Yield Response to Soil Warming: Agronomic Crops¹

Abstract

Waste heat appears in the form of warm condenser cooling water from power generating plants. It has been proposed to use this water with temperatures ranging from 25 to 40 C for warming soils by pumping it through buried pipes. Experiments were conducted to determine the effect of warming soils in this manner on the growth rates and yields of several crops. The proposed system was simulated with parallel electrical heating cables buried 92 cm deep and 183 cm apart. Heat source temperatures ranged from 35 to 38 C during the growing period. Heating increased the average temperature of the soil layer from 0 to 100 cm deep by about 10 C. The average temperature increase of the 0 to 10 cm soil layer was < 3 C. The crops tested were field corn (Zea mays L.), sudangrass (Sorghum vulgare sudanese), sorghumsudangrass hybrid (Sorghum bicolor L.), and tall rescue (Festuca arundinacea). The yield increases, expressed as percentages of yields obtained on unheated plots, ranged from 19% for tall rescue to about 50% for sudangrass. The yield increases varied widely from year to year for the same crop. The highest yield increases occurred during years when the yields on unheated plots were lowest. Correlations between yield increases and yields from unheated plots were highly significant. A yield decrease occurred only with tall fescue during the summer. Soil heating appears to be most effective when climatic conditions and management factors are limiting. The effects of higher soil temperatures on growth rates were greatest in the early spring.

Terrestrial Carbon–Cycle Feedback to Climate Warming

“…Soil warming increased the yields of crops by 19%-50% and vegetables by 19%-100% (Rykbost et al 1975), primarily owing to enhanced growth in early spring. Experimental warming increased NPP by up to 25% in a tallgrass prairie (Luo et al 2007) (Figure 3).…”

Kinetics of nutrient uptake by roots: responses to global change

“…Such changes will have a marked effect on soil biology including growth and physiological characteristics of roots. Soil temperature has long been considered as an important ecological factor that determines a variety of structural and functional characteristics in managed and natural ecosystems (Chapin, 1974 ;Rykbost et al, 1975 ;Dixon & Turner, 1991 ;Farnsworth et al, 1995 ;Chapin, 1977 ;Weih & Karlsson, 1999). In some ecosystems, temperature of the root zone is the most important factor in determining net primary productivity (Van Cleve et al, 1981 ;Risser, 1985).…”

Soil Environment Constraints to Root Growth

“…For these species, breeding for cold tolerance in the seedling stage may have little relevance to the growth and development of the plant when the nodal (adventitious) roots are following the 17 -18°C isotherm down into the soil. The observations of Allmaras et al (1973) and Rykbost et al (1975) suggest that breeding adventitious (nodal) roots of these species for cold tolerance may be highly advantageous.…”