of soil quality with a mean of five per farmer. The four most frequently mentioned were: soil colour (96%), indicator plants (90%), crop vigour (71%) and soil texture (67%). Farmers' knowledge about 10 out of 12 indicators varied with land degradation status (p b .05), and there were other variations according to location of fields along slopes, and gender. Farmers had knowledge of 51 indicator plants and 22 soil macrofaunal species and mentioned seven soil management practices, including: compost manure (83% of farmers), livestock manure (64%) and tree biomass incorporation (54%). There were variations in the practices by degradation status, slope location and gender. These variations revealed the importance of matching management options to ecological context and farmer circumstances to foster adoption. There were relationships between farmers' knowledge of indicators of soil quality and their soil management practices. This research has shown that acquiring farmers' knowledge about soils can help to identify fine-scale contextual differences useful for informing the design of soil management options and it is recommended that this is done in future so that appropriate options can be offered to different farmers making them more likely to be adopted.

Feed the crop, not the soil! : Explaining variability in maize yield responses to nutrient applications in smallholder farms of western Kenya

“…Theoretical relationships between for example, crop yield with fertilizer N applications and yield in unfertilized control treatment plots have also been developed (Vanlauwe et al, 2011), underscoring the utility of crop yields in unfertilized plots as an indicator of soil nutrient supply. Given that crop yield is among the key indicators of soil quality (Murage et al, 2000;Kuria et al, 2019) and easily assessed by farmers (Mairura et al, 2007), a plant based approach to soil nutrient supply assessment appears feasible once developed relationships are tested on a broad range of fields. For example, actual farm yields are part of the diagnostic criteria for estimating soil nutrient supply and predicting expected crop yield response to fertilizer application in Nutrient Expert (NE) a fertilizer decision support tool based on initial relationships established in the QUEFTS model (Pampolino et al, 2012).…”

Sustainability of Agricultural Crop Policies in Rwanda: An Integrated Cost–Benefit Analysis

“…In Rwanda, the policies of the government have concentrated on promoting one or two solutions to improving soil management, informed by more generic tests, rather than tailoring technologies to micro soil quality indicators [33]. This contrasts starkly to the heterogeneous and diverse traditional approaches to improving soil management by the local smallholder farmers.…”

The Options by Context Approach: A Paradigm Shift in Agronomy

“…Tippe et al (2017) provide a complex example concerning interactions between planting date, variety, striga management and rainfall that illustrates how even a ‘conventional’ practice x biophysical environment interaction can be multi-faceted making any simplistic recommendations, for example on planting date, intractable. The contextual variation that matters for suitability of land restoration options includes fine scale variation in social factors (gender, livestock ownership), landscape niche and degradation status (Crossland et al , 2018; Kuria et al , 2018). Several authors identify typologies or classifications of farms within their domain of interest that interact with options.…”