Courtesy of Wally S., Wally's Urban Market Garden, Saskatoon SK
My beds will soon be resting, due to Saskatoon's sub-zero winters, but if it were up to me I'd keep them going all year round. There is a widespread belief in "letting beds rest" after about 3 to 5 years of production. This notion has its roots in the English countryside, and in the practice there of using leys, which rebuild the soil's content of organic matter and restores the biological process. This approach works for a large acreage, but it's not practical in an urbanized/intensive context.
SPIN-scale farmers need to make full use of their land base, and they need to keep an open mind when it comes to keeping their soil healthy and productive. Several of my urban garden plots in Saskatoon have been cropped for a half century, or more, and I am still getting good production. Most serious home gardeners crop their garden continuously, adding manure or compost every year. And certain crops, such as legumes, help rebuild the soil, and they can be incorporated into a SPIN crop repertoire. Classic high-value crops like green beans, broad beans, and peas fall into this category.
When it comes to soil, letting beds rest is not always the best prescription. With proper selection of crops, and the addition of soil amendments, continuous production is entirely feasible. SPIN farmers need to work their judgment and common sense, as hard as their beds, and know which farming practices to hold onto and which ones to let go.