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CENTRE

Chemically granulated fertilizer [photo] 

Chemically granulated

Yield reaction of a chemically granulated ammonium nitrate based planter mix vs. a bulk blended urea based planter mix on maize

These trials were conducted on two different localities to test the reaction on sandy soils, as well as soil with a higher clay content. The clay content of the sandy soil was 3%, while that of the other locality was 10%.

Two different ammonium nitrate based products were used in this trial. Table 1 shows the products used. The control product used on the 10% clay soil was also the producer's standard fertilizer planter mix.

Table 1. Different products used in the trial
ProductBaseTypeTreatmentSoil
A 21:8:0 (29) 0.5% Zn 8% S Ammonium nitrate CF Control 1

10% clay

Higher K
B 6:2:1 (22) 0.5% Zn, 6% S, 6% Ca, 0.3% B, 0.3% Fe Ammonium nitrate CF Treatment 1
C 15:8:4 (27) 0.5% Zn 8% S Urea BB Control 2

Sandy

3% clay
D 6:2:1 (43) 0.5% Zn Urea BB Treatment 2
  • CF –Chemically Formulated
  • BB –Bulk Blend

During the season, the 10% clay soil locality received significantly more rainfall. Photo 1 shows the growth of maize planted with treat-ment B. Photo 2 shows the growth of maize planted using treatment D. Photo 3 shows the growth of maize planted with treatment A. The N:P:K contents of the chemically granulated ammonium nitrate based planter mixes A and B (300 kg/ha) and that of the urea based bulk blend mix D (150 kg/ha) was exactly the same. Three rows of 1.52 m were planted.

In Graph 1 the trial data is summarised. At the locality with 10% clay, treatment B lead to a higher yield than the urea based treatment D. Treatment B performed 9% better than the control planter mix A. This control ammonium nitrated planter mix (A) obtained an 11% higher yield than the urea based treatment D.

On the sandy soil (3% clay), the yield reaction was also very good, but not as drastic as the locality with 10% clay. The chemically granulated ammonium nitrate based planter mix B lead to an 11% better yield than the bulk blended urea based treatment D. The control ammonium nitrate planter mix (C) obtained a 10% higher yield compared to the urea based planter mix (D) on the sandy soil. There was a mere 1% improvement in yield when planting with treatment B against the control ammonium nitrate planter mix (treatment C).

These yield results confirm the visual reactions seen on the photos. Photo 4 shows a similar reaction, where a urea based liquid planter mix was compared to an ammonium nitrate based planter mix (five rows of 1.52 m).

From the results it is clear that yield loss will occur when using urea based planter mixes. To realise just how great the risk is, just ask yourself if you can afford to harvest 10% less at the current maize prices.

Graph 1. Percentage yield increase achieved by chemically granulated ammonium nitrate planter mixes vs. a urea based bulk blended planter mix at two localities (3% clay and 10% clay).

Graph [graph]

Photo 1. Maize planted with Treatment B (AN based chemically granulated planter mix)

Maize planted with Treatment B [graph]

Photo 2. Maize planted with Treatment D (urea based blended planter mix)

Maize planted with Treatment D [graph]
 

Photo 3. Maize planted with Treatment A (AN based chemically granulated planter mix)

Maize planted with Treatment A [graph]

Photo 4. The five rows on the left was planted with an AN based chemically granulated planter mix, while the five rows on the right was planted using a urea based liquid planter mix.

Maize planted with an AN based chemically granultaded planter mix [graph]
 

By: Kobus van Zyl
Senior Agronomist