Bermudagrass Management in the Southern Piedmont USA. II. Soil Phosphorus
- A. J. Franzluebbers *,
- J. A. Stuedemann and
- S. R. Wilkinson
Plant production can be limited by low levels of available P due to high P-fixation capacity in soils of the southeastern USA. On the other hand, there is increasing concern about excessive application of P to soil, especially when manure application is based upon N content. We evaluated changes in Mehlich-I extractable soil P during 5 yr of bermudagrass [Cynodon dactylon (L.) Pers.] management varying in fertilization [inorganic and broiler chicken (Gallus gallus) litter] and harvest strategy (unharvested, low and high cattle (Bos taurus) grazing pressure, and haying). Broiler litter supplied eight times more P than inorganic fertilization to meet the N requirement. At a depth of 0 to 6 cm, Mehlich-I extractable soil P increased 0.8 ± 1.6 mg kg−1 yr−1 (4 ± 8% of total P added) with inorganic-only fertilization, 2.4 ± 3.0 mg kg−1 yr−1 (9 ± 11% of total P added) with clover (Trifolium incarnatum L.) cover crop plus inorganic fertilization, and 8.7 ± 9.8 mg kg−1 yr−1 (6 ± 7% of total P added) with broiler litter. Haying kept Mehlich-I extractable soil P constant with time due to removal of P with harvest of biomass. At the end of 5 yr of broiler litter application to grazed land, Mehlich-I extractable soil P was 135, 50, 22, and 4 mg kg−1 higher than with inorganic fertilization at depths of 0 to 3, 3 to 6, 6 to 12, and 12 to 20 cm, respectively. Broiler litter fertilization was effective at increasing Mehlich-I extractable soil P to an agronomically productive level (50 to 60 mg kg−1 15 cm−1), but continued application could lead to excessive P accumulation that could threaten water quality from surface runoff unless appreciable soil fixation or removal of forage biomass were to occur.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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