Modeling Water and Nutrient Dynamics in Response to Conservation Agriculture Practices under Smallholder Farms in the Ethiopian Highlands.

Authors

  • Sisay Asres Faculty of Civil and Water Resources Engineering, Bahir Dar Institute of Technology, Bahir Dar University, Bahir Dar 26, Ethiopia
  • Tewodros T. Assefa Faculty of Civil and Water Resources Engineering, Bahir Dar Institute of Technology, Bahir Dar University, Bahir Dar 26, Ethiopia
  • Seifu T. Admasu Faculty of Civil and Water Resources Engineering, Bahir Dar Institute of Technology, Bahir Dar University, Bahir Dar 26, Ethiopia
  • P.V. Vara Prasad Sustainable Intensification Innovation Lab, Department of Agronomy, Kansas State University, Manhattan, Kansas, KS 66506, USA
  • Abeyou W. Worqlul Blackland Research Center, Texas A&M AgriLife Research, Temple, TX 76502, USA;
  • Tammo S. Steenhuis Department of Biological and Environmental Engineering, Cornell University, Ithaca, NY 14850, USA

DOI:

https://doi.org/10.20372/pjet.v4i1.3692

Keywords:

APEX, root zone soil water, conservation agriculture, nutrients, runoff

Abstract

The Agricultural Policy/Environmental eXtender (APEX) model have been developed to assess a wide variety of agricultural water resource and other environmental problems at a field or multi-subarea spatial scales, which further depicts its importance in decisions at plot scale farming. The model was established to evaluate the effect of conservation agriculture (CA) practices on water and nutrient loads of runoff and sediment under small on-farm experimental plots. Transferred flow model parameters from a watershed to experimental plots were used to simulate runoff with runoff and nutrient parameter adjustments under conservation agriculture and conventional tillage practices. The APEX model performed well in terms of performance measures in simulating the CA and the conventional tillage (CT) scenarios for different response variables under irrigated and supplementary irrigated vegetable production systems. It showed a decreased simulated ET by 15%, simulated average runoff by about 70%, simulated nitrogen in the runoff by 23%, and simulated phosphorus loads in the runoff by 54% under CA compared with the CT treatment while it showed increased average root zone soil water (20%), and increased average percolation (59%). The reason for the different responses of the simulated variables between CA and CT practices was obviously due to the combined use of grass mulch cover and no-tillage practices under CA treatment. APEX simulations indicated the contribution of such practices leading to the reductions in ET and runoff, which was the main reason for higher (14–27%) water-saving observed during the dry irrigation phases of various vegetable production under CA treatment. In this regard, APEX can be used as a tool to assess the impact of CA on hydrology and nutrient loads.

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Published

2026-07-23

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Vol. 4 No. 1 (2026): Volume 4 Issue 1

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Agricultural Technology, Food and Nutrition Security

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