Effects Of Different P Application Rates On P Components Of Irrigated Sierozems Under Maize/Chickpea Intercropping

The soil in irrigated sierozems in Gansu Yellow River Irrigation District is typicalcalcareous soil, with the characteristic of low levels of available phosphorus.So phosphorusin this area is difficult to be absorbed by crops, causing waste of resources, environmentalpollution, economic inefficiencies and other problems.The effects of application of differentrates of phosphorous on yield of maize and chick-pea under mono-cropping andintercropping systems were studied by Jiang-Gu inorganic phosphorus fractionationmethod(1989) and Tissen and Moir (1993) method. The main conclusions were as follows:1. The order of the contents was1MHCl-Pi> Residual-P> Concentrated HCl-Po>Concentrated HCl-Pi> NaHCO3-Po≈NaOH-Po> NaHCO3-Pi> NaOH-Pi> Resin-Pi amongthe organic phosphorus fractionation by Hedley method, amended by Tiessen and Moir.Underthe increasing phosphate fertilizer conditions, the concentrations of Resin-Pi, NaHCO3-Pi,NaOH-Pi and1MHCl-Pi could be increased significantly both in intercropping andmonoculture soils.The concentrations of concentrated HCl-Pi did not change significantlywith phosphorus increasing.The concentrations of NaHCO3-Po and NaOH-Po did not changethe law with increased phosphorus levels,but the concentrations of NaHCO3-Po in chickpeamonoculture soil and maize monoculture and intercropping soil handle the highest levels at Papplication rate of40kg/hm2(P40).The concentrations of concentrated HCl-Po did notchange significantly with increased phosphorus levels.The concentrations of Residual P couldbe increased significantly in intercropped maize soils and chickpea intercropping andmonoculture soils while without significant differences in mono-cropped maize soils.2. The contents of Resin-Pi, NaHCO3-Pi and NaOH-Pi in intercropped chickpea soilswere lower than monoculture soil.The contents of1MHCl-Pi, concentrated HCl-Pi andNaHCO3-Po had no significant differences between mono-cropped and intercropped chickpeasoils.The contents of NaOH-Po in intercropped soils were significantly lower than that ofmono-cropped in P40and P80treatments.The contents of concentrated HCl-Po did notchange significantly under the increasing phosphate fertilizer conditions.The contents ofresidual phosphorus in intercropped chickpea soils was significantly lower than that ofmono-cropped.The contents of Resin-Pi, NaHCO3-Pi and NaOH-Pi in maize intercroppingsoils were lower than monoculture soils. The contents of1MHCl-Pi and concentrated HCl-Pihad no significant differences in mono-cropped maize soils.The contents of NaHCO3-Po inintercropped maize soils were significantly lower than that of monoculture only at P80level.The contents of NaOH-Po, concentrated HCl-Po and residual phosphorus did not changesignificantly between mono-cropped and intercropped maize soils.3. The order of the contents was O-P> Ca10-P> Ca8-P> Al-P> Fe-P> Ca2-P among theinorganic phosphorus fractionation. Under the increasing phosphate fertilizer conditions，thecontents of Ca2-P、Ca8-P、Al-P and Fe-P could be increased significantly, and the contents ofO-P and Ca10-P did not change significantly. 4. The contents of inorganic P forms did not change significantly between mono-croppedand intercropped chickpea, but that of intercropped maize are less than mono-cropped maize,especially Al-P at P40level (P application rate of40kg/hm2), Fe-P at P0(Without Papplication) level and Ca10-P at P80level (P application rate of80kg/hm2) were significantlower than that of mono-cropped maize.