Residual Effects of Previously Applied Composted Manure on Water and Nutrient Loss and on Crop Performance. (3996)
Authors:
C.S. Wortmann* - Univ. of Nebraska D.T. Walters - Univ. of Nebraska
Abstract:
Manure application may result in improved soil structure and reduced runoff but also in excessive soil P levels and increased P concentration in runoff. Research was conducted from 2001-04 under natural runoff events with plots of 11 m length:
to evaluate soil P tests in prediction of P concentration in runoff and to determine the residual effects of composted manure on runoff P loss. Low and high P compost had been applied annually in the preceding years resulting in total P applications of 750 and 1150 kg/ha. Bray-1 P in the surface 5 cm of soil was increased from 16 to 780 mg/kg with application of high P compost. Runoff and sediment losses were greater with the no-compost treatment than with compost applied. Runoff P
concentration increased as Bray-1, Mehlich-3, and Olsen P increased. However, a unit increase in soil test P concentration (STP) resulted in a relatively small increase in total, BAP and soluble P concentration in runoff. Total P loss was as great with the no compost treatment as with the low P compost treatment despite great
differences in STP levels. In conclusion, agronomic soil tests are useful in predicting long term mean runoff P concentration. Transport factors are also important to P loss which may be substantial at even at low to moderate STP. The rate of increase in total runoff P concentration is approximately 0.002 times the increase in STP.
Speaker Information: Charles Wortmann, Univ. of Nebraska, 154 Keim Hall University of Nebraska, Lincoln, NE 68583-0915; Phone: 4024722909; E-mail:
Session Information: Tuesday, November 2, 2004, 1:25 PM-4:25 PM Presentation Start: 3:30 PM