Effects Of Different Fertilization Treatments On Pineapple Growth And Nitrogen And Phosphorus Loss

Pineapple production in Hainan province faces a widespread problem of over-fertilization and high risk of environment pollution due to large fertilizer loss.This study aimed to explore a reasonable fertilization practice for sustainable pineapple production.A field experiment was conducted including five treatments,e.g.no fertilization control(CK),farmer’s practice(FP),reduced chemical fertilization(OPT),reduced chemical fertilization and organic fertilization replaces part of chemical fertilizer(OPTO),and reduced chemical fertilization and organic fertilization,controlled release fertilization replaces part of chemical fertilizer(OPTS).Plant dry matter,nutrient uptake,yield,fruit quality,economic benefit and total nitrogen(TN)and total phosphorus(TP)loss were compared under different treatments.The main results were as follows:(1)Fertilization increased pineapple plant dry matter in the order of OPTS>OPTO>OPT>FP>CK,with OPTS,OPTO,OPT and FP increasing by 136.06%,120.05%,113.53% and 99.74% compared to CK,respectively.(2)The uptake of nutrient elements by pineapple was K>N> P,and the uptake of NPK mainly occurred during the planting-flowering period.The order of nitrogen accumulation in pineapple organs was,leaf>stem + root>crown>fruit stalk>fruit.The order of phosphorus accumulation was leaf>fruit stalk> stem + root>crown>fruit.The order of potassium accumulation was leaf>fruit stalk>crown>stem + root>fruit.(3)the pineapple yield OPTS>OPTO>OPT>FP>CK.OPTS,OPTO,OPT and FP increased by 83.19%,95.16%,95.38% and 113.91% compared to CK,respectively,while,OPTS,OPTO and OPT increased by 6.53%,6.66% and 16.76% compared to FP,respectively.There was no significant difference among OPT,OPTO and OPTS.(4)Compared to CK,four fertilization treatments significantly increased fruit appearance quality in terms of fresh weight per fruit,fruit height,fruit width and fruit height/width ratio,with no difference occurring between four fertilization treatments.Compared with CK,fruits under FP,OPT,OPTO and OPTS had lower levels of titrable acid and vitamin C,making a higher sugar/acid ratio.All treatments had similar levels of soluble solid.Compared with OPTS,fruits under CK,FP,OPT and OPTO had higher levels of soluble sugar.(5)Fertilizer cost was in the order of FP>OPTS>OPTO>OPT>CK,while net income was in the order of OPTS>OPT>OPTO>FP>CK.Net income under OPTS increased by 125.44%,29.47%,6.71% and 12.26% compared with CK,FP,OPT and OPTO,respectively,and OPT displayed the highest input/output ratio of 4.74 : 1.(6)TN loss in runoff was FP> OPTS>OPTO>OPT>CK,and FP is 51.05%,138.14%,216.38% and 447.64% higher than OPTS,OPTO,OPT and CK,respectively.TP loss in runoff was FP>OPTS>OPTO>OPT> CK,an FP was 57.78%,174.70%,193.96% and 254.49% higher than OPTS,OPTO,OPT and CK,respectively.It indicated that reducing fertilization effectively reduced the runoff loss of nitrogen and phosphorus.(7)TN leaching loss was FP>OPT>OPTO>OPTS> CK,and FP was 10.10%,42.62%,50.61% and 250.67% higher than OPT,OPTO,OPTS and CK,respectively.TP leaching loss was FP>OPTO>OPTS>OPT>CK,and FP was 20.51%,21.46%,21.74% and 17.21% higher than OPTO,OPTS,OPT and CK,respectively.These results showed that reducing fertilization effectively reduced the leaching loss of nitrogen and phosphorus.Therefore,reduced chemical fertilization not only increase yield without reducing fruit quality,but also effectively reduce the runoff loss and leaching loss of nitrogen and phosphorus.From the perspective of yield and economic benefit,OPTS is the best fertilizer treatment;from the perspective of quality and nitrogen and phosphorus loss,OPT is the best fertilizer treatment.