SOIL QUALITY INDICATOR RESPONSE TO CORN STALK GRAZING

Authors: CLARK, J - IOWA STATE UNIVERSITY; Karlen, Douglas; RUSSELL, J - IOWA STATE UNIVERSITY

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/6/2003
Publication Date: 11/6/2003
Citation: CLARK, J.T., KARLEN, D.L., RUSSELL, J.R. SOIL QUALITY INDICATOR RESPONSE TO CORN STALK GRAZING. ASA-CSSA-SSSA ANNUAL MEETING ABSTRACTS. 2003. CD-ROM. MADISON, WI.

Interpretive Summary:

Technical Abstract: Winter grazing of corn (Zea mays L.) residue can substantially decrease animal production costs, but will it affect future crop yields? Bulk density, wet aggregate stability, penetration resistance, acidity (pH) and electrical conductivity (EC) were measured for the 0-10 and 10-20 cm depth increments in a 3-year, on-farm study near Atlantic, IA, USA. Bulk density increased during the winter months, while soil pH and aggregate stability decreased. The changes were similar with and without grazing. The greatest change in aggregate stability occurred in year 2 when precipitation (278 mm) was twice the average (128 mm) for years 1 and 3 and soil water increased 80 to 90 g kg-1 between the autumn and spring samplings. EC changed very little, averaging 0.23 ds m-1. Grazing increased penetration resistance in the top 10 cm. Surface roughness was closely related to the amount of time the soil was frozen. Use of the soil management assessment framework (SMAF) to evaluate soil quality showed the index was sensitive to the indicators although the average change was small (-0.14 and -0.02 for the two depths). Subsequent soybean [Glycine max (L.) Merr.] yield was significantly lower for only 1 of 15 grazing periods and then only for the no-till treatment. We conclude that grazing of corn residues will generally not reduce subsequent soybean yield, especially if it is restricted to periods when soils are frozen.