THE CHANGES OF PHOSPHORUS AND POTASSIUM IN SOIL UNDER DIFFERENT LIME RATES

Abstract

The paper describes the influence of liming to phosphorus and potassium accumulation in soil. The research has been carried out at the Institute of Agronomy of Latvia University of Agriculture in the long-term subsurface drainage field established in Skrīveri in 1981. The experimental field was established with four rates of mineral fertilizers: without fertilizers (F0), N45P30K45 (F1); N90P60K90 (F2), N135P90K135 (F3) and four rates of lime: without liming (L0), 2.58 (L1), 5.70 (L2), 11.40 (L3) t ha-1 CaCO3. Primary liming was done in 1981 (Estonian oil shale ashes), the maintenance liming was performed in 1994 (dolomitic limestone) and 2014 (BALTKALK).
 After 35 years of trial similar soil parameters showed significantly different content of phosphorus and potassium related to the different rates of liming in all fertilizing levels. Without fertilizers, the liming provided the increase of phosphorus content in soil from 14 to 36 mg kg-1, but the increase of potassium – from 55 to 72 mg kg-1. On a low background of fertilizers (N45P30K45) the content of phosphorus and potassium under liming increased respectively from 20 to 32 mg kg-1 for phosphorus and 75 to 96 mg kg-1 for potassium. At the fertilizers level N90P60K90 the content of phosphorus and potassium increased respectively from 94 to 81 mg kg-1 for phosphorus and 115 to 165 mg kg-1 for potassium. At the fertilizers level N135P90K135 the content of phosphorus and potassium increased respectively from 174 to 203 mg kg-1 for phosphorus and 166 to 214 mg kg-1 for potassium.