Soil erosion from dryland winter wheat-fallow in a long-term residue and nutrient management experiment in north-central Oregon

Abstract

Soil property changes resulting from crop production practices are not often readily apparent after a few years or decades. The objective of the research reported here was to evaluate soil erodibility in treatments representing past and current cultural practices in a winter wheat-fallow field experiment established in 1931 near Pendleton, Oregon. Five treatments were evaluated: (1) fall burned residue, 0 kg N ha^-1 crop^-1 (no fertilizer); (2) spring burned residue, 0 kg N ha^-1 crop^-1 (no fertilizer); (3) spring burned residue, 90 kg N ha^-1 crop^-1 (80 lb N ac^-1 crop^-1) commercial fertilizer; (4) residue not burned, 90 kg N ha^-1 crop^-1 commercial fertilizer; and (5) residue not burned, 111 kg N ha^-1 crop^-1 (99 lb N ac^-1 crop^-1) from manure. All treatments were moldboard plowed with multiple subsequent passes with secondary tillage equipment. Weirs, stage recorders, and sediment samplers were used to collect data from January through March of 1998, 1999, and 2000. Grab samples (1 L [0.25 gal]) were collected to confirm digital stage data. Measured soil erosion progressively increased from plots with standing stubble (0.08 Mg ha^-1 y^-1 [10.04 t ac^-1 yr^-1]) to plots in crop with manure and commercial fertilizer amendments with and without the crop residue burned (0.85 Mg ha^-1 y^-1 [0.38 t ac^-1 yr^-1]), to plots in crop with crop residue burned and no fertilizer (3.30 Mg ha^-1 y^-1 [1.47 t ac^-1 yr^-1]). These results provide direct evidence of the relationship between depleted soil quality and increasing erodibility and demonstrate the importance of maintaining nutrient levels in semiarid dryland soils.