Effect Of Acidulant On Soil Phosphorus Availability And Nutrient Uptake Of Maize

Object: The pH of calcareous soil is 7.5⁸.5,due to high CaCO₃ content.Calcareous soil also show strong buffer capacity and strong water-soluble P fixation.Most of phosphorus are converted into refractory P-Ca which result in crop utilization degradation.Applying acidulant can reduce soil pH and improve soil nutrients availability,it has not been widely used in practice due to its high cost.Drip irrigation provide a new approach to applying acidulant because it can apply water/fertilizer with low dosage,high frequency and locally designated.This paper study the influences of soil pH,available phosphorus content,the dynamics of nutrients availability and maize yield under different type of acidulant or different does of acidulant application.To explore the response of soil P to acidulant and crop growth.Methods: 1.A field plot experiment was set up to study corn response to different type and does of acidulant application by drip irrigation in small amount but high frequency way.Soil pH,soil available P content was study as well.2.A field plot experiment was set up to study corn response to different ratios of acidulant（ammonium sulfate and urea phosphate）application by drip irrigation in small amount but high frequency way.Soil pH,soil available P content was study as well.3.A soil column experiment was set up to study dynamics of phosphorus fractions response to different type of acidulant application by drip irrigation.Soil pH,soil available P content was study as well.Results: 1.Chemical acidulant applied significantly decreased local soil pH.Compare with CK treatment,two acidic materials treatment reduced soil pH value by 0.11 and 0.12,and the increased of Olsen-P were 4.90mg/kg and 12.78mg/kg.After six fertilization,two acidic materials treatment increased 13.87mg/kg and 18.76mg/kg.Same amount of urea phosphate applied at low dosage,high frequency could significantly increased Olsen-P.Acidify effect had accumulative effects in drip irrigation condition.The application acidulant by drip irrigation could increased maize plant absorption for phosphate.And it could enhance yield though increased thousand seed weight of maize.2.two physiological acidulant treatment both could decreased soil pH,increased Olsen-P,and increased shoot dry matter accumulation,P uptake.And it could enhance yield though increased thousand seed weight of maize.3.Different ratios of physiological acidulant and chemical acidulant under drip irrigation applied were significantly decreased local soil pH.Continuous application of different ratios of physiological acidulant and chemical acidulant resulted in soil pH consistently decreasing.Compared with CK,the biggest decline of soil pH reached 0.35.Different ratios of physiological acidulant and chemical acidulant under drip irrigation could increased the available P in soil.Compared with CK,it could increased 3.59 mg/kg,17.58 mg/kg,18.41 mg/kg,respectively.Under the uniform nutrient inputs and management level,different ratios of physiological acidulant and chemical acidulant could enhanced yield though increased thousand seed weight of maize.It could increased production 7.72%¹0.58%.4.The center of emitter,the pH of high sulfuric acid treatment in emitter in 0,10,20,30,40,50 cm soil were7.45,7.62,7.7,7.78,7.88,respectively.Compared with CK treatment,it decreased 0.50,0.35,0.26,0.21,0.12,respectively From the emitter in 0,5,10,15,20,25 cm soil pH of 0¹0cm depth were 7.45,7.6,7.83,7.85,7.92,7.94,respectively.Compared with CK treatment,it decreased 0.50、0.37,0.15,0.13,0.05,0.06,respectively.So the acidifying effect in emitter was most intense.Available P content of high sulfuric acid treatment in emitter was 117.61 mg/kg,compared with CK treatment,soil available P content increased 164.22%.And it increased Resin-P,NaHCO₃-P,NaOH-P content in dynamics of phosphate fractions.Conclusions: 1.Under equivalent P application,applying acidic materials and physiological acidic materials both could decreased soil pH,and increased available P content.And it could increased maize nutrition absorption,and maize yield increased 4.1%¹0.79%.2.Applying different ratios of physiological acidulant and chemical acidulant under drip irrigation significantly decreased soil pH of 0⁴0cm depth,and the pH decrement was 0.35.Under drip irrigation,different ratios of physiological acidulant and chemical acidulant could increased available P content,also increased maize Pabsorption and P accumulation.Different ratios of physiological acidulant and chemical acidulant could increased maize yield though increasing thousand seed weight.And maize yield increased 7.72%¹0.58%.Applying different ratios of physiological acidulant and chemical acidulant could improved nutrient availability and crop yield in calcareous soil and is an effective method.3.Applying sulfuric acid could significantly increased Resin-P,NaHCO₃-P,NaOH-P content and decreased HCl-P content in dynamics of phosphate fractions under drip irrigation.Soil acidifying effect of 0⁵0cm soil depth in emitter both have effect in the longitudinal strength.Soil acidifying effect decreased gradually with increasing soil depth.Acidifying effect were significant from the emitter within 0¹5cm in the horizontal direction.