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Reduced tillage, including no-till, and crop rotation are common practices for corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] production in the Midwest. Benefits of no-till vary with latitude and cropping system. This study was conducted to evaluate the influence of seasonal temperature and precipitation on the effects of primary tillage (plow, disk, chisel, subsoil, ridge-till, and no-till) and rotated and continuous corn and soybean production under rainfed conditions over 16 yr in southeastern Nebraska. Corn and soybean produced less grain with greater summer temperatures. Corn yield increased with less spring and more summer rainfall. Tillage and rotation practices affected corn grain yield; but only rotation affected soybean yield. Corn produced less grain with no-till than with plow. The tillage x year interaction was significant for both crops; the yield advantage for plow was less during seasons with warmer springs. Soybean grain yield was less responsive to favorable environments with the chisel than other tillage treatments. Grain yield was greater with rotation than continuous cropping for both corn (7.10 vs. 5.83 Mg ha-1) and soybean (2.57 vs. 2.35 Mg ha-1). The benefit of rotation in terms of grain yield was greatest for corn during years with cool springs. The benefit of rotation for soybean grain yield did not vary with weather conditions. Seasonal temperature and rainfall patterns influenced the effects of tillage and rotation on corn yield. In contrast, for soybean, only the pattern of temperature influenced the effect of tillage on yield.

Soil acidity can reduce crop production by directly affecting roots and changing the availability of essential nutrients and toxic elements. Liming can neutralize soil acidity, but several factors can affect the economic benefits of liming. With continuous cropping, soil pH can decrease (i.e., increase in acidity) because of various factors, including crop removal and leaching of basic cations, application of ammoniabased nitrogen fertilizers, and organic matter decomposition. Adding lime or other materials can raise soil pH to the ideal range for crop production, create an environment for a healthy function of microbes, and increase the levels of calcium or magnesium ions.