Amendment effects on soil test phosphorus.
Applications of animal manures have increased soil test P values in many parts of the USA and thus increased the risk that soil P will be transferred to surface water and decrease water quality. To continue farming these areas, landowners need tools to reduce the risk of P losses. A field experiment was conducted near Kurten, TX, on a Zulch fine sandy loam (thermic Udertic Paleustalfs) with Bray-1 P values exceeding 3000 mg P kg(-1) soil (dry wt.) in the A(p) horizon to evaluate the effectiveness of soil amendments for reducing soil test P values. Soils were amended annually from 1999 to 2001 with 1.5 and 5.0 Mg gypsum ha(-1), 1.4 Mg alum ha(-1), or 24.4 Mg ha(-1) of waste paper product high in Al alone or in combination with 1.5 Mg gypsum ha(-1) and/or 1.4 Mg alum ha(-1). These treatments supplied a maximum of 225 and 1163 kg ha(-1) yr(-1) of Al and Ca, respectively. Soil Bray-1 P and dissolved reactive P levels were monitored from 1999 to 2004. None of the soil amendment treatments affected Bray-1 P values. Only annual additions of 5.0 Mg gypsum ha(-1) from 1999 to 2001 significantly reduced soil dissolved reactive P. Dissolved reactive P levels reached minimal levels after two applications of 5.0 Mg gypsum ha(-1) but increased in 2003 and 2004. These results indicate that soil dissolved reactive P levels can be reduced if sufficient amounts of gypsum were added to supply Ca in amounts similar to the soil test P values.
Brauer
D
D
USDA-ARS, Dale Bumpers Small Farms Research Center, Booneville, AR 72927, USA. dbrauer@spa.ars.usda.gov
Aiken
G E
GE
Pote
D H
DH
Livingston
S J
SJ
Norton
L D
LD
Way
T R
TR
Edwards
J H
JH
D000383:Agriculture / Q000379:methods; D000534:Alum Compounds / Q000737:chemistry; D002133:Calcium Sulfate / Q000737:chemistry; D004785:Environmental Pollutants / Q000032:analysis*; D008372:Manure; D010758:Phosphorus / Q000032:analysis* / Q000737:chemistry; D012987:Soil / Q000032:analysis*; D013781:Texas
D000534:Alum Compounds; D004785:Environmental Pollutants; D008372:Manure; D012987:Soil; D010758:Phosphorus; C041524:aluminum sulfate; D002133:Calcium Sulfate