The Migration Characteristics of Phosphorus in Greenhouse Soils

By investigating the management of greenhouses in Shouguang,Shandong Province and analyzing soil samples of both greenhouse and open field,the contents and fractions of phosphorus in soils were studied.The results indicated that:(1)In the topsoils(0～20 cm)of the greenhouses,the contents of total phosphorus and the fractions of inorganic phosphorus(except Ca10-P)were 2.9 times,3.7 times,5.6 times,4.1 times,3.4 times and 6.1 times higher than that of the corresponding open field soils.And the maximum values were observed in the topsoi(l0～20 cm),which displayed apparent accumulation in topsoils and tended to move downward further to the subsoil(.2)Phosphorus accumulated faster in the early stage of cultivation in the greenhouse soils.The content of the total phosphorus were 2-4-fold higher than that of the open field in greenhouses cultivated for 4 to 8 years.And the accumulation rate of phosphorus decreased as cultivating years pass by.(3)Ca8-P,Al-P,O-P were the major fractions of available phosphorus in greenhouse,with an increase of 296.5 mg.kg-1,288.5 mg.kg-1 and 306.0 mg.kg-1 over that of the open field soil(.4)The average contents of water soluble phosphorus and available phosphorus in greenhouse topsoils amounted to 10.93 mg.kg-1 and 248.40 mg.kg-1 respectively,8.7 times and 5.4 times higher than that of the open field soils.There was a great possibility of phosphorus leaching and environmental pollution.