Potassium dynamics in soil under long term regimes of organic and inorganic fertilizer application.

作者：Fareeha Habib, Shahid Javid, Ifra Saleem, Shabana Ehsan, Zeeshan Ahmad · 年份：2014 · 被引用次数：18 · 研究领域：Agricultural Science and Fertilization、Clay minerals and soil interactions、Plant Micronutrient Interactions and Effects

Knowledge of different potassium fractions in soils is essential for potassium management to determine long term sustainability of a cropping system. It is generally believed that our soils are not deficient in available potassium due to dominance of illitic clay mineral, therefore farmers usually skip the application of potassium in many crops. But increased cropping intensity and introduction of hybrid varieties are resulting in a considerable drain of potassium reserves and crops are becoming responsive to potassium fertilizer application. This study was conducted to monitor the changes in different fractions of soil potassium viz. water soluble, exchangeable, nonexchangeable and total potassium. For this study two sites were selected from research area of Institute of Soil Chemistry and Environmental Sciences, Ayub Agricultural Research Institute, Faisalabad. In 1 st long term study (since 1978) seven combinations of organic and inorganic sources were used. In 2 nd study (since 1986) two sources of potassium were tested. Soil samples from these two studies were collected from 0-60 cm depth with interval of 15 cm. Results indicated that both soluble and exchangeable potassium concentration in soil decreased with depth at both sites. At 1 st site range of soluble and exchangeable K was 2.5 to 10.5 mg kg -1 and 57 to 273 mg kg -1 , respectively, while in 2 nd study water soluble and exchangeable K varied from 1.35 to 6.0 and 63 to 83 mg kg -1 . It is interesting to note that...