12 December 1997

Precise placement at drilling means less N, same beet yields

ACCURATE placement of nitrogen when drilling sugar beet means less fertiliser is needed than when broadcasting to achieve the same yield.

Several years of trials by Belgian and French researchers show placing liquid nitrogen 6-7cm (2.4-2.75in) to one side and below seed boosts crop uptake and eliminates N losses, says Jean-Pierre Vander-geten, assistant director of Belgian beet research station IRBAB.

Results on sandy or sandy loams in Belgium showed the average dose needed for maximum sugar yields was 123kg/ha when broadcast two to three weeks before drilling.

The same yields were achieved using 44kg/ha less N when it was placed. French trials confirmed the trend. "A reduction of 20-40 kg/ha is possible on well structured, irrigated soils," says Mr Vandergeten.

UK growers tend to apply N later, at drilling and again at emergence. Whether the same savings could be made is unclear, he notes.

Other benefits could be shared. Placing N promotes early foliage development, helping yield. Quicker development also means plants can withstand nematode attack better. At almost 2200 larvae/100g of soil, applying 120kg of N in a band at drilling produced a sugar yield of nearly 6t/ha, 1.5t/ha more than where the same rate was broadcast.

Quality was also improved. Amino N fell by 8.4% in the Belgian work where 44kg/ha less N was applied.

lBritish Sugars Mike Armstrong is examining the benefits of placing smaller amounts of liquid N to boost early growth and speed leaf cover. "We would not look to cut rates, we think we have got them about right. The idea is to see if placing a starter dose will increase yields."

Placing fertiliser at drilling time can cut rates and improve sugar beet yield and quality, according to Belgian research.