**6. Summary**

Along with economic opportunities to local families, recent technological improvements, land ownership structure changes, climate variability, various governmental policies, and aging workforce are major driving factors for changing grasslands to croplands. Along with these factors, it may also be driven by a desire to increase the value of the land. For example, irrigated cropland had a higher value than grazing lands.

Higher temperature, changing precipitation pattern, increasing CO2 levels, and extreme climatic events like drought directly affect food production and land use in the NGP. For example, ranchers who faced severe drought during 2012 may have sold their livestock and may have plowed their grassland in order to produce an economic return.

Our study shows that South Dakota had higher grassland conversion rates than Nebraska. During the first 6-year period, 700,000 ha grassland was changed to cropland in South Dakota compared with only 250,000 ha in Nebraska. Similarly, 210,000 ha newly expanded cropland was estimated during the later 2-year period in South Dakota. Contrarily, Nebraska had only 110,000 ha of new cropland. The higher conversion rates in South Dakota than Nebraska are attributed to the type of land available for conversion. In Nebraska, between 2006 and 2012 and between 2012 and 2014, 76.1% and 83.8% of the change occurred on soil are considered suitable for cropland (LCC ≤ 4), respectively. However, in South Dakota, over 90% of the land that was converted was considered suitable for croplands. Again, soil types with higher LCC values are not considered suitable and can be less sustainable.

In conclusion, the majority of grasslands converted to the crop land during study period can be managed for sustainable food production with the recommended farming practices. However appropriate soil and crop management research is needed for the portion of converted land that is at higher risk to prevent degradation.
