Analysis of potato yield gap using aquacrop simulation Model

Water scarcity and food shortage worldwide is a major concern globally. In crop production, water stress affects yield if not managed properly. Solanum potato is the second most important food crop in Kenya after maize and is sensitive to water deficits. The main objective of this study was to estimate yield gaps for various water regime strategies so as to contribute to increasing potato yields in order to close the nation’s yield gap and achieve a food secure country. Field trial was conducted in the period of March 2016-July 2016 in Uswo location under Keiyo highlands climatic conditions and obtained results used to calibrate and validate AquaCrop simulation model. The model was then used to simulate the yield output under the various irrigation treatments with and without mulch for the selected years representing wet, normal and dry seasons for full supply (FS) (100%ETc) and deficit irrigation (DI) (80%ETc) for main and off-seasons. The difference between the water stressed yields and potential yields (FS) showed the potato tuber yield gap. Results showed that yield reductions (gap) were realized in DI treatments as compared to FS during both main and off-seasons. The supplemental irrigation yield percentage decline ranged from 0.7%-1.5% and 1.1%- 2.6% for main and off season during a dry year. Normal year declain ranged from 2.1%-2.5% and 1.5%-4.1% for main and off season, respectively. Wet year losses were 0.3%-2.1% and 0.8%-7.4% for main and off seasons, respectively. Rainfed yield losses ranged from 18.9%-22.2%, 6.0%-14.1% and 2.1%-3.2% for dry, normal and wet years during main season. Off-season yields were 68.1%-87.9%, 79.6%-86.1% and 36.1%-36.8% for dry, normal and wet years, respectively. In conclusion AquaCrop is a robust model that can be used to predict potato yield gaps with acceptable accuracy under various water regime strategies and this would aid in decision-making at farm levels.