QUESTION: An experiment was undertaken to examine the effect of banding P and N
ID: 100342 • Letter: Q
Question
QUESTION:
An experiment was undertaken to examine the effect of banding P and N with K fertilizer on the growth and K fertilizer recovery of wheat and chickpea in a K responsive soil. The estimate of K fertilizer recovery was undertaken using a Rb tracer and the effect on N fixation was measured by the 15N natural abundance method. The results for K recovery and 15N (‰) are presented in Table 1.
Table 1. Effect of co-locating P and N fertilizer in a band of K (100 kg K/ha) on fertilizer K recovery measured using a Rb tracer (20% of the total K applied replaced with Rb) of wheat and chickpea grown at two row spacings (25cm and 50cm) in a low K soil :
Wheat
Chickpea
25 cm
50 cm
25 cm
50 cm
Rb %
15N (‰)
Rb %
15N (‰)
Rb %
15N (‰)
Rb %
15N (‰)
K
0.79
+7.8
0.51
+7.8
0.22
+5.4
0.10
+5.4
K + P + N
1.91
+8.1
1.22
+8.4
0.49
+5.9
0.23
+6.0
Write brief comments in response to the following 4 questions:
Write brief comments in response to the following 4 questions:
1) What effect does co-location of P/N with K have on K fertilizer recovery in both species? (<400 words)
2) How does row spacing affect K fertilizer recovery in each species? Why? (<400 words)
3) How many grams of K fertilizer are in each metre of row at each row spacing? (<50 words)
4) Does the addition of N reduce the reliance of chickpea (B value = -1.7‰) on N fixation? (<550 words)
Wheat
Chickpea
25 cm
50 cm
25 cm
50 cm
Rb %
15N (‰)
Rb %
15N (‰)
Rb %
15N (‰)
Rb %
15N (‰)
K
0.79
+7.8
0.51
+7.8
0.22
+5.4
0.10
+5.4
K + P + N
1.91
+8.1
1.22
+8.4
0.49
+5.9
0.23
+6.0
Explanation / Answer
1) The experiment was conducted to determine the effect of banding P and N with K fertliser on K recovery of wheat and chickpea in a K responsive soil. The estimate of K fertliser recovery was undertaken using a Rb tracer. The results described in the table show that the co-location of P/N increases the K fertiliser recovery in both the species (wheat and chickpea).