Breaking the dry-spell: integrating water and soil management for better yields and resilience
By Jennie Barron and Manuel Magombeyi
Ensuring that we make the best use of our water to produce enough food for a growing global demand is one of the major challenges of our time. Nowhere is this challenge more apparent than in the drylands, areas that are already struggling to squeeze every drop of productivity out of their limited water resource.
FAO’s 2018 report on the State of Food Security and Nutrition in the World is showing a creeping increase in both the number of people affected by hunger and the number affected by drought. As population growth is projected to lead to a 20% increase in water demand for agriculture by 2050, the importance of managing the resource is an essential part of ensuring food and nutritional security, especially in places that are water-scarce.
Last week, researchers from all over the world came together to discuss this important issue at the Global Water Security Conference for Agriculture and Natural Resources in Hyderabad, where WLE researchers from the International Water Management Institute (IWMI), the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT) and the International Center for Agricultural Research in the Dry Areas (ICARDA) presented on Improving Agricultural Water Productivity in the Dry Areas. Anthony Whitbread of ICRISAT and co-lead on WLE’s Land and Water Solutions research theme said during his Keynote address, “Extensification and intensification haven’t led to high productivity overall in many of the drylands. If we want to scale land and water management, we have to have an explicit focus on and understand the interventions that not only improve yields, but improve resilience and livelihoods for smallholder farmers from the farm to the watershed scale.”
It’s not just about water
We have found that the best interventions for ensuring water productivity in agriculture – whether the source is rainwater or irrigation – are integrated approaches that look at both water and soil management. Our review of agricultural water and land management technologies shows that if we take advantage of what we already know, we can effectively help smallholder farmers improve their agricultural productivity with available water resources.
The study was conducted in the Limpopo Basin, a water-scarce basin where countries and diverse sectors compete over limited water resources. The review looked at more than 1400 cases of agricultural water and land management interventions in combination, such as soil and water conservation, rainwater harvesting, and applying fertilizer, to compare yield and water productivity gains, keeping in mind that maximizing use of rainwater is critical in order to reduce dependence on irrigation.
The review shows that effective agricultural water and land management can increase yields by 27% on average across all intervention technologies. More complex technologies that combine soil moisture improvement – like harvesting rainwater for infiltration into the soil and soil conservation – with supplemental or full irrigation and fertilizer use lead to better yields, especially in areas with low rainfall (200-500 mm per year). Significantly, water productivity increased by 46% as yields improved, especially in areas with low initial yields.
If yield gains and water productivity weren’t enough, we found that combining certain water and land interventions significantly improves the environmental sustainability of agriculture, which is currently one of the most polluting sector in the world. By improving and combining agricultural water and land management, both water runoff and sediment loads from fields were reduced, by 62% and 78% respectively. This means that the sediment loads in receiving rivers is lower, keeping soil and nutrients on the fields and not in the water, leading to healthier ecosystems.
And it isn’t only the case in the Limpopo. These agricultural water and land management interventions are increasingly showing their use at scale. In Ethiopia, the Yewol watershed has been rehabilitated using combinations of soil and water management, with strong emphasis on community involvement. In southern Mali, on-farm trials with soil and water conservation were shown to more than double grain yields.
As we can see from these examples, investing in a combination of water and land interventions leads to more sustainable and productive agriculture and provides the catalyst for transformation in smallholder livelihoods. These tested technologies, if widely used and promoted, can help support sustainable intensification of agriculture and the Agenda for 2030, including SDG 2 on hunger, SDG 6 on water productivity and SDG 15 on land health.
More support is needed to enable farmers to invest in and develop these practices in their fields and landscapes. Large areas of dry crop-land could be sustainably intensified by applying what we already know, thereby improving the nutritional and livelihood prospects for the peoples of the drylands while creating more resilient agricultural landscapes for all of us.