Efficiency of Phosphorus Utilization by Alfalfa from Manure and Superphosphate1
- D. W. Goss and
- B. A. Stewart2
Efficiencies of phosphorus utilization by alfalfa (Medicago sativa L.) from feedlot manure and superphosphate were examined in greenhouse and field studies. Alfalfa grown in soil treated with superphosphate removed a higher percentage of the added P than alfalfa grown in soil treated with manure. However, alfalfa grown in manured soil had the higher P utilization efficiency, as measured as yield increase per unit increase in P removed. This was due in part to more luxury consumption of P by the early cuttings on the superphosphate treatment. The P in feedlot manure was released more slowly for plant uptake and the P level remained adequate for a longer period. Apparently, microbial activity is important in the slow release of manure P. This was thought to be due to the increase in microbial activity as a result of the added energy source. Field studies indicated that P from feedlot manure carries over from year to year and becomes available with time.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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