Trees and water: smallholder agroforestry on irrigated lands in Northern India

v Trees are increasingly grown on-farm to supply wood and biomass needs, in both temperate and tropical climates, as well as in developed and developing countries. Over the last several decades, within the irrigated rice-wheat growing lands of northern India, a considerable number of fast- growing poplar trees have been planted on tens of thousands of small farms. This trend is driven by economic incentives (as wood production is often more valuable or less labor intensive) and by national policies (as they aim to limit further deforestation in regional forests). Recent debate regarding tree plantings has raised the issue that water use is often increased when trees are planted. This ongoing debate focuses primarily on afforestation or reforestation of upland and rain-fed agricultural areas, and on resulting off-site impacts such as reduced streamflow. Adoption of poplar agroforestry in northern India, in contrast, is occurring in areas where land and water are already intensively used and managed for agricultural production. This study used farmer-survey data, remote sensing, and hydrological modeling of the prevalent cropping systems to investigate the importance and role of the poplar trees within the agricultural landscape, and to estimate their water use. It was found that trees are currently grown on approximately 10% of the irrigated lands, which are located within the study area in northern India. The study observed that poplar plantation increased water productivity and profitability of the smallholder farmers. As this agroforestry system replaces an already intensively irrigated cropping system, the establishment of poplar agroforestry on 10% of the area adds only a very marginal increase to the existing water use for crops in this region. The impact on annual irrigation requirement for the region (at the current level of adoption for poplar agroforestry) is estimated to be minimal (1.6% increase), whereas the contribution of poplar trees to the local economy and farmer livelihoods is quite significant and well established. This study concludes that the widespread adoption of poplar agroforestry and other tree-based systems has created a substantial improvement in the water productivity of this intensively irrigated region. In particular, it was found that boundary plantings had little or no impact on regional water use, but could add significantly to ‘farmer-livelihood and economic- security’. The importance of growing trees outside of forests, in general, for domestic and industrial uses, and growing trees on-farm, in particular, to directly reduce pressure on forests, wildlife habitat and biodiversity, is highlighted in the study. Overall, these results illustrate a potential for meeting the increasing global demand for wood from trees grown on-farm in irrigated agroforestry systems

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