ROLE OF PHOSPHORUS IN AGRICULTURE IN CENTRAL CHERNOZEM REGION
The patterns of mobile phosphorus content changes in the arable soils of Central chernozem region over the past 45 years of their agricultural use are analyzed. Subsequent to the results of the first cycle of continuous agrochemical inspection (1964-1970) the minimal weight average content of mobile forms of phosphorus is fixed in the arable soils of Central chernozem region. It changes within 46...77 mg/kg, which was the main agrochemical factor limiting crop yield. Since the mid-seventies and to the nineties last century the balance of this element in the agriculture of CCR was positive due to its high flow with fertilizers (45.7...71.0 kg/ha). In the issue the maximum weight average contents of mobile forms of phosphorus were registered in Belgorod and Kursk regions in 1995-1999 (131 and 139 mg/kg correspondingly), in Lipetsk region in 1994-1997 (103 mg/kg), in Tambov region in 19962002 (95 mg/kg). In this period more than half of the examined lands belonged to ones with medium and higher provision of its mobile forms. Since the nineties of last century and up to date the inflow of this element decreased several times. The minimal value of this index in cycles of agrochemical monitoring in different regions varied from 2.7 to 11.7 kg/ha. Consequently the increase in the weight average content of mobile phosphorus in arable soils is fixed as compared with the maximum level by 5...15 mg/kg. According to recent complete cycles of agrochemical monitoring in soils of Kursk region it is 133 mg/kg, Belgorod region - 116 mg/kg, Lipetsk one - 91 mg/kg, Tambov one - 90 mg/kg. In general on the modern stage the provision of arable soils in CCR with mobile phosphorus decreases, however, its weight average content in soils of Kursk and Belgorod regions still remains on the level close to optimal one.