Effects of Climate on Performance of No-Tillage

Distribution and amount of rainfall and temperature have more direct effects upon performance of no-tillage row crops in dryland agriculture than any other climatic factors. As will be pointed out in Chapter 4, the distribution of rainfall during the growing season is very important to the maximum conservation of soil water due to no-tillage or a mulch. The more rainfall events which occur during the growing season, the greater the difference of soil water evaporation between no-tillage or a mulch and conventional tillage; therefore, the more soil water will be conserved from the no-tillage than from conventional tillage which is then available for transpiration through plants. In central Kentucky the ideal distribution and amount of rainfall to obtain near maximum conservation is about 2.5–3.0 cm of rain per week, a month prior to planting until the crop reaches full canopy, about mid-July (see Table 4-1). From Table 4-1, it can be seen that the average water use, soil water evaporation plus transpiration, by corn for the 1970, 1971, and 1972 and 1973 growing seasons (May through September) on the conventional tillage treatment were 35.5, 51.4, 35.5 and 50.6 cm, respectively. The grain yields were 6,136, 10,841, 10,841 and 8,795 for 1970, 1971, 1972 and 1973, respectively. The water use in 1970 and 1972 was the same, 35.5 cm, while grain yields were drastically different, 6,136 and 10,841 kg/ha.