Amelioration of acidity and iron toxicity in lateritic lowland rice soil using non-conventional sources of calcium

Abstract

A field experiment was conducted to evaluate the effectiveness of non conventional sources of calcium like phosphogypsum, limestone powder and their blends in managing soil acidity and iron toxicity and enhancing the yield of rice in comparison to conventional shell lime. The results revealed that all the liming treatments significantly reduced the soil acidity and iron toxicity problem in rice field. The soil pH was increased from 4.61 in control to 5.33 in the treatment receiving shell lime@ 600 kg ha -1. The exchangeable calcium content in soil increased from 749 mg kg -1 in control to 909 mg kg -1 in phosphogypsum applied treatment. The 0.1 N HCl extractable iron content in soil was reduced from 511 mg kg -1 in control to 353 mg kg -1 in lime stone powder 300 kg ha -1 + phosphogypsum 300 kg ha -1 applied treatment. The availability of N(295.8 kg ha-1,K (1 06.8 kg ha-1), Mg (58.2 mg kg -1), S (31.65 mg kg -1), Zn(4.19 mg kg -1), Cu (3.79 mg kg -1) and B (0.26 mg kg -1) were the highest in treatment receiving lime stone powder 300 kg ha -1 + phosphogypsum 300 kg ha -1 whereas P (97.35 kg ha -1) was the highest in treatment receiving shell lime@ 600 kg / ha. The available Mn and exchangeable Al were found to decrease with the application of liming materials.The uptake of nutrients, growth and yield parameters of rice were significantly increased due to the influence of liming treatments. The highest grain yield of rice (5.73 t ha-1) was obtained in the combined application of lime stone powder 300 kg ha -1 + phosphogypsum 300 kg ha -1.