This section is from the book "The Potato: A Compilation of Information from Every Available Source", by Eugene H. Grubb, W. S. Guilford. Also available from Amazon: The Potato: A Compilation Of Information From Every Available Source.
The rotation of crops is a fundamental practice in good farming operations. The potato is one of the most useful crops in a general rotation, because the clean and thorough cultivation required, as well as the preliminary deep plowing and the digging, puts the soil in excellent mechanical condition.
The object of rotating crops is to grow a uniform maximum product. All crops benefit by a change. The fertility requirements of no two are exactly the same. A soil is benefited both mechanically and in its store of fertility by the changing of crops. For instance, a soil may have plenty of the essential mineral elements of fertility to last for generations, but the amount of those elements available for the use of a certain plant might be exhausted by a few years'continuous cropping. Another crop would require different elements or different amounts or forms of the same elements. By the time the first crop considered would be grown again on this land, the fertility that was exhausted would either be replaced or made available by different methods and conditions. On farms where rotation is practised diseases are avoided, checked, or controlled.
The maintenance and replacing of nitrogen is one of the most important soil cultural conditions. Humus or decayed vegetable matter is a source of nitrogen. Alfalfa, clovers, peas, and other legumes grow so luxuriantly in many localities, and place and leave such large amounts of fertility in the soil, that the nitrogen problem consists simply of growing legumes in the rotation. The keeping of livestock and the return of manure to the land replace some of all of the elements to the soil in a good combination.
A rotation of crops, and their arrangement as far as location on the farm is concerned, is a matter that must be worked out for the requirements of the individual holding.
The farmer is a manufacturer. He directs the growing of meat and dairy products, the fruit, grain, and vegetable crops from the soil and other elements. To get all the returns from the business, he must have no waste, and the by-products must be manufactured into some marketable form. His unmarketable potatoes must be utilized for feed and his unmarketable fruits must be made into cider, vinegar, or jelly. The farmer who makes the greatest success is the one that produces a pound of beef, a pound of pork, or a pound of butter the cheapest. To do this he must know the value of the grain and the hay he uses in producing them. He must know on how much less food a year-old animal makes a pound of gain than a two-year-old animal. He must know how much food it takes for a pound of gain for a steer and how much for a hog. He must know how to market to the best advantage the products that he raises on his farm, whether directly from the fields or as meat, dairy products or poultry, or as draft horses, pure cattle, hogs or sheep.
There is no "best" breed of horses, no "best" breed of cattle, and likewise no "best' kind of farming. Successes have been made in every line and successes will continue to be made in every line repeatedly. No farmer cares to pursue exactly the line followed by his neighbors nor is it necessary. Individuality is just as marked here as elsewhere. To have and to pursue one ideal is the essential thing, and to know all there is to be known about it is a large part of the equipment. Success follows knowledge and application.
The diversified farm is a farm that, having a ruling central idea, grows a rotation of crops to maintain fertility, supports enough and the proper kind of livestock to best utilize those crops, and furnishes as much as is profitable of the products necessary for maintenance of everything on that farm. Any one of the component parts that make up a diversified farm is capable of being a specialty, but the combination and the utilization of the waste ends make diversity.