Impacts of forage legumes on smallholder crop-livestock systems in West Timor, Indonesia

Abstract

<p>Smallholder crop-livestock systems are critical to future food security and meeting rapidly rising demand for livestock products. Yet, increasing competition for resources and high levels of soil degradation means farmers must produce more agricultural outputs without using more land, water or other inputs. Herbaceous forage legumes are one strategy for intensifying crop-livestock systems. However, current adoption levels are low and there is great uncertainty over the benefits, trade-offs and constraints of integrating forage legumes into farming systems at a farm and household level. Forage legume research has largely focused on agronomic performance and, consequently, the socio-cultural and economic factors which define the potential role of forage legumes in smallholder farming systems are poorly understood. Critically, little consideration has been given to the impact of gender roles on forage legume adoption and the distribution of impacts within a household. This thesis identifies potential opportunities for integrating forage legumes into smallholder crop-livestock systems in West Timor, Indonesia, and the benefits and trade-offs at a farm and household level.</p><p> The impact of forage legumes on farm production depends on the allocation of legume nitrogen (N) to crop and livestock enterprises. In Chapters 2 and 3, the impact of forage legume biomass management (retained vs. cut and removed) on inputs of fixed N, soil N and subsequent maize yield was assessed for an irrigated field experiment. While retaining shoot biomass contributed equivalent to 100-150 kg urea-N/ha and increased maize yield by 6-8 t/ha, there was little or no yield benefit when legume biomass was removed. The N fixation efficiencies (9-27 kg fixed-N/t shoot DM) and maize yield responses (5.8-7.9 t/ha higher yield compared to a maize control) were also double what is commonly achieved under dryland systems, indicating effective soil N and water management and sufficient yield potential are required to realise meaningful production benefits. As large trade-offs exist between allocating legume N to crop or livestock enterprises, alternative management options, such as grazing or partial biomass removal, may be required to achieve dual soil N-fodder benefits. Good agronomic practice is required to maximise the yield benefits of forage legumes. In Chapter 4, simulations for six case study sites in West Timor indicated that increases in maize yield of up 3.5 t/ha could be achieved if legume shoot biomass was retained, maize was planted at high densities (4-6 plants/m²) and weed control was effective. Critically, in West Timor, plant available water rather than soil N constrained crop production in poor years. Thus, the largest and most consistent yield responses from forage legume production are likely to be achieved for years and sites with low soil N fertility and high rainfall.</p><p> Despite the yield benefits of green manuring legume biomass, farmers often favour allocating biomass to increasing livestock production, as it provides more substantial economic benefits. In Chapter 5, whole farm and participatory modelling quantified the production and economic impacts of forage legumes for six case study farms. When used as fodder, forage legumes can more than double farm income, although they must be integrated with staple crops or planted on unutilised land to achieve such substantial benefits. The marginal value of feed increased with herd size from 0.9-1.0 M Rp/t TLU^-1 for smaller herds (≤2 TLU) to 1.8-3.1 M Rp/t TLU^-1 for larger herds (>2 TLU), indicating there were larger economic benefits for larger herds (TLU; Tropical Livestock Unit). Participatory scenario analysis indicated that livestock focused farmers favoured larger areas of legumes than other farm types. This indicates that farmers with sufficient incentive, land, labour and capacity to invest are likely to benefit most from forage legumes.</p><p> While forage legumes can provide large economic benefits, the impacts of technologies are often unevenly distributed between men and women. In Chapter 6, participatory onfarm evaluation assessed the potential benefits and constraints of forage legume production for male and female farmers. Preferences reflected gender roles; women favoured integrating forage legumes with food crops to increase soil fertility and crop yield, while men favoured permanent stands as they provided the largest economic benefit. Labour was identified as the key constraint to adoption, with unequal distribution of household labour suggesting that forage legumes may increase women's labour requirements but maintain or decrease men's labour requirements. Thus, forage legume adoption requires labour saving options and more equitable distribution of benefits and labour inputs between men and women.</p><p> This research demonstrated that integrating forage legumes into smallholder croplivestock farming systems can provide significant production and economic benefits. Yet, there are also large trade-offs associated with legume management, labour, land use and the inequitable distribution of household impacts. Further research is required to validate these potential impacts and how they may differ for a broader range of farmers and farming systems.</p>