And the extra plant material in the soil gives the soil a firmer, less muddy texture through the growing season and makes harvesting easier if the harvest season is wet. Unfortunately, the method has significant disadvantages as well. Residues of the herbicides left in the soil may also damage subsequent crops. Leaving old plant stubble on fields in the spring keeps the soil both cooler and wetter longer, which can delay spring planting. Moreover, on some flat, poorly drained farmland, such as is found over much of Illinois, Indiana, and Ohio, the increased moisture retention associated with minimum-tillage agriculture may actually reduce crop yields.
Similar dilemmas arise in connection with other aspects of the world food problem.
Analysts actually differ in the extent to which they even perceive soil erosion as a threat to the world's food supply. Those who see this as a minor problem point out that, soil erosion or no, any associated productivity losses are apparently being more than adequately compensated. For the past three decades, world production of cereal crops has increased faster than population. It can be projected that in 100 years, there could be enough food for a stable world population of 10 billion persons. Much of the increase is attributed to increased irrigation, with irrigated acreage worldwide tripling since 1950.