Potential benefits of phosphorus fertilizer on marginal lands
1997
Osman, A.E. (ICARDA, Aleppo (Syria))
An experiment which has been carried out over 12 years (since 1984/85) at Tel Hadya, in northern Syria, showed that broadcast application of superphosphate to non-arable lands (also called marginal lands, because grazing is the only possible use), which contain annual legumes, stimulated leguminous growth and reduced nitrogen deficiency, leading to increased herbage production. Phosphate fertilizer was applied at three levels: 0, 11 and 26 kg P2O5 ha-1 every year for a 7-year period (1984-1990). Annual applications of 11 and 26 kg P2O5 ha-1 raised the Olsen-P values in the soil from approximately 7 mg kg-1 to about 20 and 40 mg kg-1, respectively, by the end of the seventh season (July 1991). The direct effect of P application was observed in improved legume and total herbage yields, and in improved productivity in sheep grazing the pasture. Also, significant effects of residual P have been recorded long after the initial application of fertilizer. The response to P in drought when drought was more accentuated suggests that a higher critical level for available P should be considered for low moisture-regime situations. The study clearly shows the value of using P fertilizer, even at modest levels, for forage production in marginal land
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