Two mechanisms are involved in using tall crops to reduce drought or heat stress of shorter crops: partial shading and reduction in wind speed. Partial shade cast by a trellised crop or a well-spaced planting of sweet corn can reduce heat stress of summer crops of spinach or lettuce (19). This may be useful in preventing early bolting. On windy sites, periodic rows of tall crops can reduce water stress by slowing wind speed. For example, one study showed that soybean yields in Minnesota increased by as much as 28 percent when pairs of corn rows were interspersed in the fields to block wind (89).