Effect of liming on EUF-extractable phosphorus, potassium and boron and their plant availability in pot trials with sugar beet

Liming of agricultural used soils is important especially on sites with poor carbonate content to increase the pHvalue and to add calcium (Ca). Interactions of the Ca-ions as well as the pHvalue on other nutrients in the soil can affect their plant availability. The objective of this study was to quantify the effect of liming on EUF-extractable and plant available nutrients in soil. In pot trials, increasing amounts of burnt lime (0, 1.4, 3.7 and 7.4 g CaOkg–1) were added to three clayey silt soils derived from loess. Afterwards the treatments were incubated for eight weeks at 12°C and 40% water-holding capacity. After incubation the soils were analyzed by electro-ultrafiltration (EUF) and used as substrate for the test-crop sugar beet in the greenhouse. As a consequence of liming the pHvalue of the soil increased from 6.8 up to 7.6, 8.1 and 8.9, respectively. The EUF-extractable phosphorus (P) content of the soil increased by 1–2mg (100gsoil)–1 with increasing amounts of lime. The P uptake of the sugar beet plants increased by up to 83% compared with the control. Consequently an increase of P extractability and plant availability occurred by liming soils with pHvalue at nearly 7. There was no effect of lime on the extractable potassium (K) and the K content of the plants. Of the micronutrients only the plant available boron decreased by liming. These results must be validated by field trials.