Impact of planting time soil moisture on cereal crop yield in the Upper Blue Nile Basin: A novel insight towards agricultural water management

Abstract

Soil moisture prior to the planting time can influence crop yield through affecting seedling rooting and emergence, making it an important factor in agronomic management. However, the degree to which initial soil moisture influences crop yield has not been quantified, especially in emerging regions where food security is a major challenge and field data on soil moisture and meteorological conditions are sparse. Here, we quantify the sensitivity of crop yield and production to initial soil moisture conditions in the Upper Blue Nile Basin (UBNB) of Ethiopia making use of a process-based spatially distributed crop model (DSSAT) linked to a hydrologic model (CREST), and assess the potential of soil moisture management in promoting agricultural outcome. Modeling results suggest that the cereal crop yield and production increase with initial soil moisture, and show a higher sensitivity in eastern UBNB than western UBNB and during dry years than wet years. In some areas of eastern UBNB, compared to normal soil moisture conditions, extremely wet initial soil can double the crop yield; in extremely dry years, wetting the soil at planting could prevent crop failure and improve crop yield to a level at or even above that of an average precipitation year. Increasing the initial soil moisture from extremely dry to extremely wet conditions leads to an additional production of 2.3 × 105, 7.7 × 105, 4.5 × 105, and 2.7 × 105 tons for barley, maize, sorghum, and wheat in UBNB respectively. The resulting improvement in total production is especially effective over eastern UBNB. These findings can provide guidance for farmers and decision makers in water allocation and optimization, and thus help improve Ethiopia’s food security.