Hedging eroding slopes in Malawi: Can the integration of contour bunds and perennial forages improve Malawian mixed farming system productivity.

Höft. M. 2024. Hedging eroding slopes in Malawi: Can the integration of contour bunds and perennial forages improve Malawian mixed farming system productivity. MSc Thesis. Wageningen University and Research. Wageningen, The Netherlands.

CONTEXT: While from a production ecology perspective solar radiation and temperature limit global ecosystem productivity to potential yields, water and nutrient availability further constrain rainfed agro-ecosystems to attainable yields, such as those in Sub-Saharan Africa. Due to soil degradation Malawian smallholders especially struggle with a recent price-induced fertilizer shortage and changing rainfall patterns. Soil and water conservation (SWC) structures and nitrogen-fixing forages offer erosion-control and soil fertility improvement, but knowledge gaps on potential benefits in varying biophysical and socioeconomic farm contexts prevent implementation and institutional support. OBJECTIVE: This research aims to design a combination of contour bunds and layered forage hedges in a participatory system approach and quantify their farm system performance effect on a smallholder village level in Malawi, depending on context-specific forage biomass allocation. METHODS: Through focus group discussions with 23 case study village smallholders in North-Malawi, expert interviews and baseline dataset analysis the baseline farm system performance was characterised and the landscape-redesign of contour bunds with layered forage hedges developed. The performance of three scenarios, Forage Feeding, Forage Composting or Forage Selling was assessed in the whole-farm model FarmDESIGN, followed by farmer evaluation. RESULTS AND CONCLUSIONS: The case study village was characterised as a maize-based production system dependent on inorganic fertilizer import, with high livestock endowment. Farmers’ main concern was soil degradation, due to a negative soil organic matter balance, dry season animal fodder scarcity and erosion, which implemented measures failed to control sufficiently. Smallholders refrained from constructing elaborate SWC structures because of required labour, cropland loss, and lack of technical knowledge. While unfamiliar with improved forages, but knowledgeable about native species, farmers’ limited understanding of animal nutrition prevented their cultivation. Farm modelling revealed that initial yield losses caused by redesign implementation would be mitigated by higher soil fertility and water availability. All forage biomass allocation scenarios resulted in baseline farm system performance increases for farm income (16 to 68%), and soil fertility (82 to 185%), while Forage Composting and Forage Selling decreased leisure time (-13 to 21%). Performance differences were attributed to trade-offs and synergies between on-farm and off-farm biomass allocation. Farmers evaluated redesign options positively, largely favouring forage to crop allocation out of soil fertility concerns. SIGNIFICANCE: This study reveals farm-specific costs and benefits of forage biomass allocation while proposing alternatives for inorganic fertilizer-dependent farm systems. The findings can incentivize farmers, policy makers and organizations to integrate SWC structures with multi-layered, nitrogen-fixing forages.