Influence of Nitrogen Fertilization and Other Factors on Yield, Prussic Acid, Nitrate, and Total Nitrogen Concentrations of Sudangarss Cultivars¹

Abstract

Herbage yields, total N, prussic acid, and nitrate‐N concentration of seven sudangrass [Sorghum sudanense (Piper) Stapf] forages treated with five levels of N (O, 22, 44, 88, and 176 kg/ha applied at seeding and after the first and the second clippings) were determined from a field experiment. The sudangrass cultivars represented included: sudangrass varieties (‘Piper’ and ‘Sweet’), sudangrass‐sudangrass hybrid (‘Trudan I’), forage sorghumsudangrass hybrids (‘Sweet Sioux’ and ‘Haygrazer’), and grain sorghum‐sudangrass hybrids (‘DeKalb SX‐11’ and ‘Horizon SP‐110’). Yield increases from N applications were nonsignificant for the first clipping but increased with increasing N increments through the 88 kg N/ha for'clippings 2 and 3. Nitrogen fertilization increased total N, prussic acid, and nitrate concentration at each clipping. The Sudangrass varieties (Sweet and Piper) and sudangrass hybrid (Trudan I) were the highest in total N percentage. Haygrazer and Horizon SP‐110 generally contained the lowest N percentage.

Effect of Nitrogen Rates and Method of Nitrogen Application on Dry Matter Yield and some Characters of Sorghum-Sudangrass Hybrid

“…In irrigated areas, N fertilizer is very important and is the main factor affecting the DM yield of sorghum cultivars. Since N fertilizers are easily soluble and leachable in most of the soils, various N application methods have been tried to increase the effectiveness of N fertilizers for sorghum varieties (Sumner et al, 1965;Harms & Tucker, 1973;Rahman et al, 2001). Different N application methods had no signi cant effect on the DM yield of the sorghum -sudangrass hybrid (Table 2).…”

“…The method has a positive effect because of the decreased risk of large losses during heavy rainfall. At the same time, excess N application results in the accumulation of nitrate (Burger & Hittle, 1967;Harms & Tucker, 1973;Kallenbach et al, 1999).…”

“…The amount of N to be applied and the method of application depends on climate, soil fertility, plant variety and the utilization purposes, i.e. whether these crops are used for grazing, silage or hay (Beuerlein et al, 1968;Harms & Tucker, 1973;Creel & Fribourg, 1981;Singh et al, 1988;Rahman et al, 2001).…”

Factors affecting the hydrogen cyanide potential of forage sorghum.

“…The HCNp of forage sorghum is not uniform throughout the plant (Loyd and Gray 1970), may differ by at least tenfold between varieties (Hedges et al 1978) and is affected by environmental and nutritional factors (Harms and Tucker 1973). It decreases with advancing maturity (Brunnich 1903;Wheeler et al 1984) and higher available phosphorus (Boyd et al 1938;Wheeler et al 1980) and increases with chronic moisture stress (Franzke and Hume 1945;Nelson 1953) and higher available nitrogen (Boyd et al 1938;Wheeler et al 1980) but is not affected by herbicide treatment (Swanson and Shaw 1954;Brown and Beaty 1970).…”

Hydrogen cyanide production by field-grown sorghums

“…Young regrowth, for example, is much more dangerous than more mature crops (Aii 1975) . Nitrogen fertilisation increases dhurrin levels (Harms & Tucker 1973) and levels can also increase when growth is slowed by injury (Franzke & Hume 1945), lack of water (Nelson 1953), or non-lethal frosting (Wattenbarger et al 1968).…”