Date Received: 30-10-2018 / Date Accepted: 03-04-2019
The present study aimed to evaluate phosphorus (P) buffering capacity and risk of P leaching to the environmentin the long-term reduced P application in the triple rice cropping paddy fields in Bac Lieu provincein the Mekong Delta of Vietnam. The soil samples were collected in the harvest stage of Winter-Spring (WS) 2013-2014 crop on the fields thatwere applied withreducedP fertilizerforsevenconsecutive crops (from WS 2011-2012 to WS 2013-2014). The P solutionsfrom 0to 60mg P/L concentration were added to the soil samples within 24 hoursto determine the soil absorption of P. The results showed that the P absorptiondecreased when the P concentration to soil samples increased in allreducedP fertilizer treatments. The P bufferingcapacityvaried in the rangeof123-132 mg P/kg and it reduced when applied 60 kg P2O5/ha compared withoutP application, with20 kg P2O5/ha or with 40 kg P2O5/ha. The degree of phosphorus saturation (DPS) ranged from 9.15 to15.6% and continuousapplication ofPatthe rate of 60 kg P2O5/hamight result in P leaching risk. It is recommended thatDPS in the other paddy soils be studied to assess the risk ofPleachingto environment,consequently, to enhance the P efficiency management in rice production in the Mekong Delta of Vietnam.
