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This article in AJ

  1. Vol. 77 No. 5, p. 699-702
    Received: Aug 28, 1983



Crop Responses to Phosphorus and Potassium Fertilization of a Sodic Soil1

  1. R. Chhabra2



Uncultivated sodic soils in the Indo-Gangetic alluvial plains of India contain high amounts of NaHCO3-extractable P. However, the P fertilizer needs of crops grown on such soils is unknown. A longterm field experiment was conducted on a representative sodic soil (Aquic Natrustalf) with the following objectives: (i) evaluating rice (Oryza sativa L.) and wheat (Triticum aestivum L.) responses to P and K fertilization, and (ii) monitoring changes in soil-extractable P and exchangeable K as affected by the addition of gypsum, fertilizers, and cropping. The treatments included annual application of 0 and 22 kg ha−1 P as single superphosphate and 0 and 42 kg ha−1 K as muriate of potash, to either wheat or to both rice and wheat grown in a rotation. In any individual year, the yields of rice and wheat were not affected by application of P and K. However, over a period of 6 yr, the mean yield of rice in control plots was lower than yields in fertilized plots. The P concentration in grain was less affected by fertilization than that of the straw. The K concentration of grain and straw of either crop was not affected. After reclamation, NaHCO3-extractable soil P for all treatments, decreased in the first year, from 46 kg ha−1 to a mean value of 22 kg ha−1. Application of 22 kg P ha−1 to both crops increased the extractable soil P to 27.6 kg ha−1. In the control plot, the extractable soil P decreased each year and was reduced to 7.2 kg ha−1 after 6 yr. Exchangeable K in the soil decreased in control and P fertilized plots, but the values were much above the critical limit. Apparently, in recently reclaimed sodic soils, rice and wheat may be grown without P and K fertilization for the initial 6 yr without reduction in yield.

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