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Sudan Journal of Agricultural Research

Response of sorghum (Sorghum bicolor L). Moench) to NP fertilizers and. cropping sequences on irrigated vertisols of the Rahad Scheme

Elfadil A. Babiker¹, A.A. Salih1and Badreldin. A. Mohamed¹

 

Abstract:

Field experiments were conducted at Rahad Research Station over three seasons to evaluate the response of sorghum to NP fertilizers and cropping sequences. Results indicated that grain yield of more than 5t/ha can be achieved without fertilizers. Effect of N on sorghum yield in the wheat-sorghum sequence was consistently significant and with high nitrogen use efficiency (NUE). The response in the groundnut-sorghum sequence, however, varied with the levels of initial soil testing for NO₃ N and total-N. Despite differences between levels-of fertilizers above 1N (43 kg N/ ha) being statistically insignificant, regression analysis indicated that economic optimum would be obtained at higher rates. Accordingly economic optimum yield was achieved at approximately 2N (85 and 95 kg N/ha for groundnut- sorghum and wheat-sorghum, respectively). Leaf-N of 2.5 percent at heading emerged as the optimum for maximum yields in both cropping se
quences. The insignificant response of sorghum to Pfertilizers was attributed to its sufficiency level being within the range of available soil tests for Na HCO₃P (6-8 ppm). On the other hand, depletion of the residual Na HCO₃ P via increasing rates of applied-N was discussed in relation to a dilution effect. Hence, frequent soil testing is needed to assess for how long such an adequate supply of P could be maintained.

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Sudan Journal of Agricultural Research Vol. 2(1999) PP. 1-8