POSITIONAL AND TEMPORAL CHANGES IN PONDED INFILTRATION IN A CORN FIELD

Infiltrating rainwater can move agricultural chemicals through soil an d may contribute to contamination of drinking water supplies. Ponded i nfiltration rates were measured in corn (Zea mays L.) fields at four p ositions relative to plants and to crop rows: center of a trafficked i nterrow (TRK), center of an untrafficked interrow (UNT), between corn plants in a row (BPIR), and directly over the base of a plant in a row (OPIR). Measurements were taken in chisel-plow plots during 1990 and 1991, and in no-till plots during 1991. A Canisteo silty clay loam (fi ne-loamy, mixed [calcareous], mesic Typic Haplaquoll) was the predomin ant soil type in the plots. In chisel-plow plots, infiltration rates f or TRK and UNT positions remained relatively constant during both year s, with temporary increases after tillage or cultivation. At BPIR and OPIR positions, infiltration rates increased steadily over the growing season. Infiltration rates at the OPIR position increased from 43 to 211 mum s-1 in 1990 and from 63 to 257 mum s-1 in 1991. At the end of both growing seasons, the OPIR position had the greatest infiltration rate, and the TRK position the lowest. In no-till, infiltration rates at all positions remained relatively constant throughout the 1991 grow ing season. Infiltration rates at BPIR and OPIR positions were not dif ferent from each other, were greater than 200 mum s-1, and were higher than rates at TRK and UNT positions. High potential infiltration rate s in the row, especially around the bases of corn plants, have implica tions for the management of row-banded chemicals.