Question 1

What is the correct way to flood DAP for Sweet Potato?

Accepted Answer

Dissolve the DAP with a DAP solvent in a drum so it fully dissolves. Do NOT open the drum valve at the start of irrigation — wait until the water has covered about 25% of the plot (roughly 1–1.5 kanal in). Then open the valve. Close the drum valve about 10 minutes before you stop the water, so the last flow of water carries the dissolved fertilizer evenly to the far end of the field.

Question 2

Should urea be flooded with irrigation water, or broadcast afterwards?

Accepted Answer

Do NOT flood urea. Flooding loses 40–50% of nitrogen through leaching (deep percolation) and denitrification (lost as gas). Instead, broadcast (chhatta) the urea 1–3 days after irrigation, when the soil is moist (tar-wattar condition). This gives 30%+ better absorption than flooding.

Question 3

How can I distribute fertilizer evenly across the field?

Accepted Answer

Open the fertilizer drum valve only after irrigation water has already entered 1–1.5 kanal — opening it too early empties the drum before the far end is reached. If the field is not laser-leveled, divide one acre into 2–4 plots (kyare): 2 plots for heavy clay soils, 3–4 for loam, and fertigate each plot separately. Keep checking both the field and the drum during irrigation until you get a feel for the timing.

Question 4

When should phosphorus and potash be applied?

Accepted Answer

Phosphorus (P₂O₅) and potash (K₂O) are best applied at sowing as a basal dose, placed in the seedbed. If you missed it at sowing, dissolve the fertilizer (use a DAP solvent for DAP) and flood it at the first or second irrigation — flooding is far more effective than broadcasting for phosphorus and potash at that stage.

Sweet Potato

비료 권장

How to Apply Fertilizer Correctly

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