Spatial Variability of pH in a Direct Seed Cropping System: Implications and Management Strategies.
(5598)
Authors:
T. Brown* - WA State Univ.
R. Koenig - WA State Univ.
Abstract:
Soil acidification and the potential for aluminum (Al) toxicity is an increasing concern in direct seed cropping systems. Soil pH values have changed from near neutral in native (non-farmed) to below 5 in farmed systems due to the use of ammonium-based fertilizers. A 30 cm deep x 60 cm wide vertical cross section was sampled at 5 cm intervals at the Palouse Conservation Field Station in Pullman, WA to evaluate the spatial variability of pH and Al under broadcast and deep band lime management strategies. Soil extractions (1:1) were performed for
determination of pH, Al, and other major soil ions for analysis using the MINTEQ speciation program. Preliminary data indicates that a stratified layer of acidity exists between 5 and 15 cm below the surface and slight acidification is evident at the soil surface. Surface acidity was ameliorated three years after a one time
broadcast lime application of approximately 7,000 kg/ha. Deep banding lime at 224 kg/ha/year for 3 years does not appear to ameliorate soil acidification. The
influence of lime placement on the spatial patterns of soil pH and Al must be
considered to develop strategies to maintain soil quality, the viability of direct seed cropping systems, and to understand the long-term movement of acidity in the soil profile.
Speaker Information: Tabitha Brown, WA State Univ., Crop and Soil Sciences
DepartmentPO BOX 646420, Pullman, WA 99164-6420; Phone: 509-335-7817; E-mail:
Session Information: Tuesday, November 2, 2004, 8:00 AM-12:00 PM Presentation Start: 8:00 AM (Poster Board Number: 2433)
Keywords: soil pH; direct seeding; aluminum; liming
