Nutritional requirements of sweet sorghum

Abstract

The mineral requirements of two sorghum cultivars, Brandes and Rio, were studied both under field and greenhouse conditions. In the greenhouse plants received full strength Hoagland's solution, whereas in the field a uniform fertilization of 150 kg N/ha, 200 kg P2O5 and Kg K(2)0 was used. Under greenhouse conditions the need for nutrients obeyed the following decreasing order: K, N, Ca, Mg, P, S, Fe, Mh;, Cu and Zn. Export of nutrients in the grains, in percentage of total uptake was as follows, respectively for Brandes and Rio: N - 55 and 59, P - 41 and 43, K - 68 and 72, Ca - 16 and 10, Mg - 47 and 44, S - 47 and 60, Cu - 55 and 66, Fe-6 and 7, Mn - 10. and 8, Zn - 14 and 10. Date obtained with field grown plants plants showed that production of 1 ton of stalk required: 3.22 - 3.93 kg N, 0.40 - 0.45 P, 3.91 - 4.39 K, 1.09 - 0.77 Ca, 0.86 - 0.54 Mg, 0.32 - 0.41 S, 63 - 37 g Fe, 3-5 - 3.0 g Cu, 16 - 18 g Mn , 8-9 g Zn and 18 - 21 g B.