Release and Uptake of Potassium and Sodium with Fly Ash Application in Rice on Reclaimed Alkali Soil

Abstract

The effects of fly ash applied @ 0, 2.5, 5.0, 7.5 and 10.0 t ha-1 to rice were studied rice-wheat cropping system on reclaimed Typic Natrustalf. Besides crop yields and K and Na contents in ———, release pattern of exchangeable, non-exchangeable and total K and Na were also monitored. Graded levels of fly ash increased grain and straw yield of rice but the overall effects were non-significant. Fly ash did not influence K content but significantly reduced Na content in rice. The residual effects of fly ash was non-significant on wheat yields and contents of K and Na in plantations. Averaged over fly ash levels, 71.8% exchangeable K and 68.4 % exchangeable Na was removed in the first extraction. Similarly, more than 35% nonexchangeable K was extracted in first extraction and a considerable part of it was also released in the subsequent extractions. Fly ash had non-significant effect on the release of exchangeable K but significantly reduced the exchangeable Na content. Non-exchangeable K, total K and total Na contents in soil were also not significantly affected by fly ash additions. Though, the soil pH and soluble salt content did not change significantly with fly ash application, but a significant reduction in Na content in rice and exchangeable Na suggested that it can be used as a resource for reclamation and management of the alkali soils.