First there was subsistence farming. Sustainable farming is in essence concerned with anything that affects the sustainability of a farm. Poorly maintained farms produce less in terms of quantity and quality.
Profitability decreases means that surplus money is no longer available for repair and improvements.
Farm land can become contaminated with chemical residues, weeds or vermin. We have created a world that relies heavily on technology to produce the food needed to sustain its human population. There is a worldwide dilemma. Everyone needs to be concerned about a decline in farm production potential. The farmer, his family, and workers are always affected first.