Abstract Non-exchangeable potassium (Knex) contributes to soil K availability and several extractants are used to access its contribution. This study evaluated sodium tetraphenylboron (NaBPh4) as a soil test of K availability in 20 soils from Northern Greece. Winter wheat (Triticum aestivum L. var. 'Yecora') was sown in a greenhouse pot experiment and five cropping cycles were carried out until K-depletion. Soils were analyzed with NH4OAc and NaBPh4 (1 and 5 min incubation periods).
Abstract Great changes have been happened over the past 30 years in chemical fertilizer input in China, and thus a gross potassium (K) budget model established to evaluate the variation of farmland K balance for China in 1980 and 2010 at the national scale is important. Results indicated that total K input in 1980 was 6. 8 million tonnes, in which chemical fertilizer, organic manure and other sources accounted for 5. 6, 77. 5 and 16. 9% respectively. Total K input in 2010 was 21.
Fotis Bilias and Nikolaos Barbayiannis, Soil Science Laboratory, Aristotle University of Thessaloniki