when the soil hot and dry
Answers
Answer:
Heating soil to extend the growing season and improve production efficiency of field and horticultural crops is another promising use of waste heat under investigation at Muscle Shoals. Experiments have been conducted since 1970 in small field plots using buried electric cables as the heat source and porous plastic pipes for subirrigation.
Sweet corn, string beans, and summer squash have been grown in all combinations of heated/unheated and irrigated/unirrigated. With early April planting, benefits included quicker emergence, more rapid early growth, somewhat earlier maturity, and greater yields from soil heating either with or without irrigation. Yield increases were generally greater than 50%.
With beans or black eyed peas planted in mid-summer, no benefit resulted from heating and yields were often decreased without irrigation. Little benefit was noted from soil warming on turnips, rye, and ryegrass planted in the fall unless seeding was delayed until the weather was so cold that germination would not occur on unheated plots. Soybeans, cotton, and corn were planted on heated and unheated soil and sampled frequently for dry matter accumulation and plant nutrient concentration. All plants made somewhat faster vegetative growth on heated soil, but only cotton showed a yield increase of possible economic potential. Plant nutrient uptake was similar on heated and unheated soils [7].