FLY-ASH AS A SOIL CONDITIONER AND FERTILIZER

Field experiments were conducted in villages around the National Capit al Power Project, Ghaziabad, Uttar Pradesh and LARI Farm, New Delhi to evaluate the effects of flyash incorporation on soil properties and t he growth and yield of wheat (Triticum aestivum L.), mustard (Brassica juncea L.), rice (Oryza sativa L.) and maize (Zea mays L.). Flyash ap plication levels (up to 50 t/ha) were decided on the basis of an ash/d ust fall range of 5-12 t/ha/y in villages adjoining the thermal power station. The grain yield of maize increased in flyash-treated plots wi th the addition of ash up to a maximum addition of 10 t/ha. Dusting cr op canopies with ash decreased the yield in proportion to the amount a pplied. The yield of wheat increased up to an addition of ash of 20 t/ ha, and declined thereafter, but was still higher than the yield when no flyash as added. Paddy yield when 10 t/ha of ash was added was simi lar to that with no flyash, whereas mustard showed improvements in see d yield with flyash addition at 10 t/ha level. Flyash-treated plots ha d a marginally higher uptake of Zn, Cu, Fe, Mn and Cd. Flyash addition to soil resulted in lower bulk density, although the differences comp ared with non-treated plots were not significant. The addition of flya sh also reduced the hydraulic conductivity and improved moisture reten tion at field capacity and wilting point, but no changes in available water were observed. These changes in soil properties might have been due to modifications in macro- and micro-pore size distribution and wh ich may also have contributed to the increased crop yields in light- a nd medium-textured soils. However, the effects of ash addition on soil health and crop productivity need to be established with long-term st udies. (C) 1998 Elsevier Science Ltd. All rights reserved.