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AMMONIUM DEPOSIT FERTILIZATION TO REDUCE NITRATE LEACHING
Three distances between placements of these ammonium deposits and lettuce plants were examined as to crop yield and residues of mineral nitrogen in soil and deposits.
The three deposit positions were – l) one deposit between every plant in a row, 2) one deposit with double amount of ammonium and urea between alternate plants in a row and 3) one deposit adjacent to the plant roots.
The results have shown that there were no differences in fresh weight yield between the three deposit positions during the growth of lettuce.
Similarly, dry matter yield and nitrogen uptake were commensurate between these treatments.
After harvest of lettuce, soil and remaining deposits were analysed for nitrogen.
The amounts of nitrogen in the soil and in remaining deposits were identical between the three applications examined.
In the interior parts of remaining deposits, the ratio of not removable ammonium : removable nitrate was 3:1 in deposit position 1 and 3, and 6:1 in position 2. Exterior parts of the remaining deposits exhibited an ammonium : nitrate ratio of 1:1 (position 1 and 3) or, if using a double dose of nitrogen in the ammonium deposit (position 2), 2:1.
Endive was fertilized with 15N labelled calcium nitrate and 15N labelled ammonium sulphate in the same amount.
At harvest, endive had produced both slightly greater fresh and dry matter yield, if fertilized with ammonium deposits.
The utilization of fertilized nitrogen in the ammonium deposits was on average more efficient than the utilization of nitrate fertilizer.
The same applies to the nitrogen uptake from soil.