John Deere may be the world’s largest manufacturer of agricultural equipment, but another business line is the real reason it’s plowing ahead. The company reported its fiscal third-quarter earnings Thursday, with revenue climbing 6.2% year over year to $11 billion, and income rising 7% to $1.4 billion. Both figures came in ahead of Wall Street forecasts. The results showed Deere crushing a new field, as its construction business proved a benefi…