The fate of fertilizers and pesticides when applied to turfgrass maintained under golf course fairway conditions
Nick E. Christians
Research relating to soil leaching properties under turfgrass conditions has often been conducted on disturbed soils where any macropore structure present has been destroyed. The objective of paper 1 was to compare the solute movement characteristics of undisturbed and disturbed soil columns covered with turfgrass. We studied the dispersivities and chloride (Cl) breakthrough curves of undisturbed and disturbed soils. Chloride was used as a conservative tracer to obtain breakthrough curves. The dispersivity was over 3 times higher for the undisturbed columns than for the disturbed columns. Chloride concentration found in; layer #1 (0 to 6.7 cm), layer #2 (6.7 to 13.4 cm), and in layer #3 (13.4 to 20.0 cm) were 2.8, 5.3, 4.8 times higher, respectively, for the disturbed soils than for the undisturbed. Applying conclusions from solute movement studies using repacked columns covered with turfgrass to actual undisturbed field conditions could lead to errors in interpretation because of the effect of the macropore structure;Little research has been done concerning the environmental effects of nitrogen (N) and pesticides applied to turfgrasses. The objectives of paper 2 were to investigate the hydrology of undisturbed soil columns with a Kentucky bluegrass turf and intact macropores under a heavy and light irrigation regime, and to measure the fate of N (using [superscript]15N as a tracer) when applied to an undisturbed soil column. We found that a heavy irrigation increased N transport in leachate by 40 times compared with light irrigation, and decreased volatilization of liquid urea compared with a light irrigation;The objective of paper 3 was to investigate the fate of pendimethalin, chlorpyrifos, isazofos, and metalaxyl when applied to Kentucky bluegrass turf established on undisturbed soil columns with intact macropores under a heavy and light irrigation regime. On average 6.3, 0.5, 7.7, and 0.2% of the applied isazofos, chlorpyrifos, metalaxyl, and pendimethalin, respectively, was found in leachate from undisturbed soil columns under a heavy irrigation compared to 0.4, 0.0, 0.2, and 0.0% from undisturbed soil columns under a light irrigation. We concluded that irrigation practices can have an impact on the movement of pesticides through soil profiles. The heavy irrigation compared to the light irrigation significantly increased isazofos, chlorpyrifos, metalaxyl, and pendimethalin found in leachate from 50-cm undisturbed soil columns covered with turfgrass.