Effects of total basal nitrogen application to chain pots using controlled release fertilizer on growth and yield of Welsh onions (Allium fistulosum L.)

We developed a method for the application of total fertilizer nitrogen within a chain pot system using a controlled release fertilizer for summer welsh onions and for winter welsh onions. The chain pot system is a method of raising seedlings which places paper pots (chain pots) connected in the shape of a chain into the nursery box of Welsh onions. This method is an epoch making method of raising seedlings because of the ability to plant the chain pot seedlings with a planting machine. 1. The ratio of nitrogen leaching out of a coated ammonium, nitrate, and phosphate preparation of the 140-day type (2401-140S), a fertilizer with initial nitrogen leaching suppressed, was 1.6% for summer welsh onions and 3.4% for winter welsh onions during the period of raising seedlings. No high-concentration damage to onion nursery plants occurred with either cropping type during the period of raising seedlings. 2. The application of the controlled release ammonium, nitrate, and phosphate preparation of the 140-day type at 120 kg/ha without top dressing yielded harvests for summer welsh onions and for winter welsh onions, which were equivalent to harvests obtained from a standard fertilizer application rate. This resulted in a low-fertilizer application: 50% of 240 kg/ha of nitrogen, the standard fertilizer application rate. 3. This fertilizer application method improved the recovery ratio of applied nitrogen to 44% for summer welsh onions of the 120 kg/ha plot from 22% of the plot of the standard application rate. This fertilizer application method also increased the ratio to 60% for winter welsh onions from 30%. 4. The amount of soil nitrate remaining after cultivation for summer welsh onions in the plot of 120 kg/ha of nitrogen applied by this fertilizer application method was less in every soil layer 0-60 cm deep than the amount of the soil nitrate in the plot of the standard rate of nitrogen application. The amount of the soil nitrate remaining after cultivation for winter welsh onions similarly decreased in soil horizons 0-45 centimeters deep.