Climate smart agriculture and global food-crop production

2.2 Implementation of CSA technologies in DSSAT The CSA scenarios simulate the use of four practices that are recurrently identified in the liter- ature for their potential to deliver across the objectives of CSA and to be adopted widely [18,34]. There are several other practices and technologies that are proposed for CSA, the ones selected are among those that can be modeled with higher accuracy. The technologies consid- ered for maize and wheat are no-till and integrated soil fertility management, while those for rice are alternate wetting and drying and nitrogen use efficiency. These practices are already utilized and widely tested due to their promising positive effects on yields, their higher resource use efficiency (e.g., water and nutrients) and their overall effects on GHG emissions (Table 1 and Supplementary Discussion S3 for a description of the technologies; Supplemen- tary Discussion S4 and Supplementary Table S3 for modeling details and an assessment of our simulation results in S1 File). Fig 1. Scenario modeling steps and information flow. Source: Authors. https://doi.org/10.1371/journal.pone.0231764.g001 Table 1. CSA technologies considered in this study. CSA technology Description Crop Potential effects on yields and GHG emissions References No tillage Minimum or no soil disturbance, often in combination with residue retention, crop rotation, and use of cover crops Maize, wheat • Positive or neutral effects on yields • Uncertain effect on GHG emissions [35–39] Integrated soil fertility management

Combination of chemical fertilizers, crop residues, and manure/ compost Maize, wheat • Positive effects on yields • Variable effects on GHG emissions [40–43] Alternate wetting and drying Repeated interruptions of flooding during the season, causing the water to decline as the upper soil layer dries out before subsequent re- flooding Rice • Lower to no significant changes in yields. • High confidence in lower GHG emissions due to reduction of methane emissions [44–48] Nitrogen use Efficiency Practices and technologies to enhance the uptake of inorganic soil nitrogen by crops Rice Ȣ Positive results on yields • Reduction of GHG emissions [44,49,50] Source: authors https://doi.org/10.1371/journal.pone.0231764.t001 PLOS ONE Climate smart agriculture and global food-crop production PLOS ONE | https://doi.org/10.1371/journal.pone.0231764 April 29, 2020 4 / 19