The sustainable intensification of crop production in West Africa is constrained by soil degradation exacerbated by climatic factors such as excessive rainfall and high temperature. Adoption of climate-smart soil and crop management practices could buffer future extreme weather effects on maize yield. To test this hypothesis, the overarching aim of our study was to (i) calibrate and evaluation the DSSAT model for maize and parameterize the DSSAT tillage module for different tillage practices (contour ridge tillage and reduced tillage), and (ii) simulate the effects of different management options (tillage and crop residue incorporation) to buffer future extreme climate events on maize yield in four soil types (Lixisols and Plinthosols) located in two landscape positions (upslope and footslopes) of Benin and Burkina-Faso in West Africa, using two climate scenarios (baseline and 2 degrees C above pre-industrial period). Scenario analysis was performed using factorial combination of two tillage operations (contour ridge and reduced tillage), one crop residue treatment (with crop residue), and two N fertilizer rates (recommended N rate: 60 kg ha(-1) and double recommended N rate: 120 kg ha-1) using HAPPI dataset. Model performance (calibration, evaluation and tillage model parameterization) was good as indicated by the lower normalized root mean square error (nRMSE, 12 %-18 %) and mean root absolute error (MRAE, 10 %-16 %), and higher D-index (0.78-0.93) depending on tillage practices and soil types. Long term future climate simulations and cumulative probability distribution confirmed that with both fertilization cases (recommended and double recommended), contour ridge tillage along with crop residue application could enhance maize yield (4 %-7 %) at upslope field sites under a future 2 degrees C warming scenario, where soil erosion and loss of water and nutrients through runoff is a serious risk. Simultaneously, reduced tillage with crop residue application under both fertilization cases could be a valuable alternative to farmer's practice in fields with deep soils at footslope position (St1 and St3), as it resulted in a higher increase of maize yield (14.5 %) under future 2 degrees C warming scenario compared to the baseline and could be preferred by risk-averse farmers. Maize production on gravelly soils with low water retention capacity (St1, 63-66 mm) may suffer (-11 %) from future 2 degrees C warming regardless of the tillage practice. However, despite the significant site-specific tillage effects, intensified N fertilizer application could reduce maize yield losses on St2, St3, and St4, irrespective of tillage practices by improving maize N uptake under elevated CO2 during future warming period. Hence, the application of site-specific tillage operations and crop residue application has the potential to buffer future warming effects on maize yield as confirmed by DSSAT simulations.
Nafi, E; Webber, H; Danso, I; Naab, JB; Frei, M; Gaiser, T
Can reduced tillage buffer the future climate warming effects on maize yield in different soil types of West Africa?
Soil & Tillage Research