Abstract
A field experiment was conducted during two winter seasons (Rabi) of 1994-1995 and 1995-1996 to study the effect of tillage practices and integrated nutrient management on P and K accumulation and grain yield of sorghum [Sorghum bicolor (L.) Moench] at harvest in Vertisols of the semi-arid tropics of Bijapur, Karnataka State, India. The experiment was laid out in split-split plot factorial design with three replications. Deep tillage and application of 50 kg N ha-1 increased the P and K accumulation in leaf, stem, and grain and total significantly, compared to shallower tillage depths (medium and shallow) and 25 kg N ha-1 and control Among the organic amendments, i.e., farmyard manure at 2.5 t ha-1, vermicompost at 1.0 t ha-1, and Leucaena sp. cuttings at 2.5 t ha-1, application of Leucaena sp. cuttings increased the P and K accumulation in leaf, stem, and grain and total significantly at harvest. In the pooled analysis (mean of 1994-1995 and 1995-1996), deep tillage increased the total P and K accumulation by 115 and 65%, respectively, compared to shallow tillage. Application of Leucaena sp. cuttings increased the total P and K accumulation by 23 and 21 %, respectively, compared to the vermicompost. Application of 25 kg N ha-1 proved beneficial when drought occurred at reproductive stages of crop growth with uneven distribution rainfall during 1994-1995, whereas, increase in N application to 50 kg ha-1 was beneficial during the normal year (1995-1996) with uniform rainfall distribution during cropping season resulting in significant increase in total P and K accumulation. During 1995-1996, application of 50 kg N ha-1 increased total P and K accumulation by 64 and 55%, respectively. Deep tillage with application of 25 kg N ha-1 during 1994-1995 and 50 kg ha-1 during 1995-1996 and in the pooled data, resulted in significantly higher total P (15.l kg ha-1) and K accumulation (108.5 kg ha-1) compared to lower rates of N application.
