engleski

Potassium effects on field crop yields on an acid soil in northwestern part of Croatia

The field experiment of increasing rates of phosphorus (P) and potassium (K) fertilization was conducted in spring of 2004 on acid (pH in KCl = 3.99) soil (a = ordinary fertilization, b = a+P1, c = a+P2, d = a+P3 , e = a+K1, f = a+K2, g = a+K3 , h = a+P2K2). The amounts either/or P2O5 and K2O were (kg/ha) 500, 1000 and 1500, for the step 1, 2 and 3, respectively. The triplephoshate (45% P2O5+1.2% S+0.06% Zn) and KCl (60% K2O) were used. The experiment was conducted in four replicates (basic plot 77 m2). In the 2005 – 2009 period residual effects of applied fertilization were tested and only ordinary fertilization was applied. Crop rotation in the 2004-2009 period was as follows: maize (2004) – soybean (2005) – maize (2006) – winter wheat (2007) – maize (2008) – maize (2009). K fertilization resulted by significant yield increases up to 6% (2004 and 2006), 18% (2005), 14% (2007), 5% (2008) and 13% (2009). However, application both P and K (kg/ha: 1000 P2O5+ 1000 K2O) was the most useful because of yield increases up to 12% (2004), 28% (2005), 8% (2006), 18% (2007), 7% (2008) and 14% (2009).

Potassium fertilization ; yield ; maize ; soybean ; wheat

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