foliar-feeding
Soil scientists and agronomists agree that nutrients essential for growth and development enter the plant either through leaf tissue or roots with uptake by roots clearly dominating the absorption process. For many years, however, the concept of absorption by leaf tissue has intrigued many researchers. There has always been a discussion on the idea that foliar absorption (foliar feeding) of essential nutrients could be a positive supplement to soil applied fertilizer.
Then in 1975, faculty at Iowa State University reported that a foliar application of an N-P-K-S fertilizer increased yield of two soybean varieties by over 20 bushels/acre (Table 1). This was a dramatic report and researchers at other universities rushed to see if they could duplicate the results. Obviously, the fertilizer industry was also very interested in this concept. As results of field trials were reported in the subsequent years, there were no positive responses of foliar application of fertilizer to soybeans. In a few situations, foliar feeding increased soybean yield; but, increases were small. Leaf burning was reported more often than a yield increase. Trials were conducted at Rosemont in 1976 and there was no increase in yield attributed to foliar fertiilization
